(, MECHANICAL DRAWING 
 
 FOR 
 
 I HIGH SCHOOLS, 
 
 A TEXT WITH 
 PROBLEM LAYOUTS 
 
 BY 
 THOMAS E. FRENCH AND CARL L. SVENSEN 
 
 DEPARTMENT OF ENGINEERING DRAWING, THE OHIO STATE UNIVERSITY 
 
 MEMBERS AMERICAN SOCIETY OF MECHANICAL ENGINEERS, SOCIETY 
 
 FOR THE PROMOTION OF ENGINEERING EDUCATION, ETC. 
 
 FIRST EDITION 
 
 ' 
 
 McGRAW-HILL BOOK COMPANY, INC, 
 239 WEST 39TH STREET. NEW YORK 
 
 LONDON: HILL PUBLISHING CO., LTD. 
 6 & 8 BOUVERIE ST., E. C. 
 
 1919 
 
COPYRIGHT, 1919, BY THE 
 MCGRAW-HILL BOOK COMPANY, INC. 
 
 THE MAPLE PRESS YORK PA 
 
PREFACE 
 
 Industrial educators are generally agreed that a textbook is 
 necessary for the most sucessful teaching of mechanical drawing. 
 However, several important considerations are involved in the 
 selection of a suitable text. It "should be more than a collection 
 of problems. It should present the subject in a clear, orderly 
 and logical arrangement of the divisions, explaining why each 
 rule or custom is made, and illustrating with examples represent- 
 ' ing good modern practice." 
 
 A survey of mechanical drawing in high schools* recently made 
 by the authors showed that "a system of standardization appears 
 to be needed to give the subject the standing to which it is en- 
 titled as a cultural subject as well as a practical one, a real lan- 
 guage to be studied and taught in the same way as any other 
 language." 
 
 The purpose of this book is to present mechanical drawing as a 
 definite educational subject with the following objectives: 
 
 To develop the power of visualization; 
 
 To strengthen the constructive imagination; 
 
 To train in exactness of thought; 
 
 To teach how to read and write the language of the industries; 
 
 To give modern commercial practice in making working draw- 
 ings. 
 
 The standardizing of mechanical drawing by the logical ar- 
 rangement of its subject matter into grand divisions will, it is 
 believed, make both teaching and learning easier. 
 
 The first seven chapters comprise a complete textbook which 
 may be used with any problems. The paragraphs are numbered 
 for easy reference. The eighth chapter is a complete problem 
 book, in which the number of problems in each division is such 
 that a selection may be made for students of varying ability, 
 and that a variation from year to year may be had. The prob- 
 lems have references to articles in the text, and the order may be 
 
 * Bulletin issued by Dept. of Public Instruction, State of Ohio. 
 
vi PREFACE 
 
 varied to suit the particular needs of a school. Definite speci- 
 fications and layouts are given for most of the problems, thus 
 making it possible for the instructor to use his time efficiently in 
 teaching rather than in the drudgery of detail, while the time 
 ordinarily wasted by the pupil in getting started can be used in 
 actual drawing. 
 
 More than enough is included for two years' work in the aver- 
 age high school. The authors will at any time be pleased to 
 advise in the selection of problems or arrangement of courses. 
 
 COLUMBUS, OHIO. 
 July 18, 1919. 
 
CONTENTS 
 
 PAGE 
 PREFACE v 
 
 CHAPTER I THE LANGUAGE OF DRAWING 1 
 
 CHAPTER II LEARNING TO DRAW 3 
 
 Attaching the paper Sharpening the pencil Ruling lines 
 Positions for triangles Parallel lines Perpendicular lines 
 Drawing arcs Using the compasses Using the bow pencil 
 Using the curve Measuring Scales Drawing to scale Spacing 
 Using the dividers Lettering Single stroke vertical capitals 
 Vertical lower case Inclined capitals Inclined lower case 
 Composition. 
 
 CHAPTER III THEORY OF SHAPE DESCRIPTION 21 
 
 Describing objects by views Positions of views in working 
 drawings The relation of views Orj^^rapjijc^projectioii 
 Principles of projection Objects with parallel surfaces Objects 
 with inclined surfaces Objects with curved surfaces Freehand 
 sketching studies Sections Auxiliary views Revolution 
 Revolution chart Pictorial drawing Isometric drawing Non- 
 isometric lines Angles Circles Sections Making an isometric 
 drawing Oblique drawing Making an oblique drawing Cabinet 
 drawing Perspective drawing Making a perspective sketch. 
 
 CHAPTER IV PRINCIPLES OF SIZE DESCRIPTION 51 
 
 Lines, figures, arrows, etc., Placing dimensions Theory of 
 dimensioning Rules for dimensioning Use of decimals Dimen- 
 sioning assembled parts Sketching and measuring Notes and 
 specifications Checking a drawing. 
 
 CHAPTER V TECHNIC OF THE FINISHED DRAWING 64 
 
 Alphabet of lines Order of penciling Inking and tracing To 
 make a tracing Order of inking Erasing Titles Bill of mate- 
 rial Screw threads The helix Bolts and other fastenings 
 U. S. Standard bolts To draw a bolt S. A. E. standard bolts- 
 Cap screws Machine screws Set screws Wood screws Con- 
 ventional symbols Blueprinting To make a blueprint. 
 
 CHAPTER VI DRAFTING, MECHANICAL AND ARCHITECTURAL .... 84 
 
 . Working drawings Detail drawings Assembly drawings, Shade 
 
 lines Choice of views Choice of scale Grouping and placing 
 
 parts Conventional representation Sections through ribs 
 
 Rule of Contour Gears Cams Architectural drawing Prelimi- 
 
viii CONTENTS 
 
 PAGE 
 
 nary sketches Display drawings Working drawings Plans 
 Elevations and sections Details Symbols, etc. 
 
 CHAPTER VII GRAPHIC SOLUTIONS AND SHEET METAL DRAFTING . 105 
 Geometrical drawing, Lines Angles Triangles The hexagon 
 The octagon Arcs and tangents The ellipse Approximate ellip- 
 ses Sheet metal drafting Development Prisms and cylinders 
 Pyramids and cones True length of a line Transition pieces, 
 development by triangulation Intersections Intersecting prisms 
 Intersecting cylinders Cylinders and prisms Cylinders and 
 cones Planes and curved surfaces Seams and lap Practical 
 problems. 
 
 CHAPTER VIII PROBLEMS 134 
 
 INDEX . 219 
 
MECHANICAL DRAWING 
 FOR HIGH SCHOOLS 
 
 CHAPTER I 
 THE LANGUAGE OF DRAWING 
 
 1. Language is defined as the expression of thought. Every 
 educated person wishes to be able to express himself readily and 
 easily, to convey his thoughts so accurately that they cannot be 
 misunderstood; and to be able to understand the exact meaning 
 expressed by another person. For this reason we make an ex- 
 tended study of English, until we know its grammar and idioms 
 and style. We read literature and practice composition in order 
 to become thoroughly familiar with the language. 
 
 FIG. 1. A perspective drawing. 
 
 2. But if we attempt to describe in words the appearance and 
 details of a machine, or bridge, or building, we find it not only 
 difficult but in most cases impossible. Here we must use another 
 language, the universal graphic language of drawing. Thus when 
 words fail to give a complete or accurate description we find books, 
 
 1 
 
2 . !*r^ i * fefaH4NlCAL DRAWING 
 
 magazines and nWsp&pefs" using pictures, diagrams and draw- 
 ings of various kinds. For illustrative purposes perspective 
 drawings, Fig. 1, which show the object as it actually appears to 
 the eye are often used. A written description of a new piece of 
 furniture would have to be very long to tell all about it, and even 
 then might be misunderstood. A picture would serve the purpose 
 much better, but the picture would not show the exact method 
 of construction and would give only the external appearance 
 without telling what was inside. It would be impossible to 
 construct a locomotive or an airplane either from a word de- 
 scription or a picture. The pictorial methods of drawing are thus 
 not suitable for constructive work. 
 
 3. Fortunately another form of description has been developed 
 by which the exact shape of every detail may be defined accu- 
 rately and quickly. It consists of different views of an object 
 arranged according to a definite system, with lines and figures 
 added to tell the sizes. This is called mechanical drawing, and 
 it forms so important a part of all industrial and mechanical 
 work that it is called the " language of industry." 
 
 The language of drawing has its own orthography and grammar 
 and style, its idioms and abbreviations, and its study not only 
 gives one the ability to express thoughts hitherto impossible 
 but develops the constructive imagination and the habit of exact 
 thinking. 
 
CHAPTER II 
 LEARNING TO DRAW 
 
 4. The previous chapter explained the necessity for drawing in 
 all industrial work, and that it was really a new language. Some- 
 times drawings are made freehand, but for accurate work it is 
 necessary to use instruments. In learning to read and write in 
 this language we must first learn what tools and instruments to 
 use, and how to use them accurately, skilfully and quickly. 
 
 FIG. 2. Adjusting the paper. 
 
 5. Attaching the Paper. Mechanical drawings are usually 
 penciled on fairly heavy unruled paper, either cream color or 
 white, which is held in place on a soft pine drawing board by 
 thumb tacks. The drawing board must have its left hand and 
 lower edges very straight and accurately square with each other, 
 as these are the "working edges." 
 
 3 
 
4 MECHANICAL DRAWING 
 
 In fastening the paper lay it on the board with its left edge an 
 inch or so from the left edge of the board, place the T-square in 
 the position of Fig. 2, and "true up" the paper with the T-square 
 blade. Holding the paper in position, move the T-square down 
 as in Fig. 3 and put a thumb tack through each of the corners, 
 pushing them in until the heads clamp the paper. For sheets of 
 firm drawing paper not larger than 12" X IS" the two lower tacks 
 may be omitted. 
 
 FIG. 3. Fastening the paper. 
 
 6. Sharpening the Pencil. A draftsman uses a hard pencil 
 with a long sharp point so that his work may be very accurate. 
 Drawing pencils are graded by letters, from 65 (very soft and 
 black), 55, 45, 35, 25, 5, HB, F, H, 2H, 3H, 4#, 5H, 6H,7H, 
 8H, $H (extremely hard). 4# and 6H are the usual grades of 
 hard pencil used for drawing lines, while H and 2H are used for 
 sketching and lettering. The ordinary No. 2 writing pencil is 
 about the same grade as HB or F. 
 
 Sharpen the pencil by cutting away the wood at a long slope 
 as shown in Fig. 4, A, being careful not to cut the lead, but ex- 
 posing it about a quarter of an inch. Then shape the lead to a 
 long conical point by rubbing it back and forth on a sandpaper 
 
LEARNING TO DRAW 5 
 
 pad or fine file, rotating it slowly in the fingers. Have this sharp- 
 ener at hand and keep the lead sharp by frequent rubbing. 
 
 Never sharpen a pencil over the paper or drawing board. 
 
 Pencil lines must be fine, light, clear lines. Get the habit 
 when drawing long lines of rotating the pencil so as to keep a 
 sharp cone on the point. 
 
 FIG. 4. Sharpening the pencil. 
 
 . The foundation of mechanical drawing is the line, so a set of 
 the different kinds of lines used is called the alphabet of lines. 
 These are explained in Art. 62. 
 
 FIG. 5. Drawing a horizontal line. 
 
 7. Ruling Lines. All the lines in a mechanical drawing are 
 made with the aid of some instrument as a guide for the pencil 
 or pen. Horizontal lines are always drawn with the upper edge 
 of the T-square blade as a guide. Hold the head of the T-square 
 against the left edge of the board with the left hand, 1 and always 
 move the pencil from left to right, Fig. 5. 
 
 1 Left-handed persons reverse this rule, using the T-square on the right 
 edge. 
 
6 
 
 MECHANICAL DRAWING 
 
 The pencil should be held about an inch from the point and 
 inclined slightly in the direction in which the line is being drawn. 
 
 FIG. 6. Drawing a vertical line. 
 
 4-5 
 
 -75 ' 
 
 90 
 
 o 
 
 FIG. 7. The 45 degree and 30-60 degree triangles. 
 
 Vertical lines are drawn by using a triangle held against the 
 T-square. Always have the vertical edge of the triangle toward 
 the left and draw up from the bottom to the top, Fig. 6. 
 
LEARNING TO DRAW 
 
 Horizontal 
 
 f 5 degrees with hor. 
 75 // ^" " verf: 
 
 3O degrees w/fh hor. 
 ' 6O u u " verf: 
 
 4-5 degrees with hor. 
 
 verf: i 3O " 
 
 6O degrees with hor. 
 
 " verf.' ~ /5 
 
 75 degrees w'fh hor. 
 
 verf- 
 
 Vertical 
 
 Verticaf 
 
 U 
 
 75 degrees with hor. 
 15 * * verf: 
 
 6O degrees w/'fh hor. 
 
 4-5 degrees wifh hot: 
 
 3O degrees wirh hor. 
 
 vert. ' 4-S u " verf: 6O - * 
 
 verf: 
 
 15 degrees w/fh hor. 
 75 " " " verr. 
 
 rfor/zonfaf A/I Together 
 
 FIG. 8. Positions of the triangles. 
 
8 
 
 MECHANICAL DRAWING 
 
 The 45 triangle, has two angles of 45 and one of 90. The 
 30-60 triangle has angles of 30, 60 and 90, Fig. 7. 
 
 Inclined lines at 30, 45 and 60 are drawn with a single 
 
 triangle held against the T-square. 
 Other angles, varying by 15 may 
 be drawn by using the two tri- 
 angles in combination with the 
 T-square. The methods of obtain- 
 ing the different angles are shown 
 in Fig. 8. 
 
 8. Parallel lines other than 
 horizontal, are drawn by using a 
 triangle in combination with a 
 T-square (or other triangle), as 
 shown in the " movie" Fig. 9. To 
 draw a line parallel to the given 
 line (1), place a triangle against the 
 T-square (2), and move them to- 
 gether until the hypotenuse of the 
 triangle matches the line (3) . Hold 
 the T-square firmly and slide the 
 triangle in the direction of the 
 arrow until the desired position of 
 the parallel line is reached (4). 
 
 9. Lines perpendicular to each 
 other may be drawn by using a 
 triangle in combination with the 
 T-square or another triangle as 
 shown in the "movie" of Fig. 10. 
 To draw a line perpendicular to a 
 given line (1). Place a triangle 
 against the T-square (2), and move 
 them together until the hypotenuse 
 of the triangle matches the line, as 
 at (3). Turn the triangle about 
 its right-angled corner as indicated 
 
 at (4), until it is in the position shown at (5) when the per- 
 pendicular line can be drawn on the hypotenuse of the triangle. 
 10. Drawing Arcs. Drawings are made up of straight lines 
 and curved lines, the curved lines generally being circles or parts 
 of circles, Circles larger than one and one-half or two inches 
 
 FIG. 9. Drawing a parallel line. 
 
LEARNING TO DRAW 
 
 FIG. 11. 
 
 FIG. 10. Drawing a perpendicular 
 line- 
 
 in diameter are drawn with the 
 large compasses. First adjust the 
 needle point so that it is a very 
 little longer than the pencil point, 
 Fig. 11. Thecompasses, Fig. 12 
 are manipulated entirely 
 with the right hand. 
 They are opened by 
 pinching between thumb 
 and second finger (1), 
 and set to proper radius 
 by placing the needle 
 point at the center and 
 adjusting the pencil leg 
 with first and second fingers (2). 
 When the radius is set, raise the 
 fingers to the handle (3), and re- 
 volve the compasses by twirling 
 the handle between thumb and 
 finger. Start the arc near the 
 lower side and revolve clockwise 
 (4), inclining the compasses in the 
 direction of the line. Do not bore 
 a hole at the center. 
 
 Small circles and arcs are drawn 
 with the bow pencil. Adjust the 
 lead and the needle, and set the 
 radius as shown in Fig. 13. In 
 changing the bow instruments 
 from a small to large radius, hold 
 the legs together with one hand 
 and spin the nut with the other, 
 in order to save wear on the 
 threads, as shown at 3, Fig. 13. 
 It is also necessary to release care- 
 fully, to prevent striking the nut 
 and stripping the threads. Always 
 be sure to relieve the springs of 
 all the bow instruments when 
 putting them away. 
 
10 
 
 MECHANICAL DRAWING 
 
 11. Curves not circle arcs are drawn with the irregular or 
 " French" curve. These come in a number of different forms 
 and are shifted to fit the required line. Figure 14 shows a line 
 being drawn by finding different parts of the curve. 
 
 12. Measuring. All measure- 
 ments of lengths or distances on 
 a drawing are made with the 
 scale. Scales are made with 
 different divisions for different 
 purposes. For machine, struc- 
 tural, and architectural drawing 
 
 FIG. 12. Using the compasses. 
 
 FIG. 13. Using the bow pencil. 
 
 the mechanical engineers' (or architects') scale of proportional 
 feet and inches is used. For school purposes the triangular 
 scale, Fig. 15, is much used, although the flat shapes are preferred 
 by many draftsmen. The symbol (') is generally used for feet 
 
LEARNING TO DRAW 
 
 11 
 
 and (") for inches. Thus three feet four and one-half inches is 
 written 3'-4K"- 
 
 When the object is not too large for the paper, it is drawn in 
 its full size, using the scale of inches and sixteenths. To lay off 
 
 FIG. 14. Use of the curve. 
 
 a full-size distance, put the scale down on the paper against the 
 line to be measured. Make a short dash on the paper opposite 
 the zero on the scale and another opposite the division represent- 
 
 - 
 
 '..... 
 
 FIG. 15. Mechanical engineers' (or architects') scale. 
 
 ing the desired distance, Fig. 16. Do not make a dot, or punch 
 a hole in the paper. 
 
 13. If the object is too large to go on the paper in its full size, 
 it is drawn in reduced proportion. The first reduction is to the 
 scale of 6" = 1', commonly called " half -size." To measure a 
 
 
 I 2 
 
 FIG. 16. Marking a measurement. 
 
 distance at the scale of 6" = 1', use the full-size scale and consider 
 each half-inch as representing an inch, each quarter inch as a 
 half-inch, etc. Thus the 12" scale will become a 24" scale. 
 Example: To lay off 3^" start at the zero and count three % 
 
12 
 
 MECHANICAL DRAWING 
 
 inches, and % of the next half inch, as shown in Fig. 17. Do 
 not divide the size of the piece by two. 
 
 If the drawing cannot be made " half-size" the next scale is 
 
 o 
 
 FIG. 17. Measuring to "half-size." 
 
 3" = 1', often called " quarter size/' Find this scale and ex- 
 amine it. The actual length of three inches becomes one foot, 
 divided into 12 parts, each representing one inch, and these are 
 
 FIG. 18. Reading the scale. 
 
 further divided into eighths. Learn to think of these as real 
 inches in reduced scale. Example : To lay off the distance I'-O^j", 
 Fig. 18. Notice the position of the zero mark, placed so that 
 
 FIG. 19. Holding the dividers. 
 
 inches are measured in one direction from it and feet in the 
 other, as shown in the figure. Other scales found on a trian- 
 gular scale are, 1^" = I/; 1" = 1'; M" = 1': V 2 " = l'-,%" = 1' '; 
 
LEARNING TO DRAW 
 
 13 
 
 Take each of these scales in turn, and decide what is the longest 
 distance that can be measured in one setting, and what is the 
 smallest division. Measure 2'-5" with each scale. 
 
 14. Spacing. Dividing lines into spaces, and transferring dis- 
 tances is done with the dividers, or with the bow spacers. The 
 dividers are held in the right hand and adjusted as shown in 
 
 FIG. 20. Using the dividers. 
 
 Fig. 19. The method of dividing a line into three equal parts is 
 shown in the " movie" of Fig. 20. Adjusting the points of the 
 dividers until they appear to be about one-third of the length of 
 the line, place one point on one end of the line, and the other 
 point on the line as shown at (1). Turn the dividers about the 
 point which rests on the line as at (2) , then in alternate direction 
 as at (3). If the last point falls short of the end of the line, in- 
 
14 
 
 MECHANICAL DRAWING 
 
 crease the distance between the points of the dividers by an 
 
 amount estimated to be % of m-n and start at the beginning of 
 
 the line again. Several trials may be necessary. If the last 
 
 point overruns the end of the line, 
 
 decrease the distance between the 
 
 points by % the extra distance. 
 
 The bow spacers, Fig. 21, are 
 
 used when working with small 
 
 distances. 
 
 15. It is often convenient to 
 use the scale as means of dividing 
 a line. If the distance is not 
 easily divisible, the scale may be 
 used as shown in the " mo vie" 
 of Fig. 22, where (1) shows the 
 line which is to be divided into 
 nine equal parts. Draw a per- 
 pendicular line AC through an 
 end of the line as at (2). Apply 
 the scale so that nine divisions 
 of the scale (in this case half- 
 
 FIG. 21. 
 
 FIG. 22. Dividing a line. 
 
 inches) are included between point B and line AC as shown at (3). 
 Mark opposite each one-half inch and draw vertical lines, which 
 will divide the given line into nine equal parts (4). The geo- 
 metrical method upon which Fig. 22 is based is given in Art. 103. 
 
LEARNING TO DRAW 
 
 LETTERING 
 
 15 
 
 16. Lettering. The complete description of a machine or 
 structure requires the use of the graphical language to describe 
 shapes, and the written language to tell sizes, methods of making, 
 kinds of materials, and other notes. The ''written language" 
 as used on drawings is always in the form of lettering and not 
 script writing. Simple freehand lettering, perfectly legible 
 and quickly made is an important part of modern engineering 
 drawings. 
 
 The standard form of letter used on working drawings is the 
 style known as single-stroke Gothic. There are two varieties, 
 vertical, and inclined. Some concerns use vertical letters 
 entirely, some use inclined entirely, others use vertical for titles 
 and inclined for dimensions and notes. In the same way some 
 schools adopt vertical lettering as the standard, and some adopt 
 inclined lettering. The young draftsman accepting a position 
 with a company must be able to use the standard of that com- 
 pany. In learning both styles it is better to take up vertical 
 lettering first. 
 
 The ability to letter well and rapidly can be acquired only by per- 
 sistent and careful practice. The forms and proportions of each 
 
 FIG. 23. Position for lettering. 
 
 letter must be thoroughly mastered by study and practice, and 
 the letters combined into uniform easily read words. 
 
 The term "single stroke" means that the width of the stem of 
 the letter is the width of the stroke of the pen. Two satisfac- 
 tory pens are Hunt's 512 for titles and large letters, and Gillott's 
 404 for ordinary dimensions and notes. The pen should be 
 
16 
 
 MECHANICAL DRAWING 
 
 held in the position shown in Fig. 23, the strokes drawn with a 
 steady even motion and a slight uniform pressure on the paper, 
 not enough to spread the nibs of the pen. Lettering in pencil 
 should be done lightly with a softer pencil than used for drawing. 
 
 Guide lines, ruled lightly with a sharp pencil should always 
 be drawn for the tops and bottoms of each line of letters. 
 
 17. Single-stroke Vertical Capitals. In Fig. 24 the vertical 
 capitals are arranged in " family order," first the straight letters, 
 
 CM 13 IMS 
 
 .J L-J -*i i f- V J ' 
 
 16 
 
 FIG. 24. Single stroke vertical capitals. 
 
 then the slant line and curved letters. Each letter is shown in 
 a square, so that the proportion of its width to height may be 
 easily learned. In this style many of the letters just about fill 
 the square. The arrows and figures give the order and direction 
 
 n op eff s fill v w xyy z 
 
 FIG. 25. Single stroke vertical lower case. 
 
 of strokes, which must be learned for each letter. Vertical 
 strokes are all made downward and horizontal strokes from left 
 to right. 
 
 Special care and practice must be given to the numbers. Notice 
 that the shapes of the figures are just as different from those 
 used in ordinary figuring as the letters are from ordinary writing . 
 
LEARNING TO DRAW 
 
 17 
 
 FIG. 26. 
 
 Particularly is this true of the 2, 4, 6, 8 and 9. Fractions are 
 always made with a horizontal division line with figures two- 
 thirds the height of the whole numbers and a clear space above 
 and below the division line. 
 
 18. Single-stroke Vertical Lower Case. Words lettered in 
 lower case or " small" letters are easier to read than when made 
 
 in capital letters. The single-stroke lower- 
 case alphabet as used with the capitals of 
 Fig. 24 is shown in Fig. 25. These letters 
 are made with bodies two-thirds the height, 
 of the capitals, the ascenders (6, d, f, etc.) 
 extending up to the cap line and the descenders (g, p, q, etc.) 
 dropping the same distance below. They are based upon the 
 combination of circle and straight line, Fig. 26. The " mono- 
 gram" in the figure contains eighteen of the twenty-six letters. 
 
 19. Single-stroke Inclined Caps. In making inclined letters 
 there are two things to watch, 
 
 first, to keep a uniform slope, 
 second, to get the rounded let- 
 ters of the correct shape. 
 
 Slanting ' ' direction lines ' ' 
 should be drawn either with a 
 lettering triangle (of about 
 67J^) or by setting a slope of 
 2 to 5 by marking two units on 
 a horizontal line and five on a 
 vertical line, and using T-square 
 and triangle as shown in Fig. 27. 
 
 The form taken by the rounded letters when inclined is illus- 
 trated in Fig. 28, showing that the curves are sharp in the upper 
 right-hand and lower left-hand corners and flattened in the 
 other two corners. 
 
 FIG. 27. 
 
 
 FIG. 29. 
 
 The letters H, A, V and W are shown enlarged in Fig. 29. 
 Note particularly that the lines of A, V and W must make equal 
 angles on each side of the sloping direction lines. 
 
 The alphabet and numerals are given in family order in Fig. 30. 
 
18 
 
 MECHANICAL DRAWING 
 
 20. Single-stroke Inclined Lower Case. This letter, some- 
 times called the Reinhardt letter, is in general use for notes on 
 drawings as it is very legible and effective and can be made very 
 rapidly. The bodies are two-thirds the height of the capitals, 
 
 TL 
 
 f A//- A/ 4 
 
 /f^* /^ J ' ^ ^D trlii '//T " 
 
 o a <s w & 
 
 FIG. 30. Single stroke inclined capitals. 
 
 with the ascenders extending to the cap line, and the descenders 
 dropping the same distance below the base line. 
 
 For study, the letters may be divided into four groups: 
 
 Group I,ijkltvwxyz 
 
 Group II, a b d / g p q 
 
 Group III, h m n r u y 
 
 Group IV, c e o s 
 
 FIG. 31. 
 
 FIG. 32. 
 
 Group I contains the straight letters. Be particularly careful 
 about the slant of the angle letters v w x y and z. 
 
 The letters of Group II are made up of a partial ellipse whose 
 axis slants 45 degrees, and an inclined straight line, Fig. 31. 
 The hook letters of Group III are' made with a part of the same 
 ellipse. The monogram of Fig. 31 illustrates this group also. 
 
LEARNING TO DRAW 
 
 19 
 
 The letters of Group IV are made with the same ellipse as the 
 capitals, Fig. 32. 
 
 The alphabet with order and direction of strokes is given in 
 Fig. 33. 
 
 & t tt'& f?ft i k/'ffi 
 
 fuv wxyz 
 
 FIG. 33. Single stroke inclined lower case. 
 
 21. Composition. Composition in lettering means the selec- 
 tion of appropriate styles and sizes of letters, and their arrange- 
 ment and spacing. After the shapes of the separate letters have 
 
 LETTERING COMPOSITION 
 involves the spacing of letters in words. 
 the spacing of words and lines, and the 
 choice of appropriate styles and sizes. 
 
 FIG. 34. An example of spacing. 
 
 been mastered the entire practice should be on words and sen- 
 tences. Letters in words are not spaced at equal distances along 
 
 FIG. 35. Spacing guide lines. 
 
 the guide lines, but so that the areas of white spaces between the 
 letters are approximately equal, making them appear to be spaced 
 uniformly. Figure 34 is an illustration of composition. 
 
20 MECHANICAL DRAWING 
 
 In spacing words the clear distance between them should be 
 about equal to the height of the letters. The clear distance be- 
 tween lines varies from one-half to one and one-half times the 
 height of the caps. Figure 35 illustrates a method of spacing guide 
 lines for tops and bottoms when several lines of letters are to be 
 
 ABCDEFGH1JKLMN 
 
 OPQJISTUVWXYZ&' 
 
 1234567890 
 
 abcdefthijklmnopqrjtuvwxyz 
 
 FIG. 36. Single stroke Roman. 
 
 made. Mark the height of the letter on the first line, then set 
 the dividers to the distance wanted between base lines and 
 step off the required number of lines. With the same setting 
 step down again from the upper point. 
 
 The composition of titles is referred to in Art. 68. An alpha- 
 bet of single-stroke Roman letters for use in architectural draw- 
 ing is given in Fig. 36. 
 
