i I ^ CEN 'Tu (nn^ /^%e. ? TOOLS FOR ENGINEERS AND WOODWORKERS •‘p'.'i'-f.' •‘®'..-f^' 'i^j-'i^iPi <. _i 'r 1 ~ ’fr .-J,-^ 6> ’■< *'*^15 ‘ 'gj*" . •>■.::« V , ■*/ . » 7 ft ^ -■ . J* . . , r \ 'v ' . ^.-H' li -■Ui '1' ft; tiDEf CC-rj J^;-*» ^ . S "■ O i '*A' • fr m i.'>>4-, r? . ' ■ s -, • ■3 ■ . .j'. TOOLS FOR MACHINISTS AND WOODWORKERS INCLUDING MODERN INSTRUMENTS OF MEASUREMENT. A PRACTICAL TREATISE COMPRISING A GENERAL DE¬ SCRIPTION AND CLASSIFICATION OF CUTTING TOOLS AND TOOL ANGLES, ALLIED CUTTING TOOLS FOR MACHINISTS AND WOODWORKERS ; SHEARING TOOLS ; SCRAPING TOOLS ; SAWS ; MILLING CUTTERS ; DRILLING AND BORING TOOLS ; TAPS AND DIES ; PUNCHES AND HAMMERS ; AND THE HARDENING, TEMPERING AND GRINDING OF THESE TOOLS. TOOLS FOR MEASURING AND TESTING WORK, INCLUDING STANDARDS OF MEA¬ SUREMENT; SURFACE PLATES ; LEVELS; SURFACE GAUGES; DIVIDERS; CALIPERS; VERNIERS; MICROMETERS; SNAP, CYLINDRICAL, AND LIMIT GAUGES ; SCREW THREAD, WIRE AND REFERENCE GAUGES ; INDICATORS, TEMPLETS, ETC., ETC. BY JOSEPH G. HORNER, A.M.I.Mech.E. Author of “ Pattern Making," Hoisting Machinery," etc., etc. ILLUSTRATED BY FOUR HUNDRED AND FIFTY-SIX ILLUSTRATIONS. NEW YORK THE NORMAN W. HENLEY PUBLISHING CO. 132, NASSAU STREET 1906 PREFACE. Teie object of this book is to give an account of such Tools as are commonly used by Engineers and Wood¬ workers, written chiefly from the standpoint of the men who have to use them, and who desire to understand the principles which underlie the forms in which those Tools are found. Practical instructions for their employment, as suggested by the writer’s own experience, have been added. The work (it is believed) is more comprehensive in its scope than any which has preceded it, the subject of Instruments of Measurement being treated in a very full manner and freely illustrated (as are all sections of the work) with drawings of leading types. Although, in strictness. Tools and Measuring In¬ struments form distinct groups, they cannot be separately regarded in shop practice, since modern methods of measurement are directly related to certain systems of manufacture, both general and special in character. The subjects treated here have never previously assumed such great importance as in recent years. Tool-making has been developed into highly specialised branches of manu¬ facture, different firms taking up different classes or groups of Tools and Instruments, with the perfection of results and fine precision that come of specialisation. Some of VI PREFACE. these results will be found here illustrated in book-form for the first time. The great and growing importance of Cutting Tools in modern practice is evidenced by the numerous experiments to which they have been subjected. But the experience of the shops still remains of highest value, and only in very general terms can these experiments be applied as yet to practical issues. As they relate to Lathe Tools chiefly, some account of them will be found in another work (now in the press) by the same Author, dealing with “ Engineers’ Turning.” • It should be mentioned that a large part of the matter included in this volume consists of selections from various articles contributed by the Author to the English Mechanic and the Mechanical World, which have been carefully re¬ vised and supplemented where necessary, but several chapters are chiefly or entirely new, and a substantial proportion of the illustrations given have been specially drawn and engraved for the work. JOSEPH HORNER. Bath, November 1904. CONTENTS. Introduction.— A General Survey of Tools. page The Term Tool Defined—Distinction between a Tool and a Machine —and an Appliance—Instruments for Measurement and Test— Broad Grouping—Machine-operated Tools, and Modern Manu¬ facture— Percussive Tools — Moulding Tools — Interchangeable System—The New Steels ------ i Chapter I.—Tool Angles. Knives and Razors—The Chisel Group—Planes—Chisels for Metal— Principles Underlying Tool Angles—Tool Formation—A Com¬ promise—Lessons from the Chisel—Angles Controlled by Charac¬ teristics of Materials—Shavings and Chips—Action of the Plane Compared with Metal Cutting Tools — Lessons Learned from Hand Tools—Rigidity of Tools—Summary of Practical Results— No Hard and Fast Rules—The Importance of Support Afforded to the Work and the Tools—and of Lubrication—Tools that Em¬ body the Chisel Action—The Scrape—Abrasion—Shearing—De- trusion—Tools which Occupy an Uncertain Position - - 6 SECTION L—THE CHISEL GROUP. Chapter H. —Chisels and Allied Forms for Woodworkers. Antiquity of Chisels—Primitive Forms of Stone, Bronze, and Iron— Single and Double-bevelled Chisels—Cutting Action—Angle and Edge—The Wedge Principle—Splitting Action—Operation by Thrust or Pressure—and Percussion—Importance of Rigidity— Angles of Grinding and Sharpening—Skill required for Operation —Methods of Holding—and of Thrusting—Grain—Plane Surfaces —Paring and other Chisels compared—The Axes and Adzes— Control of—Draw-knife—Carvers’ Chisels—Lock Chisels—Turning Chisels—Sharpening Chisels—Permanence of Edges—The Gouges —Antiquity of—Outside and Inside Types—Firmer and Paring— Millwrights’ and Coachmakers’—Curves of Gouges—Value of Paring Gouge—Carvers’ Gouges—Their Varieties—Method of Operation—Turning Gouges—How to Use 20 Vlll CONTENTS. Chapter III.