!» "mui- Class. Book_ i3-5La. Wo CqBiiglitN^_ COF^fRIGKT DEPOSm SHOP SKETCHING A COURSE OF PROBLEMS FOR MECHANICAL DRAWING STUDENTS By RALPH F. WINDOES Supervisor of Manual Arts, Rock Island, 111. Author of "Architectural Drawing for Secondary Schools," "Cedar Chests: How to Make Them," "Stories of the Industries," etc. THE BRUCE PUBLISHING COMPANY MILWAUKEE, WIS. 5 5^ Copyright 1919, by The Bruce Publishing Company M 1 1 f9fg ©CI.A529164 CONTENTS Page Preface --.-___ 5 General Statement ------ 7 Problems in Sketching ----- 13 The Perspective Protractor - - - - 26 The Circle in Perspective - - - - 30 Sketching on Cross Section Paper - - - 54 Supplementary Problems - - - - 56 PREFACE THE ability to rapidly make freehand sketches, either in perspective or orthographic, is one of the essential accomplishments of all good draftsmen. By this means they may interpret to persons not informed how to read working drawings. With this ability draftsmen are able to rapidly sketch some detail of a machine or a broken part too largo to carry to the drafting room, where a working draw- ing can be made from the sketch. A study of sketch- ing is one of the quickest means of learning how to read working drawings, as it does not involve ths r.bility to use the drafting instruments skillfully. These are only a few of the many advantages that are well known and appreciated by teachers — ad- vantages that have given shop sketching an important place in every mechanical drawing course. This text presents a carefully arranged and thoroughly tested course of problems in shop sketch- ing which will leave with the average student com- pleting it the ability to make sketches from objects; perspective sketches from working drawings : and the ability to accurately read working drawings. It should be given in the last half of the first year's work, or in the second year. Since so many students drop out of school after the first year, the latter part of that year is recommended for this work, as nothing can be given that has the practical ad- vantages of shop sketching. As much theory as possible has been omitted from this course. Technicalities concerning perspec- tive have been carefully explained, simplified, or left to a more advanced course. The one aim has been to impart to the student the knowledge and practice necessary to rapidly make clear and accurate free- hand shop sketches. - The work as arranged can be covered in one half year of five months when the students work forty- five minutes each day of the school week. This should take the average through plate twenty. Other plates have been added to supplement this work, lengthen the course, or to provide work for the more apt stu- dents. These more advanced plates will be of help where the course is used in normal and technical schools. EALPH P. WIISTDOES. General Statement Shop Sketching. The practical value of free- hand sketching can not be overestimated. It is not too much to say that nothing that can he given in an elementary mechanical drawing course is of more importance to the man who expects to advance in the profession, and the student just beginning his draft- ing course will do well to bear this fact in mind. Tracers and detailers — mere routine men — may be proficient without the abilit}' to make good, clear, and accurate freehand sketches, but the engineer and the designer must have this abilitj''. The inventor whose time is too valuable to spend in mechanical execution at the drafting board must be able to ma- terialize his thoughts by the means of freehand sketches, which will later be passed on to the drafts- men to execute. Definitions. Shop sketches may be of various kinds — as many kinds as there are modes of technical expression, though they are usually in one of two methods — orthographic or working sketches, and perspective sketches. Any one of the axonometric projections can be utilized — especially isometric — or cabinet projection may be used. As a general rule, sketches from objects which are to be later drawn up to scale in the regular manner will be made in ortho- graphic. Inventive sketches in either orthographic Figure 1 SHOP SKETCHING or perspective, and sketches that are used to explain working drawings to the uninitiated, in perspective. The camera, when properly focused, shows an ob- ject in true perspective. Figure 1 illustrates a library table from a photograph, Figure 2 is a perspective of the same table, and Figure 3 is its orthographic pro- jection. The close resemblance between the photo- graph and the perspective is very apparent, while the orthographic gives the exact appearance of the top, front, and side views as if each were viewed alone and the others could not be seen. Hence each view in the orthographic shows but two dimensions, while the perspective and photograph show three. This will make it apparent that at least two views are neces- sary in orthographic projection to properly show all three dimensions of length, breadth, and