CHAPTER III 
 
 THEORY OF SHAPE DESCRIPTION 
 
 22. There are two things which a designer, inventor or builder 
 must be able to do; first, he must be able to visualize, or to see 
 clearly in his mind's eye what an object looks like without actually 
 having the object; second, he must be able to describe it so 
 that it could be built. A few lines properly drawn on paper will 
 describe an object more accurately and clearly than a picture 
 or a written description. To describe the true shape of an object 
 by means of lines, and to be able to read and understand such 
 descriptions requires a thorough knowledge of the theory upon 
 which this method is based. 
 
 23. Describing Objects by Views. For the graphical description 
 of an object we have available the paper, pencil and instruments 
 
 explained in Chapter II. On the 
 paper we can make measurements 
 in a single plane only, while all 
 objects have dimensions perpen- 
 dicular to the paper as well as 
 parallel to it. A picture can be 
 
 FIG. 37. 
 
 FIG. 38. Top view. 
 
 made which would show just as a photograph would do, 
 the general appearance of the object, but it would not show 
 the exact forms and relations of the parts of the object. It would 
 show it as it appears and not as it really is. 
 
 Our problem then is to represent solid objects on a flat sheet 
 of paper in such a manner as to tell the exact shape. This is 
 done by drawing a system of "views" of the object as seen from 
 different positions, and arranging these views in a definite manner. 
 
 A picture of a telephone, Fig. 37, shows the instrument as it 
 
 21 
 
22 
 
 MECHANICAL DRAWING 
 
 ordinarily appears to us, but it does not show the true shapes of 
 the parts. The base appears as an ellipse, although we know that 
 it really is circular. If we look down at the instrument from 
 directly above we obtain a view showing the exact shape of the 
 base, and the outline of the other parts as seen from above. This 
 is called a top view or plan, Fig. 38. This view does not tell us 
 the height of the instrument, so it is necessary to take another 
 view from a position directly in front or else from the left or 
 right side. In this way either a front view or side view to show the 
 
 FIG. 39. The~ three views. 
 
 height, is added, Fig. 39. Often, as in this case, both front view 
 and side view in addition to top view are needed to describe the 
 object. 
 
 Since the bottom of the base is level it will show as a straight 
 line in the front and side views, as will the bottom of the receiver 
 and all other horizontal circles. The front view shows the 
 circular shape of the transmitter, while the side view shows the 
 true shape of the connection between transmitter and post. 
 
 The three views taken together completely define the shapes 
 of all the parts of the instrument and their exact relations to 
 each other. 
 
THEORY OF SHAPE DESCRIPTION 
 
 23 
 
 It is evident that the front and side views are exactly the same 
 height. When drawn they are placed directly across from each 
 other. The top view is placed directly above the front view, 
 and the three views together appear as in Fig. 39. 
 
 Sometimes a left side view describes the object more clearly 
 than the right side would do. Fig. 40 shows the top, front and 
 left side views. 
 
 Notice in Figs. 39 and 40 that the mouthpiece is toward the 
 front in the top views, and also toward the front view in both 
 the right and left side views. 
 
 FIG. 40. Top, front and left side views. 
 
 As a further explanation of the relation of the three views, 
 study the drawing of the chair shown in Fig. 41. Notice that 
 the magazine holder is at the right in the top and front views 
 and therefore shows in the right side view. The front of the 
 chair is toward the front view in the top and two side views. 
 
 24. Theory of the Relation of Views. The principle of repre- 
 senting an object by different views, as just described, is called 
 Orthographic Projection, and is the basis of all kinds of industrial 
 drawing. The real theory of orthographic projection must be 
 well understood before complicated or difficult drawings can be 
 made or read. 
 
24 
 
 MECHANICAL DRAWING 
 
 The following definition has been given: "Orthographic pro- 
 jection is the method of representing the exact form of an object in 
 two or more views on planes generally at right angles to each other, 
 by dropping perpendiculars from the object to the planes" 
 
 FIG. 41. Relation of views. 
 
 Suppose the book end shown in Fig. 42 is to be represented. 
 The draftsman imagines himself to be looking through a trans- 
 parent plane set up in front of the object, Fig. 43. If from every 
 point of the object perpendiculars be imagined as extended or 
 
 FIG. 42. 
 
 FIG. 43. The vertical plane. 
 
 projected to the plane, the result on the front of the plane would 
 be the projection on the plane, called the vertical projection, or 
 front view, or in architectural drawing the front elevation; and 
 would show the true height and length of the object. 
 
THEORY OF SHAPE DESCRIPTION 
 
 25 
 
 Suppose now that a horizontal plane is hinged at right angles 
 to the first plane, the observer looking through it at the top of 
 the object. Perpendiculars from the object to this plane will 
 give the horizontal projection, or top view, or as called in architec- 
 
 FIG. 44. The glass box. 
 
 tural drawing, the plan. This view will show the width of the 
 object from front to back, as well as the length already shown on 
 
 FIG. 45. The box opened. 
 
 the front view. These two planes represent the drawing paper, 
 and if the horizontal plane be imagined as swung up on the hinges 
 until it lies in the extension of the front plane, the two views will 
 be shown in their correct relationship as they would be drawn on 
 the paper, and together give the length, breadth and height. 
 This explains the reason for the statement made in the preceding 
 section, that the top view is always drawn directly over the front 
 view. 
 
26 
 
 MECHANICAL DRAWING 
 
 The side view or side elevation is imagined as made on a plane 
 perpendicular to both top and front planes. Thus the object 
 may be thought of as being inside of a glass box, or show case, 
 as in Fig. 44. The projections on the sides of this box would be 
 
 FIG. 46. 
 
 FIG. 47. 
 
 the views which we have discussed, and when these sides are 
 opened up into one plane, the views take their relative positions 
 as on the paper, with the top view directly over the front view 
 and^the side views directly across from the front view, Fig. 45. 
 
 FIG. 48. 
 
 FIG. 49. 
 
 25. From a study of these projections the following principles 
 will be noted: 
 
 1. A face parallel to a plane of projection is shown in its true size, 
 as A on the front view, Fig. 43. 
 
 2. A face perpendicular to a plane of projection is projected as 
 a line; as B and C, Fig. 43. 
 
THEORY OF SHAPE DESCRIPTION 
 
 27 
 
 3. A surface inclined to a plane of projection shows foreshortened, 
 as B, Fig. 48. 
 
 Similarly 
 
 4. A line parallel to a plane of projection will show in its true 
 length. 
 
 FIG. 50. 
 
 FIG. 51. 
 
 5. Aline perpendicular to a plane of projection will be projected as 
 a point. 
 
 6. An inclined line will have a projection shorter than its true 
 length. 
 
 FIG. 52. 
 
 FIG. 53. 
 
 26. As a further explanation of how the theory of projection 
 is applied, study the drawings of the objects in the following 
 figures. In Fig. 46 each view represents a single surface. In 
 Fig. 47 the top view shows two surfaces A and B at different 
 levels, and as shown by the front view, surface A is above surface 
 B. In the side view the surfaces C and D are shown. In Fig. 
 48 the surface B is inclined and shows slightly foreshortened in 
 
28 
 
 MECHANICAL DRAWING 
 
 the top view and very much foreshortened in the side view. To 
 obtain the true size of the surface B, its length must be taken 
 from the front view and its width from the top or side view. A 
 surface which is inclined in three ways is illustrated in Fig. 49 
 where the corner of the block has been cut away. 
 
 27. Since it is necessary to describe every part of an object, 
 all surfaces must be represented whether they can actually be 
 
 ^!i!i!!!^ 
 
 FIG. 54. 
 
 seen or not. To distinguish surfaces which cannot be seen in 
 the views, they are represented by dotted lines as in Figs. 50, 
 51 and 52. Notice that a dotted line touches the line from which 
 it starts, that dots touch at corners, but that if a dotted line is 
 the continuation of a full line, a space is left between the full 
 line and the first dot of the dotted line. 
 
 FIG. 55. 
 
 FIG. 56. 
 
 FIG. 57. 
 
 28. The fact that curved surfaces do not show as curves in all 
 views is illustrated in Figs. 53 and 54. A cylinder appears as a 
 circle in one view and as a rectangle in the others, as in Figs. 
 55, 56 and 57, which show three views of a cylinder when placed 
 in different positions. 
 
 Figure 58 shows a bearing made up of flat and curved surfaces 
 and requiring visible and invisible lines. Note that surface A 
 of the side view is shown by a full line a-a in the front view and 
 by a dotted line a-a' in the top view. 
 
THEORY OF SHAPE DESCRIPTION 
 
 29 
 
 FIG. 58. A bearing. 
 
 FIG. 61. 
 
 FIG. 62. 
 
30 
 
 MECHANICAL DRAWING 
 
 Pictures and drawings of several objects are given in Figs. 59 
 to 64 for study and comparison. 
 
 29. Freehand Studies. In Fig. 65 is shown the picture of an 
 overhanging V block, and in Fig. 66 a freehand sketch in pencil 
 
 FIG. 63. 
 
 FIG. 64. 
 
 of the views required for describing its shape. The objects 
 shown in Figs. 67 and 68 are designed to give the pupil practice 
 in shape description by freehand sketching either in pencil on 
 
 FIG. 65. V block, to be sketched. 
 
 plain or squared paper, or on the blackboard. The necessary 
 views of selected objects are to be blocked in and brightened as in 
 Fig. 66. The pictures are not to be copied. 
 
THEORY OF SHAPE DESCRIPTION 
 
 31 
 
32 
 
 MECHANICAL DRAWING 
 
 FIG. 67. Problems for freehand sketching. 
 
THEORY OF SHAPE DESCRIPTION 
 
 33 
 
 FIG. 68. Problems for freehand sketching. 
 
34 
 
 MECHANICAL DRAWING 
 
 30. Sections. We have learned that parts of an object which 
 cannot be seen are represented by dotted lines, and this method 
 is satisfactory where the object is solid or the interior simple. 
 There are many cases, especially if there is considerable interior 
 detail, or if several pieces are shown together, when the dotted 
 lines become confusing or hard to read. This difficulty is avoided 
 by using a sectional view. 
 
 FIG. 69. Cutting plane. 
 
 FIG. 70. Object after front half 
 removed. 
 
 A sectional view is a view obtained by supposing the piece to 
 be cut apart and the front portion removed, thus exposing the 
 interior, as shown in pictorial form in Figs. 69 and 70, and by 
 views in Fig. 71. 
 
 The plane of the cut surface is shown extended in Fig. 69. In 
 Fig. 70 we imagine that the part of the object in front of the plane 
 
 
 
 
 
 
 f- 1 - 
 
 
 
 FIG. 71. Sectional view. 
 
 has been removed. In Fig. 71 the cut surface is indicated by 
 cross-hatching, or section lining, with uniformly spaced fine lines, 
 which are generally drawn at a slope of 45 degrees. In "the top 
 view the position of the cutting plane is indicated by a line (see 
 alphabet of lines, Art. 62) but the part supposed to be cut away 
 is not left out. Study each piece shown in Fig. 72 until the reason 
 for every line is clear. 
 
THEORY OF SHAPE DESCRIPTION 
 
 35 
 
 The cutting plane need not be continuous but may be taken 
 so as to show any desired details of the interior. 
 
 FIG. 72. Sections for study. 
 
 FIG. 73. A half section. 
 
 A full section is the view obtained when the cutting plane ex- 
 tends clear through the object, whether continuous or not, 
 Fig. 71. 
 
36 
 
 MECHANICAL DRAWING 
 
 A half section is a view obtained when the cutting plane ex- 
 tends only halfway through the piece, that is when one quarter 
 of the piece is imagined to have been removed, Fig. 73. This 
 method is used to advantage when a machine or construction is 
 symmetrical, as it shows both the interior and the exterior. The 
 dotted lines are generally left out on both sides of the center line. 
 
 FIG. 74. 
 
 For simple pieces all lines beyond the plane of the section, 
 both full and dotted are drawn. 
 
 Any piece must have the section lines in the same direction 
 on all parts of its cut surface. When two pieces are shown to- 
 gether they are sectioned in different directions, Fig. 74. 
 
 FIG. 75. Bolts, shafts, etc., on sectional views. 
 
 It is not necessary to cut through all the parts of a machine. 
 Such parts as bolts, nuts, screws, keys, shafts, etc., are not sec- 
 tioned, Fig. 75. 
 
 Different materials are sometimes indicated by varying the 
 kinds of section lines and the spacing between them. A system 
 for this purpose is shown in Fig. 159, page 81. As there are 
 
THEORY OF SHAPE DESCRIPTION 
 
 37 
 
 other standards, such symbols should not be depended upon alone 
 as a means of specifying the material. Always use a note for 
 this purpose. 
 
 The spacing of section lines should be such as will give the 
 effect of an even tint. For most purposes the distance between 
 lines is about inch, spaced entirely by eye. Uneven spacing 
 
 FIG. 76. An auxiliary view. 
 
 will ruin the appearance of a drawing and make it harder to read. 
 Very small pieces require somewhat closer spacing than large 
 
 ones. 
 
 FIG. 77. 
 
 FIG. 78. 
 
 FIG. 79. 
 
 31. Auxiliary Views. We have found, Art. 26, Fig. 48, that 
 slanting surfaces are foreshortened when represented in the usual 
 views. It is sometimes necessary or desirable to show a slanting 
 surface in its true shape, especially when it has an irregular out- 
 line. Such a view can be drawn by looking directly at the slant- 
 ing surface. When this is done all the regular views do not have 
 to be drawn, Fig. 76. 
 
38 
 
 MECHANICAL DRAWING 
 
 The object shown in Fig. 77 would ordinarily be drawn as in 
 Fig. 78, obtaining the side view by looking in the direction of 
 arrow I. The face A, does not show in its true size in Fig. 78. 
 However, if we look in the direction of arrow II perpendicular to 
 face A the object would be drawn as in Fig. 79, and instead of the 
 usual side view we would have an auxiliary view placed as shown, 
 and giving the true size and shape of face A. The auxiliary view 
 of Fig. 77 has thus been made on an auxiliary plane parallel to 
 face A, Fig. 79. 
 
 When making working drawings for practical use, the whole 
 object is not generally projected, part views being used instead as 
 in Fig. 80. 
 
 FIG. 80. An auxiliary part view. 
 
 32. The usual method of drawing an auxiliary view is by mak- 
 ing use of a center line. To obtain an auxiliary view of the cut 
 surface of the hexagonal prism, Fig. 81, draw a horizontal center 
 line in the top view and another center line parallel to the cut 
 face at any convenient distance from it. Draw projecting lines 
 perpendicular to the cut face from each point. On each of these 
 lines locate points by measuring on each side of the auxiliary 
 center line, distances obtained from the top view. Distances 
 a and 6 are toward the front of the object as shown in the top 
 view and therefore are measured toward the front in the auxiliary 
 view. In Fig. 82 the entire object has been projected to the 
 auxiliary plane, using the method just described. 
 
 The auxiliary view of the cut surface of a cylinder is shown in 
 Fig. 83. In this case the vertical center line of the end view 
 
THEORY OF SHAPE DESCRIPTION 
 
 39 
 
 corresponds with the inclined center line. Select a convenient 
 number of points on the front view of the inclined surface and 
 draw perpendiculars from them to the parallel center line. 
 Locate the points in the end view by projecting from the front 
 
 FIG. 81. 
 
 FIG. 82. 
 
 view, thus obtaining the distances to measure toward the front 
 or back from the inclined center line. 
 
 FIG. 83. 
 
 Similar methods are used for obtaining the auxiliary projec- 
 tions of cones, pyramids and other objects. 
 
 33. Revolutions. It is generally possible to place an object 
 in a simple position so that most of its lines show in their true 
 length or can be easily located on the planes of projection. Ordi- 
 narily, drawings are made in this way. However, it is, of course, 
 possible to represent an object tipped about one of its edges or 
 resting on one of its corners. To obtain the views of an object 
 
40 
 
 MECHANICAL DRAWING 
 
 in such an unnatural position draw it first in its natural position, 
 then revolve to the new position about one or more imaginary 
 axes taken perpendicular to the planes of projection. 
 
 FIG. 84. Revolutions. 
 
 FIG. 85. . 
 
 FIG. 86. Double revolution. 
 
 At A in Fig. 84 we have two views of an object in a natural 
 position. Suppose a hole is drilled through from the front and 
 a shaft inserted as shown. The object might be revolved about 
 the shaft or axis into a new position as at B. It will be observed 
 
THEORY OF SHAPE DESCRIPTION 
 
 41 
 
42 MECHANICAL DRAWING 
 
 that the front view of B is the same as the front view of A except 
 that its position has been changed. The top view of B is ob- 
 tained by projecting up from the new front view, and across 
 from the top view of A. The rule of revolution may now be 
 stated : 
 
 First. The view perpendicular to the axis of revolution is un- 
 changed except in position. Second. Distances parallel to the 
 axis of revolution are unchanged. 
 
 In Fig. 85 the method of drawing an object when revolved 
 about a vertical axis is shown. Given the two views as at A, it 
 is required to draw three views after the piece has been revolved 
 through 30 about a vertical axis. First draw the top view 
 in its new position, B. Since the axis is vertical, the height 
 has not been changed, so a horizontal projecting line may be 
 drawn from point 1, of A and a vertical projecting line from the 
 top view of B. The intersection of the two lines just drawn will 
 locate 'the position of point 1 in the new front view. Proceed 
 in the same way for each point and join the points to complete 
 the view. The side view is obtained from the front and top views 
 in the usual manner. 
 
 After an object has been revolved about an axis perpendicular 
 to a plane it may 'be revolved about an axis perpendicular to 
 another plane. This is double or successive revolution and is 
 illustrated in Fig. 86, where the piece has been revolved about a 
 vertical axis through 30, and from this position about an axis 
 perpendicular to tne vertical plane through 45. 
 
 An object may be revolved to the right- or to the left about an 
 axis perpendicular to the horizontal or vertical plane, or it may 
 be revolved forward or backward about an axis perpendicular 
 to the profile or side plane. The various positions are illustrated 
 in Fig. 87. The view which is unchanged in size and shape is 
 shown slightly tinted in each case. 
 
 PICTORIAL DRAWING 
 
 34. Pictorial Drawing. Thus far we have studied shape de- 
 scription by the exact method of separate views, or orthographic 
 projection. In addition to a knowledge of this method it is 
 very necessary for a draftsman to be able on occasion to make a 
 pictorial view, either freehand or with instruments. 
 
 By those familiar with the subject, sketches are often made 
 in perspective, showing the object as it would actually appear to 
 
THEORY OF SHAPE DESCRIPTION 
 
 43 
 
 the eye., An easier way, although the result is not so pleasing 
 in appearance as a well-made perspective, is to use one of the 
 pictorial methods of projection, of which the commonest are 
 isometric drawing, oblique drawing, and cabinet drawing. These 
 all show three faces in one view and have the advantage that the 
 principal lines can be measured directly. While similar in effect, 
 these three methods must not be confused. 
 
 35. Isometric Drawing. This simple method is based on 
 revolution, Fig. 88. If a cube be imagined as tilted up on one 
 corner to such an angle that its front view shows three faces 
 equal in shape and size it is said to be in isometric^ projection. 
 
 Isomefr/c Pruning 
 
 FIG. 88. The isometric cube. 
 
 In this position the edges would evidently not show in their true 
 length. An isometric drawing of the same cube is the same shape 
 but a little larger in size as the edges are drawn in their true 
 length instead of in the foreshortened length. 
 
 Isometric drawings are thus built on a skeleton of three lines 
 ^presenting the three edges of the cube. These three lines form 
 three equal angles of 120 and are called the isometric axes. 
 One is drawn vertically, the others with the 30 triangle as 
 shown in Fig. 89. The intersection of these lines would be the 
 front corner of a block with -square corners. Measuring the 
 length, breadth and thickness of the block on the three axes, and 
 drawing through these points lines parallel to the axes will give 
 the isometric drawing of the block. It is often better to start 
 with the axes in the " second position," representing the lower 
 corner as in Fig. 90. 
 
 Any line on the object parallel to one of these edges is drawn 
 parallel to it and is called an isometric line. The first rule of 
 
 1 Isometric equal measure. 
 
44 
 
 MECHANICAL DRAWING 
 
 isometric drawing is: Measurements can be made only on iso- 
 metric lines. The second rule is: Remember the isometric cube. 
 36. Non-isometric Lines. Lines not parallel to one of the 
 isometric axes are called non-isometric lines. Such lines will 
 not show in their true length and cannot be measured, but must 
 be drawn by locating their two ends. 
 
 
 
 
 \ 
 1 
 
 FIG. 89. Isometric axes. First position. 
 
 FIG. 90. Isometric axes. Second position. 
 
 G B 
 FIG. 91. Construction for non-isometric lines. 
 
 37. Angles between lines on isometric drawings do not show 
 in their true size, and cannot be measured in degrees. All the 
 angles of a cube are right angles but in the isometric drawing 
 some would measure 120 and some 60. In drawing angles other 
 than 90, the lines forming them must be transferred from the 
 orthographic views as shown in Fig. 91. To make an iso- 
 
THEORY OF SHAPE DESCRIPTION 
 
 45 
 
 metric drawing of the packing block shown at I, first drop per- 
 pendiculars on the front view from the points D and E, giving 
 the construction lines DF and EG. Then draw the two isometric 
 axes, AB and AC as at II, and measure the distances AF and 
 BG. Draw vertical lines at F and G equal to the corresponding 
 lines in the front view. The non-isometric lines AD and BE 
 can then be drawn and the angles at A and B will be represented 
 correctly. Finish the figure as at III. 
 
 FIG. 92. Construction of isometric circle. 
 
 38. Circles will appear as ellipses in isometric drawing, but 
 instead of drawing a true ellipse a. fonr-gpntered apprflriflna.t.inTi 
 is usually made. To draw an isometric circle, first make the 
 isometric drawing of the square which will contain it, Fig. 92. 
 From the points of tangency draw perpendiculars. Their inter- 
 
 Orthograph/c 
 
 FIG. 93. Isometric arcs. 
 
 FIG. 94. Isometric half-section. 
 
 sections will give four centers for arcs tangent to the sides of the 
 square. Two of these centers will fall at the corners of the square, 
 as shown at II. Thus the entire construction may be made with 
 the 60 triangle. The construction for quarter rounds is the 
 same, as shown in Fig. 93, where the radius is measured from 
 the corner and actual perpendiculars of 90 drawn to find the 
 required center. 
 
 39. Sections. Isometric drawings are generally made as out- 
 side views, but sometimes a sectional view is needed. The sec- 
 tion is taken on an "isemetric plane," that is, on a plane parallel 
 
46 
 
 MECHANICAL DRAWING 
 
 to one of the faces of the cube. Figure 94 shows a half section 
 and Fig. 95 a full section of the same piece. 
 
 40. Making an Isometric Drawing. Problem: Make an 
 isometric drawing of the guide, Fig. 96. First, draw the axes 
 AB, AC and AD, in second position, Fig. 97. 
 
 Measure from A } the length 3" on AB 
 
 Measure from A, the width 2" on AC 
 
 Measure from A, the thickness %" on AD 
 
 FIG. 95. Isometric section. 
 
 FIG. 96. Problem for isometric drawing. 
 
 Through these points draw isometric lines, blocking in the base. 
 Second, block in the upright, making two measurements only, 
 2" and %". Third, locate center of hole, and draw its center 
 lines as shown. Block in a 24" isometric square and draw the hole 
 
 FIG. 97. First stage. 
 
 FIG. 98. Second stage. 
 
 as an approximate ellipse by Art. 38. At the upper corners 
 measure the one-half inch radius on each line, Fig. 98, and draw 
 real perpendiculars to find the centers of the quarter circles. 
 Fourth, finish the drawing as 'in Fig. 99. 
 
 41. Making a Freehand Isometric Drawing. Freehand iso- 
 metric sketches are of great help in reading orthographic views 
 
 V 
 
THEORY OF SHAPE DESCRIPTION 
 
 47 
 
 and in explaining objects or parts of construction. The princi- 
 ples of isometric drawing form the basis of isometric sketching, 
 but since sketches arg not made to scale, their appearance 'is 
 improved by flattening, that is, giving the axes an angle less than 
 30 with the horizontal, and by slightly converging the lines, 
 as well as foreshortening the lengths, thus avoiding the distortion 
 and giving the effect of perspective. 
 This is sometimes called "fake per- 
 spective." 
 
 Always block in construction squares 
 before sketching circles or arcs, and 
 remember that the long axes of 
 ellipses representing circles on the 
 top face are horizontal. 
 
 42. Oblique Drawing. This form 
 of pictorial drawing is based upon 
 the theoretical principle that the ob- 
 ject is placed parallel to the plane of projection and projected 
 to it by oblique projecting lines instead of perpendicular ones. 
 Practically it is drawn on three axes, just as isometric, but two 
 of the axes always make right angles with each other, that is, 
 one axis is drawn vertically, one horizontally and the third at 
 any convenient angle, Fig. 100. 
 
 60* to right reversed 
 
 FIG. 99. Completed "drawing. 
 
 30" to right 
 
 45* to left 60" to right 
 
 FIG. 100. Axes in oblique drawing. 
 
 The same methods and rules as used in isometric apply to ob- 
 lique, but compared with isometric it has the distinct advantage 
 of showing one face without distortion. Thus objects with 
 irregular outlines can be drawn by this method much more easily 
 and effectively than in isometric, and many draftsmen prefer it 
 for practically all pictorial work. 
 
 The first rule in oblique drawing is: Place the object so that 
 the irregular ouiline or contour faces the front. 
 
 If there is no irregular outline the second rule should be fol- 
 lowed: Always place the object so that the longest dimension 
 shows in the front. 
 
48 
 
 MECHANICAL DRAWING 
 
 43. Circles. On the front face circles and curves show in 
 their true shape. On the other faces they are drawn as in 
 isometric, by drawing perpendicular lines from the tangent points. 
 
 44. Making an Oblique Drawing. Problem: Make an oblique 
 drawing of the bearing, Fig. 101. First, draw the axes for- the 
 
 FIG. 101. Problem for oblique drawing. 
 
 base, AB, AC, and AD, in second position, and measure on them 
 the length, width and thickness of the base, Fig. 102, A. Draw 
 the base and on it block in the upright omitting the projecting 
 
 B c 
 
 FIG. 102. Stages'in oblique construction. 
 
 boss, as shown in the figure. Second, block in the boss, as at B 
 and find the centers for all circles and arcs. Third, draw the 
 circles and circle arcs. Fourth, finish the drawing as at C. 
 
 45. Cabinet Drawing. In this form of drawing the axes are 
 taken the same as in oblique drawing but all measurements 
 parallel to the oblique or cross axis, or in other words all thickness 
 measurements from front to back, are reduced one-half. It is 
 used sometimes in making drawings of wood construction. 
 
THEORY OF SHAPE DESCRIPTION 
 
 49 
 
 46. Perspective Drawing. Perspective drawing is the repre- 
 sentation of an object as it actually appears to the eye. A sketch 
 made in perspective thus gives the best pictorial effect. The 
 elementary principles of perspective are familiar .to most students 
 
 FIG. 103. Angular perspective. 
 
 ' ' * c 
 
 
 
 .x 
 
 I 
 
 '/ 
 
 FIG. 104. Parallel pei^pective. 
 
 through the study of freehand drawing and they will find this 
 knowledge of value in studying shape description. 1 
 
 1 In the scope of this book the interesting subject of mechanical perspective 
 construction cannot be taken up. With a knowledge of its methods per- 
 spective drawings can be made from working drawings, as for example 
 when an architect makes a picture of a proposed building, the result being as 
 accurate as a photograph of the building. 
 4 
 
50 
 
 MECHANICAL DRAWING 
 
 In the perspective sketch, Fig. 103, it will be noted that the 
 vertical lines remain vertical and that the two sets of horizontal 
 lines each converge toward a point called the vanishing point. 
 These two vanishing points lie on a horizontal line at the level 
 of the eye called the horizon. The first rule is, all horizontal 
 lines vanish on the horizon. 
 
 When the object is turned at an angle as in Fig. 103, the draw- 
 ing is said to be in angular or "two point" perspective. 
 
 If the object is turned so that one face is parallel to the front 
 plane, the horizontal lines on that face, or parallel to it, remain 
 
 horizontal and have no vanishing 
 point. This drawing is called paral- 
 lel or "one point" perspective, 
 Fig. 104. 
 