—Planes, page Great Variety in—Setting of Chisel or Iron in its Stock—Fastening of the Iron—Convexity of Same—Choking—Utility of Top Iron— The Question of Angles, as affected by Re-sharpening—Linear Guidance—Related to Length of Stock—Preservation of Truth of Face—Planes for Concave Sweeps—The Profiles of Planes—Draw¬ backs to the Moulding Planes—Iron Planes—Gripping of Planes— Pressure on—Guidance of—Aids derived from Shooting, and Angle Boards—The Aid of Strips—Checking the Truth of Planed Surfaces—Details of Planing—Faces—Ends—Setting Irons in Stocks—Removal of Irons—Good and Bad Timber—Sharpening Moulding Planes—Wear and Tear of Planes-—Shooting—Mouth¬ pieces—Selection—and Preservation of Planes—Toothing Planes - 38 Chapter IV.—Hand Chisels and Allied Forms for Metal Working. The Cold Chisel—Cutting Angles—Shape—Breadth—Method of Use —The Cross-cut Chisel—Diamond Point—Cold and Hot Setts— and Gouges—Setts for the Steam Hammer—Nicking Chisel— Drifts or Broaches ------- 54 Chapter V.—Chisel-like Tools for Cutting Metal by Turning, Planing, &c. Roughing and Finishing Type—Roughing Tools—Finishing Tools— Parting Tools—Inside Tools—Tools for Planer and Shaper— Cranking—Overhang—Stiffness of Tool and Support—Roughing and Finishing Tools—Straightforward Tools—Cranked Tools— Broad Finishing—Slotting Tools ----- 58 Chapter VI.—The Shearing Action, and Shearing Tools. Shearing a Detailed Operation—Diagonal Cutting with Chisel—Fox Trimmer—Square and Skew-mouthed Rebate Plane—Turning Chisel—Reamers and Milling Cutters—Roughing Tools—Walker Planer Tool—Profiled Tool—Shear Blades—Necessity for Support to the Substance being Shorn—Staggered Cutting in Mills—Flat Drill—Combination of Shearing with Staggering - - - 69 SECTION IL—SCRAPING TOOLS. Chapter VII.— Examples of Scraping Tools. The Nature of the Operation—The Metal-worker’s Scrape—Some Wood-turner’s Finishing Tools—Arboring Tools—Fly Cutters 75 CONTENTS. IX SECTION III.—TOOLS RELATED TO BOTH CHISELS AND SCRAPES. Chapter VIII.—Saws. page Wide Scope of the Subject—Saw Teeth, Scrapes and Chisels—Shapes Varied to Suit Materials—Examples—Spacing—Types of Saws— Reciprocating—Continuous—Variations in Speeds—Tension of Blades—Thickness of Blades—Stiffening of Blades—Back Saws— Wear of Teeth—Degree of Set—Keeping Saws in Order—Set— Its Amount and Regularity—Methods of Setting—by Bending— by Hammering—Test of—Sharpening Saws—Topping the Teeth —by Stoning—by Filing—Files for Sharpening—Angles for Filing —Gulleting—The Use of Saws—Forcing—Buckle—-Packing—-The Place of Coarse and Fine Teeth—Holding Work—Cutting to a Line 78 Chapter IX.—Files. The Forms of the Teeth—Mode of Action—General Plmployment of Files—Sections—Derivations of—Longitudinal Forms—Degrees of Coarseness of Cut — Terms —- Special Files — Length — Special Handling -------- 93 Chapter X.—Milling Cutters. More Economical than Single-Edged Tools—^Multiplication of Edges— Discounted by Shallowness of Cutting—Rake—Durability—Spiral Twist—Period of Rest during Revolution—Question of Speeds—■ How Effected—Average Rates—The Work of each Tooth—Neces¬ sity of Keeping Edges Sharp—Heavy Feeds—Pitching of Teeth— Direction of Feeding—Varieties in forms of Cutters—Face and Edge Mills — Their Proper Spheres — Gang Milling — Devices Adopted in Building Up—Milling Parallel Grooves—The Wear of the Mills—Combinations of Edges—Angular Mills—The Case of Profiled Forms — Examples — Profile Milling Compared with Grinding—and Planing — Profiling Machines — Face Mills with Inserted Teeth—Methods of Insertion—and Securing—Advantages —Staggered Teeth in Solid Mills—Taper Shank Mills—Formed Mills—Lubrication of Cutters—Pickling - - - - 98 Chapter XL—Boring Tools for Wood. The Bradawl—The Performance of the Gimlet Type—Its Drawbacks— Bits, and Augers—Centre-Bit—Its Unbalanced Action—Expanding Centre-Bit—American Screw Bits—Forms of their Cutters—Their Advantages—Counterboring—Improved Braces b 120 X CONTENTS. Chapter XII.— Boring Tools for Metal. page The Drill—Variations in Flat Drills—Its Characteristics—Angles— Grinding—Twist Drills—Early Forms—Increase Twist—Constant ditto—Cutting Angles—Clearances—Effects of Grinding—The Point—Speed of Drills—Conditions which Affect Speed—Lubrica¬ tion—Oil Tubes—Shanks—Enlargement of Holes—Reamers— Boring Tools—Pin Drill or Counterbore - - - - 127 Chapter XIII.— Taps and Dies. Taps and Dies a Compromise—Difference between these, and Cutting with Lead Screw—Relation between a Tap and its Screwed Hole— Initial and Final Diameters—Sets of Taps—Operation of—Reliev¬ ing—Cutting Angles—Dies—Balance of Guidance and Cutting Power—Size of Master Taps, or Hobs—Action of Dies—Notches— Guide Screw Stocks—Dies in Screw Machines—Echolls Taps - 151 SECTNV.