thickness. To the student who has made a study of orthographic projection these statements will come as a review. As stated before, all of the problems in this course will be made as freehand orthographic or perspective sketches. Figure 2 DRAViriNG MATERIALS REQUIRED. A 2 H pencil, a 4 H pencil, a pencil eraser, paper, drawing board, and thumb tacks are all the materials needed for the drawing work. The paper should have a rather hard surface as the rough surface of the ordinary drawing paper soils too rapidly. The plates are to be made on sheets measuring ll"x 15", which can be cut with- out waste from the standard size of 22"x 30". The pencils should be sharpened to long, conical points. r-T hv luL. 1 r K lill 1"! TOP V/E^\A/' 1 -■ ■ 1 1 1 11 '1 i ij II fj k lJ LJ rRotsjT \y/E:v\/ si^E \//E\A/ Figure 3 £ FT RULE l|l|l|l|l|l|l|l|l|l{l|MI|l|l|l|l| III oil l6 Igf 1| 2| 3, 41 ililililililiiiliiililili lilililihlililililiiiliiiliiilililiiilili i 12" STEEL RULE quTj5IDE f INSIDE CALIPERS PLUMB lllllllllllllll l|l|MI .|l|l|l II niiiiiiiHi iiiiiiii .. , 1 i llrlllllillllllllllllllllllllll lIlllllllllIlN i,i,i;|,ij COMBINATION SQUARE m SURFACE G^UGE Figure 4 GENERAL STATEMENT 11 Measuring Tools. A two-foot rule and a pair of calipers will be all the measuring tools actually needed for this course, but some additional tools will be of great help, especial^ when taking measurements of large or complicated machines and parts. These tools are all illustrated in Figure 4 and consist of, in addition to the tn^o-foot rule and calipers, a 12" steel rule or straight edge, plum bob, combination square, and surface gauge. How TO Sketch. All work on the drawing board should be done freehand. The T-square and tri- angles may be used in laying out the trimming edge of the plates, but for no other purpose. The vertical lines should be sketched as illustrated in Figure 5. The fingers grasping the pencil as in writing, control the movement entirelj'. The side of the hand rests upon the board, also the forearm. The lines are sketched downward, each one about one inch long, where longer lines are desired, and con- nected so as not to overlap. Vertical sketching is a finger movement. Figure 5 12 SHOP SKETCHING Horizontal lines are sketched as Figure 6 illus- trates. In this case the third and fourth fingers rest upon the board, as does the forearm. The lines are sketched from left to right, hinging at the wrist. This permits of drawing lines of about one inch and connecting them without laps for longer lines. Re- member, horizontal lines are drawn with a wrist movement, while vertical lines are drawn with a finger movement. Study the illustrations carefully and impress these methods strongly in mind. References : Crawshaw and Phillips — "Mechanical Drawing foi Secondary Schools." Phillips and Orth — "Mechanical Drawing." French — "Engineering Drawing." Figure 6 Problems in Sketching Plate Layout Plate Layout. Tack the paper on the draw- ing board near the upper left hand corner. Lay out the trimming edges of the plate, 10".x 141^", exact, using the T-square and triangles to pencil in these lines. Now put these tools away as all the rest of the work will be freehand. Sketch the border lines in with the 4 H pencil, estimating 1" in from the left hand trimming line, and %" in from the others. Sketch these lines as nearly vertical and horizontal as possible. Thia much will be done on every jjlate of the course, and is termed the plate layout. Plate 1 To draw the first plate, proceed as follows: 1. Draw the horizon line 21/2" down from the upper border line, using the 4 H pencil for all of this construction work, and estimating all dimensions. 2. Mark points in on this line for the right and left vanishing points }i" from the vertical border lines. 3. Draw a vertical line through the center, and establish point A 1%" down from the horizon on this line. TTote carefully that the two vanishing points are on the horizon and the vertical line through the horizon intersects it at the level of the eye of the person who is viewing the perspective drawn. 4. Estimate 1" down from A to B and sketch the horizontal line through this latter point. 5. Connect A and B with the vanishing points, being very sure that the angle of inclination on both sides of AB is the same. 6. This much of the work has been almost me- chanical ; now the student must estimate the distance between the vanishing lines that will give him the appearance of faces of a cube, and draw these vertical lines. Although the front edge AB of a 1" cube is 14 '(y-TJSCH //■' X/S " PiSBKB IO"Xl^k' TRIM e"X/3" BO R PER PL£TS ufiy-our i i^fc '-PjTs: -2f- PL^TE NO o T5T A T^TT* T A ^rj'^TT'n 16 SHOP SKETCHING 1", none of the remaining edges will measure true, since the faces are "foreshortened" as they approach the vanishing points. 