 47. Making a Perspective 
 Sketch. In sketching from the 
 object, place it below the level of 
 the eye (unless very large) and so 
 as to show the outline of shape to 
 the best advantage. Start by 
 drawing a line for the nearest 
 vertical corner. From this sketch 
 lightly the directions of the prin- 
 cipal lines, running them past the 
 limits of the figure. Test the di- 
 rections and proportionate lengths 
 with the pencil as follows: With 
 the drawing board or sketch pad held perpendicular to the "line of 
 sight "from the eye to the object, hold the pencil at arm's length 
 paralklto the board and rotate the arm until the pencil appears to 
 coincide with the line on the model, then move it parallel to this 
 position back to the board. This gives the direction of the line. 
 To estimate the apparent lengths hold the pencil the same way 
 and mark with the thumb, Fig. 105, the length of the pencil 
 which covers the line. Rotate the arm with the thumb held in 
 position until the pencil coincides with another line and estimate 
 the proportion of this measurement to the second line. 
 
 Block in the enclosing squares for all circles and circle arcs 
 and carry on the figure. Work with light free sketchy lines 
 and do not erase any lines until the whole sketch is blocked in. 
 Draw main outlines first, then add details. Finally, brighten 
 the sketch with heavier lines. 
 
 FIG. 105. Estimating proportions. 
 
CHAPTER IV 
 PRINCIPLES OF SIZE DESCRIPTION 
 
 48. We have learned that the two things to be told about an 
 object are its shape and its size. In the previous chapter we 
 studied the methods of representing the shape. When informa- 
 tion regarding the size is added to the shape description, the two 
 together give the complete working drawing of the object. 
 
 While working drawings are always made to scale, it would 
 require too much time to take off distances by applying a scale 
 to the drawing. Furthermore, the chances of making a mistake 
 would be numerous especially with small distances or for draw- 
 ings made to small scale. 
 
 For convenience in using, insuring accuracy, and saving time, 
 the size description is given in the form of dimensions and notes, 
 arranged on the drawing in a definite manner. 
 
 4- 
 
 
 Dimension line 
 
 Extension //ne 
 
 FIG. 106. Dimension lines. 
 
 49. Lines, Figures, Arrows, Etc. Certain conventional lines 
 and symbols are used and the draftsman to make a successful 
 drawing must not only be familiar with these but must know the 
 principles of dimensioning and be acquainted with the shop 
 processes which will be used in building or making the object 
 represented. 
 
 51 
 
52 MECHANICAL DRAWING 
 
 The dimension line is made a light full line, in contrast with 
 the heavier shape outline. See Alphabet of Lines, Art. 62. The 
 line is terminated by long pointed arrow-heads, Fig. 106. Great 
 care must be taken to have all arrow-heads the same size, and 
 correctly shaped, Fig. 107. 
 
 A space is left in the dimension line for a figure to tell the 
 actual distance on the full-size piece. When the dimension is 
 placed outside of the outline of the view 
 
 I Nrtthus extension or witness lines are drawn from the 
 
 - Not thus view to show the points or surfaces measured 
 on the object. Extension lines are fine lines 
 drawn from the outline and extending past 
 the arrow-head. Since extension lines are not part of the 
 shape they should not touch the outline, see Fig. 106. 
 
 Figures must be carefully made and of a size easily readable 
 but not so large as to overbalance the drawing. In general 
 make them about %" high. To avoid crowding, extension 
 lines should be KG" or more f rom the lines of the drawing and 
 from each other. A fraction is always made with a horizontal 
 division line. Figures for fractions are made about two-thirds 
 the height of whole numbers, see Fig. 24. 
 
 50. Placing Dimensions. In placing dimensions the impor- 
 tant thought is for the man who has to read the drawing and make 
 the piece from it. It is necessary to think of the actual piece in 
 space. Since the shape is already defined, select the view which 
 tells most about the piece and give two dimensions of each part. 
 One of the other views must be used to tell the third distance. 
 In general it is better to place the dimensions between the views 
 so as to be near both views. Horizontal dimensions must always 
 read from the bottom of the sheet and vertical dimensions from 
 the right side of the sheet, no matter what part of the sheet they 
 are on. 
 
 Inches are indicated by (") and feet by (') and a dash is always 
 placed between feet and inches thus, 5'-7J", or 0'-9J". 
 When the drawing is dimensioned entirely in inches, the inch 
 marks may be omitted. When the space is too small to admit 
 of arrow-heads and figures, one of the methods of Fig. 108 is 
 used. 
 
 When there are few lines within the outline, dimensions may 
 be placed inside, making it unnecessary to draw extension lines. 
 
PRINCIPLES OF SIZE DESCRIPTION 
 
 53 
 
 Dimension lines should never cross extension lines. Larger 
 dimensions should be placed outside of smaller dimensions. 
 51. Theory of Dimensioning. The theory of dimensioning 
 
 FIG. 108. Dimensioning in limited space. 
 i 
 
 is based upon the idea of considering any object as made up of 
 a number of simple shapes. When the size of each simple piece 
 is defined and the relative posi- 
 tions given, the size description 
 is complete. When a number 
 of pieces are assembled, each 
 piece is first considered separately 
 and then in relation to the other 
 pieces. In this way the size de- 
 scription of a complete machine, 
 
 of a piece of furniture or of a building %s no more difficult than 
 the dimensioning of a single piece. 
 
 r 
 
 1 
 
 *r''-i' 
 _ 
 
 FIG. 110. First rule applied. 
 
 FIG. 111. First rule applied. 
 
 52. The first shape is a flat piece, requiring the length, breadth 
 and thickness, Fig. 109. Such an elementary shape may appear in 
 a great many ways, a few of which are shown in Figs. 110 and 111. 
 
54 
 
 MECHANICAL DRAWING 
 
 Flat pieces of irregular shape are dimensioned in a similar way, 
 Figs. 112 and 113. 
 
 Rule. For any flat part give the thickness in one of the edge views 
 and all other dimensions on the outline view. 
 
 FIG. 112. An irregular flat shape. 
 
 FIG. 113. An irregular flat shape. 
 
 FIG. 114. The second shape. 
 
 FIG. 115. Second rule applied. 
 
 The second shape is the cylinder, requiring two dimensions, 
 the diameter and length, Fig. 114. 'A washer may be thought of 
 as two cylinders, Fig. 115, requiring two diameters and one 
 length. 
 
PRINCIPLES OF SIZE DESCRIPTION 
 
 55 
 
 Rule. For cylindrical pieces give the diameter and length on the 
 same view. 
 
 Combinations of the first and second shapes are shown in Figs. 
 116 and 117. The dimensions A, B, 
 C and D, Fig. 117, establish the rela- 
 tion between the single shapes. 
 
 53. General Rules. In the appli- 
 cation of dimensioning there are cer- 
 tain practices which have come to 
 represent good form to such an extent 
 as to have the force of rules. 
 
 1. Regardless of location on the sheet, 
 dimensions must read in line with the 
 dimension line and either from the lower or 
 right-hand side of the sheet. 
 
 2. On machine drawings detail dimen- 
 sions up to 24" should be given in inches. 
 
 Above this feet and inches are generally ^ 116 _ First and second 
 used, except for gear drawings, bore of cyhn- shapes, 
 
 ders, length of wheel bases, etc. 
 
 FIG. 117. First and second shapes. 
 
 3. On architectural and structural drawings, dimensions of 12" and ovei 
 are given in feet and inches. 
 
 4. Sheet metal drawings are usually dimensioned entirely in niches. 
 
 5. Furniture and cabinet drawings are usually dimensioned in inches. 
 
 6. Feet and inches are designated thus, 7'-3", or 7 ft.-3 in. Where the 
 dimension is in even feet it is indicated thus, 7'-Q". 
 
56 
 
 MECHANICAL DRAWING 
 
 7. The same dimension is not repeated on different views unless there is a 
 special reason for it. 
 
 8. When it is necessary to place a dimension within a sectioned area do 
 not run the section lines across the number, Fig. 118. 
 
 9. Dimensions should be given from 
 or about center lines. Finished surfaces 
 are always located from other finished 
 surfaces or from center lines. 
 
 10. Never use a center line as a 
 dimension line. 
 
 11. Never use a line of the drawing as 
 a dimension line. 
 
 12. Never have a dimension line a 
 continuation of a line of the drawing. 
 
 13. Never place a dimension so that 
 it is crossed by a line. 
 
 14. Always give the diameter of a 
 circle, not the radius. 
 
 15. Always give the radius of an arc. The abbreviation R or Rad. is 
 used when necessary, Fig. 108. 
 
 54. Use of Decimals. Dimensions are given in feet, inches 
 and fractions of an inch. In ordinary work binary fractions 
 
 FIG. 118. 
 
 L 
 
 a -Spot for sef screw 
 
 FIG. 119. Dimensioning with limits. 
 
 such as Yz", K", H", Ke", M 2 ", Hi" are used. For parts 
 which must fit very accurately the dimensions are given in deci- 
 mals instead of the usual fractions, and the workman is required 
 to work within a certain fixed limit of accuracy. The number 
 
PRINCIPLES OF SIZE DESCRIPTION 57 
 
 of thousandths or 1 " ten-thousandths of an inch which will be 
 allowed as variance from the absolute measurement is called the 
 tolerance. The limits between which the measurement must 
 come are given as in Fig. 119, which shows that the diameter of 
 the hole must not be over .8130" nor under .8125". 
 
 55. Dimensioning Assembled Parts. The drawing of a sepa- 
 rate part is called a detail drawing. When the different parts of 
 a machine or structure are shown together in their relative posi- 
 tions the drawing is called an assembly drawing. The rules and 
 methods given for dimensioning apply to all cases where a com- 
 plete description of size is required. 
 
 Drawings of complete machines, pieces of furniture, etc., are 
 made for different uses and have to be dimensioned to serve the 
 purpose desired of them. If the drawing is simply to show the 
 arrangement of parts all dimensions are left off. When it is 
 desired to tell the space required, give "over-all" dimensions. 
 Where it is necessary to locate parts in relation to each other 
 without giving all of the detail dimensions, it is usual to give 
 center distances and size of parts which might affect putting 
 together the machine or construction. Assembly drawings may 
 be completelv dimensioned, either with or without extra part 
 views, see Fig. 163. Such drawings serve the purpose of both 
 detail and assembly drawings. 
 
 For furniture and cabinet work the major dimensions only are 
 sometimes given, such as length, breadth, height, and sizes of 
 stock, leaving the details of joints to the cabinetmaker. This is 
 common practice where machinery is used and where many 
 details of construction are standardized. 
 
 56. Sketching and Measuring. Sketching as a means of shape 
 description and study has been considered in Chapter III. When 
 sketches are made from machine or furniture parts, to be used 
 in making drawings it is necessary to define the size, the material, 
 the kinds of surfaces, either " finished" or "rough," the limits 
 of accuracy and all information that might have any possible 
 future value. 
 
 57. After sketching the views of a piece, add all necessary 
 dimension lines in exactly the same way as for a drawing. The 
 piece should now be examined, the kind of material noted, to- 
 gether with the kinds of finish and the location of all finished 
 surfaces. When everything else is done it is time to measure 
 the piece and fill in the figures, telling the size. For this purpose 
 
58 
 
 MECHANICAL DRAWING 
 
 various measuring tools will be required. A two-foot rule, a 
 steel scale and a pair of calipers will be found sufficient for most 
 measurements. Other machinists' tools are often necessary or 
 convenient and the pupil should know something about the tools 
 which are available and how to use them. 
 
 FIG. 120. Taking a measurement. 
 
 58. The flat scale or the steel scale and straightedge can be 
 used in many ways, as suggested in Fig. 120 and the distances 
 read directly. 
 
 FIG. 121. Outside and inside calipers. 
 
 Whenever possible, always take measurements from finished 
 surfaces. Inside and outside calipers with their use illustrated 
 are shown in Fig. 121. The distance between the contact points 
 is read by applying the calipers to a scale, Fig. 122. 
 
PRINCIPLES OF SIZE DESCRIPTION 
 
 59 
 
 When the calipers cannot be removed from a thickness, the 
 plain calipers may be used by inserting an extra piece or "filler" 
 Fig. 123; or the " transfer" calipers, Fig. 124, may be used. The 
 distance x must be subtracted from the total distance to obtain 
 
 FIG. 122. Reading the calipers. 
 
 the desired thickness t when a filler is used. The transfer calipers 
 are provided with a false leg which is set so that the calipers may 
 be opened and then brought back to the same position after 
 removing from the casting. 
 
 FIG. 123. Use of filler. 
 
 FIG. 124. Use of transfer calipers. 
 
 All measurements of wood construction can generally be ob- 
 tained with sufficient accuracy by using the two-foot rule. 
 
 For very accurate measurements vernier calipers and microme- 
 ter calipers, Figs. 125 and 126 are used. Other tools which 
 are useful if at hand are the steel square, try square, combination 
 square, surface gauge, depth gauge, radius gauges, protractor, 
 etc. 
 
 When a pictorial sketch is dimensioned the only additional 
 consideration is to use care to see that all extension lines are 
 
60 
 
 MECHANICAL DRAWING 
 
 either in or perpendicular to the plane on which the distance is 
 being given, Fig. 127. 
 
 3 4 
 
 AS6789|12345676? I 123456769 
 lllinillllllllHIIIIIIIIIIIttllllllllll 
 
 FIG. 125. Vernier calipers. 
 
 59. Notes and Specifications. Information which cannot be 
 represented graphically must be given in the form of lettered 
 
 A- Frame 
 B- Anvil 
 C-Sp/nd/e 
 D-Sleere 
 - Th/'mb/e 
 
 FIG. 126. Micrometer calipers. 
 
 notes and symbols. Generally understood trade information 
 is often given in this way. Such notes include the following 
 
 FIG. 127. Dimensioning a pictorial sketch. 
 
 items: Number required, material, kind of finish, kind of fit, 
 method of machining, kinds of screw threads, kinds of bolts 
 and nuts, sizes of wire, thickness of sheet metal, etc. 
 
 The materials in most general use are wood, cast iron, wrought 
 
PRINCIPLES OF SIZE DESCRIPTION 61 
 
 iron, steel and brass. All parts which go together must be of the 
 proper size so they will fit. Some pieces are left in the rough 
 and others must have a smooth " finish." The wood used for 
 making a piece of furniture is first shaped with wood-working 
 tools. Cast iron and brass are given the required form by mould- 
 ing, casting, and machining. First a wooden " pattern" of the 
 shape and size required is made. This pattern is placed in sand 
 to make an impression or mould, into which the melted metal is 
 poured. Wrought iron and steel are made into shapes by rolling 
 or forging in the rolling mill or blacksmith shop. Some kinds of 
 steel may be cast as described for cast iron. 
 
 There are many interesting ways of forming metals for special 
 purposes, and many special alloys, that cannot be described in a 
 drawing book, but the pupil will learn much by observing the 
 shapes of parts of machinery and the materials of which they are 
 made. 
 
 After a part is cast or forged it must be "machined" on all 
 surfaces which are to fit other surfaces. Round surfaces are 
 generally formed on a lathe. Flat surfaces are finished or 
 smoothed on a planer, milling machine, or shaper. For making 
 holes drill presses, boring mills or lathes, are used. 
 
 Extra metal is allowed for surfaces which are to be finished. 
 To specify such surfaces a small "f" is placed on the lines which 
 represent the surfaces. If the entire piece is to be finished a 
 note such as "fin. all over" may be used and all other marks 
 omitted. 
 
 Specifications as to methods of machining, finish and other 
 treatment are given in the form of notes, as spot face, grind, 
 polish, knurl, core, drill, ream, countersink, hardened, case- 
 hardened, blued, and tempered. 
 
 It is often necessary to add notes in regard to assembling, 
 order of doing work or other special directions. 
 
 60. Checking a Drawing. After a drawing has been completed 
 it must be very carefully examined before it is used. This is 
 called checking the drawing. It is very important work, and 
 should be done by someone who has not worked on the drawing. 
 
 Thorough checking requires a definite order of procedure, and 
 consideration of the following items: 
 
 1. See if the views completely describe the shape of each piece. 
 
 2. See if there are any unnecessary views. 
 
 3. See that the scale is sufficiently large to show all detail clearly. 
 
62 
 
 MECHANICAL DRAWING 
 
 FIG. 128. An incorrect drawing. To be redrawn. 
 
 FIG. 129. The drawing corrected. 
 
PRINCIPLES OF SIZE DESCRIPTION 63 
 
 4. See that all views are to scale and that correct dimensions are given. 
 
 5. See that sufficient dimensions are given to define the size of all parts 
 completely. 
 
 6. See that the kind of material and the number required, of each part is 
 specified. 
 
 7. See that the kind of finish is specified, that all finished surfaces are 
 marked and that finish is not called for where not heeded. 
 
 8. See that all necessary explanatory notes are given, and that they are 
 properly placed. 
 
 An incorrect drawing with some of the mistakes noted on it 
 is shown in Fig. 128, and the same drawing when corrected in 
 Fig. 129. 
 
CHAPTER V 
 TECHNIC OF THE FINISHED DRAWING 
 
 61. We have had it impressed upon us that in the language of 
 drawing an object is described by telling its shape and its size. 
 All drawings whether for machinery, structural work, buildings 
 or ships are made on the same principles. 
 
 Sometimes an unfavorable comparison is made between a 
 student's drawing and a real drawing. The finished appearance 
 of a real drawing as made by a draftsman or engineer is due to a 
 thorough knowledge of the technic of commercial drafting. The 
 correct order of going about the work and some of the conven- 
 tional representations in common use are described in this chapter. 
 The pupil must become thoroughly familiar with this practice 
 if his drawings are to have the style and good form which are 
 so desirable and necessary. 
 
 62. Alphabet of Lines. The kinds of lines in general use in 
 
 (1) Visible outline. 
 
 (2) Invisible outline. 
 
 (3) Center line. 
 
 9 X/ 
 ' 2 of =*-J (4) Dimension line. 
 
 ' (5) Extension line. 
 
 (6) Cutting plane. 
 
 (7) Limiting break. 
 
 (8) Broken parts. 
 
 . Fia. 130. The alphabet of lines. 
 
 making drawings are given in Fig. 130. Each line is used for a 
 definite purpose and must not -be used for anything else. Detail 
 drawings should have fairly heavy outlines, with light center 
 lines and dimension lines so that the drawing will have contrast 
 and be easy to read. If all the lines are the same weight the 
 drawing will have a flat appearance making it hard to read. 
 
 64 
 
TECHNIC OF THE FINISHED DRAWING 65 
 
 63. Order of Penciling. After learning about shape and size 
 description the most important thing for the young draftsman 
 to get is good form, a systematic method of working. The order 
 of making the different parts of the drawing is the first item. A 
 drawing is started by drawing center lines and base lines, which 
 form the skeleton for the views. The views should be carried 
 along together. Do not attempt to finish one view before making 
 another. Learn the following order of penciling and follow it as 
 nearly as possible in every drawing. 
 
 1. Lay off the sheet to proper size, and block in the title space or record 
 strip. 
 
 2. Plan the arrangement of views. 
 
 3. Draw the primary center and base lines. 
 
 4. Lay off the principal measurements. 
 
 5. Block in the views by drawing the preliminary and final "blocking- 
 in" lines. 
 
 6. Lay off the detail measurements. 
 
 7. Draw the center lines for details. See that two intersecting center 
 lines are drawn to locate all circles, and that there are center lines for the 
 axes of all cylinders. 
 
 8. Draw all complete circles and the preliminary and final lines for 
 details. 
 
 9. Draw part circles, fillets and rounded corners. 
 
 10. Draw such lines as could not be previously drawn. 
 
 11. Draw all extension and dimension lines. 
 
 12. Put on dimensions and notes. 
 
 13. Cross-hatch all sectioned surfaces. 
 
 14. Put on title. 
 
 15. Check drawing. 
 
 64. Inking and Tracing. Finished drawings are generally 
 inked, either by going over the pencil lines with drawing ink or 
 more commonly by putting a piece of tracing cloth or paper over 
 the pencil drawing and tracing it in ink. From such tracings 
 blueprints can be made for use on the work. The method of 
 procedure is the same for paper or cloth. 
 
 All straight lines are inked with the ruling pen. Hold the pen 
 point downward and fill by touching the quill on the ink bottle 
 cork to the inside of the pen blades. The nibs of the pen are 
 set to the desired width of line by turning the adjusting screw, 
 using the thumb and second finger of the pen hand. Then 
 hold the pen against the T-square or triangle in the position of 
 Fig. 131. 
 
66 
 
 MECHANICAL DRAWING 
 
 Note the following: 
 
 Do not hold the pen over the drawing while filling. 
 
 Keep the blades parallel to the direction of the line. 
 
 FIG. 131. Correct position of pen. 
 
 Do not press too hard against the T-square. 
 Do not screw the nibs of the pen too tight. 
 Have a pen wiper at hand. 
 
 Pen pressed aga/nsf T square 
 
 Per? s/oped away from Tsqvare 
 
 Pen foo c/ose fo edge /nk ran under 
 
 fnk on oufs/de of b/ade, ran under 
 
 Pen b/ades r?of kepf para//e/ fo Tsauare 
 
 Tsqyare(orfr/ang/eJ s/ipped into wef//ne 
 
 Not enough ink fo finish //ne 
 
 FIG. 132. Faulty lines. 
 
 Keep the pen clean. Always wipe it out carefully after using. 
 Never dip the pen into the ink bottle or allow ink to get on the outside of 
 the blades. 
 
 Do not put too much ink in the pen. (Not over Y inch.) 
 
TECHNIC OF THE FINISHED DRAWING 
 
 67 
 
 Faulty lines occur from different reasons. The pen may need 
 dressing or sharpening. The beginner should not attempt to 
 do this but should ask the teacher to do it for him. Figure 132 
 shows some of the common faults and suggests the remedy. 
 
 The irregular curve, Fig. 14, is used for guiding the pen when 
 inking curves other than circle arcs. It is used by matching a 
 portion of the curved line and drawing a piece of the line, then 
 moving the curve to a new position. The new position must 
 always match a part of the line already inked. 
 
 For inking circles the compasses and bow pen are used. Re- 
 move the pencil leg from the compasses and insert the pen leg, ad- 
 justing the needle point until it is very slightly longer than the pen. 
 
 FIG. 133. Inking a circle. 
 
 The joints of the compasses should be adjusted so that the legs 
 are perpendicular to the paper. Always draw a circle in one 
 stroke, inclining the compasses in the direction of the line and 
 rolling the handle between the thumb and finger, Fig. 133. 
 Small circles are drawn with the bow compasses. 
 
 65. To Make a Tracing. First tear off the selvage and tack 
 the cloth down smoothly over the pencil drawing. Most drafts- 
 men place the dull side up. Dust the surface with chalk and 
 rub over with a cloth to remove all traces of grease so as to 
 obtain smooth ink lines. Be sure to remove all dust before 
 starting to ink. With the tracing cloth in position and properly 
 prepared inking is done in exactly the same way as on paper. 
 
MECHANICAL DRAWING 
 
 As tracing cloth is very sensitive to atmospheric changes and 
 will stretch if left over night, no view should be started which 
 cannot be finished on the same day. When work is again started 
 the cloth should be restretched. 
 
 66. Order of Inking. Good inking is the result of two things, 
 careful practice and a definite order of working. Smooth joints 
 and tangents, sharp corners and neat fillets not only improve 
 the appearance of a drawing but make it easier to read. 
 
 1. Ink center lines. 
 
 2. Ink small circles and arcs. 
 
 3. Ink larger circles and arcs. 
 
 4. Ink irregular curves. 
 
 5. Ink horizontal full lines. 
 
 6. Ink vertical full lines. 
 
 7. Ink inclined full lines. 
 
 8. Ink dotted circles and arcs. 
 
 9. Ink dotted lines. 
 
 10. Ink extension and dimension lines. 
 
 11. Ink arrow-heads and figures. 
 
 12. Ink section lines. 
 
 13. Letter notes and title. 
 
 14. Ink border lines. 
 
 15. Check drawing. 
 
 67. Erasing. The ideal way of course is to complete a drawing 
 or tracing without having to do any erasing. Sometimes, how- 
 ever, it is necessary to make an erasure on account of a change 
 or a mistake. Ink lines may be removed by rubbing rather hard 
 with a pencil eraser, which does not abrade the surface of the 
 paper or cloth as does an ink eraser. Do not use a knife or 
 scratcher. An erasing shield is very convenient. One can be 
 made by cutting a slot in a card or piece of drawing paper. 
 Pencil lines are removed with artgum or a pencil eraser. 
 
 
 
 fix* Number 
 
 
 
 Number Req. 
 
 Material 
 
 
 
 
 
 
 THE 
 
 SEAC 
 
 IRAVE 
 
 CO., C 
 
 JOLUNI 
 
 BUS, OHIO 
 
 
 
 
 
 DATE 
 
 
 
 
 
 DRAWER 
 
 
 FIG. 134. A boxed title form. 
 
 68. Titles. Every sketch and drawing must have some kind 
 of title, The form, completeness and location vary. On work- 
 
TECHNIC OF THE FINISHED DRAWING 69 
 
 ing drawings the title is usually " boxed" in the lower right-hand 
 corner, Fig. 134, or as part of a record strip extending across the 
 bottom or end of the sheet, Fig. 135. 
 
 The title gives as much as is necessary of the following in- 
 formation : 
 
 1. The name of the construction. 
 
 2. The name of the part shown (or simply "details"). 
 
 3. Manufacturer; company or firm name and address. 
 
 4. Date; usually date of completion of tracing. 
 
 5. Scale, or scales. 
 
 6. Drafting-room record; names or initials of draftsman, tracer, checker, 
 and approval of chief draftsman, engineer or superintendent. 
 
 7. Numbers, of the drawing; of the order. 
 
 In larger drafting rooms the title is often printed in blank 
 on the paper or cloth used. 
 
 
 
 UNIT 
 
 HAUC MCCC 
 
 
 KMT. 
 
 "" MlST^WMMC 
 
 DM. 
 
 
 
 
 AT. 
 
 race - 
 
 
 
 THE LODGE 4. SHIPLEY MACHINE TOOL Co. 
 
 CINCINNATI. OHIO. U. . A. 
 
 
 FIG. 135. A record strip title. 
 
 69. Bill of Material. Drawings may have the name of the 
 part, material, number required, part number, etc., given in a 
 note near the views of each part. Another method often used 
 is to place the number of the part in a circle near the views and 
 then collect all the information in a tabulated list, called a bill 
 of material, or material list. Sometimes this list is placed on the 
 drawing over the title, and sometimes it is typewritten on a 
 separate sheet. If for wood construction the bill will give 
 the stock sizes, kind and quality of wood, board measure, and 
 number of each part required, Fig. 136. Sometimes the cost is 
 added. Bolts and other metal parts are often specified and 
 marked with an identification number or mark. 
 
 70. Screw Threads. The use of screw threads is so frequent 
 that the common forms and methods of representation must be 
 understood. The most familiar occurrence of screw threads is 
 on the ordinary wood screw, and common bolt, Figs. 137 and 
 138. 
 
70 
 
 MECHANICAL DRAWING 
 
 The form of thread generally used in this country for machine 
 bolts and metal constructions is the United States Standard, 
 shown in Fig. 139. Wood screw threads have a space between 
 them to allow for the difference in strength of wood and metal. 
 
 \DEScximoN 
 
 Gauge X -3 -J 
 
 BOX FOR 
 OVERSEAS SHIPMENT 
 
 FIG. 136. Drawing with bill of material. 
 
 Other forms of threads used 'to meet various requirements are 
 illustrated and named in the figure. 
 
 To draw a true representation of a screw thread it is necessary to 
 draw the projection of a cylindrical helix. A cylindrical helix 
 
 Round head 
 
 Slot, 
 
 Diameter *( ^ Pitch 
 
 Flat- head 
 FIG. 137. Wood screws. 
 
 =J/ ^ Root diameter 
 
 Head h Length H 
 
 FIG. 138. Hex head bolt and nut. 
 
 is a curve generated by a point moving uniformly around a cylin- 
 der and uniformly lengthwise of the cylinder at the same time. 
 The hypotenuse of a right triangle will form one turn of a helix 
 if it is wrapped around a cylinder, as in Fig. 140. The base of 
 
TECHNIC OF THE FINISHED DRAWING 
 
 71 
 
 the triangle is equal to the circumference of the cylinder and the 
 altitude is the pitch of the helix. 
 
 71. To Draw the Projection of a Helix. Draw two projec- 
 tions of the cylinder, divide the top view into a number of equal 
 parts and the pitch into the same 
 number of parts as at A, Fig. 141. 
 From each point in the top view drop 
 perpendiculars to meet horizontal 
 lines drawn through the same num- 
 bered division of the front view as at 
 B. A smooth curve drawn through 
 the points found will give the projec- 
 tion of the helix, as at C. 
 
 The application of the helix is 
 shown in Fig. 142, which is the actual 
 projection of a square thread. Such 
 drawings are seldom made as they 
 require too much time and are no T~ 
 better practically than the conven- J 5 
 tional representations commonly used. 
 For diameters of more than one inch 
 the representations of Fig. 143 may 
 be used. The order of drawing the 
 lines for V threads is shown in Fig. 
 144. 
 