—PERCUSSIVE, AND MOULDING TOOLS. Chapter XIV. —Punches, Hammers, and Caulking Tools. The Punch—Spiral ditto—Taper of Punch—Burr—Various Punches— Drifts—Hammers—Varieties of—Force of Blow—Mallets—Caulk¬ ing Tools—for Plates—for Pipes - - - - - 160 Chapter XV. —Moulding, and Modelling Tools. Two Great Groups—That which is Related to Percussive Tools— Smiths’ Flatters, Fullers, and Swages—Their Co-relation to the Fibrous Characters of the Materials—Trowel Group—Plasterers’ Tools—Moulders’ditto—Cleaners—Sleekers of Various Sections - 168 Chapter XVI.— Miscellaneous Tools, and Tool Handles. Spanners—Wrenches—Ratchet Braces—-Woodworkers’ Braces—Tap Wrenches—Pincers—Pliers—Tongs—Tool Handles—Forms Used for Thrusting — for the Mallet — for Turning — for Planes — for Swinging—Summary - - - - - - 172 SECTION V.—HARDENING, TEMPERING, GRINDING, AND SHARPENING. Chapter XVH.—Hardening and Tempering. Distinction between Hardening and Tempering—Method of Heating— Precautions—Methods of Hardening—Quenching—Drawing Tem¬ per—Annealing—Mechanical Processes - - • - 182 CONTENTS. XI Chapter XVIII. —Tool Grinding and Sharpening. Hand Grinding — Variable Results of—Mechanical Grinding — Due Largely to Emery Wheels—Precision of—Natural Grindstones— Lack of Homogeneity—-Composition—Hardness and Softness— Glazing — Truing — Double Grindstone — Speeds of Running— Mounting—Water—Comparison between Grindstones and Emery Wheels—Grading—Speeds of Truing—Forms of Wheels—Wet Grinding—Tool Grinding—Tool Grinders—Examples of, for Hand Grinding—Grinding Woodworkers’ Tools by Hand—Plane Irons— Gouges — Sharpening —Wire Edge—Errors in Practice—Gouge Slips—Mechanical Grinding—Examples of Machines for Single- edged Tools—Sharpening Reamers—Milling Cutters, &c. - SECTION FI—TOOTS FOR MEASUREMENT AND TEST. Chapter XIX.—Standards of Measurement. Definition—Rule and Gauge Measurement—Standards—Temperature— Interchangeability—Limits of Accuracy—Early English Standards of Measurement—Basis of—Pratt & Whitney Standards—Details— Line Measures and End Measures—Refined Tests—Rules—Varied Forms of—Use and Wear—Scales—Forms of—Tapes—Rods Chapter XX.—Squares, Surface Plates, Levels, Bevels, Protractors, &c. Origination of Straight-edges—Care of—Surface Plates — Flexure— Plates for Standard Reference—Large Straight-edges—Winding Strips—Squares—Try Squares—Testing of—Method of Making— Combination Squares—Centre Squares—Bevels—Bevel Protractors — Scale of Chords—Set Squares — Levels — Wear of—Various Forms—Plumb Bobs ...... Chapter XXL—Surface Gauges, or Scribing Blocks. The Work of Lining-out—Preliminary Checking of Leading Dimen¬ sions—Centre Lines—Cardinal Dimensions— The Basis of a Level Table—Packing Up—Details—Scribing Block—Its Work—Illus¬ trations of its Use—Differences between Good and Bad Forms— Various Kinds—Refinements Described—Sciibers - Chapter XXII.—Compasses and Dividers. Distinction between Coarse and Fine Adjustment—Stiffness of Legs— Modified Forms—Combination Types—Trammels—Examples— Centring Balls—Parallel Dividers - ... PAGE 187 215 230 247 263 xii CONTENTS. Chapter XXIII.—Calipers, Vernier Calipers, and Related Forms. Essentials in Calipers—-Proportions—Weight—Adjustability—External and Internal Types—Capacity for Adjustment, How Met—Special Forms—How to Use Calipers—Examples—Compass Calipers— Keyway ditto—Vernier Calipers—Principle of the Vernier—Dif¬ ference between Vernier and Micrometer—Caliper Rules—With and without Verniers — Examples of Vernier Calipers — How to Read—Examples of Various Forms . . . . Chapter XXIV.—Micrometer Calipers. Principle of Design — Mechanism of—Details in Combination with Vernier—Taking up Wear—Various Forms Described—Horseshoe Type—Beam Micrometer Calipers—Screw Thread ditto—Gear Teeth ditto -------- Chapter XXV.—Depth Gauges and Rod Gauges. Measuring Depths, and Diameters—By Rod and Rule—Applications of Micrometer and Vernier to—Forms of Depth Gauges—Reading Dimensions—Refinements in Design—Combination Form—Rod Gauges—Examples ------- Chapter XXVI.—Snap, Cylindrical, and Limit Gauges. Horseshoe Calipers—Difference between Standard and Limit Gauges— The Newall System — Provisions against Wear — Accuracy of Cylindrical Gauges—and Horseshoe ditto—Examples of Gauges— Plug and Ring—Snap Gauges . - - . . Chapter XXVIL—Screw Thread, Wire, and Reference Gauges. Gauges for Grinding and Setting Screw Thread Tools—Thread Gauges —Combination Forms—Reference Gauges—Pipe Threads—Gauges for Holes for Screwing, and for Keyways—Wire Gauges - Chapter XXVIH.