7. When these lines have been drawn, connect their upper ends with the vanishing points, as il- lustrated, which will enclose the remaining faces of the cube. 8. If the cube appears as a true perspective, go over its outlines with the 2 H pencil, causing them to stand out from the construction lines. Eepeat with the border lines. ■ 9. Complete the plate by putting in the lettering as indicated on the copy, omitting the "instructions" and the dimensions in the circles. You have now drawn your measuring cube, the basis for all future dimensions in perspective. Ee- member the following points : a. Only the front edge is in its true length. b. The other lines do not actually measure 1", but they give that appearance. '-'OC/^C/V Figure 7 M£^3UPIIf\/G ,CUB£. VPL. - Vi^siiSMtr^e Poii\/-r I-£PJ- INSTRUCTJONS Copy TMia Pi^^re : FPfEEH/^r^o . PQjgiy laUL. COhJSTFIUCT ior~i L INeSS - l-l&HTUY WITH 4H PElslCIU Go 0\y£f? OUTL-ir^JES WITH < g/Y PEI^CIL. D^TE /\IO . Plate 1 18 SHOP SKETCHING c. This is due to the "foreshortening" of lines as they approach the vanishing points. d. The level of the eye as you are observing the cube is above the object, hence you see the upper surface. If the level of the eye is below the object, Plate 1. Lay out this plate as you did Plate 1. 2. Locate point A 5" in from the right hand vertical border line and 2>4" down from the horizon. At this point sketch your measuring cube. The lines to the VPR are estimated the same as those to the VPL which is located on the drawing. Your problem is to sketch a pile of 108 one -inch cubes, 36 in a layer, three layers high. 3. Draw two cubes directly below your measur- ing cube, remembering that the front edges are in their true length. you see the lower surface. If the level of the eye is neither above nor below, you see neither the upper nor the lower surfaces as- Figure 7 illustrates. e. In this particular kind of perspective which is known as 45 degree perspective, the angles of inclina- tion of similar lines are the same. 4. Connect the edges with VPL. 5. Between the upper converging lines, estimate the faces of six cubes. These will get smaller as tliey approach the vanishing point. 6. If they appear as cubes, drop vertical lines through the other converging lines. 7. Estimate the angles of inclination toward the right, and repeat. 8. Complete the construction by drawing the lines toward the vanishing points that will give the upper faces of the cubes. PEnsPsc 77 \/£ o^ ^ p/L.£: of=^ cubes INSTRUCTIONS THIT VPR rPIOM /?/VC^£ : of jr\ICLlN ~ flTlQM OP- TME SIMIUSS LJNES XQ THE . VPl- L^e^YS C ONS TPfUC T/ON L.«SieS IJ^J L-iGHT Omit oir^ENSioNs us; ciRcues . eUj£TE fs/O . Plate 2 20 SHOP SKETCHING 9. Go over the outlines of the cubes with the 2 H pencil. Omit the "instructions" and the dimen- sions in the circles. In this problem you have learned how to secure the measurements in perspective for any object, ex- amples of which will follow. Plate 3 This plate represents both an orthographic and a perspective sketch of a small block grooved through the center. It is to be copied freehand, observing the "instructions" on the copy. 1. Lay out the plate as before. 2. Sketch the orthographic, using the 4 H pencil for all of the preliminary work. 3. At point A, draw a measuring cube, and to the right and left of it draw two similar cubes, repre- senting a surface l"x 3"x 3". 4. As the block is 2" high, estimate another inch down from the measuring cube, thus forming your enclosing solid for a block 2"x 3"x 3". 5. Complete the construction of the perspective by drawing the groove through the center, as shown. 6. Go over the outlines of both the orthographic and the perspective with the 2 H pencil, leaving the dimensions on the orthographic light lines. 7. Draw a horizontal through the object for a table line. This will be done on all future perspec- tive drawings. In this example no vanishing points are to be located, the lines appearing to meet at some dis- tance off the drawing board. Remember that this is 45 degree perspective and the angles of inclination are the same on both sides of the vertical center. FREEHAND SKETCH OF GROOVED BLOCK -o- 3 - I- OR THOGR^PHIC PERSPECTIVE INSTRUCTIONS The: student is to m^ks d f^RE:EHi^rsio copy QE ZtiI2 PL£TE, £3T/M^TirslG f^LL. MEi^S - UREMEMT3 . OmiT DIMENSIONS IM ClfCLES ^NO CONSTRUCTION LIMES IN PERSPECTIVE . Pl-^-T£ /VO- Qj^te: N/SaE Plate 3 22 SHOP SKETCHING Plate 4 This plate involves new work in the form of an incompleted orthographic which is to be completed by the student, and lines in perspective other than vertical or horizontal. 1. Lay out the plate. 2. Sketch the orthographic as indicated, com- pleting it where lines are omitted. 3. Draw the "enclosing solid" as a 3" cube. 4. Since the upper edge of the prism comes exactly in the center, estimate IJ^" over from A and connect this point with the bottom edges by the means of slant lines. 