 For small diameters the representa- 
 tion is further conventionalized to 
 one of the forms of Fig. 145. The 
 pitch or distance between threads is 
 not measured but the lines are spaced 
 so as to look well, as indicated in the 
 figures. The simple form shown at C 
 is generally satisfactory and is easily 
 and quickly made. 
 
 Screw threads in section are shown in Fig. 146. Threaded 
 holes in plan, elevation and section may be drawn as in Fig. 
 147. Any one of the plan representations may be used with any 
 of the elevations or sections. A small threaded hole is called a 
 "tapped" hole and a note such as "tap for %" U. S. Std. Thread" 
 placed on the drawing. If a threaded hole does not go clear 
 
 WfiJTWOPTH 
 
 SQUARE 
 
 KNUCKLE 
 FIG. 139. Threads. 
 
72 
 
 MECHANICAL DRAWING 
 
 FIG. 140. Helix. 
 
 i r : 
 
 T FIG. 141. Drawing a^helix. 
 
 FIG. 142. True projection of square thread. 
 
 A B 
 
 FIG. 143. Straight line'thread representations. 
 
 * 
 
TECHNIC OF THE FINISHED DRAWING 
 
 FIG. 144. Order of drawing a V thread. 
 
 A 
 
 fc 
 
 a< 
 
 // 
 
 Fl 
 
 FIG. 145. Usual methods of drawing threads. 
 
 FIG. 146. Threads in section. 
 
 FIG. 147. Various methods of drawing threaded holes. 
 
74 
 
 MECHANICAL DRAWING 
 
 through a piece the "drill point " or shape of the bottom of the 
 hole should be drawn as shown. 
 
 72. Bolts and Other Fastenings. The various kinds of bolts, 
 screws, and rivets used for fastening parts together occur on so 
 many drawings that the draftsman must know what kind of 
 fastenings to use and how to represent them conventionally. 
 In the previous paragraphs the methods of representing threads 
 conventionally have been shown. These are always used on 
 shop drawings on account of the saving of time. 
 
 There are many forms of bolts made for different purposes. 
 The ones which we must be familiar with are the United States 
 Standard hex head and square head bolts and nuts. The number 
 of threads per inch is standard for each diameter. Data for U. S. 
 Standard bolts and nuts is given in Table I. 
 
 TABLE I. DIMENSIONS OP U. S. STANDARD BOLTS AND NUTS 
 
 Diam. 
 
 of bolt, 
 
 in. 
 
 Threads 
 per 
 inch 
 
 Diam. at 
 root of 
 thread 
 
 Area at 
 root of 
 thread 
 
 Distance 
 
 across 
 
 flats, in. 
 
 Distance 
 across corners 
 
 Hexagon, 
 
 Square, 
 
 Thickness 
 
 Nut, 
 in. 
 
 Head, 
 in. 
 
 X 
 
 H 
 KG 
 
 X 
 X 
 
 IX 
 IX 
 
 IX 
 
 2 
 
 20 
 18 
 16 
 14 
 13 
 12 
 11 
 10 
 
 9 
 
 8 
 
 7 
 
 7 
 
 6 
 
 6 
 
 5 
 
 4% 
 
 0.185 
 0.241 
 0.294 
 0.345 
 0.400 
 0.454 
 0.507 
 0.620 
 0.731 
 0.838 
 0.940 
 1.065 
 1.159 
 1.284 
 1.490 
 1.711 
 
 0.026 
 0.045 
 0.068 
 0.093 
 0.126 
 0.162 
 0.202 
 0.302 
 0.420 
 0.551 
 0.693 
 0.889 
 1.054 
 1.293 
 1.744 
 2.300 
 
 x 
 
 1X4 
 IX 
 
 1X4 
 
 IX 
 
 IX 
 
 IX 
 
 2 
 
 2^6 
 
 2% 2 
 
 2% 6 
 
 2% 
 
 2% 
 
 3^6 
 
 2^2 
 2^4 
 
 2% 6 
 
 3^2 
 
 X 
 
 Ke 
 
 Me 
 X 
 
 * 
 1 
 
 IX 
 IK 
 
 IX 
 IX 
 
 2 
 
 X 
 
 1 
 IXz 
 
 iMe 
 
 Both hex and square forms have the same dimensions " across 
 flats," which is equal to one and one-half times the diameter of 
 the bolt plus %", oTS = l%d + %". 
 
 The thickness of a bolt head is one-half the distance across 
 
TECHNIC OF THE FINISHED DRAWING 
 
 75 
 
 o 
 
 flats or = ~- The thickness of a nut is equal to the diameter, 
 
 
 = d. 
 
 FIG. 148. To draw a hexagon. 
 
 73. To Draw a Bolt. The easiest way to understand a bolt 
 head is to draw the top and front views. Since 
 the hexagonal form is oftenest used we must 
 know how to draw a regular hexagon. 
 
 To Draw a Hexagon. Given the distance 
 between two sides, called the short diameter, 
 or "distance across flats, " Fig. 148. First 
 draw horizontal and vertical center lines. 
 With the intersection as a center, draw a cir- 
 cle having a diameter equal to the distance 
 across flats. With the T-square and 30-60 
 triangle, draw lines tangent to the circle in 
 the order given. 
 
 A hex bolt head is a hexagonal prism with 
 the corners chamfered as shown in the picture 
 of Fig. 138. 
 
 74. To Draw a Bolt Head. Start the top 
 view by drawing the chamfer circle with a 
 diameter equal to one and one-half times the 
 diameter of the bolt plus one-eighth of an inch. 
 S = 1% d -f- %". About this circle draw a 
 hexagon as just described. For the front 
 view draw a horizontal line representing the 
 under side of the head. The thickness of the 
 
 cr 
 
 head is ~> or the radius of the chamfer circle. 
 
 Draw top line and project from top view 
 Complete the front view by drawing three 
 The middle arc has a radius 
 
 FIG. 149. 
 
 to obtain edges. 
 
 circle arcs as shown in Fig. 149. 
 
76 
 
 MECHANICAL DRAWING 
 
 equal to d and the side arcs are of such radius as to line across 
 with the middle one. Their centers may be found by the con- 
 struction shown, but draftsmen often draw the arcs by trial, 
 without construction. 
 
 p 
 
 ^ 
 
 /I 
 
 
 
 > 
 
 / > 
 
 
 
 
 
 /v > 
 
 
 
 > / 1 
 
 
 
 ? V > 
 
 
 
 = d= Djafr? of 3o/f 
 
 x .x 
 
 /*** found /by trio/ 
 
 E\ yv \ vv \ s+ 
 
 r^-+-^^\ C 
 
 FIG. 150. To draw a U. S. Standard hex head and nut. 
 
 r 
 
 E C 
 
 FIG. 151. To draw a U. S. Standard square head and nut. 
 
 75. In drawing a bolt head or nut it is not necessary to draw 
 the top view. A convenient method of -drawing bolts and nuts 
 is illustrated in Fig. 150, where a simple diagram is used to obtain 
 
TECHNIC OF THE FINISHED DRAWING 
 
 77 
 
 the dimensions. To draw the diagram shown at A, lay off on 
 a horizontal line the diameter of the bolt, half the diameter of the 
 bolt and J^ /7 . From one end of the line draw a 30 line with 
 the triangle and from the other end draw a vertical line. 
 Complete the diagram as shown. The distances are marked on 
 
 
 
 
 ~^ 
 
 
 
 t 
 
 ~^\ 
 
 1 
 
 1 
 
 " ' *^r 
 * 
 
 1 
 
 4 
 
 r 
 
 ^>~ 
 
 -> 
 
 <" 
 
 , 
 
 FIG. 152. Dimensioning a Standard bolt. 
 
 FIG. 153. A stud. 
 
 the diagram to correspond with the same distances on the bolt 
 head and nut. 
 
 Figure 151 shows the same method applied to a square head 
 bolt and nut, in which the diagram is constructed with a 45 
 angle instead of 30. 
 
 The proportions of bolt heads and nuts are so well standardized 
 that they are not dimensioned on a drawing. For a bolt it is 
 
 only necessary to specify three 
 dimensions, the diameter, length 
 from under side of head to end of 
 bolt," and length of thread, as in 
 Fig. 152. 
 
 A stud or stud bolt, Fig. 153, has 
 threads on both ends and is used 
 where bolts are not suitable and 
 for parts which must be removed 
 often. One end is screwed perma- 
 nently into a tapped hole and a nut 
 is screwed on the projecting end. 
 
 Various arrangements are used 
 to prevent nuts from working loose 
 under vibration. Locknuts such as illustrated in Fig. 154, are 
 the commonest. 
 
 76. S. A. E. Standard Bolts. Bolts used for automobile work 
 have finer threads, and smaller heads and nuts than U. S. Stand- 
 ard. A pin through the bolt is used to prevent loosening of the 
 
 
 ]' 
 
 / 
 
 / 
 
 
 1 
 
 1 
 
 --d 
 1 
 1 
 
 I 
 
 
 
 
 
 
 1 
 
 1 
 | 
 
 1 
 
 1 
 
 \ 
 
 
 i 
 
 \ 
 
 \ \ 
 
 FIG. 154. Locknuts. 
 
78 
 
 MECHANICAL DRAWING 
 
 "castle nut" and the head is slotted for the use of a screw driver. 
 The dimensions for the standard of the Society of Automotive 
 Engineers is given in Table II. 
 
 TABLE II. DIMENSIONS OF S. A. E. STANDARD BOLTS AND NUTS 
 
 ^xJ J=( 1... 
 
 Threads 
 
 K 
 
 KG 
 
 H 
 
 KG 
 
 28 
 24 
 24 
 20 
 20 
 18 
 18 
 16 
 16 
 14 
 14 
 
 KG 
 
 5 /32 
 
 5 /32 
 5 /32 
 5 /32 
 
 KG 
 
 y 
 
 H 
 
 He 
 
 3 /32 
 
 y 8 
 y 8 
 y 8 
 y 8 
 
 y 8 
 
 KG 
 KG 
 
 15 /32 
 
 KG 
 3 A ' 
 
 S /32 
 
 77. Cap screws have various forms of heads and are used for 
 fastening two pieces together by passing through one and screw- 
 ing into a tapped hole in the other. The usual range of sizes 
 and dimensions for drawing are given in Table III. 
 
 Machine screws are used where small diameters are required, 
 they are specified by number and run from No. (.06" diam.) 
 to No. 30 (.45" diam.). They are similar to cap screws in 
 appearance. 
 
TECHNIC OF THE FINISHED DRAWING 79 
 
 TABLE III. DIMENSIONS OF CAP SCREWS 
 
 Hexagor, 
 
 Square Ortt ft///ster P/af Fillte'er Button Counfersunk 
 
 D K 
 
 He K 
 
 Ke 
 
 I He 
 
 IK i IK 
 
 He 
 K 2 
 K 
 
 K 
 He 
 
 K 
 
 Ke 
 
 H 
 
 ni 
 
 He 
 
 M 
 
 H 
 
 He 
 
 1 
 IK 
 
 He 
 
 Set screws, Fig. 155, are used for holding two parts in a desired 
 position relative to each other by screwing through a threaded 
 hole in one piece and bearing against the other. 
 
 -o 
 
 KGULAfi LOW HEAD HEADLESS 
 
 FIG. 155. Set screws. 
 
 SAFETY 
 
 78. Wood screws are made of steel or brass, and are finished 
 in various ways. Steel screws may be bright (natural finish), 
 blued, galvanized or copper plated, while both steel and brass 
 are sometimes nickel plated. Round head screws have the head 
 above the wood while flat head screws are set flush, or counter- 
 sunk. They are drawn as in Fig. 156. Wood screws are speci- 
 fied by length, style of head, number, and finish. Length of 
 
80 
 
 MECHANICAL DRAWING 
 
 flat head screws is measured over all and round head screws 
 from under head to point. A lag screw, drawn as in Fig. 157, is 
 used for fastening machinery to wood supports and for heavy 
 wood constructions when a bolt cannot be used. It is similar to 
 a machine bolt but has wood screw threads. The head may be 
 
 either square or hexagonal. Lag 
 screws are specified by diameter 
 and length from under side of 
 head to end of screw. 
 
 FIG. 156. Wood screws, as drawn. 
 
 FIG. 157. Lag screw. 
 
 Several other forms of screws and bolts are drawn as in Fig. 
 158. Screw hooks and screw eyes are specified by diameter and 
 length over all. 
 
 79. Conventional Symbols. There are a number of commonly 
 accepted symbols used on drawings. The symbols for represent- 
 
 Hanger Bo/t Drive Screw 
 
 fi ' FIG. 158. Various bolts and screws 
 
 ing the cut surfaces of sectional views as given by a committee 
 of the American Society of Mechanical Engineers are shown in 
 Fig. 159. For showing the cross-section of long, uniformly 
 shaped pieces and for "breaking out" parts the representations 
 of Fig. 160 are used. 
 
TECHNIC OF THE FINISHED DRAWING 
 
 81 
 
 Rock Origino/ Filling Sand Other' frlater/a/s 
 
 Earth 
 
 FIG. 159. Symbols for materials in section (A. S. M. E.). 
 i 
 
 ROLLED SHAPES 
 
 ROPE OR CABLE 
 
 <XJ| | | |- CXI 
 
 BEARING 
 
 XLJBffl) 
 
 ^SQUARE SECTION 
 
 FIQ. 160. Conventional breaks and other symbols. 
 
82 MECHANICAL DRAWING 
 
 80. Blueprinting. Practically all work in shops or on struc- 
 tures is done from blueprints, which are copies made from a trac- 
 ing, on chemically treated paper, giving white lines on a blue 
 background. As many copies as desired can be made from a 
 single tracing. Blueprints can be made from pencil or ink 
 drawings on tracing cloth, tracing paper or bond paper. The 
 original drawing is never allowed to go into the shop but is kept 
 in the files of the drawing room. Blueprint paper is usually 
 bought ready sensitized and may be had in different degrees of 
 rapidity, when fresh it is of a yellowish green color and an un- 
 exposed piece should wash out perfectly white, with age or ex- 
 posure to light or air it turns to a darker gray blue color, and 
 spoils altogether in a comparatively short time. 
 
 Blue-print frame. 
 
 81. To Make a Blueprint. Place the tracing in a blueprint 
 frame with the inked side next to the glass and lay a sheet of 
 blueprint paper with the sensitized side next to the tracing. Put 
 the back of the frame in place and lock it in position so as to 
 hold the tracing and paper. Expose to sunlight or electric light 
 for from 30 seconds to several minutes, depending upon the 
 sensitiveness of the paper. The yellowish green color of the 
 unexposed paper will turn to a grayish color. Take the paper 
 from the frame and wash in a bath of running water for five or 
 ten minutes. This fixes the blue color and washes the lines to a 
 clear white. Hang up until dry. The prints may be improved 
 in color and clearness by dipping in a dilute bath of sodium 
 bichromate or hydrogen peroxide and rinsing after taking from 
 the original bath. Changes may be made on blueprints by using 
 any alkaline solution in a writing or drawing pen. 
 
TECHNIC OF THE FINISHED DRAWING 83 
 
 NINETEEN NEVERS 
 
 1. Never begin work without wiping off table and instru- 
 ments. 
 
 2. Never use the scale as a ruler. 
 
 3. Never use a dull lead pencil. 
 
 4. Never draw with the lower edge of the T-square. 
 
 5. Never put either end of a pencil into the mouth. 
 
 6. Never take dimensions by setting the dividers on the 
 scale. 
 
 7. Never run backward over a line either with pencil or pen. 
 
 8. Never try to use the same thumb tack holes when putting 
 paper down a second time. 
 
 9. Never use a blotter on inked lines. 
 
 10. Never leave the ink bottle uncorked. 
 
 11. Never dilute ink with water. If too thick throw it away. 
 
 12. Never put a writing pen which has been used in ordinary 
 writing ink, into the drawing-ink bottle. 
 
 13. Never scrub a drawing all over with the eraser after 
 finishing. It takes the life out of the inked lines. 
 
 14. Never cut paper with a knife and the edge of the T-square 
 as a guide. 
 
 15. Never use the T-square as a hammer. 
 
 16. Never jab the dividers into the drawing board. 
 
 17. Never use the dividers as reamers or pincers or picks. 
 
 18. Never put instruments away without cleaning. This 
 applies with particular force to pens. 
 
 19. Never put bow instruments away without opening to 
 relieve the spring. 
 
CHAPTER VI 
 DRAFTING, MECHANICAL AND ARCHITECTURAL 
 
 82. Working Drawings. A working drawing is a drawing 
 which completely describes the shape and size, and gives speci- 
 fications for the kinds of material, methods of finish, accuracy 
 required and all other information necessary for making a single 
 part, or a complete machine or structure. 
 
 Working drawings are based upon orthographic projection, 
 Chapter III, with dimensions and notes added as described in 
 Chapters IV and V. A working drawing may be made for a sepa- 
 rate piece, for a group of pieces, or for a completely assembled 
 construction. 
 
 ::::--"- ~t ^ ~ V I 
 
 PLANING JIG FOR TAPER GIBS 
 
 FIG. 161. A detail drawing. 
 
 83. Detail Drawings. A drawing of a single piece which gives 
 all the information necessary for making it is called a detail draw- 
 ing. This is the simplest form of working drawing and must be 
 a very complete and accurate description of the piece, with care- 
 fully selected views and well-located dimensions. Sometimes 
 separate detail drawings are made -for the use of different work- 
 men, as the patternmaker, blacksmith, machinist, etc. Such 
 drawings have only the dimensions and information needed by 
 the workmen for whom the drawing is made. 
 
 84 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 85 
 
 forging, esf/motecf tveighf /533 Lhs. 
 
 Section xJ-A Section B-B Section C-C SecfionD'O 
 
 BLACK FORGING FOR JACKET 
 75 MM FIELD GUN 
 
 FIG. 162. A forging drawing. 
 
 FIG. 163. An assembly working drawing. 
 
86 
 
 MECHANICAL DRAWING 
 
 An ordinary machine detail drawing is shown in Fig. 161, and 
 a forging drawing in Fig. 162. 
 
 When a large number of machines are to be manufactured, it 
 is usual to make a detail drawing for each part on a separate sheet. 
 
 84. Assembly Drawings. A drawing of a completely assembled 
 construction is called an assembly drawing. Such drawings 
 vary greatly in regard to completeness of detail and dimensioning. 
 Their particular value is 'in showing the way in which the parts 
 
 FIG. 164. An outline assembly drawing, with shade lines. 
 
 go together and the appearance of the construction as a whole. 
 When complete information is given they may be used for work- 
 ing drawings. This is possible when there is little or no complex 
 detail. Figure 163 shows such a drawing. Furniture and other 
 wood constructions can often be represented in assembly working 
 drawings by adding necessary enlarged details or extra partial 
 views. 
 
 Assembly drawings of machines are generally made to small 
 scale with selected dimensions to tell over-all distances, important 
 center-to-center distances and location dimensions. All or al- 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 87 
 
 most all hidden lines may be left out and if to very small scale 
 unnecessary detail may be omitted. 
 
 Either exterior or sectional views may be used. When the 
 general appearance is the main purpose of the drawing, only 
 
 \ 
 
 \ 
 
 FIG. 165. Conventional shade lines. 
 
 : shade 
 
 one view or two views may be used, sometimes with 
 lines" to bring out the shape more clearly, Fig. 164. 
 
 85. Shade Lines. When shade lines are used the simple 
 conventional method is to shade the lower and right-hand lines 
 of each part in all views. Assume parallel rays of light at 
 
 FIG. 166. Shade lines on circles and arcs. 
 
 an angle of 45 in the direction shown in Fig. 165. Each view is 
 considered by itself. Edges over which the rays of light pass are 
 shaded. Dotted lines are never shaded. Light lines are made 
 very fine. Shade lines are made at least three times the width 
 
88 MECHANICAL DRAWING 
 
 of fine lines. The extra thickness of line is added outside the 
 boundaries of 'the view. 
 
 A circle is shaded by moving the center of the compasses on a 
 45 line toward the lower right-hand corner a distance equal to 
 the thickness of the shade line, and drawing a tangent semi-circle 
 as shown in Fig. 166. 
 
 86. Choice of Views. Much of the ease with which a drawing 
 can be used depends upon proper selection of views. For the 
 complete description of an object at least two views are required. 
 While a drawing is not a picture it is always advisable to select 
 the views which require the least effort to read. Each view 
 must have a part in the description or it is not needed and should 
 not be drawn. In some cases one view is all that is necessary, 
 provided a note is added or the shape and size is standard or 
 evident. Complex pieces may require more than three views, 
 some of which may be partial views, auxiliary and sectional 
 views. The reason for making the drawing must always be kept 
 in mind when a question arises. The final test of the value of a 
 drawing is its clearness and exactness in giving the complete 
 information necessary for making the piece. 
 
 87. Choice of Scale. The choice of scale for a detail drawing 
 is governed by three things the size necessary for showing all 
 details clearly, the size necessary for carrying all dimensions with- 
 out crowding and the size of paper used. It is always desirable 
 to make detail drawings to full size. Other scales commonly 
 used are half, quarter, and eighth, see Art. 13. Such scales as 
 2" = 1', 4" = 1', and 9" = 1', are to be avoided. If a part is 
 very small it is sometimes drawn to an enlarged scale, perhaps 
 twice full size. 
 
 When a number of details are drawn on one sheet they should 
 if possible be to the same scale. If different scales are used they 
 should be noted near each drawing. A detail or part detail 
 drawn to a larger scale may often be used to advantage on assem- 
 bly drawings. This will save the making of separate detail draw- 
 ings. General assembly drawings can be made to such a scale 
 as will show the desired amount of detail and work up well on the 
 size of paper used. Sheet-metal pattern drawings for practical 
 use are always made full size, although practice models may be 
 constructed from small scale layouts. 
 
 88. Grouping and Placing Parts. When a number of details 
 are used for one machine only, they are often grouped on a single 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 89 
 
 sheet or set of sheets. A convenient arrangement is to group 
 the forging details together, the brass details together and simi- 
 larly for other materials. In general it is well to represent parts 
 in the position which they will have in the assembled machine, 
 with related parts near each other. Long pieces, however, such 
 
 FIG. 167. Rib in a section. 
 
 as shafts, bolts, etc., are drawn with their long dimensions 
 horizontal. 
 
 89. Conventional Representation. The principles upon which 
 the description of shape by means of views is based have been 
 explained and they form the basis for working drawings. In 
 
 FIG. 168. Pulley in section. 
 
 the actual use of mechanical drawing it has been found desirable 
 under certain conditions to violate the rules previously given. 
 
 90. Sections Through Ribs, Arms, Etc. When the plane of a 
 section passes through a rib or pulley arm the drawing is made 
 
90 
 
 MECHANICAL DRAWING 
 
 as in Figs. 167 and 168, where the plane is thought of as being just 
 in front of the rib or arm. A true section would give the idea of a 
 very heavy solid piece. When a section or elevation of a drilled 
 flange is drawn, the holes are shown at their true distance from 
 the center regardless of where they would project, Fig. 169. 
 
 FIG. 169. Flanges, in elevation and section. 
 
 A revolved or turned section is sometimes inserted in a view to 
 show the shape, as in Figs. 170 and 171. 
 
 91. Rule of Contour. In general preserve the characteristic 
 contour of an object. Sections or elevations of symmetrical 
 pieces are sometimes hard to read when drawn in true projection. 
 It is usual in such cases to revolve a portion of the object until 
 
 FIG. 170. Revolved section. 
 
 FIG. 171. Revolved section. 
 
 the characteristic contour shows. This has been done in Fig. 
 172, which is the correct method of drawing the object shown. 
 
 It is always desirable to show true distances even though the 
 views do not project. This may be illustrated by bent levers 
 and similar pieces which are represented by revolved or stretched 
 out views as in Fig. 173 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 91 
 
 92. Gears. If two wheels are in contact and keyed to parallel 
 shafts, both will revolve if either one of the shafts is turned, Fig. 
 174. If the driven shaft turns hard the wheel will slip. To 
 
 FIG. 172. The "rule of contour." 
 
 prevent slipping, teeth are added to the wheels. The shape of 
 these teeth is such that the same kind of motion as with the 
 rolling wheels is obtained. Gearing is a separate study but the 
 student should know how to show a gear on a drawing. Spur 
 
 FIG. 173. A stretched out view. 
 
 gears and bevel gears, Figs. 175 and 176 are the most common 
 forms. A small gear used with a large one, .or with a "rack" is 
 called a " pinion." The parts of gear teeth have names as given 
 
92 
 
 MECHANICAL DRAWING 
 
 in Fig. 177. There are three diameters and two kinds of pitch to 
 remember. The three diameters are indicated on the figure. 
 The circular pitch is the distance from a point on one tooth to 
 the same point on the next tooth, measured along the pitch circle. 
 
 Outside Diameter 
 'oof Diameter 
 
 FIG. 174. 
 
 PINION RACK 
 
 FIG. 175. Spur gears. 
 
 Let N = number of teeth 
 
 D = diameter of pitch circle 
 P c = circular pitch 
 P = diameter pitch 
 
 Addendum = - 
 Dedendum = + 
 
 Width of Face 
 
 Circular Pitch 
 
 FIG. 176. Bevel gears. 
 
 FIG. 177. 
 
 The diameter pitch is a number found by dividing the number of 
 teeth by the diameter of the pitch circle. 
 
 It is not necessary to draw the actual teeth when making work- 
 ing drawings of gears. Cut spur and bevel gears are drawn as in 
 Figs. 178 and 179, which show "gear blanks" with notes to give 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 93 
 
 required information. The representations of Fig. 180 are 
 used on assembly drawings. 
 
 93. Cams. A cam is a machine element used to obtain an 
 irregular or special motion not easily obtained by other means. 
 
 /OP.. 43 T: 
 
 DEPTH OF CUf.Z/6 * 
 
 FIG. 178. Working drawing of a cut spur gear. 
 
 5 P/TCH - 35 TEETH 
 
 finish a// over 
 
 FIG. 179. Working drawing of a cut bevel gear. 
 
 The shape of a cam is derived from the motion required of it. 
 One form of plate cam is shown in Fig. 181. A cylindrical cam 
 is shown in Fig. 182. 
 
94 
 
 MECHANICAL DRAWING 
 
 FIG. 180. Gears in elevation. 
 
 FIG. 182. A cylindrical cam. 
 
 FIG. 183. Drawing of plate cam. 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 95 
 
 To find the cam outline, Fig. 183, given point C, the center of 
 the shaft and point A, the lowest position of the center of the 
 roller. It is required to raise the center of the roller with uni- 
 form motion during three-eighths of a revolution of the uniformly 
 revolving shaft, allow it to drop two-thirds of the way down in- 
 stantly, remain at rest for one-eighth of a revolution, drop uni- 
 formly during three-eighths of a revolution, and remain at rest for 
 the remaining one-eighth of a revolution. 
 
 Divide the rise into a number of equal parts. Divide the arc 
 ADE into the same number of equal spaces as there are spaces 
 in the rise, and draw radial lines. With C as a center and radius 
 Cl draw an arc intersecting the first radial line at 1'. In the 
 same way locate points 2', 3', etc., and draw a smooth curve 
 through them. If the cam is revolved in the direction of the 
 arrow, it will raise the roller with the desired motion. Draw 
 B'J equal to two-thirds of AB. Draw arc JK with radius CJ. 
 Divide A2 into six equal parts and arc FGH into six equal parts. 
 Circle arcs drawn as shown will locate points on the cam outline. 
 Draw arc HA with radius CH to complete the cam. This out- 
 line is for the center of the roller, allowance for which may be 
 made by drawing the roller in its successive positions and then 
 drawing the tangent curve as shown in the auxiliary figure. 
 
 ARCHITECTURAL DRAWING 
 
 94. Architectural Drawing. All kinds of technical drawing 
 are based upon the same general principles. Architectural 
 drawings have to do with the representation and specification 
 of buildings. The drawing of a building has to be made to a 
 very small scale as compared with a machine drawing, which 
 makes it necessary to use conventional symbols for the different 
 parts. They differ also in that only one view usually is drawn 
 on a sheet. 
 
 There are three general classes of architectural drawings: 
 
 1. Preliminary sketches: These are freehand studies of the 
 arrangement of rooms, first made as very small "thumb-nail" 
 sketches without using the scale, and when a satisfactory scheme 
 is decided upon, worked up in larger freehand sketches to ap- 
 proximate scale. 
 
 2. Display and competitive drawings: These are more or less 
 elaborate preliminary drawings of a proposed building, often 
 
96 
 
 MECHANICAL DRAWING 
 
 including a perspective, and are rendered in water-color, pen-and- 
 ink, or pencil to make them legible and attractive . 
 