—Indicators and Templeting. Principle of Design—Examples—Relation to the Surface Gauges— Templeting—Templets and Jigs—Their Preparation—Weight— Stamping—Metric System ------ FAGB 271 287 300 309 317 327 INDEX - 334 TOOLS FOR ENGINEERS AND WOODWORKERS. INTRODUCTION. A General Survey of Tools. The Term Tool Defined—Distinction between a Tool and a Machine—-and an Appliance—Instruments for Measurement and Test—Broad Grouping —Machine-operated Tools, and Modern Manufacture—Percussive Tools —Moulding Tools—Interchangeable System-—The New Steels. I T is necessary to have a clear definition of the meaning of the word tool. What is a tool ? in what respect is it dis¬ tinguished from a machine, an appliance, an implement, or an instrument? The term is used in a very loose fashion, but the scope of this volume must be restricted to the legitimate meaning of the word. On first thoughts, it might seem as though the dictionary definition were correct—being any instrument of manual opera¬ tion, one dependent for its effect on the strength and skill of the operator. But, though that would hold good in a primary sense, and absolutely so, say about a hundred years ago, it does not by any means cover the legitimate meaning of the term to day. Such a definition would exclude all the vast numbers of tools which are held in and operated by machines, all of which are directly related to, or derived from hand tools, and, in some cases, are similar to, or identical with the latter. The machines themselves, however, do not come under the classification of tools, though this term is commonly and loosely applied to them, and also, and more correctly, the phrase machine-tools. These therefore will not receive any treatment in this volume. A 2 TOOLS. The distinction between a'tool and an appliance is also to be borne in mind. Anything by which the progress of work is facilitated we call an appliance, or in some forms, a templet, or a jig, the three terms denoting different objects. Just where to draw the line here is difficult. A spanner is a tool, but though a vice may be considered as a tool, it is strictly an appliance, since it holds, but does not operate on work. In these and kindred matters, the limitations of a volume must be borne in mind in making selection, and so only those articles which can be legiti¬ mately classed as tools will receive treatment. There is another large group of tools which are also termed instruments, being those employed for marking out, and in the measurement and testing of work. They are tools, because employed in and being essential to the conduct of manual opera¬ tions. The growth of, and the increased importance of these in recent years has been of a phenomenal character, and no treatise on tools from which these are to be omitted can now be con¬ sidered as in any sense complete. Having defined the sense in which we propose to regard tools, let us now see how the subject most naturally divides itself. First we have the two broad groups—of tools; and of instru¬ ments for measurement. The first includes a large number which we can classify broadly as follows, notwithstanding that overlap¬ ping occurs in some of the groups. Tools which act by cutting, by shearing, by scraping, by abrasion, by detrusion, by percussion, tools which operate by moulding on plastic, or on loose materials, and those of the lever class. And in connection with all except the last two, there is the question of the maintenance of maximum efficiency, by hardening, tempering, and grinding. Under the head of instruments of measurement are included tools used for marking lines, straight and circular, on work, for obtaining the geometrical relations of such lines, and for producing centres. These constitute several large groups. Another great class which includes several groups is employed for checking and testing the accuracy of work in progress and when completed. And these again include two important subdivisions—those which are employed for direct measurement, and those for measurement by the sense of touch or contact, e.g., rules, and gauges. Overlapping occurs in these groups, as in many cutting. INTRO D UCTION 3 shearing, and abrasive tools, in detrusive and shearing tools, and in those used for measurement and test by contact, combined with direct measurement. Tools of the lever class include spanners and clamps, pincers and pipe wrenches, tap wrenches, screwdrivers, and allied forms. Percussive tools form a very large group, for almost every trade has its own distinct group of hammers. Besides there are the hammers incorporated with machines. Moulding tools are used by plasterers, modellers, and iron and brass founders, and these are large groups. There is also the distinctly modern aspect of the study of tools, which must be indicated, because it looms so large in the practice of present-day engineering. The substitution of the machine-operated tool for the hand tool has been follow'ed and supplemented and modified extensively by a system of manu¬ facture known as the Interchangeable. The essential difference between this system and the older one is, that all similar pieces will interchange in the first, and that they will not in the second. That is, if a thousand pieces were thrown in a heap, any one picked up at random would fit at once in its position in any one of a thousand mechanisms of which it forms a part. Little know¬ ledge of machine work is required to understand that perfect interchangeability demands a very fine adherence to fixed dimen¬ sions. A variation of only a few