5. Complete the plate as previously instructed. Note that the distance toward the front edge is greater than the same distance toward the far side, since the lines are foreshortened as they approach the vanishing points. This method may be used to locate any slant lines in perspective. Simply draw verticals and hori- zontals around the slant lines, and estimate the dis- tances on. the verticals and horizontals. The half-inch dimension of the lower edge of the prism must be estimated on the front vertical edge of the enclosing solid and carried back to the point where needed. All horizontal measurements are estimated on this edge since here they are in their true length. FRCEH/^ND 3KET_CH Of TRIi^NGULfilR PRISM (3) -J I O ORTHOGRAPHIC PE.P>3P£CTIVE INSTRUCTIONS Cosy THI3 PL./^T e r-p/ETEH/^hJO . COMPUETir^G THE WORKir-IO DRi^W- //VG. ElSTIM^TE ^L.U DII^ EI^rSIOl^S . £p- I^SE. /^UL . C OISSTPUC Tl Oi^ L-ir^E3 /}r^D Or-JIT DIMeMSIOIsIS ll-J CIRCl-ES. PL^TE NO Plate 4 24 SHOP SKETCHING Plate 5 The new work on this plate involves invisible edges. 1. Lay out the plate. 2. Sketch the orthographic, completing it where lines have been omitted on the copy. 3. Draw the enclosing solid representing a block 2i/2"x 4"x 4". Figure 8 illustrates the constructive lay-out. 4. Sketch the slant lines as you did on the last plate, and complete the left hand and upper surfaces. 5. Copy the invisible edges, noting that they follow the same principles as visible edges. 6. Complete the plate as before. Invisible edges are seldom used in perspective, since the idea, as with the camera, is to show an Figure 8 object as it would appear to a spectator. They have been included in this plate as a matter of practice. FREcZH.^ND QKgrrcH OF BJ-OCK h V PERSPECTIVE f^l^ TIC. Ut_ fiFf WITH THE Circles Q WORKINe. Op_ ORTHOGRi^PHlC . SKETCH PL./1TE /vp Plate 5 26 SHOP SKETCHING Plate 6 Make a working drawing and a perspective from some small straight line, square object assigned by the teacher. This may be a model joint, a geometrical solid, a block of some kind made for the purpose, or a small piece of furniture such as a footstool or taboret. Figure 9 gives suggestions as to type. In drawing the orthographic, sketch the views without taking any measurements. Estimate the measurements and draw the object as near to scale as possible. When the views are finished, put in the dimension lines, then the dimensions, which will be measured on the object with the rule. The Perspective Protractor Our previous examples have all been in 45 de- vertical touching the horizon at the level of the eye. gree perspective, that is, the angles of inclination of It is apparent that if the object is of irregular similar lines have been the same; hence the vanishing shape, much longer than it is wide or high, the 45 points have been the same distance each side of the degree perspective will not balance up well on the Figure 9 PROBLEMS IN SKETCHING 27 drawing. Hence we will construct a protractor that will be of help in solving problems involving irregu- lar dimensions. Figiire 10 Figure 10 illustrates the "perspective protractor." It is constructed as follows, using the regular draw- ing instruments : On a piece of heavy drawing paper or Bristol board, draw the vertical and horizontal center lines. With their intersection as center, draw two circles, one 1" in diameter, and the other 3" in diameter. Divide the larger circle into 24 equal parts, and, by the means of radials, divide the smaller likewise. From the divisions on the smaller circle draw hori- zontal lines to the right and left. From the same divisions on the larger circle draw verticals intersect- ing these horizontals. The intersection of these lines, as shown in the lower half of the construction, will locate points on the curve of the ellipse. The upper half is drawn in the same manner. Use the irregu- lar curve to obtain an accurate figure. Erase all construction lines within the ellipse, and connect radials to the points located on its curve, as in the upper half of the construction. Xumber these points in degrees — starting at the left hand end of the horizontal center line — 15°, 28 SHOP SKETCHING 30°, 45°, etc. With a sharp knife or scissors trim the ellipse carefully. Figure 11 shows the protractor in use in the drawing of a measuring cube. In this case the left hand edge makes an angle of 30 degrees with the horizontal, hence the right hand must be at 120 degrees since the corner of the cube is a right angle. If the left hand edge had been at 15 degrees, the right hand would have been at 105 degrees, etc. When the object is square on the front corner, there must be 90 degrees between the two faces represent- ing that corner in perspective. „ Figuie 11 Plate 7 This plate involves the use of the perspective protractor. It is largely a copy plate, but, as far as possible, each student should be assigned a different angle for the perspective, Place the working drawing nearer the center as your plate will not contain the "instructions." The sketching of the perspective is like the previ- ous work with the exception of the different angles. JA'/T i-g-i Of r- 3L. ocK INS TRUCTIO NS Copy th'5 ^L-^r^ f^Rf^ rr- CErSTCR p.