 3. Working drawings: These form the most important class, 
 and include plans, elevations, sections and detail drawings which 
 when read with the specifications for details of materials and 
 
 FIG. 184. Sketch plan. 
 
 finish, give [the ^working information for the erection of the 
 building. 
 
 95. Plans. A floor plan is a horizontal section taken above 
 the floor represented. It shows all the walls with their doors and 
 windows, gives the location of lighting, heating and plumbing 
 
 FIG. 185. 
 
 outlets, and shows part of the stairways starting up or down 
 from the floor. A plan is always laid out with the front of the 
 building at the bottom of the sheet. Ordinary house plans are 
 drawn to the scale of Y' = V . 
 Fig. 184 is a freehand sketch plan of the first floor of a house. 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 97 
 
98 
 
 MECHANICAL DRAWING 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 99 
 
 1 
 
100 
 
 MECHANICAL DRAWING 
 
DRAFTING, MECHANICAL AND 
 
!l62 ; ; 5 j itfECjIANICAL DRAWING 
 
 'oQ^ 
 
 ss 
 
 u - 
 
DRAFTING, MECHANICAL AND ARCHITECTURAL 103 
 
 With this as a basis it is required to draw the plans of the house. 
 The first floor as shown in Fig. 187, is drawn first, then the 
 second floor and basement plans. Draw a horizontal line rep- 
 resenting the outside face of the front wall. Complete the 
 exterior walls and interior partitions. Frame walls are drawn 
 6" thick. . Locate doors and windows and draw them with the 
 conventional symbols as shown. 
 
 96. In drawing the stairway first make a diagram to find the 
 number of steps and space required. The rise, or height from 
 one step to the next, is from 6^" to 7K" and the tread so 
 that the sum of rise and tread is about 17J inches. On the 
 plan the lines drawn represent the edges of the risers and are 
 drawn as far apart as the width of the tread, as shown in Fig. 
 185. The entire flight is not drawn on the plan but is broken so 
 as to show what is on the floor under it. The other end is shown 
 on the plan of the floor above. 
 
 97. The second floor for a two story house is best planned by 
 laying a piece of tracing paper over the first floor plan. Trace 
 the exterior walls and locate stairways and chimney flues. The 
 interior partition walls need not be continuous with the first 
 floor. See that closets are provided for every room. Note 
 that the second floor, Fig. 188, is for a cottage type and account 
 must be taken of headroom under the roof. 
 
 The basement plan is shown in Fig. 186. It should be com- 
 pletely dimensioned as the construction of the house is started 
 with this plan. Windows should be under the first floor windows. 
 The furnace should be near the center of the house. 
 
 98. Elevations and Sections. A front and one side elevation 
 are shown in Figs. 189 and 190. In a complete set of plans the 
 other side and rear elevations should be drawn. In drawing 
 elevations start with the grade line as a base line. The figures 
 show the information usually given on elevations. A wall sec- 
 tion to a larger scale is shown in Fig. 189. 
 
 99. Details. In addition to the quarter-inch scale drawings, 
 larger scale drawings are made of such parts as cannot be shown 
 with sufficient detail on the small scale drawings. Figure 191 is 
 a typical sheet of details. As the building progresses the archi- 
 tect furnishes full size drawings made with soft pencil, for mill- 
 work and other details. 
 
 100. Symbols. The usual symbols for doors, windows, fire- 
 places, etc., have been shown on the plans. Different building 
 
104 
 
 MECHANICAL DRAWING 
 
 materials are indicated in section as shown in Fig. 192, and some 
 of the standard wiring and lighting symbols in Fig. 193. - 
 
 'ROY6H'LVM5El'lfi$KTION' 
 
 -" .. " .. "- 
 
 BRI(K'iri'ELEVATIOrHAR6E'$(AlE' 
 
 FRAME -WALL- in-SECTIOri' CEMEHWLASTEfcirt'SECTIOM' aEttKOTTA'WAlblN -SECTION' 
 
 FIG. 192. Symbols for building materials. 
 
 Outlet; Electric only Numeral 
 in center indicates number of 
 Standard 16 C.f Incandescent Lamps. 
 
 Cei/ing Outlet; Combination indicates 
 4--I6CP Standard Incandescent 
 Lamps and 2 Gas Lamps 
 
 Ceiling Outlet G-** On/y. 
 
 Drop Cord Ot/t/et. 
 
 tan 
 
 Bracket Outlet; Electric only. Numeral 
 in center indicates number of 
 Stahdara' If.Cf Incandescent Lomf*s 
 
 Bracket Outfet: Combination tnaf (cotes 
 4-/6 C.f 'Standard Incandescent 
 Lamps and 2 Gas t-a/r>/os. 
 
 BracAsf Oi/t/ef; Gas on/y 
 
 r~/oor Out /ft ; Numeral in center 
 ind/catvs nt/mber of Standard 
 16 C.P /ncantfescenf Lamps- 
 
 Bel/ Ovttcf ^=| Te/ephone Ovt/ct 
 
 FIG. 193. Symbols. 
 
 Lettering on architectural drawings is usually done in light 
 single-stroke Roman as shown in Fig. 36. 
 
CHAPTER VII 
 GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 
 
 101. Our study of drawing in the preceding chapters has con- 
 sidered two main purposes shape and size description of space 
 constructions. There are, however, many other ways of using 
 drawing as a means of solving the problems which arise in indus- 
 trial work. Graphic solutions require a working knowledge of 
 some geometrical constructions as the basis for the "laying out" 
 of wood and metal work as well as for sheet-metal drafting. 
 
 102. Lines. A line may be divided into two equal parts by 
 measurement with the scale, by trial with the dividers, or geomet- 
 rically as in Fig. 194. Given the line AB. Draw arcs with A 
 
 FIG. 194. To bisect a line. FIG. 195. To divide a line. 
 
 and B as centers and a radius greater than one-half AB. A line 
 drawn through the intersections of the arcs will be perpendicular 
 to AB and will divide it into two equal parts, or " bisect" it. 
 
 103. A line may be divided into any number of equal parts by 
 trial with the dividers, as described in Art. 14, or by using the 
 scale as described in Art. 15. Another way is by the geometrical 
 method of Fig. 195. To divide the line AB into five equal parts. 
 From B draw another line at an angle. On it step off five equal 
 spaces of any convenient length. Connect the last point (c) 
 with A. Through the other points draw lines parallel to CA, 
 using triangle and T-square as shown in Fig. 9. 
 
 104. Sometimes it is necessary to reduce or enlarge linear 
 dimensions from one size to another. A special scale for this 
 purpose may be made geometrically on the well-known theorems 
 of proportional triangles. Draw two parallel lines at a con- 
 venient distance apart, one, A B, to the given scale and the other, 
 
 105 
 
106 
 
 MECHANICAL DRAWING 
 
 CD, to the desired length, either shorter, Fig. 196, or longer, 
 Fig. 197. Lines through AC and BD will intersect at point 0. 
 Draw lines from point through each division of the given scale 
 AB. These will divide CD into proportional spaces, thus making 
 a new scale, Figs. 198 and 199, from whichjthe desired measure- 
 ments can be taken. 
 
 o o 
 
 Reducing 
 
 FIG. 196. 
 
 Enlarging 
 
 FIG. 197. 
 
 FIG. 198. 
 
 FIG. 199. 
 
 FIG. 200. A protractor. 
 
 105. Angles. When two lines meet at a point they form an 
 angle. Lines which are perpendicular to each other form right 
 angles. If a right angle is divided into 90 equal parts, each part 
 is called a degree. A circle contains 360 degrees. An angle is 
 measured in degrees. 
 
 In Art. 7 we learned that angles varying by 15 degrees may 
 be constructed with the 30-60 and 45 triangles. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 107 
 
 For measuring and laying out angles an instrument called a 
 protractor is used. The usual form is semicircular as shown in 
 Fig. 200. 
 
 106. An angle of 90 may be jeadily 
 bisected by using the 45 triangle or 
 trisected with the 30-60 triangle. To . 
 bisect any angle, Fig. 201. With as 
 a center and any radius, draw an arc 
 cutting the sides at A and B. With 
 A and B as centers and any radius 
 greater than one-half AB, draw intersecting arcs. A line through 
 this intersection and point will bisect the angle. 
 
 A/ew position of tvrfex O 
 
 FIG. 201. To bisect an 
 angle. 
 
 Mew pos/fton of / 
 one side ofangfe ^ 
 
 FIG. 202. To copy or transfer an angle. 
 
 107. To copy an angle, Fig. 202. Given the angle AOB. 
 Draw an arc with as a center and any convenient radius. With 
 the same radius and center at new position 0', draw another arc. 
 
 A With radius equal to chord DC and 
 
 center at E draw an arc giving an in- 
 tersection at F through which a line may 
 be drawn to the vertex to complete the 
 angle in its new position. 
 
 108. Triangles. To construct a triangle, 
 having given the three sides, Fig. 203. 
 FIQ. 203. TO construct Given the lengths A, B and C. Draw 
 a triangle. one side A in the desired position. With 
 
 its ends as centers and radii B and C draw two intersecting 
 arcs as shown. An equilateral triangle has three equal sides. 
 It may be constructed by drawing one side in the desired 
 
108 
 
 MECHANICAL DRAWING 
 
 position and drawing intersecting arcs with the ends as centers 
 and the length of the side as a radius, Fig. 204. Another 
 method is to draw 60 lines from each end of the base, using the 
 30-60 triangle. 
 
 An isosceles triangle has two equal sides, Fig. 205. It may be 
 constructed by locating the base and drawing intersecting arcs 
 from each end, using one of the equal sides as a radius. 
 
 FIG. 204. Equilateral 
 triangle. 
 
 FIG. 205. Isosceles 
 triangle. 
 
 H 6Vmts J 
 
 FIG. 206. Right 
 triangle. 
 
 A right triangle is one which has a right angle. A right triangle 
 may be easily constructed by the " 6-8-10 method." Draw a 
 line 6 units long. From one end draw an arc with a radius 10 
 units long and from the other end with a radius 8 units long. 
 Complete as shown in Fig. 206. 
 
 FIG. 207. Hexagon. 
 
 FIG. 208. Hexagon. 
 
 109. The Hexagon. The regular hexagon can be drawn in a 
 number of ways and has already been explained in Art. 73. If 
 the distance across corners AB is given, draw a circle with AB 
 as a diameter, Fig. 207. With A and B as centers and the same 
 radius draw arcs and connect points. A hexagon may be con- 
 structed directly on line AB, without using the compasses, by 
 drawing lines with the 30-60 triangle in the order shown in Fig. 
 208. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 109 
 
 110. The Octagon. To draw an octagon, first draw a square. 
 Fig. 209. Draw the diagonals of the square. With the corners 
 as centers and a radius of half a diagonal draw arcs cutting the 
 sides of the square, and connect these points. 
 
 FIG. 209. Octagon. 
 
 FIG. 210. Circle. 
 
 111. Arcs and Tangents. A circle may be drawn through any 
 three points which do not lie in a straight line. To draw a circle 
 through points A, B and C, Fig. 210. Draw lines AB and BC. 
 Using the method of Art. 102 bisect these lines. Where the 
 bisectors cross at will be the center for the required circle for 
 which OA, OB and OC are radii. 
 
 FIG. 211. To draw a tangent. 
 
 112. To draw a tangent to a circle at a given point, Fig. 211. 
 Arrange a triangle in combination with the T-square (or another 
 triangle) so that its hypotenuse passes through center and 
 point C. Holding the T-square firmly in place, turn the triangle 
 about its square corner, move it until the hypotenuse passes 
 through C, and draw the tangent. 
 
 113. To draw an arc tangent to two lines, Figs. 212 and 213. 
 Given two lines AB and CD and radius R. Draw lines parallel 
 to A B and CD at a distance R from them. The intersection of 
 
110 
 
 MECHANICAL DRAWING 
 
 these lines will be the center of the required arc. The points of 
 tangency are found by drawing a line through the center of the 
 arc and perpendicular to the tangent lines. 
 
 114. To draw an arc tangent to two lines at right angles, 
 Fig. 214. This case frequently occurs in drawing fillets and 
 
 f 
 
 1* 
 
 1 
 
 v/ 
 
 \ 
 
 A ff A 
 
 FIG. 213. FIG 214. 
 
 To draw an arc tangent to two lines. 
 
 rounds. It is desired to round the corner ABC with an arc 
 having a radius equal to R. With B as a center and radius R, 
 draw an arc cutting the two lines. With the points D and E 
 thus found as centers and the same radius as before draw arcs 
 intersecting at 0. An arc drawn with center and radius R will 
 be tangent to the straight lines at points D and E. 
 
 F/rstArc 
 
 FIG. 215. To draw tangent arcs. 
 
 115. Sometimes a smooth curve is made up of circular arcs 
 having different radii. In such cases we must be very careful 
 to have the arcs join at a point of tangency. The two centers 
 and the point of tangency are in the same line, as shown in Fig. 
 215. 
 
 116. To lay off on a straight line the approximate length of a 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 111 
 
 circle arc, Fig. 216. Given the arc AB. At A draw the tan- 
 gent AD. Set the dividers to a small space. Starting at B 
 step along the arc to the point nearest A, and without lifting the 
 dividers step off the same number of spaces on the tangent, as 
 shown. 
 
 117. A reverse or "ogee" curve is shown in Fig. 217, joining 
 lines AB and CD. Join B and C by a straight line. Draw pert 
 pendiculars at B and C. Arcs tangent to lines AB and CD mus- 
 have their centers on these perpendiculars. Point E through 
 which the curve is to pass may be taken any place along BC. 
 
 FIG. 216. Length of an arc. 
 
 FIG. 217. An ogee curve. 
 
 Draw perpendiculars at the middle points of BE and EC, Art. 
 102. Any arc to pass through B and E must have its center on 
 a perpendicular at the middle point. The intersection therefore 
 of these perpendiculars with the two first perpendiculars will 
 be the centers for arcs BE and EC. The construction may be 
 checked by drawing the line of centers, which must pass through 
 E. 
 
 118. The Ellipse. If a circle is parallel to a plane its projec- 
 tion on the plane will be a circle. If it is perpendicular to the 
 plane its projection will be a straight line. If it is at an angle 
 its projection will be an ellipse. A square card with a circular 
 hole, drawn in different positions as in Fig. 218 illustrates the 
 above statements. jLn ellipse is defined as a curve generated 
 by a point moving so that the sum of its distances from two fixed 
 points, called^the foci, is constant, and is equal to the longest diame- 
 ter or major axis. 
 
 A line through the center perpendicular to the major axis is 
 called the short diameter or minor axis. To find the foci, draw 
 an arc with center at one end of minor axis and radius equal to 
 
112 
 
 MECHANICAL DRAWING 
 
 one-half the major axis. This arc will cut the major axis at the 
 foci, F l and F 2 , Fig. 219. 
 
 There are a number of ways of constructing an ellipse, two of 
 which are given. 
 
 119. The easiest method for large work is the pin-and-string 
 method. Given the major and minor axes, Fig. 220. Locate 
 
 FIG. 218. Circle projected as ellipse. 
 
 FIG. 219. Ellipse. 
 
 the foci by the method just described. Drive pins at points Fi, 
 C, and F 2) and tie a cord tightly around the three pins. If the 
 pin C be removed and a marking point moved in the loop, keep- 
 ing the cord taut, it will describe a true ellipse. 
 
 FIG. 220. To draw an ellipse by pin-and-string method. 
 
 120. A very accurate method for finding the points on an el- 
 lipse is by concentric circles, Fig. 221. Draw two circles about 
 the center of the desired ellipse, one with a diameter equal to 
 the minor axis and the other with] a diameter equal to the 
 major axis. Divide the large circle into a number of equal 
 parts, and draw radii OP, OQ, intersecting the small circle at P', 
 Q', etc. From P and Q draw lines parallel to OD, and from P' 
 
GRAPHIC SOLUTIONS AND SHEET- METAI/DRAFTING 113 
 
 and Q' lines parallel to OB. Where the lines through P and P' 
 cross is one point on the ellipse. The lines through Q and Q' 
 give another point. In this way each radial line will locate a 
 point on the ellipse. For accuracy extra points should be taken 
 close together toward the ends, where the curve is changing 
 rapidly. The curve is sketched in very lightly freehand before 
 drawing it in with the irregular curve. A tangent at any point 
 H may be drawn by dropping a perpendicular from the point to 
 the outer circle at K, and drawing the auxiliary tangent KL 
 cutting the major axis produced, at L. From L draw the required 
 tangent LH. 
 
 FIG. 221. Two circle method. 
 
 FIG. 222. Approximate ellipse. 
 
 121. Approximate ellipses may be drawn with arcs of circles. 
 When the minor axis is at least two-thirds of the major axis, the 
 four center approximation shown in Fig. 222 is satisfactory. Make 
 OF and OG each equal to AB minus DE. Make OH and 01 each 
 equal to three-fourths of OF. Draw FH, FI, GH and GI, ex- 
 tending them as shown. Draw arcs through points D and E 
 with centers at G and F, and through A and B with centers I 
 and H. 
 
 SHEET-METAL DRAFTING 
 
 122. Sheet-metal Drafting. There is a large class of metal- 
 work made from thin sheets of metal, formed into the required 
 shape by bending or folding up and fastening by rivets or seams 
 or soldering. In this kind of work the drawings consist of 
 the representation of the finished object, arid the drawing of the 
 shape of the flat sheet, which when rolled or folded and fas- 
 
114 
 
 MECHANICAL DRAWING 
 
 tened will make the object. 1 This second drawing is called the 
 development or pattern of the piece and making it comes under 
 the term, sheet-metal pattern drafting. 
 
 123. Development. There are two general classes of surfaces, 
 plane surfaces and curved surfaces. The six faces of a cube are 
 plane surfaces. The bases of a cylinder are plane surfaces, 
 while the lateral surface is curved. 
 
 It is possible to cut out a piece of paper so as to fold it up into 
 a cube, as in Fig. 223. The shape cut out would be the pattern 
 
 FIG. 223. Pattern for a cube. 
 
 of the cube. Those who have studied solid geometry recall that 
 there are five regular solids and that their patterns are made as 
 shown in Figs. 224 to 228. A good understanding of the nature 
 of developments may be had by laying out the above patterns 
 and folding them to form the figures. 
 
 Thus the pattern for any piece which has plane surfaces may 
 be made by first deciding where the seam is to be, then opening 
 up each face in order, showing it in its true size. One example, 
 the development of a square prism, is illustrated in. Fig. 229. 
 The light lines on the pattern are called folding or crease 
 lines. The dotted lines on the second figure are to indicate 
 extra material to allow for lap in making joints. 
 
 1 A great many thin metal objects are formed without seams by die-stamp- 
 ing or pressing a flat sheet into shape under very heavy presses. Examples 
 range from brass cartridge cases to steel wheelbarrows. Still another 
 division is made by "spinning," as brass and aluminum ware. In stamped 
 and spun work the metal is stretched out of its original shape, and making 
 blanks for it depends upon much technical knowledge and experience. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 115 
 
 In geometry we learn that a cylinder may be thought of as a 
 prism with an infinite number of sides. The development of 
 a cylinder then would be a rectangle having a width equal to 
 
 FIGS. 224,>25,[226, 227, 228. The five regular solids. 
 
 FIG. 229. A pattern, showing lap. 
 
 the height of the cylinder and a length equal to the distance 
 around the cylinder, Fig. 230. 
 
 The length of the pattern of a prism or cylinder is measured 
 on a straight line called the stretchout line. This line is the 
 stretched out length of the shortest distance around the figure. 
 When the base is perpendicular to the axis it will roll out into a 
 
116 
 
 MECHANICAL DRAWING 
 
 straight line and form the stretchout. If the prism or cylinder 
 does not have a base perpendicular to the axis, a "right section" 
 must be taken in order to get a straight stretchout. 
 
 - -Stretchout =* Circumference - 
 
 FIG. 230. Cylinder and pattern. 
 
 124. Development of Prisms. To develop the prism of Fig. 
 231 draw the stretchout line SL and on it lay off 1-2, 2-3, 3-4 
 and 4-1, obtained from the top view. This gives the length of 
 
 FIG. 231. Development of a prism. 
 
 the stretchout and the true distances between the vertical edges. 
 At points 1, 2, 3, 4, 1 on the stretchout draw vertical "creases 
 lines" equal in length to the corresponding edges of the prism. 
 These lengths may be easily projected across from the front 
 view. The true size of the inclined surface is found by the 
 method of auxiliary projection, Art. 31, and attached to one 
 of the sides in its proper relation. The development of the bot- 
 tom may be added if desired. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 117 
 
 To develop the lateral surface of the triangular prism, Fig. 
 232, draw the stretchout line SL and lay off the distances 1-a, 
 a-2, 2-3, 3-6, 6-1, taken from the top view. Points a and 6 
 do not locate crease lines but are required to find the line of the 
 cut. Such extra " measuring lines" are often necessary. 
 
 FIG. 232. Development of a prism. 
 
 125. Development of Cylinders. Consider a cylinder as being 
 a many-sided prism. To develop the cylinder of Fig. 233 assume 
 the position of any convenient number of imaginary edges. For 
 ease of working these are equally spaced, which makes it possible 
 
 M i Mm; i ii 1 1 in Nun. 
 
 / 3 + f 6 T $ /O /I /2 /3 *4 & /6 / 
 
 FIG. 233. Development of a cylinder. 
 
 to obtain the length of the stretchout by taking as many spaces 
 along SL as there are spaces in the top view. At each point on 
 the stretchout draw a vertical " measuring line." Project the 
 length of each imaginary edge across from the front view and 
 draw a smooth curve through the points. 
 
118 
 
 MECHANICAL DRAWING 
 
 Since the surface is curved, the stretchout as obtained is only 
 approximate. The more edges assumed the closer will be the 
 approximation, but it is seldom necessary to have the points 
 less than J^" apart. The accuracy in length of the stretchout 
 may be tested by measuring on it the figured length of the cir- 
 cumference, which equals the diameter X 3.1416, or ird. 
 
 ItlllflUtfKUtfA 
 
 . <iap 
 
 1 
 
 J i i i 1 1 1 1 i i 1 1 1 1 1 1 u 
 
 / Z 3 -4- 5 6 7 9 /O // /2 S3 /<* & M I 
 
 Fia. 234. Pattern for square elbow. 
 
 126. To draw the pattern for a two-piece, or square, elbow 
 Fig. 234. This elbow consists of two cylinders cut off at 45 
 degrees, so only one need be developed. The explanation of Fig. 
 233 applies to this figure except that lap must be allowed as 
 indicated. 
 
 V 
 
 i i i i i i i I I I i I i I i l_ 
 
 FIG. 235. Square elbow pattern, short method. 
 
 Sheet-metal workers use short-cut methods for many problems 
 when laying out directly on the metal. The square elbow 
 pattern can be constructed as in Fig. 235, where a circle is drawn 
 with a diameter equal to the diameter of the pipe and divided into 
 a number of equal parts. These parts are spaced along the 
 stretchout L. Horizontal lines from the points on the circle 
 and vertical lines from the points on the stretchout will cross at 
 points on the desired curve. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 119 
 
 127. The development of a four-piece elbow is illustrated in 
 Fig. 236. To draw the elbow, first draw arcs having the desired 
 inner and outer radii as shown at I. Divide the outer quarter 
 circle into six equal parts. Draw radial lines from points 1, 3 
 and 5 to locate the joints. Draw tangents to the arcs at points 
 2 and 4 and complete the figure as shown at II, by tangents to 
 the inner quarter-circle. With this view completed we are ready 
 to start the development. Draw a circle representing the cross- 
 section of the pipe (one-half of this view is sufficient). Divide 
 
 Mini 
 
 FIG. 236. Patterns for four-piece elbow. 
 
 it into a number of equal parts, and lay out the stretchout line 
 with the same number of equal parts. From the circle project 
 to the elevation to locate the imaginary edges. The pattern 
 for the first section is obtained by projecting across from the 
 elevation in the same way as Fig. 233. 
 
 The patterns for the four pieces may be cut without waste 
 from a rectangular piece if the seams are made alternately on the 
 inside or throat line and outside line. To draw the pattern for 
 the second section extend the measuring lines of the first section 
 and with the dividers take off the lengths of the imaginary edges 
 on the front view, starting with the longest one. The third and 
 
120 
 
 MECHANICAL DRAWING 
 
 fourth sections are made in a similar way. Since the curve is 
 the same for all sections one only need be plotted. 
 
 128. Galvanized iron mouldings and cornices are made up of a 
 combination of cylinder and prism parts. A practical problem 
 in developments is making the pattern for a piece miter ed to 
 "return" around a corner as shown in the sketch of Fig, 237. 
 An inspection of the figure shows the method of working to be 
 the same as Fig. 233, the section of the moulding taking the place 
 of the top view and having its length laid out on the stretchout 
 line. 
 
 / 3 3 4 s 67 
 
 FIG. 237. Pattern for square return miter. 
 
 129. Development of Pyramids and Cones. In the case of 
 prisms and cylinders the stretchout was a straight line with the 
 measuring lines perpendicular to it and parallel to each other. 
 And as their edges were all parallel to the front plane their true 
 lengths were always shown in the front view. Pyramids and 
 cones or any objects larger at one end than at the other will not 
 roll straight, hence their stretchouts are not straight lines. Also 
 since they have sloping sides their edges will not always show in 
 their true lengths. 
 
 130. To find the true length of a line, revolve the line 
 until it is parallel to one of the planes of projection. Its pro- 
 jection on that plane will then be the true length of the line. 
 The pyramid of Fig. 238, 1, is shown by top and front views at II. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 121 
 
 The edge OA does not show in its true length in either view. 
 However, if we draw the pyramid in the position shown at III 
 the true length of OA is shown in the front view. In Fig. Ill 
 the pyramid has been revolved from the position of II about a 
 
 A' 
 
 FIG. 238. True length of line. 
 
 vertical axis until the line OA is parallel to the vertical plane. 
 At IV the line OA is shown before and after revolving. Thus 
 
 FIG. 239. Development of a pyramid. 
 
 the construction for finding the true length of a line is as follows : 
 In the top view with radius OA and center revolve the top 
 view of OA until it is horizontal, project the end of the line down 
 to meet a horizontal line through the front view of A. Join 
 this point of intersection with the front view of 0. 
 
 131. To draw the pattern for a rectangular pyramid, Fig. 239. 
 
122 
 
 MECHANICAL DRAWING 
 
 Find the true length of one of the edges by swinging it around 
 as shown. With this true length as a radius draw an arc of in- 
 definite length for a stretchout line. On this mark off as chords 
 
 FIG. 240. Development of a cone. 
 
 the four edges of the base 1-2, 2-3, 3-4, 4-1. Connect 
 these points with each other in turn, and draw the crease lines by 
 joining each point with the center. 
 
 
 FIG. 241. Frustum of a cone. 
 
 132. To draw the pattern for a cone, Fig. 240. Consider a 
 cone as being a many-sided pyramid and assume the positions 
 of any convenient number of imaginary edges, using equal spac- 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 123 
 
 ing for convenience. With the front view OA as radius draw an 
 arc of indefinite length as a stretchout. On this step off as many 
 points as were assumed in the top view, and at the same distance 
 apart. Connect beginning and ending points by lines to the 
 center. The resulting sector is the developed surface. 
 
 If the cone is cut off as in Fig. 241 develop as before, then 
 with OC as radius draw another arc between the limiting sides. 
 
 If the cone is cut off at an angle it will be necessary to find 
 the true length of every imaginary edge and lay it off on the pat- 
 tern, as shown in Fig. 242, by revolving it around the axis until 
 it is parallel to the front plane. 
 
 FIG. 242. Truncated cone. 
 
 133. Development of a Transition Piece. A transition piece 
 is used to connect a pipe of one shape with another of a different 
 shape. Transition pieces are made up of parts of different kinds 
 of surfaces and are developed by triangulation. The example 
 shown in Fig. 243 connects a round pipe with a rectangular one. 
 From the picture it is seen that this piece is formed of four tri- 
 angles, between which are four conical parts, with apexes at 
 the corners of the rectangular opening and bases each one-quarter 
 of the round opening. 
 
 Starting with the cone whose apex is at A divide its base 1-5 
 into a number of equal parts as 2, 3, 4, and draw the lines A-2, 
 A-3, A-4, giving triangles approximating the cone. Find the 
 true length of each of these lines. This is done in practical 
 
124 
 
 MECHANICAL DRAWING 
 
 DIAGRAM i 
 
 FIG. 243. Development of transition piece. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 125 
 
 work by constructing a separate diagram, as at I, knowing that 
 the true length of each line is the hypotenuse of an imaginary 
 triangle whose altitude is the altitude of the cone and whose base 
 is the length of the top view of the line. 
 