thousandths of an inch makes all the difference between too close a fit and one too loose. Such fine dimensions are worked to in hand operations by a tedious pro¬ cess of fitting, of mutual adjustments, of trial and error. In this way perfect fitting of parts can be effected. But the important point is this, that much more than a close mutual fitting of parts is required if pieces are to interchange. They must all be to exact and absolute dimensions, which is quite another condition. There is almost an infinite 'difference between the mutual fitting of a few parts and of, say, a thousand similar pieces, the cost of which would be excessive if done by hand-operated tools. The difference is that between shaping pieces to exact gauged dimen¬ sions in machines, and their correction by the manual skill of the fitter after the work of the machines has been completed. Then the parts are mutually fitted only, but not to dimensions predetermined to some minute fractional parts of an inch or millimetre. 4 TOOLS. The difference is most important from the point of view of shop economies and of competitive manufacture. To put the case in a concrete fashion, suppose that small arms, sewing machines, and typewriting machines were each finished by the manual skill of the fitter, instead of being put together or “assembled,” as the parts come from the machines. The cost would not only be enhanced enormously, but whenever a part should require renewal, the entire mechanism, or a considerable portion of it, would have to be sent back to the factory to be refitted. It was in France first of all, in the manufacture of muskets, but subsequently in America, that the interchangeable system received its early development. Machines and accessories, jigs, templets, and special tools were designed at great cost, and with much labour, to ensure absolute uniformity in the dimensions of similar parts independently of the skilled craftsman, and with corresponding economy of labour and reduction in the cost of manufacture. Milling machines, screw machines, and the turret lathe were early employed in this work. The system reached its highest development in the United States, and from thence was imported to England, being applied at first to the manufacture of small arms. But the Americans subsequently adapted the system to the production of sewing machines, of watches, and numbers of small articles, and then lastly into the work of machine tool making. Many engineering firms in England and Germany have adapted their shop systems to the production of strictly interchangeable parts. It requires little prescience to see that on the extent to which this system is adopted, the vitality and permanence of many competitive firms will depend. I’here is an immense difference in machine manufacture carried on under such a system and the older one. In the latter, each machine is the product of high manual skill, made to order and singly, each part being produced and carried singly through all the departments, and subjected in the process of putting together to innumerable corrections at the hands of the skilled mechanic. No dimensions are gauged precisely, but corrected to fit “ full ” or “ bare,” as required for mutual fitting. In the new system, machines are produced, not by the labour of highly skilled, highly paid mechanics, but either by unskilled cheap labour or by skill of a low grade. Such close accuracy in INTRO D UCTION 5 absolute dimensions, produced in parts in large quantities at a low cost, are apparently antagonistic conditions. They are not so in fact in modern practice. They are obtained with ease, and with variations so slight that fine gauges are required to detect them. Parts are made an “ easy fit,” a “ tight fit,” a “ driving fit,” as desired, and, out of thousands, the percentage of misfits is very small. The difference between the old and’ the new, the heterogeneous and the uniform, the mutual fitting by skilled labour, and the absolute fitting to gauge, is wholly a question of machinery of an automatic or semi-automatic character. The broad contrast between these machines and methods and those which they displace is this : The provisions for cutting to the re¬ quired dimensions are embodied in the machines themselves, while in the older system accuracy depends on the care exercised by the attendant in checking the size of work while in progress. The movements of modern machines are not arrested until the work is finished, and the product is then removed without measur¬ ing it at the machine. The main difference is therefore that due to the substitution of automatic and semi automatic action and control for that of the workman. Another, the latest development in tools, relates to the material employed, the “ high speed steels,” by which output is trebled or quadrupled. These steels .date from 1900, when the Taylor White brand was exhibited at Paris. Many other brands are now in the market, and the remarkable result is that lathes are being re-designed to endure the