- PL/^TE The : per spec ti\/e: P/^ W re NO Plate 7 30 SHOP SKETCHING Note that when the angles of inclination are not the same, the vanishing points ^vill be at difEerent distances from the front corner of the object. Plate 8 This plate requires no orthographic. The prob- lem is to make a perspective from the working sketch given. The long axis is to slope toward the left at 30 degrees on the perspective protractor. Figure 12 is from a photograph of this joint, which will be of some assistance in sketching the perspective. Figure 13 , The Circle in Perspective None of the previous plates have contained cir- cles or arcs of circles. This feature of the work will now be considered. All perspective circles are in the form of the ellipse. Figure 13 shows how they are formed on the Figure 12 SKEITCH Of^ .^C.^RF- L/Q//VT \ t 1 ( 1 1 i ■ ■' ■ i - 4 - ^ (\ 1 trtco ■ ■? ■ iniO -i- t ■ 1 ■ 1 J 1 1 [ j s-jO —J in!<0 < i ^3 1 1 .5.1. 3 , 3 , a 1 a a 1 ^4 /A/3 r/7 uc TION5 The stuoent /s to oq^w g persP£cti\/£: £f-reTCM f^PfOM Tf-fJS WOClKII\JG SKETCH - TH^ UOr^G /^AIS TO THE i Pi-^T£ : /WO Plate 8 32 SHOP SKKTCHING surfaces of a cube. Note carefully that the circles are tangent to the sides of the square faces where the center lines of the squares touch the outlines. This is apparent when the orthographic circle is considered^, since the circle is tangent to the square at the same points, Figure 14. Hence, in order to draw circles in perspective, enclose the circles in the orthographic with squares, draw the squares on the perspective with their center lines, and sketch in the perspective circles tangent at these four points. Arcs are treated in the same manner, though in this ease it is only part of the circle desired. After a little practice in this longer method, the student will be able to sketch in perspective circles and arcs without the aid of the squares. Figure 14 the: circl-E in perspective INSTRUCTIONS Sketch thre:b . 2" cuai^s which ia^ill encuose qyljn- OEPS 'Si SHOiVN. COMDl-ErjC THE P!IGHT OVL^IMOEFi w/vp QR_s}y the : l.e f^T with the : ci p!cl./= : ij^j the : /RIGHT M^hjp FHOE :. ER^SE COM3 TF> UC TIOM CUOBS on COr^PI-ETEO PU/^TE . d^te PLATE NO . N/^r^E Plate 9 34 SHOP SKETCHING Plate 9 This plate gives practice in the drawing of cir- cles and arcs in perspective. It represents three cylinders, two in the horizontal position, and one in the vertical. The instructions are given on the plate. In the horizontal position, the far side curve is not quite parallel with the front, but it is easily sketched if the far side face of the cube is put in and the curve made as directed before. The slight differ- ence is caused by the foreshortening. Erase all construction cubes on the finished plate, leaving the three cylinders with the table line. Plate 10 This plate is an application of the principles holes are sometimes indicated with a note, which previously learned, the object being a small machine part. The two view orthographic and the perspective are both required. Notice that in a working sketch, gives the size as well as the method of making them — "drill," "bore," etc. The student is to copy this plate. I I ! : ! SKETCH OF BR^CK^ T i^'Li^TE NO . D^TE N£IME. Plate 10 36 SHOP SKETCHING Plate 11 This plate is a further application of the prin- ciples stated. Here more curved surfaces are given. Note that on a perspective, curves that are not sharp, such as filleted corners on a casting, can only be in- dicated with short, curved lines. The photograph. Figure 15, will be of help when drawing the perspec- tive. Figure 15 PUf^tN RE,<>RINe "1 O.tL, )-HO(_-Z J: INs5 TRUC T IOM C C2£Y OF= -rt-f/3 PL.n PL^TE NO DfJTE NhJME Plate 11 38 SHOP SKETCHING Plate 12 This plate requires the completion of the top view in the orthographic, and a perspective sketch. Figure 16 will be of help in the making of this perspective. Bun the long axis to the left at an angle of 30° on the persj)ective protractor, since the eccentric is much longer than it is wide. Figure 16 ECCENTRIC SHiQFT INSTRUCTIONS Complete the working dq/^wii\g QBsvy 6 perspeictive : sketch ih this 5PBCE I PUi^TE NO MTE Nr=iM£ Plate 12 40 SHOP SKETCHING Plate 13 Plate 13 is a dimensioned perspective of a buffet, from which a two view working sketch is required. This sketch must be dimensioned completely, and in- side construction must be indicated. The student's knowledge of furniture construction will be of help in this; also working drawings of similar types will make good references. Dimensioned perspectives are not as practical as working sketches, as they usually consume more time in the making, and it is more difficult to show inside construction with them. But, for small, simple pieces such as washers, bolts, nuts, etc., from which work- ing drawings will be made later, they are sometimes used. And again, they are used occasionally when explaining what is meant by a working drawing to a craftsman who cannot read one. PEPSPECT/\y£ or &UFFET p •fla i rg ETgiEliEOjZn INSTRUCTIONS pRmy fj Tv/o VIEW wcai'iNO SKETCf FROM THIS PEPSPeC ? IV £ PL£TE rs/O Plate 13 42 SHOP SKETCHING Plate 14 This problem requires the sketching of a perspec- the plate well, as it will occupy the plate alone — the tive from the working sketch and the photograph, orthographic not being required. Figure 17. Make the sketch large enough to balance Put the dimensions on the perspective. Figure 17 L^THE. P^OT IN5 TRUCTI OIMS Mi^KE ^ PERSPEC TIVE 3K£TCH OF- THE Oe-JEC T FROM THIS WORKING SnCTQH . PuT ON PRINCIP/^L PlMENSIOI\l3 . Mf^KE SKETCH l-i^RGE EjNCUGH TO B/^L^NCE PL^TE. -J -j-.j.. I D^TE. /\yjme: Plate 14 44 SHOP SKETCHING n Plate 15 This problem is similar to the last — a dimen- sioned perspective alone being required. Note that in the side view, a full section is given on the plate. This is often done in working draw- ings since the inside construction can be more clearly shown. A section is an imaginary drawing. In this ex- ample, we have imagined that we have cut the piston on a center line through the two wrist pin bearings. We have then removed the front portion and drawn the remainder of the object. Where we have im- agined the saw to have cut the metal, we have drawn light 45 degree lines, known as "section lines." On future sketching plates from objects' show sec- tions if it will make the interior construction any clearer. Figure 18 S«5 g/VG//V£ PISTON /r^ 'S TRuc riONS •i2SiC£ H f^^i^S PEC Ti we : sKc^rc H of the Piston £H- t TO B>^L/=ir-JC£. PUf^T.^ J- 2' Soae I Plate 15 46 SHOP SKETCHING Plate 16 Make an orthographic and a perspective sketch of some small object selected by the teacher. Type suggestions are given in Figure 19. Place dimen- sions on the orthographic. When sketching from objects, take no measure- ments until the vievfs are sketched in. Estimate your proportions to scale as nearly as practical. That is, if you are sketching as nearly full size as possible, try to make your sketches show it in every view and every part. If the object is about 5" long, make it as near 5" as you can estimate, but have the length the same on both the top and front views. Have the width about the same on the top and side views. Have the height about the same on the front and side views. If you are reducing the object in size on the sketch, show this reduction evenly all the way through. "V\Tien the sketches have been completed — ^no measurements having been taken — put in the di- mension and extension lines. Put on the arrow heads, and then measure up the object. As each measurement is taken, put it down in its proper dimension line. When all have been completed, check it over to see if any dimensions have been omitted. Are the three dimensions given for every piece and every part? Are the sizes and centers of holes carefully located, etc.? Remember that in actual practice if a working drawing is being made from a sketch, the drafts- man must not take the time to go back to the object and measure it for missing dimensions. Every di- mension and every detail must be shown in the sketch. PROBLEMS IN SKETCHING 47 Figure 19 48 SHOPSKETCHING Plate 17 Figure 20 illustrates the body of a hanger and the front and side views, put on dimension lines, place it is required to make a working sketch from this the dimensions that are given, and estimate the figure. A few dimensions are given — just enough to others. This will give excellent practice in propor- secure correct proportions. The problem is to sketch tion and balance. Check your dimensions carefully. Figure 20 50 SHOP SKETCHING Plate 18 Make a perspective sketch from a piece of furni- ture, but do not dimension it. The cabinet shop projects can be used as models, or the tables, benches, stools, cases, desks, chairs, etc., in the drawing room can be utilized. Each student should be assigned a different project as far as possible. Finish these perspectives carefully, using the 2 H pencil sharpened to a long point for the finished pencilling stage. A small amount of shading and graining can be added to this dravi^ing if desired, but do not spoil the effect with too much. Figure 21 is a good sug- gestion. PROBLEMS IN SKETCHING 51 Plate 19 From a rather small, complicated object such as a valve, carburetor, etc., make a set of detailed orthographic sketches, and an assembly sketch. This luaj' require more than one sheet. If so, number them Plates 19-A, 19-B, 19-C, etc. This problem is no more difficult than a single object sketch, it simply requires more sketches. Each part should be drawn up as a single object, but the Figure 22 52 SHOP SKETCHING dimensions should be so carefully taken that the de- tailed parts will go together in the assembly with- out a conflict. Plate 20 This final plate of the sketching course is to be drawn up from some machine — ^a lathe, Figure 23, for example — a gas engine, or any large machine. The character of the work on this plate will be determined by the amount of time left