 On the front view draw the vertical line AE as the altitude of 
 the cone. On the base EF lay off the distances A-l, A-2, 
 etc. This is done in the figure by swinging each distance about 
 the point A in the top view, and dropping perpendiculars to EF. 
 Connect the points thus found with the point A in diagram I, 
 thus obtaining the desired true lengths. Diagram II, constructed 
 in the same way gives the true lengths of lines B-5, B-Q, etc., 
 of the cone whose apex is at B. After the true length diagrams 
 are constructed start the development, with the seam at A-l. 
 Draw a line a-1 equal to the true length of A-l. With 1 as 
 a center and radius 1-2 taken from the top view draw an arc. 
 Intersect this arc with an arc from center a and radius equal to 
 the true length of A-2, thus locating the point 2 on the develop- 
 ment. With 2 as center and radius 2-3 draw an arc and inter- 
 sect it by an arc with center a and radius of the true length of 
 A -3. Proceed similarly with points 4 and 5 and draw a smooth 
 curve through the points 1, 2, 3, 4, 5 thus found. Then attach 
 the true size of the triangle A-5-B, locating point B on the 
 development by intersecting arcs from a with radius A-B 
 taken from the top view, and from 5 with radius the true length 
 of B-5. Continue until the piece is completed. 
 
 FIG. 244. Intersections. 
 
 FIG. 245. Intersections. 
 
 134. Intersections. Whenever surfaces come together there 
 is said to be a line of intersection. In Figs. 244 and 245 a number 
 of lines of intersection are shown. It is necessary for both the 
 machine designer and the sheet-metal worker to be able to locate 
 a line of intersection when one occurs. 
 
126 
 
 MECHANICAL DRAWING 
 
 135. Intersecting Prisms. Several illustrations of intersect- 
 ing prisms are illustrated in Fig. 246. 
 
 To draw the intersection of two prisms, first start the ortho- 
 graphic views. In Fig. 247 a square prism passes through a hex- 
 agonal prism. Through the front edge of the square prism pass 
 a plane parallel to the vertical plane. The top view of this plane 
 
 FIG. 246. Intersecting prisms. 
 
 appears as a line A- A. The intersection of the plane A- A and 
 one of the faces of the vertical prism shows in the front view as 
 
 8- 
 
 FIG. 247. Intersection of two 
 prisms. 
 
 FIG. 248. Intersection of two 
 prisms. 
 
 line a-a, and is crossed by the front edge of the square prism, 
 at point 1, which is a point on both prisms and therefore a point 
 in the desired line of intersection. Plane B-B is parallel to 
 plane A-A and contains an edge of the vertical prism and an 
 edge of the inclined prism which meet at point 2 in the front view. 
 Plane B-B also determines point 3. 
 
 These planes are called cutting planes and they may be used for 
 the solution of most problems in intersections. For intersecting 
 prisms pass planes through all the edges of both prisms within 
 the limits of the line of intersection. Where the lines cut from 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 127 
 
 both prisms by the same plane cross is a point on the required 
 line of intersection. In Fig. 248 four cutting planes are required. 
 The limiting planes are A-A and D-D as a plane in front of 
 A-A or back of D-D would cut only one of the prisms. 
 
 136. Intersecting Cylinders. To draw the line of intersection 
 of two cylinders, Fig. 249. Since there are no edges on the cyl- 
 inders it will be necessary to assume positions for the cutting 
 
 Fio. 249. Intersection of two cylinders. 
 
 planes. Plane A-A contains the front line of the vertical cylinder 
 and cuts a line from the horizontal cylinder. Where these two 
 lines intersect in the front view is a point on the required curve. 
 Each plane cuts lines from both cylinders, which intersect at points 
 common to both cylinders. The development of the vertical 
 cylinder, obtained by the method of Art. 125 is shown in the 
 figure. 
 
 The solution for an inclined cylinder is given in Fig. 250 where 
 the positions of the cutting planes are located by an auxiliary 
 view. To develop the inclined cylinder the auxiliary view is 
 used to get the length of the stretchout. If the cutting planes 
 have been chosen so that the circumference of the auxiliary view 
 is divided into equal parts, the measuring lines will be equally 
 spaced along the stretchout. 
 
128 
 
 MECHANICAL DRAWING 
 
 To develop the portion of the vertical cylinder having the hole 
 for the inclined cylinder, lay out a portion of the stretchout and 
 project from the front view to the measuring lines as shown. 
 
 FIG. 250. Intersection and development of two cylinders. 
 
 137. Intersecting Cylinders and Prisms. The intersection 
 of a cylinder and a prism is found by the use of cutting planes as 
 already described. In Fig. 251 a triangular prism intersects a 
 
 FIG. 251. Intersection and development of cylinder and prism. 
 
 cylinder. The planes ABCD cut lines from the prism and lines 
 from the cylinder which cross in the front view and determine 
 the curve of intersection as shown. The development of the 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 129 
 
 triangular prism is found by taking the length of the stretchout 
 line from the top view and the lengths of the measuring lines 
 from the front view. Since one plane of the triangular prism is 
 perpendicular to the axis of the cylinder, the curve of intersec- 
 tion on that face is the radius of the cylinder. 
 
 Fia. 252. Cylinder and cone. 
 
 FIG. 253. A cutting plane. 
 
 138. Intersection of Cylinders and Cones. The intersection 
 of a cylinder and a cone may be found by passing planes parallel 
 to the horizontal plane as shown in Fig. 252. Each plane will 
 cut a circle from the cone and straight lines from the cylinder. 
 
 FIG. 254. Cone and plane. 
 
 The straight lines of the cylinder cross the circle of the cone in 
 the top view at points on the curve of intersection, which are 
 then projected to the front view as in Fig. 253, where the con- 
 struction is shown for a single plane. Use as many planes as are 
 necessary to obtain a smooth curve. 
 
 9 
 
130 
 
 MECHANICAL DRAWING 
 
 139. Intersections of Planes and Curved Surfaces. The line 
 of intersection of a cone cut by a plane EE as in Fig. 254, may 
 be found by horizontal cutting planes A,B,C,D. Each plane 
 cuts a circle from the cone, and a straight line from the plane EE, 
 
 FIG. 255. Intersection of plane and turned surface. 
 
 thus locating points common to both the plane EE and the cone 
 as shown in the top view. These points when projected to the 
 front view give the curve of intersection. 
 
 The intersection at the end of a connecting rod is found by 
 passing planes perpendicular to the 
 axis, which cut circles as shown in the 
 end view of Fig.. 255. The points at 
 which these circles cut the "flat" are 
 projected back as points on the curve. 
 140. Development of Pint Measure. 
 To draw the development of a pint 
 measure, Fig. 256. Draw the view 
 shown with the half circles at top and 
 bottom in Fig. 257. Observe that the 
 body is a frustum of a cone. Extend 
 the outline to complete the cone. With MN as a radius draw 
 an arc. Step off one-half the circumference of the base on this 
 arc and draw the radial lines MK and ML. With M as a 
 center and MD as a radius draw arc PQ, completing the develop- 
 ment of the body. Add the necessary allowance for lap. 
 
 FIG. 256. 
 
GRAPHIC SOLUTIONS AND SHEET-METAL DRAFTING 131 
 
 To develop the handle divide it into a number of spaces 
 and step them off on the stretch out RS. At R lay off one- 
 half the width of the upper end of the handle on each side 
 and at S one-half the width of the lower end of the handle on 
 
 FIG. 257. Pattern for measure. 
 
 each side of the stretchout. Add allowance for laps and hems. 
 The true development of the lip would require the drawing of 
 lines through each point and finding the length of each line as 
 described for the truncated cone, Fig. 242. The usual practical 
 method is as follows, Fig. 258. On a center line oa draw an 
 
132 
 
 MECHANICAL DRAWING 
 
 arc with OA as a radius and space off one-half the circumference 
 of the top of the body on each side as shown by dad. Draw 
 the radii od. Increase OA by ac = AC and increase od by de 
 = DE as obtained from the elevation. Draw ce and the per- 
 pendicular bisector of ce intersecting the center line at g. With 
 
 FIG. 258. Pattern for lip. 
 
 g as a center and gc as a radius draw arc ece to complete the 
 pattern. Add the necessary material for seams and hems. 
 
 141. Seams and Lap. The basis of sheet-metal pattern draft- 
 ing is development. For practical work it is necessary to know 
 the processes of wiring, seaming and hemming, and the allow- 
 ances of material to be made. Open ends of articles are usually 
 
 FIG. 259. Wiring, seaming and hemming. 
 
 reinforced by enclosing a wire in the edge, as shown at A in Fig. 
 259. The amount added to the pattern may be taken as two 
 and one-half times the diameter of the wire. Edges are also 
 stiffened by hemming. Single and double hemmed edges are 
 shown at B and C. Edges are fastened by soldering on lap 
 seams, D, folded seams, E, or, the commonest way, by grooved 
 seams, shown in three stages, both inside and outside, at F. 
 An important consideration in allowing lap on patterns is the 
 shape of the space left at the corners to prevent thick places in 
 the seam. This is called notching, and is illlustrated on Figs. 
 257 and 258. 
 
PROBLEMS 
 
 133 
 
CHAPTER VIII 
 
 PROBLEMS 
 
 142. The important part of any course in mechanical drawing consists of the 
 working of a large number of properly selected and graded problems. The^probr 
 lems which follow are arranged somewhat hi the order of difficulty in each of ther 
 divisions of the subject. The methods of presentation vary with the requirements 
 of the problems. Graphic layouts are given wherever practicable as they are 
 definite and save time for both teacher and pupil. It is not necessary nor intended 
 that all the problems be worked, but that a selection be made by the teacher to suit 
 his own particular needs. A large number of references to text matter bearing 
 upon the methods of solution or principles involved are given in connection with 
 the problems. 
 
 Any or all of the drawings may be inked but the best results are generally 
 obtained by delaying this until the pupil has acquired the ability to make a good 
 pencil drawing. 
 
 One some of the sheets it may be found desirable to include a freehand pictorial 
 sketch in the style of Figs. 308 and 310, to indicate that the pupil has visualized 
 the object clearly. 
 
 The problems are designed for use on the size of sheet and layout given in 
 Fig. 260, but it is of course easily possible to use other sizes. 
 
 Fia. 260. Layout of sheet. 
 134 
 
PROBLEMS 
 
 135 
 
 143. Layout of the Sheet. Tack the 
 paper to the board as described in Art. 5. 
 The outside dimensions of the finished sheet 
 are 11" X 15" with margin lines and record 
 strip as shown in Fig. 260. The guide lines 
 for lettering the record strip must be drawn 
 very lightly. They should not be drawn 
 until ready to be used. On the laj^outs the 
 title for the^sheet in given. Where problems 
 ^Ve stated hi words the general title of the 
 sheet is printed in black face type. When 
 the following method is understood the 
 
 layout of the sheet should not take more 
 
 than two minutes. 
 
 FIG. 261. 
 
 FIG. 262. 
 
 Now with T-square draw horizontal lines 
 through horizontal marks as shown in Fig. 
 262. Next draw vertical lines through 
 vertical marks as in Fig. 263. Then 
 brighten up the trim and border lines and 
 the sheet will appear as in Fig. 264, ready to 
 begin a drawing. 
 
 On the following problems the figures 
 enclosed in circles are for locating the start- 
 ing lines and are always measured full size 
 regardless of the scale of the views of the 
 drawing. When such dimensions are given 
 
 The two minute method. Make two 
 short vertical marks near the bottom of 
 sheet, 15" apart. Measure and mark %" 
 in from the right hand end and 1" hi from 
 left hand end, Fig 261. Place scale verti- 
 cally near left edge of paper and make 
 short horizontal marks 11" apart. Measure 
 down %" from top and mark. Measure up 
 %" from bottom and mark. From last 
 mark measure %" up and mark, Fig. 261. 
 
 FIG. 263. 
 
 the lines which they locate should be drawn 
 first. Upon these lines the drawing is built. 
 Use light full pencil lines and work very 
 accurately as errors in starting often are 
 not evident until the drawing is nearly 
 completed. 
 
 FIG. 264. 
 
136 
 
 MECHANICAL DRAWING 
 
 Prob. 1. The first sheet, Fig. 265, is a one-view drawing of a templet. The 
 complete specification would require that the thickness of material and kind of 
 material be given. 
 
 NAME OF SCHOOL 
 LOCATION 
 
 (Date; I9_ APPROVED BY 
 
 FIG. 265. Prob. 1. 
 
 In this and the following three one-view problems the order of making the 
 drawing in progressive stages. These stages should be followed carefully as they 
 represent the draftsman's practice as to procedure in making drawings. 
 
 It is very necessary for the beginner to learn to draw in good form, and the 
 most important feature in this regard is the order of working. Do not simply 
 follow the explanations as being directions for the particular problem, but try to 
 understand the system and the reasons for it. This system, thoroughly mastered 
 at the start will apply to all drawings regardless of the number or complexity of 
 views and will develop the two requirements in execution, accuracy and speed. 
 
 (1) Lay out the sheet as described in 
 Art. 143. 
 
 (2) Measure 2%" from left border 
 line and from this mark measure 8%" 
 toward the right. 
 
 (3) Lay the scale on the paper verti- 
 cally near the left edge, make a mark 2" 
 up and from this measure 53^" more. 
 The sheet will appear as in Fig. 266. 
 
 FIG. 266. 
 
PROBLEMS 
 
 137 
 
 (4) Draw horizontal lines i and 2 
 with the T-square, and vertical lines 8 
 and 4 with T-square and triangle, Fig. 
 267. These four lines "block in*' the 
 figure. 
 
 FIG. 267. 
 
 (5) Between the two vertical lines 
 make marks 1%" apart, and from 
 lowest line of the figure measure two 
 distances vertically, 2>" and !>" 
 The sheet will appear as in Fig. 268. 
 
 FIG. 268. 
 
 (6) Draw the two horizontal lines 
 across the sheet. 
 
 (7) Draw the vertical lines, stop- 
 ping them on the proper horizontal 
 lines, Fig. 269. 
 
 FIG. 269. 
 
 (8) Brighten some of the lines and 
 erase others to obtain the finished 
 drawing, Fig. 270. 
 
 Write your name, sheet number 
 and date lightly in the record strip. 
 The record strip is to be lettered in 
 after the lettering problems have been 
 mastered. Trim the sheet to finished 
 size. 
 
 FIG. 270. 
 
138 
 
 MECHANICAL DRAWING 
 
 Prob. 2. To make a drawing of the stencil, Fig. 271. This drawing gives 
 practice in accurate measuring with the scale, a v nd making careful corners with 
 short lines. 
 
 NAME OF SCHOOL 
 LOCATION 
 
 (Date) 
 
 APPROVED BY 
 
 FIG. 271. 
 
 
 (1) Find the center of the sheet inside the border by laying the T-square blade 
 across the corners and drawing a short piece of the diagonals, Fig. 272. 
 
 (2) Through the center draw a horizontal center line and on it measure and mark 
 off points for the four vertical lines, Fig. 273. 
 
 Draw the vertical lines lightly with T-square and triangle. On the first one 
 measure and mark off points for all horizontal lines, Fig. 274. 
 
 (4) Draw the horizontal lines as finished lines, and measure points for the 
 stencil border lines on left side and bottom as shown in Tig. 275. 
 
 (5) Draw border lines and measure on them the points for ties, Fig. 276. 
 
 (6) Complete the border by drawing the cross lines as finished lines and bright- 
 ening the other edges, Fig. 277. 
 
 (7) Brighten the vertical lines and finish as in Fig. 278. 
 
 (8) Write name, sheet number and date in the record strip, and trim the sheet 
 to finished size. 
 
PROBLEMS 
 
 139 
 
 
 
 
 
 \x 
 
 
 
 
 
 
 
 
 /N 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 I 
 
 IG. 275 
 
 
 
 
 FIG. 273. 
 
 
 
 
 
 
 
 
 _ 
 
 
 
 
 
 
 
 
 
 
 
 " 
 
 
 \/ 
 
 
 
 \x 
 
 
 
 
 
 /> 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 I 
 
 'IG. 27^ 
 
 t. 
 
 
 FIG. 275. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 II II II II 1 
 
 
 
 
 
 
 
 
 . _ 
 
 
 
 
 
 
 
 
 := - 
 
 
 
 
 
 \ X 
 
 
 
 \/ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 := - 
 
 
 
 
 
 
 
 
 . _ ' ' * 1 
 
 
 
 
 
 
 
 
 1 11 M 1! II 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 I 
 
 ^IG. 27( 
 
 5. 
 
 
 FIG. 277. 
 
 
 
 
 
 
 acme 
 
 )C= 
 
 3DdDC! 
 
 
 
 
 
 
 D 
 
 
 D 
 
 
 
 
 
 
 II 
 
 
 D 
 
 
 
 
 
 
 D 
 
 D 
 
 
 a 
 
 o 
 
 
 
 
 
 
 nczDi: 
 
 nzz 
 
 3DCIZDD 
 
 
 
 
 
 
 
 
 
 FIG. 278. 
 
140 
 
 MECHANICAL DRAWING 
 
 Prob. 3. To make a drawing of the shim, Fig. 279. When circles and circle 
 arcs occur on a drawing, their centers are first located. The second step is to 
 locate the points of tangency, and make sure of smooth joints. 
 
 FIG. 279. Prob. 
 
 Before starting this problem examine the large compasses and bow pencil. 
 Be sure that the lead is carefully sharpened and that it is adjusted with the needle 
 point as shown in Fig. 11, Art. 10. Draw intersecting lines on a separate sheet 
 and practice handling of both instruments in drawing circles, carefully observing 
 the operations illustrated in Fig. 12 and 13. Awkward manipulation of the com- 
 passes is a severe handicap. 
 
 Tangents occur constantly on all machine drawings and must be drawn 
 quickly and neatly. Accuracy in setting the compasses to a required radius should 
 be practiced as any error is doubled when the diameter is measured. This test 
 should be applied frequently. 
 
 The needle point may be placed at the exact crossing of the two centerlines 
 by guiding it with the little finger of the left hand, resting the other fingers on 
 the paper. Art. Ill should be read and the tangent arc and tangent line con- 
 structions practiced until the student is thoroughly familiar with them. 
 
 FIG. 280. 
 
PROBLEMS 
 
 141 
 
 (1) Measure %" from left border 
 and from this mark measure 2^", 
 7", and 2%' thus locating four start- 
 ing points, Fig. 281. 
 
 (2) Measure vertical distances. 
 Sheet will appear as in Fig. 281. 
 
 FIG. 281. 
 
 (3) Draw horizontal and vertical 
 ines as in Fig. 282. 
 
 FIG. 282. 
 
 (4) Draw circle arcs with bow 
 pencil (Art. 10). Be sure to stop at 
 tangent points, which are located by 
 lines through the centers, Fig. 280. 
 The sheet will appear as Fig. 283. 
 
 FIG. 283. 
 
 (5) Brighten the horizontal lines 
 md finish as in Fig. 284. 
 
 (6) Write name, sheet number and 
 late lightly in the record strip, and 
 brim the sheet. 
 
 FIG. 284. 
 
142 
 
 MECHANICAL DRAWING 
 
 Prob. 4. To make a drawing of the shearing blank, Fig. 285. When a view 
 has inclined lines it should first be "blocked in" with square corners. Angles of 
 30, 45 and 60 are drawn with the triangles after locating one end of the inclined 
 line. 
 
 OP SCHOOL SHEARING BLANK 
 
 LOCATION Scale 3"=l' (DoteJ. 
 
 DRAWN 6Y 
 
 APPROVED BY. 
 
 FIG. 285. Prob. 4. 
 
 FIG. 286. 
 
 (1) Locate the vertical center line 
 and measure one-half of 3'- 9" on each 
 side, Fig. 286. Note that this drawing 
 must be made to the scale of 3" I' 
 (Art. 13). 
 
 FIG. 287. 
 
 (2) Locate vertical 'distances for top 
 and bottom lines. 
 
 (3) Draw main blocking-in lines as 
 in Fig. 287. 
 
PROBLEMS 
 
 143 
 
 FIG. 288. 
 
 FIG. 290. 
 
 FIG. 291. 
 
 FIG. 289. 
 
 (4) Make measurements for inclined 
 lines. The drawing will appear as in Fig. 
 288. 
 
 (5) Draw inclined lines with 45 
 and 30-60 triangles, Fig. 289. 
 
 (6) Brighten lines and finish as in 
 Fig. 290. 
 
 (7) Write name, sheet number and 
 date in the record strip, and trim to size. 
 
 144. Geometrical Constructions. 
 The working of a limited number of 
 geometrical exercises is valuable for 
 the practice in the use of instruments 
 and to give familiarity with the con- 
 structions which occur most fre- 
 quently. Such problems must be 
 worked very accurately, with a very 
 sharp pencil and comparatively light 
 lines. A point should be located by 
 two intersecting lines, and the length 
 of a line by two short dashes crossing 
 the given line. 
 
 The following problems are for use 
 in one-quarter of the working space. 
 Lay out the sheet as in Fig. 260 and draw horizontal and vertical lines to divide 
 the space into four equal parts, Fig. 291. 
 
 Prob. 6, Art. 102, Fig. 194. Near the center of the space draw a horizontal line 
 3-Ke" long and bisect it. 
 
 Prob. 6, Art. 102, Fig. 194. Near the center of the space draw a vertical line 
 3JiV long and bisect it. 
 
 Prob. 7, Art. 103, Fig. 195. Above the center of the space draw a horizontal 
 line 4% e" long. Divide it into five equal parts geometrically. 
 
 Prob. 8, Art. 103, Fig. 195. To the left of the center draw a vertical line 2%" 
 long and divide it into three equal parts geometrically. 
 
144 MECHANICAL DRAWING 
 
 Prob. 9, Art. 106, Fig. 201. Locate a point %" above lower line of space and 
 Yz" from left side. Draw lines joining this point with the middle points of the 
 upper and right hand sides of the space. Bisect the angle between these lines. 
 
 Prob. 10, Art. 106, Fig. 201. Locate a point %" below the middle of the upper 
 line of the space. Draw lines joining this point with the lower right hand corner 
 and with the middle of the left side of the space. Bisect the angle between these 
 lines. 
 
 Prob. 11, Art. 107, Fig. 202. Draw a vertical line 3^" from left edge of space. 
 From a point on this line %" below top of space draw another line making any 
 angle. Copy this angle so that one side is W from right side of space and vertex 
 is %" above bottom of space. 
 
 Prob. 12, Art. 107, Fig. 202. From the middle point of the left side of space 
 draw lines to upper and lower right hand corners. Copy this angle so that one 
 side is horizontal and 3^" above bottom of space. 
 
 Prob. 13, Art. 108, Fig. 203. Draw a horizontal line 4%" long and %" above 
 bottom of space. On this line as a base construct a triangle having sides of 3%" 
 and 2%". 
 
 Prob. 14, Art. 108, Fig. 203. Draw a vertical line 2%" long and %" from left 
 side of space. On it construct a triangle having sides of 4%" and 434". 
 
 Prob. 15, Art. 108, Fig. 206. Draw a horizontal line 4" long and 3" above 
 bottom of space. Using this as the longer of the two sides, construct a right 
 triangle by the "6-8-10" method. 
 
 Prob. 16, Art. 108, Fig. 206. Draw a horizontal line 3%" long and 1>" 
 above bottom of space. Using this as the hypotenuse, construct a right triangle 
 by the "6-8-10" method. 
 
 Prob. 17, Art. 109, Fig. 207. Draw a regular hexagon having a distance 
 across corners of 334"- 
 
 Prob. 18, Art. 110, Fig. 209. Draw a regular octagon having a distance be- 
 tween parallel sides of 3". 
 
 Prob. 19, Art. Ill, Fig. 210. Locate three points as follows: Point A 334" 
 from left edge of space and 3%" above bottom of space; B 4%" from left edge 
 and 2" from bottom; C 1%" from left edge and 134" from bottom. Draw a 
 circle through A, B, and C. 
 
 Prob. 20, Art. 113, Fig. 212. Locate a point K" from bottom of space and %" 
 from left edge. Draw lines from this point to middle of top of space and to lower 
 right hand corner. Draw an arc tangent to these two lines with a radius of \Y^" . 
 
 Prob. 21, Art. 116, Fig. 216. Draw an arc having a radius of 3", with its 
 center %" from top of space and Yi" from left edge. Find the length of an arc of 
 60. 
 
 Prob. 22, Art. 117, Fig. 217. From the left edge of the space draw a horizontal 
 line 13^" long and 134" below top of space. From right edge draw a horizontal 
 line 13^" long and 134" above bottom of space. Join these two lines by an "ogee " 
 curve. Point E to be one-third the distance from B to C. 
 
 Prob. 23, Art. 120, Fig. 221. Draw an ellipse having a major axis of 5" and 
 minor axis of 23^". Use concentric circle method. 
 
 Prob. 24, Art. 120, Fig. 221. Draw an ellipse having a major axis of 6" and 
 a minor axis of 1". Use concentric circle method. 
 
 Prob. 25, Art. 121, Fig. 222. Draw an approximate ellipse having a major 
 axis of 4J" and a minor axis of 334". 
 
PROBLEMS 145 
 
 Lettering. These exercises are for use in one-quarter of the working space of a 
 regular sheet (see Fig. 291). 
 
 For pencil letters use a long conical point. Rotate the pencil in the fingers 
 after each few strokes to keep the point symmetrical. 
 
 For ink letters use a penholder with a cork grip and set the pen well into the 
 holder. Always use drawing ink for lettering. To get clean cut letters it is 
 necessary to wipe the pen frequently with a cloth penwiper. 
 
 Problems are given for both vertical and inclined letters but only one kind 
 should be taught beginners. 
 
 Prob. 26, Fig. 292. Single stroke vertical caps. Lay out a sheet as in Fig. 291. 
 Starting with the top border line rule guide lines %" apart. With a pencil make the 
 letter I on the first line. Make each of the other letters six times. Make a careful 
 study of the letters with the order and direction of strokes as given in Fig. 24. 
 
 Prob. 27, Fig. 293. Make %" pencil letters. Complete each line (Fig. 24). 
 
 Prob. 28, Fig. 294. Make %" pencil letters. Complete each line (Fig. 24). 
 
 Prob. 29, Fig. 295. Vertical Figures. Make %" pencil figures. Complete 
 each line. 
 
 Prob. 30, Fig. 296. Rule guide lines %*" apart. Make the first two lines in 
 pencil. Make the next two lines very lightly in pencil and go over them with pen 
 and ink. Use 404 Gillott pen. Make the fifth and sixth lines in ink without first 
 penciling. 
 
 Prob. 31, Fig. 297. Single stroke vertical lower-case. Starting one inch from 
 left edge and one inch up, rule guide lines as shown. The bodies of the letters are 
 y%" high. The first space is %" up, the next KG", and the next { 6 ". Repeat 
 until there are guide lines for eight lines of letters. Make pencil letters shown and 
 complete each line (Fig. 25). 
 
 Prob. 32, Fig. 298. Same as Prob. 31, except directly in ink. 
 
 Prob. 33, Fig. 299. Rule as for Prob. 31. Copy the sentences, first in pencil 
 and then in ink as shown. 
 
 Prob. 34, Fig. 300. Single stroke inclined caps. Lay out a sheet as in Fig. 291. 
 Starting with the top border line rule guide lines %" apart. With a pencil make 
 the letter I on the first line. Make each of the other letters six times. Make a 
 careful study of the letters with the order and direction of strokes as given in 
 Fig. 30. 
 
 Prob. 36, Fig. 301. Make %" pencil letters. Complete each line (Fig. 30). 
 
 Prob. 36, Fig. 302. Make %" pencil letters. Complete each line (Fig. 30). 
 
 Prob. 37, Fig. 303. Inclined figures. Rule guide lines %" apart. Make each 
 figure six times in pencil. On the last line make the fractions (Fig. 30). 
 
 Prob. 38, Fig. 304. Rule guide lines ^ie" apart. Make the first two lines in 
 pencil. Make the next two lines very lightly in pencil and go over them with pen 
 and ink. Use 404 Gillott pen. Make the fifth and sixth lines in ink without first 
 penciling. 
 
 Prob. 39, Fig. 305. Single stroke inclined lower case. Starting one inch from 
 left edge and one inch up, rule guide lines as shown. The bodies of the letters are 
 }/%" high. The first space is }/%" up, the next KG", and the next f 6 ". Repeat 
 until there are guide lines for eight lines of letters. Make pencil letters shown and 
 complete each line (Fig. 33). 
 
 Prob. 40, Fig. 306. Same as Prob. 39, except directly in ink. 
 
 Prob. 40, Fig. 307. Rule as for Prob. 39. Copy the sentences first in pencil 
 and then in ink as shown. 
 
 10 . 
 