stresses imposed by the new cutting steels, which are often capable of removing over a ton of cuttings in a day of nine hours. CHAPTER 1 . Tool Angles. Knives and Razors—The Chisel Group—Planes—Chisels for Metal—Principles Underlying Tool Angles—Tool Formation—A Compromise—Lessons from the Chisel—Angles Controlled by Characteristics of Materials—Shavings and Chips—Action of the Plane Compared with Metal Cutting Tools— Lessons Learned from Hand Tools—Rigidity of Tools—Summary of Practical Results—No Hard and Fast Rules—The Importance of Support Afforded to the Work and the Tools—and of Lubrication—Tools that Embody the Chisel Action—The Scrape—Abrasion—Shearing—Detrusion —Tools which Occupy an Uncertain Position. W E will now endeavour to trace rapidly the tool angle principle through many diverse forms, ranging from the keenest cutting tools to those which operate by scraping only. The principle on which the forms of cutting tools are based is traceable through many, and on first thoughts unrelated, types. Tools of the chisel form will cut anything from cork and leather to the tough and hard steels. The saw will sever wood, stone, brass, iron, and steel. The differences are simply different applications of the fundamental principles on which the tools are made. The keenest tools are the knife and razor, in which the cutting angles measure a few degrees only, seldom or never exceeding 20°. These are not required to sever or shave hard substances, and they therefore retain their edge for a reasonably long period. The next increase in angle occurs in the chisels and cognate forms for cutting soft and hard woods. The grinding angle here is increased to from about 20° to 25°, and we have our first examples of a sharpening facet, the angle of which with the permanent face is slightly greater than the grinding angle. This, however, is only a matter of convenience, because less time is occupied in sharpening such a narrow facet, than would be re¬ quired for sharpening all over the ground bevel. TOOL ANGLES. 7 Akin to the chisels in degree of angle, and in method of sharpening just noted are the gouges, draw-knife, hatchet, axe, adze, turning chisels, and gouges, carvers’ tools, and allied forms. A feature which all these have in common is, that no coercion is exercised upon them, save that of the workman’s hands. They can lay when in action flat against the work, or be tilted, and thrust, or driven to suit the shape of the surface of the piece operated on, and the object which the workman has in view. The chief distinction between the tools of this group is that of operation by thrust, as in the true chisels and gouges, and that by percussion, as in the hatchet, and adze group. Here, however, overlapping occurs, since most chisels can be operated either by 'hand thrust, or be struck with a mallet. In the next, and an important group, the chisel is controlled by the guidance of a stock of wood or metal, and becomes a plane. This is not a fanciful distinction, for ordinary chisels are so rigged up frequently in a temporary fashion, in a wooden block, for a special and temporary duty. The fixing of a chisel in a plane stock gives rise to a large range of possibilities, as a study of the immense range of the plane group reveals. There are several scores of distinct types of planes, and made in different sizes. Most are used for producing plane surfaces, but large numbers, have profiled forms, to reproduce the opposite sections, some sections being simple regular curves, others profiled, and moulded. Some have double irons, that is a break, or top iron in addition to the cutting iron. But from the point of view of angle, the principal thing to note is that the controlling face is no longer the face of the plane iron itself, but that of the stock in which it is rigidly embraced, and the iron does not lie flatwise on the work. Such being the case, we find great variations in the angles at which the irons are set in their stocks, the practical advantage of which is that the planes can be accom¬ modated to the cutting of diverse materials, hard and soft, harsh, stringy and knotty, or mild and sweet. In most cases the bevel is set downwards, or next the face, bringing the sharpened facet nearly into line with the surface of the work being cut, giving an “angle of relief.” In others the flat face is set downwards, and the iron is then fixed at a very low angle in the stock. Following the chisel form into the working of metals—the softer kinds, as lead and copper, being excluded—there is no 8 TOOLS. 