to devote to it. Considering the lathe as an example, one student might detail the headstock, another the tailstock, another the tool rest, a fourth the bed, etc., thus com- pleting a set of sketches of a large machine. Or, if time permits, one student could do this alone, other students working on other machines. If the instructor desires any more perspective sketches, these machines might serve as models for this advanced perspective sketching. Figure 22 illustrates a few of the objects suggest- ed for this work. Sketching on Cross-Section Paper 54 SHOP SKETCHING Sketching on Cross-Section Paper Some draftsmen prefer to make their sketches on cross section paper. Figure 24 illustrates such a sketch. This practice has a number of advantages over the plain paper sketch, especially if the paper used is ruled off in inches and subdivided into eights. The vertical and horizontal lines can be eights of an inch. The vertical and horizontal lines can be used to guide tlie pencil in drawing straight lines, and the divisions make it easy to sketch to scale. The main difference between this method and the other is that it becomes necessary to take measure- ments from the object as the views are drawn if the correct scale is to be maintained. ^ In this course it is recommended that a few of the orthographic sketches be made on cross section paper in order to familiarize the students with this procedure. Another ruled paper that might be of help is the isometric paper now on the market. By its use isometrics can be sketched in' place of perspectives, but this is not to be recommended if the ability to make rapid perspectives is to be acquired. 1 : i 1 —\ 1 III r L 'j 1 ■- ' — ^- H^fM lo tH-Ji;? - i i>^~tS-J A j-'rj'JTliJ/^ii^; :",: Jrijt ' i' M / lri< 1 / ! 1.. L J i.tX 1 jj ; 1 iX^ 1 "* " 1 ^ 1 ■ i i f ' !* ' ' 1 1 1 r^[ ' 1 ^^ ' 1 1 1 ' i ! 1 i ^"^S* B**'*T i 11 i ! I ' 111 Jx'' ^ "^ 1 ' i I ' 1 ' -V^X i ' i ' ' j ' ' i ' ffl * " ' JT j : ^; 1 1 II I ' ! i f - -;--^J^ 1 , — -j ,-Jra -L ■ J — -1 1 ■ J-g^^ T . y M-ir+i-i-! L-L-, ! 1 , M Al 1 , i , - -^ ! !!i : '■ '' 'i — \ — V — 4irH: r-^-ry^z^-^w^^'^^^' i ^ 1 1 \-" — ■ — h 111 L ^. . ..- .... f /^ \ ' ' 'frbt > ! 1 r If,' i U^ 1 — 1 i I .4--' ■ 1 /*'^ J 1 ' ! 1 ,, 4 ^ Vv'liVy i "^-J-/ / II r;,!j --t-j- -- \^\tH| S-' 1 i T /I ^ ^ ' i tr ! - -- V i /i ! i 1 j 1 1 V. i ! ; 1 .'' 1 1 i 1 ' ' k 1 / i 1 ! \ \ :__.,:• 1 \ 1 A 1 i 1 f 1 \ •"Ts, 1^ ; ■ \ ' \ i i \ f i y ' ! i 1 1 i i ! ^(k ! W' J i/ i 1 M i ■ 1 1 L 4. \ i > jV / ! ' II 1 i 1 1 — .^f- ^^ -Ir IT ' < ■ Mill ^* i i ■ 1 , \t^ ij^ i 1 1 1 i „ ^^ ^^X-*^ 1 1 r j ■ ! i w' ~r 1 i ! i ' ■ i M- |r»^.^^-t^ 1 ■ ! ! i a L i i 14 . J ^ i , . i ; yi'/ rA/7v^-Oi -.^frt i^'6n ^ ja./M%oni^'.^ip-\ "2 "^ 1 i 1 M 1 i ill 1 _Ji,.,. M 1. 1 1 1 1 .III 1 Figure 24 56 SHOP SKETCHING Supplementary Problems The following plates have been added to sup- plement the course. They may be used in a number of ways. They may serve as additional plates for the more apt students to work upon while the slower are catching up; they may serve as regular plates in longer courses such as might be given in trade or normal schools; or they may be used to make regular mechanical machine drawings for the ma- chine drawing courses. Supplementary Plate 1 This plate represents a test plate to follow regu- lar plate 6. It contains less instructive material than the plates preceding, hence the students must use more initiative to work it out. No instruction should be given concerning it, and students should not be allowed to visit with each other nor look at each other's work while solving it. GROOVED BLOCK INSTRUC T!C!NS CO/^^L E rs THE -TOP WHVy Th±3 .Sf^jsss.- •6 P- I ■vl Supplementary Plate 1 58 SHOPSKETCHING Supplementary Plate 2 This plate represents two small machine parts in sketch and a copy of the perspective can be required dimensioned perspective. Its use may be restricted of each piece, to the drawing of working sketches, or a working PRILL Block T BLOCK Supplementary Plate 2 60 SHOP SKETCHING Supplementary Plate 3 A working sketch of a special wrench is illus- trated on this plate. One feature is a revolved sec- tion — a section at right angles to the center line at any chosen point to show the shape of the object at that point. A revolved section is often used to il- lustrate the shape of the spokes in fly-wheels and pulleys, and is sometimes drawn on the object itself rather than to the side as illustrated. The problem in sketching is to make a perspec- tive from this working sketch, or to make a similar sketch from a wrench furnished by the teacher. SPECML WRENCH V 1 / ,-/o 'a .IS ■7 O 'ifo '" 1 ^^>-i= i '^l& a ' y-ir r ! 