146 
 
 MECHANICAL DRAWING 
 
 IE :ET 
 
 z 
 
 HEEEZ I 
 
 FIG. 292. Prob. 26. 
 
 FIG. 293. Prob. 27. 
 
PROBLEMS 
 
 147 
 
 _ A IZI._ZZZZIZLE___.ZZZZZ 
 
 flEZZZZZZZI^TZZZZZZZ 
 _..... __ 
 
 _Q ^ j 
 
 tszzzziizzsizzzziz: 
 ^_L^^.ZI.ESESZSC:REWD. J 
 
 FIG. 294. Prob. 28. 
 
 ci:::::.::::i.:z 
 
 HZZZZZZ3 
 
 [ISIZZZIIZIE 
 
 t:^zz: 
 
 i 
 
 
 
 FIG. 295. Prob. 29. 
 
148 MECHANICAL DRAWING 
 
 i J;KLM:N:O P 
 
 
 ^TERTICAL : SINGLE.' STROKE:; 
 
 FIG. 296. Prob. 30. 
 
 ^ 
 
 ::::::::^p-:::::^ 
 
 , . | 
 
 ::oS3:ga^ffttes:j 
 
 i 
 
 FIG. 297. Prob. 31. 
 
PROBLEMS 149 
 
 aaaaa 
 
 bb 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 I 
 
 J 
 
 k 
 
 / 
 
 m 
 
 n 
 
 
 
 P 
 
 q 
 
 r 
 
 s 
 
 t 
 
 u 
 
 V 
 
 w 
 
 X 
 
 y 
 
 z. 
 
 Lower- case letters 
 
 a re used for notes and sub -titles. 
 
 FIG. 298. Prob. 32. 
 
 r 
 
 Words lettered In lower-case letters 
 are easier to read than when made in 
 capitals. These letters are made with 
 bodies two-thirds the cap height 
 
 FIG. 299. Prob. 33. 
 
150 
 
 MECHANICAL DRAWING 
 
 ..,- _.... y~ _*> - - -.*-=*-*- --, ,- - -.= 
 
 1 LLT FTLLh 
 
 ._/_.* .t^^,....J...... /....._/,. i^-, L. f .^,jL~~~. 
 
 FIG. 301. Prob. 35. 
 
PROBLEMS 
 
 151 
 
 
 
 \-'f / 
 
 s: 
 
 : 
 
 ! 
 
 :s 
 
 FIQ 302. Prob. 36. 
 
 5 
 
 FIG. 303. Prob. 37. 
 
152 
 
 MECHANICAL DRAWING 
 
 ABCDEFGHIJKLMNOPQRS 
 TUVWX YZ& 123456 789 O 
 ABC S 
 
 T O 
 
 INCLINED SINGLE STROKE 
 
 FIG. 304. Prob. 38. 
 
 
 :r:: rzrfr^f 
 
 
 FIG. 305. Prob. 39, 
 
PROBLEMS 153 
 
 i 
 
 
 
 
 aaaaaa 
 
 bb 
 
 c 
 
 d 
 
 e 
 
 f 
 
 g 
 
 h 
 
 
 
 j 
 
 k 
 
 1 
 
 m 
 
 n 
 
 
 
 P 
 
 q 
 
 r 
 
 s 
 
 t 
 
 u 
 
 V 
 
 w 
 
 X 
 
 w 
 
 z 
 
 Lower-c 
 
 ,as< 
 
 are used for notes and sub-titles 
 
 FIG. 306. Prob. 40. 
 
 
 In making inclined letters there are 
 two things to watch, first to keep a uni- 
 form slope, second to get the rounded 
 letters of the correct shape. 
 
 FIG. 307. Prob. 41, 
 
154 
 
 MECHANICAL DRAWING 
 
 145. Shape Description. Problems in the representation of objects by views 
 are to be drawn with the instruments and are for the purpose of giving a thorough 
 understanding of the theory of shape description, Chap. III. 
 
 Probs. 42, 43, 44, 45, Fig. 308. The working space is to be divided into fouri 
 equal spaces, Fig. 291. In each one of the spaces draw three views of the block 
 shown in the picture, Fig. 308. The dimensions are given on the partial views. 
 The student is required to draw three complete views of each object and when his 
 plate is completed it will appear as in Fig. 309. Use full size scale. Refer to 
 Article 26, Figs. 46 and 47. After completing the drawing, letter the record strip, 
 Figs. 260 and 310. 
 
 Probs. 46, 47, 48, 49, Fig. 310. Draw three complete views of each of the blocks. 
 Note that each block has an inclined surface. Refer to Article 26, Fig. 48. Locate 
 the views as shown. Do not copy the dimensions or picture unless require/! by 
 your instructor. 
 
 Prob. 50, Fig. 311. The front and side views of a support are shown and 
 located. Draw three complete views. 
 
 Prob. 51, Fig. 312. Given two views of a fulcrum. Draw three complete 
 views. First draw two views of the base, then draw the 60 lines using the 30- 
 60 triangle. The height of the fulcrum is found in the side view where the 60 
 lines cross, and then projected to the front view. Draw the top view to complete 
 the drawing. 
 
 Prob. 52, Fig. 313. Given top and front views of a cast iron dovetail. Draw 
 three complete views. In the top view note the center line and lay off one-half 
 of 1%" on each side of it. Draw 60 lines to intersect the %" depth line. 
 
 Prob. 53, Fig. 314. Draw three views of the dovetail joint with the two pieces 
 together. Note the 60 lines in the top view. 
 
 L 
 
 KZH 
 
 UQ-J 
 
 IAME OF SCHOOL- 
 LOCATION 
 
 SHAPE DESCRIPTION -BLOCKS 
 Full Size (Date) I9_ 
 
 DRAWN BY " 
 
 APPROVED BY. 
 
 FIG. 308. Probs. 42, 43, 44, 45. 
 
PROBLEMS 
 
 155 
 
 OF SCHOOL- I SHAPE DESCRIPTION -BLOCKS I DRAWN BY HH 
 
 LOCATION I Full Size (Date; I9_ I APPROVED BY. 
 
 Fia. 309. 
 
 OH 
 
 L 
 
 -m- 
 
 E OF SCHOOL 
 LOCATION 
 
 SUPPORT BLOCKS 
 
 (Dote; __ I9_ APPROVED BY 
 
 FIG. 310. Probs. 46, 47, 48, 49. 
 
156 
 
 MECHANICAL DRAWING] 
 
 - 
 
 NAME OF SCHOOL 
 
 (Date) 19. 
 
 I DRAWN BY 
 APPROVED BY_ 
 
 FIG. 311. Prob. 50. 
 
 NAME OF SCHOOL 
 
 LOCATION Full Size 
 
 FULCRUM DRAWN BY 
 
 (DateJ I9_| APPROVED BY_ 
 
 FIG. 312. Prob. 51. 
 
PROBLEMS 
 
 157 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 -,H 
 
 n 
 
 > 
 
 H 
 
 jt 
 
 -3 
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 H 
 
 
 ; 
 
 f 
 
 
 
 
 
 /* 
 
 -" 
 
 
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 V,e~ 
 
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 y 
 
 
 
 
 
 C 1 O 
 
 OVETA 
 
 
 
 
 PRAWN BV ... 6 EET 
 
 
 
 
 
 
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 FIG. 313. Prob. 52. 
 
 H 
 
 
 ,^ 
 K k 
 \ 
 
 
 
 
 I 
 
 1 
 
 13 
 
 - r^ 
 
 r * 
 
 * y 
 
 
 l//ff*v 
 
 NAME OF" SCHOOL 
 
 LOCATION I Full Sire 
 
 DOVETAIL JOINT 
 
 (Date)_ 
 
 I DRAWN BY: 
 APPROVED BV. 
 
 
 
 FIG. 314. Prob. 53. 
 
158 
 
 MECHANICAL DRAWING 
 
 146. Placing Views. The location of the views for the preceding problems has 
 been given. When making drawings from objects or for things which have not been 
 made, it is necessary for the draftsman to be able to place the views so that they 
 will go in the space to advantage. This is done by considering the space necessary 
 for each view and comparing the total room required with the size of the sheet. 
 
 FIG. 315. 
 
 Note the object of Fig. 315. The working space in our sheet is 9>" X 13%". 
 The top view will require 2" in a vertical direction and the front view 3%". 
 Allowing (say) 1" between views, the total is 6%". If we subtract 6%" from 
 the height of the space, we have 9K" less %" = 2%" to be divided between top 
 and bottom. In Fig. $16 the lowest line of the front view has been placed 1^" 
 
 r 
 
 
 A 
 
 JL.I 
 
 f 1 ~- 
 
 r~ 
 
 FIG. 316. 
 
 up which leaves 1%" above the top line of the top view. Thfe sum of the hori- 
 zontal dimensions of the front and side views is 8%". If we allow \W between 
 views there is left 3%" for the two side spaces. In Fig. 316 the left space is 1%" 
 and the right l%". It is not necessary to have the spaces_exactly alike either 
 between views or around them. 
 
 
PROBLEMS 
 
 159 
 
 FIG. 317. Prob. 54. 
 
 
 Prob. 54, Fig. 317. From the picture of the vertical holding piece, draw three 
 (bmplete views. First work out the placing of the views as described for Figs. 315 
 and 316. Do not dimension unless required by your instructor. 
 
 Prob. 55, Fig. 318. From the picture and part view of the post cap draw two 
 
 views. Work out the plac- 
 ing of the views before 
 starting the^drawing. Three 
 Views are ^not needed as two 
 of the three would be just 
 alike. 
 
 Prob. 56, Fig. 319. Draw 
 three complete views of the 
 bench hook. Work out the 
 placing of the views. Note 
 that the end view is to be 
 drawn by projecting from 
 the top view instead of from 
 the front view. This ar- 
 rangement is sometimes de- 
 sirable, as in this case. 
 
 Prob. 57, Fig. 320. 
 
 Draw three complete views of the book rack. Work out the placing of the views. 
 Show both ends in position on the base as the book rack would appear when put 
 together. Scale 6" = 1'. Add dimensions if required by your instructor. 
 
 Part Side K/e*v 
 
 FIG. 318. Prob. 55. 
 
160 
 
 MECHANICAL DRAWING 
 
 NAME OF SCHOOL 
 LOCATION 
 
 BENCH HOOK 
 
 (Oote;_ 
 
 I DRAWN BY 
 APPROVED BY_ 
 
 FIG. 319. Prob. 56. 
 
 NAME OF" SCHOOL 
 LOCATION 
 
 Scale 6"=l' 
 
 BOOK RACK 
 
 (Date>_ 
 
 DRAWN BY ~ 
 
 APPROVED BY_ 
 
 FIG. 320. Prob. 57. 
 
PROBLEMS 
 
 161 
 
 FIG. 321. Prob. 58. 
 
 Prob. 68, Fig. 321. Draw top and front views of the nail box. Place views 
 carefully. Draw full size. 
 
 FIG. 322. Prob. 59. 
 
 Prob. 59, Fig. 322. Draw three complete views of the step bracket. Place 
 views carefully. Draw full size. 
 11 
 
162 
 
 MECHANICAL DRAWING 
 
 Hole clear through 
 
 5 Diameter 
 
 FIG. 323. Prob. 60. 
 
 FIG. 324. Prob. 61. 
 
 Prob. 60, Fig. 323. Draw two complete views of the cast iron collar. Place 
 views as shown in the layout, Fig. 325. 
 
 Prob. 61, Fig. 324. Draw two complete views of the socket. Place views as 
 shown in the layout, Fig. 325. 
 
 NANNIE OF SCHOOL COLLAR AND SOCKET DETAILS I DRAWN BY: 
 
 LOCATION Full Size (Datej I9_ | APPROVED BY, 
 
 FIG. 325. Layout for Probs. 60 and 61. 
 
163 
 
 See text 
 for deta/. 
 
 Prob. 62, Fig. 326. Draw two complete 
 views of the centering plate. Place views 
 as shown in layout, Fig. 328. 
 
 Prob. 63, Fig. 327. Draw two complete 
 views of bearing. Place views as shown in 
 layout, Fig. 328. 
 
 Diameter 
 
 FIG. 327. Prob. 63. 
 
 CENTERING PLATE AND BEARING DRAWN BY 
 
 FUII Size (Date) I9_ APPROVED BV_ 
 
 FIG. 328. Layout for Probs. 62 and 63. 
 
164 
 
 MECHANICAL DRAWING 
 
 FIG. 329. Prob. 64. 
 
 Prob. 64, Fig. 329. Draw three complete views of the horizontal guide. Lo- 
 cate views as shown in layout, Fig. 330. Add dimensions if required by instructor. 
 
 NAME OF SCHOOL HORIZONTAL GUIDE 
 
 LOCATION Full Size (Dote) 
 
 FIG. 330. Layout for Prob. 64. 
 
PROBLEMS 
 
 165 
 
 FIG. 331. Prob. 65. 
 
 Prob. 65, Fig. 331. Draw three complete views of the bird feeding stick. 
 Work out the placing of the views as for Figs. 315 and 316. Draw full size. 
 After blocking in the three views, measure the depth of the holes on the top and 
 side views. Then draw the holes in the front view and project to the top and 
 side views. Show center lines for the holes. 
 
 147. Sections. As explained in Article 30, a sectional view shows an object as 
 if it had been cut and a part removed. The cut surface is indicated by section 
 lining with a fine line, generally at 45, spaced uniformly. The spacing is done 
 entirely by eye. In the following figures use the spacing of the first rectangle of 
 Fig. 159. 
 
 Prob. 66, Fig. 332. The layout for problem 66 is shown as a freehand sketch. 
 The student is required to make a mechanical drawing of the cylindrical spacer. 
 The right-hand view is to be drawn as a section, Art. 30. 
 
 Prob. 67, Fig. 333. The sketch layout for a clamping disc is shown in the 
 figure. Make a mechanical drawing. The right view is to be in section. 
 
 Prob. 68, Fig. 334. The sketch layout for a cast iron piston body is shown in 
 the figure. Make a mechanical drawing showing the left view in section. 
 
 Prob. 69, Fig. 335. The sketch layout of a protected bearing is shown in the 
 figure. Make a mechanical drawing showing the right view as a half section, 
 Art. 30, Fig. 73, 
 
 Prob. 70, Fig. 336. Draw three views of the yoke, the front view to be a sec- 
 tion. Note that there are two pieces, the yoke and the bushing. Read Article 
 30 in regard to section lines when two pieces are drawn together, Fig. 74. 
 
166 
 
 MECHANICAL DRAWING 
 
 FIG. 332. Prob. 66. 
 
 
 
 NAME OF SCHOOL. 
 LOCATION 
 
 CLAMPING DISC 
 
 (Date;. 
 
 DRAWN BY 
 
 19 APPROVED BY. 
 
 FIG. 333. Prob. 67. 
 
PROBLEMS 
 
 167 
 
 / 
 
 - 
 
 - 
 
 r 
 
 _ 
 
 
 
 i 
 
 [ i 
 
 
 
 i 
 
 ..V! 
 
 
 
 
 _Tfc 
 
 L, 
 
 
 
 i 
 i 
 
 
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 t 
 
 
 
 
 JL_ 
 
 ! 
 
 
 
 i 
 
 
 -- 
 
 H 
 
 
 i 
 i 
 
 
 <r - 
 
 1 
 
 | 
 
 
 i s . 
 
 
 *I 
 
 -*i*- 
 
 1 
 
 / 
 
 *|* e* 
 
 
 
 1 
 
 
 I 
 
 D 
 
 
 V.. 
 
 J 
 
 ,J 
 
 
 NAIV1E OF SCHOOL 
 
 LOCATION | Full Size 
 
 PI3TON BODY 
 
 (Date;. 
 
 DRAWN BY 
 
 j_ APPROVED BY_ 
 
 FIG. 334. Prob. 68. 
 
 JAME OF SCHOOL" PROTECTED BEARING DRAWN BY = 
 
 LOCATION Full Size (Date) I9_ APPROVED BY. 
 
 FIG. 335. Prob. 69. 
 
168 
 
 MECHANICAL DRAWING 
 
 NAME OF SCHOOL. I YOKE I DRAWN BY 
 
 LOCATION | Full Size (Date) I9_| APPROVED BY_ 
 
 FIG. 336. Prob. 70. 
 
 148. Auxiliary Views. Center or other reference lines are used in working 
 problems in auxiliary projection. See Arts. 31 and 32. 
 
 Prob. 71, Fig. 337. The figure gives the layout for two problems. Draw the 
 top, front and the complete auxiliary view of the rectangular prism as shown. 
 
 Prob. 72, Fig. 337. Draw the two views given and the complete auxiliary 
 view of the square prism. 
 
 Prob. 73, Fig. 338. The figure gives the layout for two problems. Draw the 
 views given and the complete auxiliary view for the dovetail moulding. 
 
 Prob. 74, Fig. 338. Draw the two views given and the complete auxiliary 
 view of the "half round." 
 
 Prob. 75, Fig. 339. A picture and layout for an angle stop are shown in the 
 figure. Draw the two views given and a part auxiliary view. The picture need 
 not be copied. Dimension if required by instructor. This is the form in which 
 auxiliary projection most frequently occurs in practical work, Art. 31, Fig. 80. 
 
 Probs. 76, 77, 78, 79, 80, 81, Figs. 340 to 345. Choice of any two of these 
 problems will require the same space as problems 71 and 72. Draw the two views 
 given and the complete auxiliary view on the center line indicated. 
 
 Prob. 82, Fig. 346. The figure gives the layout and picture of a hollow mould- 
 ing. Draw the two views given, and from these draw the complete auxiliary 
 view. 
 
PROBLEMS 
 
 169 
 
 NAME OF SCHOOL 
 LOCATION 
 
 AUXILIARY PROJECTION DRAWN BY 
 
 3 (Date) 19_ 
 
 FIG. 337. Probs. 71 and 72. 
 
 OF SCHOOL AUXILIARY PROJECTION 
 
 LOCATION Full Size (Date)- 
 
 FIG. 338. Probs. 73 and 74. 
 
170 
 
 MECHANICAL DRAWING 
 
 NAME OF SCHOOL ANGLE STOP DRAWN BY 
 
 LOCATION Full Size (Date) I9_ APPROVED BY 
 
 FIG. 339. Prob. 75. 
 
 r 
 
 
 (3 
 
 I 
 
 FIQ. 340. Prob. 76. FIG. 341. Prob. 77. FIG. 342. Prob. 78. 
 
PROBLEMS 
 
 171 
 
 FIG. 343. Prob. 79. FIG. 344. Prob. 80. 
 
 FIG. 345. Prob. 81. 
 
 NAME OF SCHOOL AUXILIARY PROJECTION DRAWN BY r^ 
 
 LOCATION Full Size (Date) 19 APPROVED BY _ 
 
 FIG. 346. Prob. 82. 
 
172 
 
 MECHANICAL DRAWING 
 
 NAME OF SCHOOL REVOLUTION 
 
 LOCATION Full Size (Date; I9_ 
 
 DRAWN BY : 
 APPROVED BY_ 
 
 FIG. 347. Prob. 83. 
 
 .NAME OF SCHOOL 
 LOCATION 
 
 REVOLUTION 
 
 (Date; _ 
 
 DRAWN BY 
 
 APPROVED BY_ 
 
 FIG. 348. Prob. 84. 
 
PROBLEMS 
 
 173 
 
 148. Revolutions. Prob. 83, Fig. 347. The figure shows the completed prob- 
 lem. This should not be copied but is given for comparison. The sheet is divided 
 into four spaces as shown. The first space is for three views of the object. In 
 space No. 2 (upper right hand) the object is shown after being revolved from the 
 position of space No. 1, through 45, about an axis perpendicular to the vertical 
 plane. 
 
 The front view was drawn first and the top and side views obtained by pro- 
 jection. In space No. 3 (lower left hand) the object is shown after being revolved 
 from position No. 1 through 30 about an axis perpendicular to the horizontal 
 plane. In space No. 4 the object has been revolved from position No. 2 through 
 30 about an axis perpendicular to the side plane (Art. 33). Problem 84 is to be 
 worked in the same way, using the dimensions given. 
 
 Prob. 84, Fig. 348. From the given views draw three complete views of the 
 object in the position indicated in each space. Read explanation of Problem 83. 
 
 Probs. 85 to 90, Fig. 349. These figures are given as alternates for problem 84. 
 Draw three views of the one selected, and revolve using the same positions and 
 placing as in Fig. 348. 
 
 Prob. 85. Prob. 86. Prob. 87. Prob. 83. Prob. 89. Prob. 90.] 
 
 FIG. 349. Probs. 85 to 90. 
 
174 
 
 MECHANICAL DRAWING 
 
 ISOMETRIC DRAWING 
 Full Size (Date)_ 
 
 DRAWN BV 
 
 _/9_ APPROVED SV_ 
 
 FIG. 351. Probs 91 and 92. 
 
 .1 
 
 - 
 
 NAME OF SCHOOL 
 LOCATION 
 
 ISOMETRIC DRAWING 
 
 (Date). 
 
 DRAWN BY 
 
 _I9_ APPROVED BV_ 
 
 FIG. 352. Probs. 93 and 94. 
 
PROBLEMS 175 
 
 149. Pictorial Drawing. When making isometric drawings it is necessary to 
 decide upon the point which will be taken for the center of the three axes. The 
 sometric cube with the two starting positions for the axes is shown in Fig. 350. 
 rhe position to use is given on the layout for each of the following problems. 
 Remember that all measurements must be taken parallel to the axes (Arts 34 to 
 40). 
 
 Prob. 91, Fig. 351. Draw the orthographic views as given for the block. 
 Construct the isometric drawing using the axes in the second position as started 
 on the layout. The heavy lines indicate the corner of the object from which the 
 axes start (Art. 35). 
 
 Prob. 92, Fig. 351. Draw the given views and an isometric drawing of the 
 lalf lap joint (Art. 35). 
 
 Prob. 93, Fig. 352. Draw the views 
 riven and an isometric drawing of the tenon. 
 Prob. 94, Fig. 352. Draw views given 
 and an isometric drawing of the mortise. 
 
 Prob. 95, Fig. 353. Make an isometric 
 Irawing of the notched block. Locate as on 
 ?ig. 355. Start with the corner indicated 
 >y heavy lines. 
 
 Prob. 96, Fig. 354. Make an isometric FIG. 350. 
 
 Irawing of the plate. Locate as on Fig. 355. 
 
 Prob. 97, Fig. 356. Make an isometric drawing of the stirrup. The drawing 
 is started on the layout, of Fig. 358. Note the heavy lines at the starting corner. 
 The slant lines of Fig. 356 are non-isometric lines (Art. 36). 
 
 Prob. 98, Fig. 357. Make an isometric drawing of the brace. The drawing 
 is started in Fig. 358. Note the 60 angle and read Art. 37 before making the 
 [rawing. 
 
 Prob. 99, Fig. 359. Make an isometric drawing of a cube each edge of which 
 measures 3". On each face construct an isometric circle by method of Art. 38. 
 
 Prob. 100, Fig. 359. Make an isometric drawing of a cylinder 2^" diameter 
 and 3^" high? resting on a square plate as shown. First draw the square plate. 
 )n it construct a square prism having sides of 2^2" and a height of 3}^". On the 
 ;op and bottom faces of the prism construct isometric circles. Vertical tangent 
 ines will complete the drawing. Note that the distance between these vertical 
 ines is more than the actual diameter of the cylinder. Why? 
 
 Prob. 101, Fig. 360. Draw the three views given of the hung bearing and make 
 an isometric drawing. Most of . the construction is indicated on the layout. 
 Vlake the drawing as though all corners were square and then construct the curves 
 [Art. 38). 
 
 Prob. 102, Fig. 361. Make an isometric drawing in section of the post socket. 
 Locate as on Fig. 363 (Art. 33, Fig. 95). 
 
 Prob. 103, Fig. 362. Make an isometric drawing as a half section of the box. 
 Locate as on Fig. 363 (Art. 39, Fig. 94). 
 
176 
 
 MECHANICAL DRAWING 
 
 T 
 
 1 
 
 K- 
 
 ?r 
 
 FIG. 353. Prob.^QS. 
 
 FIG. 354. Prob. r 96. 
 
 JAME OF SCHOOL. 
 LOCATION 
 
 ISOMETRIC DRAWING 
 
 (DoteJ. 
 
 DRAWN BY ZZH 
 19 _ APPROVED BV_ 
 
 FIG. 355. Layout for Probs. 95 and 96. 
 
PROBLEMS 
 
 177 
 
 FIG. 356. Prob. 97. 
 
 3f 
 
 FIG. 357. Prob. 98. 
 
 NAME OF SCHOOL ISOMETRIC DRAWING 
 
 LOCATION Full 5ize (Oote.L 
 
 DRAWN BY 
 
 _ (9 APPROVED BY 
 
 FIG. 358. Layout for Probs. 97 and 98. 
 
 12 
 
178 
 
 MECHANICAL DRAWING 
 
 NUMV1E OF SCHOOL 
 LOCATION 
 
 ISOMETRIC CIRCLES DRAWN BY rZ 
 
 Full S\ze (Date) ___ I9_ APPROVED BY_ 
 
 FIG. 359. Probs. 99 and 100. 
 
 FIG. 360. Prob. 101. 
 
PROBLEMS 
 
 179 
 
 ~i 
 
 "5 
 
 FIG. 361. Prob. 102. 
 
 FIG. 362. Prob. 103. 
 
 NAN/IE OF SCHOOL 
 LOCATION 
 
 ISOMETRIC SECTIONS 
 Full Size (Cta*eL 
 
 FIG. 363. Layout for Probs. 102 and 103. 
 
180 
 
 MECHANICAL DRAWING 
 
 FIG.- 364. Prob. 104. 
 
 FIG. 365. Prob. 105. 
 
 Prob. 104, Fig. 364. Make an oblique drawing of the angle using layout of 
 Fig. 366 (Arts. 42 to 44). 
 
 Prob. 105, Fig. 365. Make an oblique drawing of the crank. 
 Prob. 106, Fig. 367. Make an oblique drawing of the clock case. 
 
 ~ @~ 
 
 * 
 
 4AVIE OF SCHOOL- 
 LOCATION 
 
 OBLIQUE DRAWING 
 
 (Date;. 
 
 DRAWN BY 
 
 . _I9_ APPROVED BY. 
 
 FIG. 366. Layout for Probs. 104 and 105. 
 
PROBLEMS 
 
 181 
 
 FIG. 367. Prob. 106. 
 
 Prob. 107. Make a cabinet drawing of the bird feeding stick (Fig. 331). 
 
 Probs. 108 to 115, Fig. 370. Make freehand pictorial sketches of the objects 
 shown, in any of the methods studied. Problem 108 is illustrated in Fig. 368 as 
 it would appear when sketched in isometric and oblique drawing. The same problem 
 is shown in Fig. 369 as a single figure on one sheet sketched in angular perspective. 
 This sheet illustrates in general such assignments as may be made in pictorial 
 sketching from actual parts of machines or other objects. 
 
 As described in Arts. 46 and 47 a perspective sketch is drawn from the object 
 by estimating the directions of lines and proportions of lengths by observation, 
 testing with the pencil as the sketch proceeds. 
 
 To make a sketch in angular perspective when the orthographic views are given 
 instead of the object itself, the plan is first drawn with its front corner against 
 a line representing the picture plane, as shown in Fig. 369. A point S in front of 
 this corner is taken as the "station point" of the observer. Lines drawn from this 
 point to each point on the object cross the line of the picture plane and give the 
 widths of the picture. From S lines drawn parallel to the lines of the plan give 
 the vanishing points V and V. The line V-V then becomes the horizon. Below 
 the horizon draw the horizontal line G.L. called the ground line. At the intersec- 
 tion of G.L. and a perpendicular from the front corner of the plan, draw a vertical 
 line representing the front edge of the object. Vertical measurements are all made 
 on this line. A study of Fig. 369 will show the method of making the sketch by 
 vanishing the horizontal lines to their vanishing points and dropping perpendiculars 
 from the picture plane to locate the widths. 
 
182 
 
 MECHANICAL DRAWING 
 
 FIG. 368. Solution of Prob. 108 in isometric and oblique. 
 /" 
 
 4*. 
 
 FIG. 369. Solution of Prob. 108 in Perspective. 
 
PROBLEMS 
 
 C 
 
 FIG. 370. Probs. 108 to 115. 
 
184 
 
 MECHANICAL DRAWING 
 
 150. Size Description. Size description or dimensioning is a very important 
 part of mechanical drawing. The principles of Chapter IV should be applied 
 to the solutions of the following problems. 
 
 Prob. 116, Fig. 371. Three partial views of a slide rod carrier are given. 
 Make a complete working drawing with all necessary dimensions (Art. 49). 
 
 Prob. 117, Fig. 372. Make a complete three view working drawing of the 
 adjustable center. Locate the views carefully (Art. 146). 
 