1 example of a hand-operated chisel being used by simple thrust. Either the tools of this type are used percussively, as in the cold chisels, or if thrust, or drawn, it is done by the power of a machine. In each case the difference between metal, and timber and kindred soft materials is the reason for alterations in the cutting angles. These angles are much more obtuse for metal cutting, and they increase with the growing toughness and hard¬ ness of the metals, and depending also on whether a given material is being cut cold or hot. The percussive tools afford examples of this difference, the hot-sett of the smith and boiler¬ maker having keener angles than the cold-sett. The principles underlying the angle of a cutting tool are these: The edge formed by the meeting of the upper and lower facets must be sufficiently keen—that is, must possess sufficient wedge formation—to penetrate and sever the material; it must also be strong enough to retain its keenness of edge with reason¬ able permanence, without the need of frequent regrinding. The friction between the work and the portion of the tool adjacent to the edge must be reduced as much as practicable, and so, too, must the friction between the severed chip and the face against which it comes in contact. The result is that tool formation is always a compromise, a balancing of conditions:—a keen cutting angle and reduction of friction being opposed to the strength and permanence of the cutting edge. Thus in Fig. 6i, p. 58, which represents in profile a typical roughing tool suitable alike for turning and planing, shaping or slotting, it will be observed that the tool faces are all included a good way within 90°. If a tool filled up the angle of 90° it would not cut at all, but only scrape; nor would it have any clearance. The proper starting point from which to determine the shape of a tool is the angle of clearance a, which varies in practice from 3° to 15° or even 20°. 5° should be sufficient in any tool, because that affords just enough clearance to prevent friction between the face of the tool and the surface of the work next it, and the less the amount given, the more permanent, of course, is the edge, because it is well supported by the mass of metal that backs it up. In some tool grinders 10° is a standard clearance angle, and it is probably a general average. One reason why very small clearance angles often exist is, that in hand-grinding, men will just touch the tool near the edges instead of grinding down the entire TOOL ANGLES. 9 face, and this tends to thicken the edge, just as a woodworker’s chisel becomes thickened by sharpening a small facet, instead of rubbing across the whole bevel at which it leaves the grindstone. I'here is reason for this, but none for grinding a narrow facet only. A great deal can be learned about these tool angles from the common chisel, and planes of the woodworker, operated in good and bad order, and on soft and hard wood, since they are cousins- german to the tools of the metal-turner. A much keener cutting angle on a chisel can be adopted than on the iron-turner’s tool, simply because wood is softer than metal. The chisel has its angle of top rake, up which the shaving or chip curls (Fig. lo, p. 26). When the cutting angle of the chisel becomes thickened by repeated re-sharpenings, greatly increased force is required behind it to enable it to penetrate the wood. And a chi.sel ground and sharpened very keenly, cutting pine easily, will have its edge turned over against very hard wood, or its edge will sometimes even become notched and fractured, indicating the necessity for a slight increase in cutting angle. There is no front rake in the chisel; but, in fact, a workman usually tips the tool a very minute amount in taking a paring cut, and so intuitively gives a little front rake for easier working. The angle b in Fig. 61, p. 58, which is that of top rake, governs both the incisive action of the tool, and the amount of freedom of movement of the severed chip, while the angle c—the tool angle—-determines the strength of the tool and its perma¬ nence. The greater the slope of the top face the better for cutting fibrous metals, for reasons to be noted directly; but too much slope causes the tool to dig in, especially into crystalline metals and alloys. But the slope cannot be increased indefinitely, because the angle c would be reduced too much, with resulting weakening of the tool edge, which would be impaired rapidly. 'I'o realise these points it is only necessary to compare the razor, or newly-ground chisel for wood, with a tool angle of, say, about 15°, and a tool for cutting hard steel with an angle of, say, 80°. Average tool angles c, for average wrought iron, cast iron, and gun metal are 50”, 65°, 80°, or 90“ respectively. The angles of top rake b, just now referred to, will range from 35° to 40° for wrought iron, 20° to 25° for cast, and 10° to zero for gun metal. But these can only be accepted as fair averages, though for con¬ venience in shop systems, where grinding is done to gauge, it is lO TOOLS. desirable and usual to settle certain angles and adhere to them. It is better on the whole as regards results, because it favours the use of tool grinders and gauges, and of some kinds of tool-holders. The materials operated on by tools are hard, and soft, tough, and brittle, fibrous, and crystalline. Each occurs in extreme forms, and in a large range of intermediate grades. The varia¬ tions in the character of