11 * nT /^ 1 1 ^-v T L -i-« T Supplementary Plate 3 62 SHOP SKETCHING Supplementary Plate 4 Plate 4 illustrates two working sketches, one of a it being imaginea that a part of the object has been clamp handle such as is sometimes used to tighten broken away in order to show the threads. This is the tail stock of a wood lathe, and the other an S called a "partial section." wrenc . j^ jg suggested that perspectives be required of The clamp handle shows scre'w threads in section, these objects. WRENCH CL/3MP HANDLE. Supplementary Plate 4 64 SHOPSKETCHING Supplementary Plate 5 Many good problems in sketching can be secured sketches can be made from these perspectives, or in the wood shop. The footstool and taboret are similar sketches can be made from the working draw- very familiar objects to most students. "Working ings which the cabinet shop will have in abundance. T/^&OKET roQ-rs-rooi^ \ ^l N >i ■"N .15' Supplementary Plate 5 66 SHOP SKETCHING Supplementary Plate 6 The working sketch of a tumbling shaft bracket is a good example of a simple bearing. Notice that on the front view two full circles are represented, the large one being the hole bored out in the body of the bracket, and the small one the inside bearing suiface of the bushing which is driven or pressed in place. An oil liole tlirough both the bearing and the bushing allow lubrication for the shaft which move:3 back and forth in the bearing. A perspective from this working sketch is the required ijrobleni in this case. TUMBLING SH/^rr BR/^CKC; . Pfl't-L. ro.-^ 14:" SDLTS U- - 3S- ■-^ ;,-i & v y»-4=^— -^ »'^ ^ •T^TT^^^r --■ 3; Supplementary Plate 6 68 SHOP SKETCHING Supplementary Plate 7 This dimensioned perspective shows a valve yoke of it. Notice the manner of showing the curved such as is used on most types of locomotives. A edges in perspective, working sketch, completely dimensioned, is required \MIA/E YOKE WROUGHT IRON Supplementary Plate 7 70 SHOP SKETCHING Supplementary Plate 8 This bearing shows two views in full section. When it is necessary, any number of sections can be used to illustrate, clearly, the internal construction of a piece. A large object with many holes inside. such as the cylinder block of a gas engine, may re- quire at least a dozen sections, taken through various parts of the body. A perspective sliould be made of this project. Q/3E &OPy SIDE BE^RIN e FOR UP RErR. C£R3 M, I T, ! 5;- CfJST IRON Supplementary Plate 10 76 SHOP SKETCHING Supplementary Plate 11 The last three plates represent projects of interest to agricultural and architectural students. In the first the perspective of a watering trough is given. The principal dimensions are attached. The ability to make such sketches will be appreciated by the farmer who very often is called upon to ex- jDlain some part of his farm equipment to another person who is to build it for him. CONCRETE WATERING TPfOUOH Bo-TTOr^-l <3" TJ-4ICK Supplementary Plate 11 78 SHOP SKETCHING Supplementary Plate 12 The perspective of an ordinary window frame is head, stile, and sill, dimensioning the parts in the shown en this plate. regular manner. The student should draw sections through the UJih{DGyj F-fi.iq[v1Er •'"4 'DLir^P 3J0P H, Xl| puLLEry oyiLt H x^l •?TT'^^ 570P ix| 51LL l|x&| Supplementary Plate 12 80 SHOP SKETCHING Supplementary Plate 13 The problem presented on this plate is an inter- esting one to the student of agriculture. After solv- ing it and putting on its principal dimensions, he should have acquired the ability to make working sketches of simple structures of this type. If a neighbor owns a hog pen which the student's father wishes to duplicate on his farm^ it will be a very use- ful procedure for the student to measure up and sketch the hog pen in such shape that the building can -be built from his sketches without the need of further reference to the existing building. CHIOKEJN HOUSE 'r;%^;;!-l-'ffl| i .^ pfi sr* if as jLiieH^-fe? pi--k'..°' pE^CTiV7r IN5T QUCTiON5 O/^ T/i'/.S CHICKS^/ ^lOUSg. A'o 0//vf - l^i^f^ pk/5ri Supplementary Plate 13 INDEX Page Angle of Inclination 14 Board S Calipers 11 Circle in Perspective 30 Contents 3 Cross-Section Paper 54 Definitions 7 Drawing Materials 8 Enclosing Solid 20 Erasers 8 Foreshortening 16 Forty-five degree Perspective 18 Horizon Line 14 Horizontal Sketching 12 How to Sketch 11 Index S3 Inventive Sketches 7 Measuring Tools 11 Paper 8 Pencils 8 Perspective Protractor 26 Plate Layout 14 Plate 1 14 Plate 2 18 Plate 3 20 Plate 4 22 Plate 5 24 Plate 6 26 Plate 7 28 Plate 8 30 Plate 9 34 Plate 10 34 Plate 11 36 Plate 12 38 Page Plate 13 40 Plate 14 42 Plate 15 44 Plate 16 46 Plate 17 48 Plate 18 50 Plate 19 51 Plate 20 52 Plumb Bob 11 Preface 5 References 12 Rule 11 Section 44 Shop Sketching 7 Supplementary Plate 1 56 Supplementary Plate 2 58 Supplementary Plate 3 60 Supplementary Plate 4 02 Supplementary Plate 5 64 Supplementary Plate 6 66 Supplementary Plate 7 68 Supplementary Plate 8 70 Supplementary Plate 9 72 Supplementary Plate 10 74 Supplementary Plate 11 76 Supplementary Plate 12 78 Supplementary Plate 13 80 Square 11 Surface Gauge 11 Table Line 20 Test Plate 56 Vanishing Points 14 Vertical' Sketching 11 Working Sketches 7 . l!l'!!l|IUllll/ll)i! 1 ;,iil!ill'i'iiin;l;iMI I' III llliii lillill! Llnimm)' °'' CONGRESS 0019936900 ?l