 Prob. 118, Fig. 373. Make working drawings of the gland and bearing with 
 complete dimensions. The diameter of the hole (1") and of the hub (!%") 
 should be added to the gland. For the bearing the distance from the under side of 
 base up to center of hole is 2". The length of the hole is 1%", and the diameter of 
 the hole is %". 
 
 Prob. 119, Fig. 374. The figure is drawn half size. Make a full size working 
 drawing and dimension completely. Either the dividers or the scale can be used 
 to transfer the views to the student's drawing. Obtain dimensions by scaling 
 your drawing. 
 
 Prob. 120, Fig. 375. Copy the views double size, 
 views. Obtain dimensions by scaling your drawing. 
 
 Completely dimension the 
 
 J- L_ > 
 
 _i 
 
 h- 
 
 Nfi 
 
 NXXA/1E OF SCHOOL- 
 LOCATION 
 
 SLIDE ROD CARRIER 
 
 (Dote;. 
 
 DhAWN BV 
 
 APPROVED BY. 
 
 FIG. 371. Prob. 116. 
 
PROBLEMS 
 
 185 
 
 NAME OF SCHOOL 
 LOCATION 
 
 ADJUSTABLE CENTER 
 
 (Dare) i9_ 
 
 ORA*VN BV rrz; 
 
 APPROVEP 6Y_ 
 
 FIG. 372. Prob. 117. 
 
 text for missing dirheratonsf 
 
 NAME OF SCHOOL DIMENSIONING STUDIES I DRAWN BY 
 
 LOCATION Full Size (Date) 19 APPROVED BY_ 
 
 FIG. 373. Prob. 118. 
 
186 
 
 MECHANICAL DRAWING 
 
 I 
 
 f 
 
 I 
 I 
 
 I 
 
 FIG. 374. Prob. 119. 
 
PROBLEMS 
 
 187 
 
 FIG. 375. Prob. 120. 
 
188 
 
 MECHANICAL DRAWING 
 
 Prob. 121, Fig. 376. Make a complete working drawing of the lever. Give all 
 dimensions. Do not copy notes nor locations from the picture. The student 
 is required to draw dimension and extension lines. Fig. 377 is the layout for this 
 problem. 
 
 6J Center to Center 
 
 FIG. 376. Prob. 121. 
 
 FIG. 377. Layout for Prob. 121. 
 
PROBLEMS 
 
 189 
 
 Diam. of hub I 
 . . hole j 
 
 Prob. 122, Fig. 378. Make a 
 complete working drawing of the bell 
 crank. Give all dimensions. Do not 
 copy the notes from the picture. Fig. 
 379 is the layout. 
 
 Length 
 
 of hub ij 
 
 FIG. 378. Prob. 122. 
 
 NAME OP SCHOOL 
 LOCATION 
 
 BELL CRANK 
 
 _I9_| APPROVED BY. 
 
 FIG. 379. Layout for Prob. 122. 
 
190 
 
 MECHANICAL DRAWING 
 
 [See text for instructions] 
 
 NAME OF SCHOOL 
 
 LOCATION Half Size 
 
 (Datej __ I9^_ 
 
 APPROVED BV_ 
 
 FIG. 380. Prob. 123. 
 
 FIG. 381. Prob. 124. 
 
PROBLEMS 
 
 191 
 
 FIG. 382. Prob. 125. 
 
 Prob. 123, Fig. 380. Draw the two views of the rail, and locate dimensions 
 carefully. Scale 6" = 1'. The distances are as follows: 
 Stock is 1%" X 6" X 22". 
 Distance from A to B is 19%". 
 Distance from C to D is %". 
 Distance from E to F is I". 
 
 Prob. 124, Fig. 381. Draw two views of the saw horse, and completely dimen- 
 sion. Scale 3" = 1'. 
 
 Prob. 125, Fig. 382. Make a complete working drawing at the support. 
 Choose views and locate carefully (Art. 86). 
 
192 
 
 MECHANICAL DRAWING 
 
 Stretchout 
 
 NAME OF SCHOOL. DEVELOPMENT DRAWN BY _ 
 
 LOCATION Full Size (Date) |9__ APPROVED BY 
 
 FIG. 383. Prob. 126. 
 
 Prob. 126, Fig. 383. Develop the lateral surface of the truncated square 
 prism. Use the given stretchout (Art. 124). 
 
 Probs. 127 to 130, Figs.*384*to'387. Developjthejlateral surface. 
 
 384 
 
 \ 
 
 60' 60* 
 
 385 386 
 
 FIGS. 384 to 387. Probs. 127 to 130. 
 
 387 
 
 J 
 
PROBLEMS 
 
 193 
 
 Stretchout 
 
 <D 
 
 NAME OF SCHOOL DEVELOPMENT 
 
 LOCATION Full Sire 
 
 DRAWN BV=T 
 APPROVED BY 
 
 FIG. 388. Prob. 131. 
 
 Prob. 131, Fig. 388. Develop the lateral surface of the cylinder. Use the 
 given stretchout (Arts. 125 and 126). 
 
 Probs. 132 to 135, Figs. 389 to 392. Develop the surfaces. 
 
 389 
 
 390 391 
 
 FIGS. 389 to 392. Probs. 132 to 135. 
 
 392 
 
 13 
 
194 
 
 MECHANICAL DRAWING 
 
 4AIV1E OF SCHOOL 
 LOCATION 
 
 DEVELOPMENT 
 
 (Dote; I 
 
 DRAWN BY 
 
 APPROVED BY_ 
 
 FIG. 393. Prob. 136. 
 
 Prob. 136, Fig. 393. Develop the truncated rectangular pyramid. First 
 revolve edge 04 until its true length shows in the front view. Start with this edge 
 in the position shown to the right of the views (Arts. 129 and 130). 
 
 Probs. 137, 138, 139, Figs. 394, 395, 396. Develop the slanting surfaces. 
 
 
 
 
 *.- ' ,:^.4.'~ 
 
 FIG. 394. Prob. 137. FIG. 395. Prob. 138 FIG, 396. Prob. 139. 
 
PROBLEMS 
 
 195 
 
 NAME OF SCHOOL DEVELOPMENT 
 
 LOCATION Full Size (Dote)_ 
 
 DRAWN BY "3IZ 
 APPROVED BT 
 
 FIG. 397. Prob. 140. 
 
 Prob. 140, Fig. 397. Develop the lateral surface of the frustum of the cone 
 (Art. 132). 
 
 Probs. 141, 142, 143, Figs. 398, 399, 400. Develop the lateral surfaces of the 
 parts of cones. 
 
 FIG. 398. Prob. 141. FIG. 399. Prob, 142. Fio. 400. Prob. 143. 
 
196 
 
 MECHANICAL DRAWING 
 
 Center line for 
 , development of 
 i (Width o f handle I one ha/f 
 
 Width of handle * 
 
 \~ 3 "Di* 
 
 Center line for handle 
 
 ./IE OF SCHOOL 
 LOCATION Full Sire 
 
 PATTERN FOR MEASURE 
 
 (Date; 19 _ 
 
 DRAWN BY 
 
 APPROVED BY 
 
 FIG. 401. Prob. 144. 
 
 Prob. 144, Fig. 401. Make a complete development of the pint measure (Arts. 
 140 and 141). 
 
 FIG. 403. Prob. 146. 
 
 FIG. 402. Prob. 145. 
 
 Prob. 145, Fig. 402. Make a complete development of the_funnel. 
 Prob. 146, Fig. 403. Make a complete development of the scoop. 
 
PROBLEMS 
 
 197 
 
 Find lines of intersection . 
 
 L_3 
 
 t 
 
 NAIVIE OF SCHOOL 
 
 INTERSECTIONS 
 
 (Date) 19 APPROVED BY 
 
 FIG. 404. Probs. 147 and 148 (Art. 135). 
 
 f/nc/ lines of infersec tion 
 
 NAME OF SCHOOL- INTERSECTIONS DRAWN &f 
 
 LOCATION Full Size (Date; I9_ APPROVED BY_ 
 
 FIG. 405. Probs. 149 and 150 (Art. 136). 
 
198 
 
 MECHANICAL DRAWING 
 
 N/MVIE OF SCHOOL- INTERSECTIONS DRAWN BY 
 
 LOCATION full Size (Date) _ I9_ APPROVED BY 
 
 FIG. 406. Probs. 151 and 152 (Art. 137). 
 
 Find line of intersection and develop cylinder 
 
 4AME OF SCHOOL DEVELOPMENT 
 
 LOCATION Full Size (Date) I 
 
 DRAWN BY 
 
 > I APPROVED BY_ 
 
 FIG. 407. Prob. 153. 
 
PROBLEMS 
 
 199 
 
 FIG. 408. Prob. 154. FIG. 409. Prob. 155. FIG. 410. Prob. 156. 
 
 Prob. 164, Fig. 408. Find line of intersection and develop lateral surface of 
 the pyramid. 
 
 Prob. 155, Fig. 409. Find line of intersection and develop lateral surface of 
 the pyramid. 
 
 Prob. 156, Fig. 410. Find line of intersection and develop lateral surface of cone. 
 Any of the intersection problems may be used for development by solving one 
 problem on a sheet. 
 
200 
 
 MECHANICAL DRAWING 
 
 k// J 
 
 True fength diagram 
 here 
 
 NAME OF SCHOOL I TRANSITION PIECE DRAWN BV = 
 
 LOCATION | Full Size (Date; I9_J APPROVED BY_ 
 
 Fia. 411. Prob. 157. 
 
 Prob. 157, Fig. 411. Develop the surface of the transition piece (Art. 133). 
 Probs. 158, 159, 160. Figs. 412, 413, 414. Develop surface of transition 
 
 pieces. 
 
 FIG. 412. Prob. 158, Fia. 413. Prob. 159. 
 
 FIG. 414. Prob. 160. 
 
PROBLEMS 
 
 201 
 
 152. Screw threads and bolts. It is very necessary for a draftsman to know 
 the forms of screw threads and the conventional methods of drawing bolts and 
 screws. Threads are always understood to be single and right hand unless other- 
 wise specified. A right hand thread enters when turned clockwise. A left hand 
 thread enters when turned counter clockwise, and is always marked "L.H." on a 
 drawing. 
 
 Prob. 161, Fig. 415. In the left half of the sheet construct two complete turns of 
 a right hand helix whose diameter is 4" and pitch 1%" (Arts. 70 and 71). In 
 the right half of the sheet draw, as shown in the layout, the forms of the V thread, 
 U. S. Std. thread and square thread. Pitch l"(Art. 70). Letter the name of 
 each form under the drawing of it. 
 
 Prob. 162. In the left half of the sheet construct two complete turns of a right 
 hand helix whose diameter is 3" and pitch 2" (Arts. 70 and 71). Sometimes in 
 drawing a helix a templet is made by laying out the curve on a piece of cardboard 
 or thin wood and cutting out with a sharp knife. In the right half of the sheet 
 draw as in the layout Fig. 415, the forms of the U. S. Std. thread, Whitworth thread 
 and knuckle thread, 1" pitch (Art. 70, Fig. 139). Letter the name of each form 
 under the drawing of it. 
 
 HELIX AND THREAD FORMS DRAWN BY 
 
 (Date) I9_ APPROVED BV 
 
 FIG. 415. Prob. 161. 
 
202 
 
 MECHANICAL DRAWING 
 
 iE OF SCHOOL 
 LOCATION 
 
 THREAD REPRESENTATIONS 
 Full Size (DdteJ_ 
 
 DRAWN BY 
 
 )_ APPROVED BY- 
 
 FIG. 416. Prob. 163. 
 
 NAME OF SCHOOL 
 
 U.S. STANDARD BOLTS 
 
 (Dafej I9_ 
 
 APPROVED BY_ 
 
 FIG. 417. Prob. 164. 
 
PROBLEMS 
 
 203 
 
 Draw nut here. 
 
 E' OF SCHOOL 
 LOCATION/ 
 
 T/ASTENIN6S 
 
 (Dcte;_ 
 
 DRAWN BY 
 
 _ I9_ APPROVED BY . 
 
 FIG. 418. Prob. 165. 
 
 Prob. 163, Fig. 416. Locate center lines as shown and draw the conventional 
 thread representations given in the layout (Art. 71). These and several other 
 conventional forms are in use for representing screw threads, and are drawn here 
 for practice. On working drawings one of the forms should be selected and used 
 for all thread representations. The casting drawn on the right half of the sheet 
 has threaded holes represented conventionally under three different conditions 
 (Art. 71). 
 
 Prob. 164, Fig. 417. Locate the center lines. On the upper line draw a hex 
 head bolt and nut in the two positions shown, across corners and across flats. 
 
 On the lower line draw a square head bolt and nut across corners and across 
 flats (Arts. 73, 74, 75). 
 
 Prob. 165, Fig. 418. Divide the working space into four spaces as shown. In 
 the upper left hand space draw a stud and U. S. Standard nut. Diameter, %"; 
 length 5"; length of thread on each end IK"- In the upper right hand space draw 
 an S. A. E. St'd. bolt and nut. Diameter %"; length 4" (Art. 76, Table II). 
 
 In the lower left hand space draw three forms of cap screws, at A, B, and C. 
 Diameter % 6 "; length !>" (Art. 76, Table III). 
 
 In the lower right hand space draw three set screws, regular head, low head, 
 and headless. Diameter %"; length 1^" (Art. 76, Fig. 155). 
 
204 
 
 MECHANICAL DRAWING 
 
 FIG 419. Prob/166. 
 
 Prob. 166, Fig. 419. Make 
 a complete working drawing of 
 one of the plate couplings in 
 section. Show bolts and key 
 in position. Choose scale. Di- 
 mensions given in Table are 
 inches. 
 
 For \Y shaft use three W 
 
 bolts and % 6 " square key. 
 
 For \Y 2 shaft use three Y^" 
 
 bolts and %" square key. 
 
 For 3% shaft use six %" 
 
 bolts and %" square key. 
 
 For 4 shaft use six J- 8 " 
 
 bolts and 1" square key. 
 
 Missing dimensions are to 
 
 be supplied by the student. 
 
 Prob. 167, Fig. 420. Make 
 a three view working drawing 
 of the bracket bearing, com- 
 pletely dimensioned. Draw 
 full size. Locate the views as 
 described for Figs. 315 and 316. 
 
 / Diam 
 
 FIG. 420. Prob. 167. 
 
PROBLEMS 
 
 205 
 
 NAME OF SCHOOL CARRIER IRON 
 
 .OCATION I Scale 6*-' 
 
 APPROVED BY 
 
 Fio. 421. Prob. 168. 
 
 Prob. 168, Fig. 421. Make a three view working drawing of the carrier iron. 
 Scale 6" = 1'. Draw the front view as a section. Draw a bottom view instead 
 of the top view. 
 
 Design fo suit 
 
 Base i stock 
 
 AH other stock 
 
 FIG. 422. Prob. 169. 
 
 Prob. 169, Fig. 422. Make an assembly working drawing with complete 
 dimensions, for the book rack. Select views and scale. 
 
206 
 
 MECHANICAL DRAWING 
 
 ,X?// ho/es cored g d. 
 
 T 
 
 NAME OF SCHOOL RIBBED CAP 
 
 UOCATION Scale 6"= l' (Date; 
 
 DRAWN BY" 
 APPROVED BY_ 
 
 FIG. 423. Prob. 170. 
 
 Prob. 170, Fig. 423. Make a three view working drawing with complete 
 di m ensions for the ribbed cap. Show the front and side views as half sections. 
 
 Fio. 424. Prob. 171. 
 
 Prob. 171, Fig. 424.- Make a two view working drawing of the plug wrench. 
 Completely dimension. 
 
PROBLEMS 
 
 207 
 
 FIG. 425. Prob. 172. 
 
 Prob. 172, Fig. 425. Make a three view working drawing of the slide valve. 
 Show the front view as a section. Completely dimension. 
 
 Prob. 173, Fig. 426. Make a two view working drawing of the lever with all 
 necessary dimensions. 
 
 FIG. 426. Prob. 173. 
 
208 
 
 MECHANICAL DRAWING 
 
 Prob. 174, Fig. 427. Make 
 an assembly working drawing 
 with extra part views if neces- 
 sary, from which the costumer 
 might be built. Choose a 
 proper scale. 
 
 Prob. 175, Fig. 428. Make 
 a three view working drawing 
 of the rod bracket. Show 
 either the front or side view as 
 a half section. 
 
 Prob. 176, Fig. 429. Make 
 a three view working drawing 
 of the oil level gauge bracket. 
 Show the part of the front view 
 to the left of the irregular line 
 A- A as a section. A 134" pipe 
 tap has an outside diameter of 
 1.66". Ask your teacher about 
 pipe and pipe threads. 
 
 FIG. 427. Prob. 174. 
 
PROBLEMS 
 
 209 
 
 c 
 
 3 Core tor j bo/ts 
 
 NAME OF SCHOOL ROD BRACKET 
 
 LOCATION I Full Size (Ddte;_ 
 
 Fia. 428. Prob. 175. 
 
 SAE 
 
 li Pipe Top. 
 
 NAME OF SCHOOL OIL LEVEL GAUGE BRACKET 
 
 LOCXXTION I Full Size (Date) 19 _ APPROVED BV_ 
 
 [Fm. 429. Prob. 176. 
 
210 
 
 MECHANICAL DRAWING 
 
 Prob. 177, Fig. 430. Make an assembly working drawing with extra part 
 views if necessary, for the tea table. Some of the dimensions are not given, 
 and are to be obtained from the students' drawing. 
 
 FIG. 430. Prob. 177. 
 
 . Prob. 178, Fig. 431. Make a two view working drawing of the operating 
 wheel. Show the left view as a section. 
 
 Prob. 179, Fig. 432. Make a two view working drawing of the valve. Show 
 the left view as a section. Locate point A, and using it as a center draw an arc 
 with a 9^Hj" radius cutting the center line at B. With B as a center and same 
 radius draw arc to locate point C. 
 
PROBLEMS 
 
 211 
 
 FIG. 431. Prob. 178. 
 
 FIG. 432. Prob. 179. 
 
212 
 
 MECHANICAL DRAWING 
 
 FIG. 433. Prob. 180. 
 
 Prob. 180, Fig. 1 433. Make an assembly working drawing with necessary part 
 views for the book rack. 
 
 Prob. 181, Fig. 434. Make a complete working drawing of the fan bracket. 
 Draw top, front and left side views. Do not draw bottom or right side. 
 
 FIG. 434. Prob. 181. 
 
PROBLEMS 
 
 213 
 
 LAYOUT FOR FLANGE 
 
 FIG. 435. Prob. 182. 
 
 Prob. 182, Fig. 435. Make a two view working drawing of the 4%" X 
 steel crosshead pin. Note the size and kind of holes in the flange. 
 
 Drill for/ c 
 
 FIG. 436. Prob. 183. 
 
 Prob. 183, Fig. 436. Given the top, front, and left side views of the uncoupling 
 rod bracket. Make a working drawing showing the top, front, and right side views. 
 
214 
 
 MECHANICAL DRAWING 
 
 FIG. 437. Prob. 184. 
 
 Prob. 184, Fig. 437.^Make a three view working drawing of the center plate. 
 One view to be a section. 
 
 Prob. 185, Fig. 438. From the details make an assembly drawing showing 
 two views of the tool post. Dimension as required by your instructor. 
 
 Prob. 186, Fig. 163. Make a detail drawing of each part of the belt tightener. 
 If drawn full size, use two sheets. 
 
PROBLEMS 
 
 215 
 
 <__ 
 
 H-^ : 
 
 
 
 * 
 
 t 
 
 Tool Post- 3 fee/ forging 
 
 77 
 
 Wedge - Steel forging 
 
 Block- Cold rolled sfeel 
 
 FIG. 438, Prob. 185. 
 
216 
 
 MECHANICAL DRAWNIG 
 
 KITCHEN I 7- x 4 
 
 o'li'.rtlii" I a? n 
 
 DINING 
 
 LIVING RAT 
 
 7-2"xi2-; 
 
 POR.CH 
 
 L 1 I 
 
 KlKHErt& PANTRY 
 9y*9-i(*|4'-jo'| PINING 
 
 Mpi ' ' 
 
 FIG. 439. 
 
 FIG. 440. 
 
 FIG. 441. 
 
 HALL! 
 
 DINING 
 
 j 
 
 FIG. 442. 
 
 1 
 
 I 
 7-WIDE 
 
 LIVING 
 
 DINING 
 
 FIG. 443. 
 
PROBLEMS 
 
 217 
 
 FIG. 444. 
 
 Probs. 187 to 192, Figs. 439 to 444. Select one of the suggested floor plans 
 and make architectural working drawings as required by your instructor. 
 
 1. Basement plan. 
 
 2. 1st floor plan. 
 
 3. 2nd floor plan. 
 
 4. Front elevation. 
 
 5. Right side elevation. 
 
 6. Left side elevation. 
 
 7. Rear elevation. 
 
 8. Details. 
 
 (Arts. 94 to 100.) 
 
INDEX 
 
 Alphabet of lines, 64 
 Angles, 106 
 
 isometric, 44 
 to bisect, 107 
 to transfer, 107 
 Architectural drawing, 95 
 
 details, 103 
 
 elevations, 103 
 
 plans, 96 
 
 symbols, 104 
 Arcs and tangents, 109, 110, 111 
 
 length of, 111 
 
 to draw, 9 
 Arrow heads, 52 
 Assembly drawings, 86 
 Auxiliary views, 37 
 
 B 
 
 Bill of material, 69 
 
 Blueprinting, 82 
 
 Bolts, 74^77 
 
 to draw, 75, 76 
 
 S. A. E. standard, 78 
 
 various, 80 
 
 Bow pencil, 9, 10 
 spacers, 14 
 
 Cabinet drawing, 48 
 Calipers, 58, 59 
 Cams, 93 
 Cap screws, 78 
 
 table for, 79 
 Checking a drawing, 61 
 Circle, isometric, 45 
 
 tangent to, 109 
 
 to draw, 9 
 
 through three points, 109 
 Compasses, 9 
 
 use of, 10 
 
 Cone, development of, 120-123 
 Conventional representation, 89 
 
 symbols, 80 
 
 Cornice, pattern for, 120 
 Cross-hatching, 34, 36, 37 
 
 symbols for, 80 
 Curve, French or irregular, 10 
 Curved surfaces, representation of, 28, 29 
 Cylinder, development of, 117 
 
 Decimals, use of, 56 
 
 Detail drawings, 84 
 
 architectural, 103 
 
 Development, 114 
 of cones, 120-123 
 of cylinders, 117 
 of pint measure, 130 
 of prisms, 116 
 of pyramids, 120, 121 
 of transition piece, 123 
 
 Dimensioning, 51 
 
 assembled parts, 57 
 for standard bolt, 77 
 pictorial sketches, 60 
 rules for, 54, 55 
 theory of, 53 
 with limits, 56 
 
 Dimensions, placing, 52 
 of U. S. bolts, 74 
 
 Dividers, use of, 13 
 
 Dotted lines, use of, 28 
 
 Drafting, 84 
 
 Drawing, architectural, 95 
 cabinet, 48 
 isometric, 43 
 language of, 1 
 mechanical, 2 
 oblique, 47 
 perspective, 2, 49 
 pictorial, 42 
 sheet metal, 113 
 
 Drawing arcs, 9 
 
 219 
 
220 
 
 INDEX 
 
 Drawing board, 3 
 Drawing pencils, 4 
 Drawings, assembly, 86 
 
 checking, 61 
 
 detail, 84 
 
 shade line, 87 
 
 working, 84 
 
 E 
 
 Elbow, four piece, 119 
 two piece, 118 
 
 Ellipse, 111, 112, 113 
 approximate, 113 
 
 Erasing, 68 
 
 Finish marks, 61 
 Freehand sketches, 30 
 isometric, 46 
 perspective, 50 
 problems for, 32, 33 
 
 Gears, 91 
 
 Geometrical constructions, 105 
 
 Half sections, 36 
 isometric, 45 
 Helix, to draw, 71 
 Hexagon, to draw, 75, 108 
 
 Inclined letters, 17, 18 
 
 Inclined surfaces, representation of, 27, 
 
 28 
 Inking, 65 
 
 order of, 68 
 Intersections, 125 
 
 cylinders, 127 
 
 cylinders and cones, 129 
 
 cylinders and prisms, 128 
 
 planes and curved surfaces, 130 
 
 prisms, 126 
 Isometric drawing, 43 
 
 to make, 46 
 
 Laying out the sheet, 135 
 Learning to draw, 3 
 Lettering, 15 
 
 composition of, 19 
 
 inclined, 17, 18 
 
 roman, 20 
 
 spacing for, 19 
 
 titles, 68 
 
 vertical, 16 
 Line, to bisect, 105 
 
 to divide by trial, 13 
 
 to divide geometrically, 105 
 
 to divide with scale, 14 
 
 true length of, 120, 121 
 Lines, alphabet of, 64 
 
 dimension, 51 
 
 faulty, 66 
 
 shade, 87 
 Locknuts, 77 
 
 M 
 
 Machine screws, 78 
 Measuring, 11, 57 
 Mechanical drawing, 2 
 
 N 
 
 Needle point, adjustment of, 9 
 Notes and specifications, 60 
 
 Oblique drawing, 47 
 
 to make, 48 
 Octagon, to draw, 109 
 Ogee curve, 111 
 Orthographic projection, 24 
 
 Paper, attaching, 3 
 Parallel lines, to draw, 8 
 Pattern, for cornice, 120 
 
 for four piece elbow, 119 
 for pint measure, 130 
 for two piece elbow, 118 
 Pattern drafting, 114 
 ""Penciling, order of, 65 
 
INDEX 
 
 221 
 
 Pencils, drawing, 4 
 
 sharpening, 4 
 Pens, lettering, 15 
 Perpendicular lines, to draw, 9 
 Perspective drawing, 2, 49 
 Pictorial drawing, 42 
 Planes of projection, 25 
 Plans, architectural, 96 
 Prism, development of, 116 
 Problems, 134-217 
 
 freehand sketching, 32, 33 
 Projection, auxiliary, 37 
 
 orthographic, 24 
 
 principles of, 26, 27 
 Protractor, 107 
 Pyramid, development of, 120, 121 
 
 R 
 
 Revolutions, 39 
 
 chart for, 41 
 Roman letters, 20 
 Ruling lines, 5 
 
 S 
 
 S.'A. E. bolts, 78 
 Scales, 11, 12 
 
 choice of, 88 
 
 to construct, 105 
 Screw threads, 69-73 , 
 Seams and lap, 132 
 Sections, 34 
 
 isometric, 45 
 
 revolved, 90 
 
 symbols for, 80 
 
 through ribs, 89 
 Set screws, 79 
 Shade lines, 87 
 
 Shape description, theory of, 21 
 Sheet metal drafting, 113 
 Single stroke lettering, 15 
 Size description, principles of, 51 
 Sketches, freehand, 30 
 
 Sketching and measuring, 57 
 Slope for inclined letters, 17 
 Spacing, 13 
 
 guide line, 19 
 Specifications, 60 
 Square elbow, pattern for, 118 
 Stud bolt, 77 
 Surfaces, curved, 28, 29 
 Symbols, architectural, 103 
 
 conventional, 80 
 
 wiring, 104 
 
 T square, use of, 4, 5 
 Tangents, 109, 110, 111 
 Technic, 64 
 
 Theory of shape description, 21 
 Threads, screw, 71-73 
 Titles, 68 
 Tracing, 65, 67 
 Transition piece, 123 
 Triangles, position of, 7 
 
 to construct, 107 
 
 use of, 6, 7, 8, 9 
 True length of line, 120 
 
 U 
 
 U. S. standard bolts, dimensions of, 74 
 V 
 
 Vertical letters, 16 
 Views, auxiliary, 37 
 
 choice of, 88 
 
 describing objects by, 21 
 
 positions of, 23 
 
 sectional, 34 
 
 theory of relation of, 24 
 
 W 
 
 Wood screws, 79 
 Working drawing, 84 
 
Bl 
 
 14 DAY USE 
 
 RETURN TO DESK FROM WHICH BORROWED 
 
 LOAN DEPT. 
 
 This book is due on the last date stamped below, or 
 
 on the date to which renewed. 
 RenewecLbpoks are subject to immediate recall. 
 
 65 -5 PM 
 
 REC'CyS> 
 
 REC'D LD 
 
 
 DEC7 196508 
 
 REC'D 
 
 ^ ! 1963 
 
 -Q 
 
 LTOD- 
 
 1989 
 
 iDTODiSft HARol 1989 
 
 LD 2lA-50m-8,'61 
 
 General Library 
 University of California 
 
U.C. BERKELEY LIBRARIES 
 
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 UNIVERSITY OF CALIFORNIA LIBRARY