these materials help largely to explain the action of the tools of different classes. Comparing at extremes, soft wood, or leather, and hard, or tough steel, or brittle cast iron, it would seem almost incredible that tools formed on identical principles should be capable of cutting these strongly contrasted substances. The thickening of tool angles, therefore, cannot be considered alone, since it is related to the fibrous, crystalline, or other char¬ acteristics of the numerous and varied qualities of metals and alloys, and is controlled also by the angle of the cutting, and relief faces of the tool between which it is included. A wide angle is a very different thing from bluntness of edge. An edge must be keen and sharp for severing metal, as for wood, but in order that the edge shall retain its keenness for a reasonable time, it must be backed up by sufficient metal; in other words, by a wide tool angle. This is the principle which underlies the formation of the various metal-cutting tools of the chisel type, as will be explained in their proper sections. Other requirements have to be fulfilled, of course, such as the power necessary to sever the metal, dependent largely on whether the material is removed in the form of shavings, or chips. It is an axiom that if the severance of metal is to be effected with the minimum of power, then the more nearly the portion removed approximates in length to-the surface from which it was taken, and the larger and longer the shaving, or the longer, and less broken up the chips are, the more nearly will this con¬ dition be fulfilled. The distinction being shavings and chips is closely related not only to the nature of the material operated on, but also to the forms of the tools, and the various conditions under which they are used. To render this clearly understood by workers in wood, and in metal, the action of the plane iron can be compared with that of the tools of the iron-turner, and their cognate forms used on planer, or shaper. TOOL AJVGLES. 11 Take two planes exactly alike with regard to the angles at which the irons are set in the stock, and sharpened exactly alike, the only difference being that one has a single iron—the cutting one; and that the other has two—the cutting iron, and the back, or top iron. The first will throw off rough shavings, and leave a roughly planed surface; the second will, if the top iron is set close down to the edge of the cutting iron, produce silky shavings, of an even thickness, and leave a smooth surface. And in pro¬ portion to the hardness, harshness, cross grain, knottiness of the timber operated on, will these differences be in stronger contrast. In fact, in the extreme conditions of hardness, &c., the use of a single iron is impossible, the case of certain iron-stock planes excepted. The explanation of the difference is that the action of the top iron is coercive, that it bends the shaving over, and by causing it to turn, and curve, lessens the tendency of the cutting iron to tear or split the wood in wedgelike fashion. Putting it in another way, it resembles the difference between the combined wedging and splitting action of the axe, or adze, and the paring action of the chisel. In the metal-turner’s tools, we have the turning over of the shavings cut from those materials that are capable of bending, as the mild steels, wrought iron and copper, and in a lesser degree in the softer qualities of cast irons. It is in order to permit of this, that top rake is imparted to the roughing, and to many of the finishing tools. A larger angle of top rake would be given than is the practice, but for the fact that the tool would be weakened thereby. In theory the nearer the top face approaches the tangent to the work, the better for cutting. But as a wide angle—the tool angle—must be included between the top face and the front clearance angle, this limits the degree of .slope which can be imparted to the top face. The reason why greater slope is necessary for cutting fibrous metals like wrought iron, and the tougher steels, than for cast iron and brass, is that continuous shavings come off from the former, and chips, that break up instantly, from the latter. The shavings grind hard, and are curled against the top face of the tool, while the chips fall away directly. The more slope that can be given, therefore, to the tool face in the first instance, the better, while it is a matter of less importance in the latter. This accounts 12 TOOLS. for the common practice of turning brass with a scraping tool. The small chips fly off at once. But, all the same, it is better when roughing down brass to use a tool with some top rake. And, generally, the tougher the material, the greater in reason' should be the slope of the top face of the tool, in order to permit the cuttings to roll off more easily. This is the explanation of the yards of shavings that are readily cut off unbroken from these materials. If there were no top rake, shavings would not be produced, but broken chips. And when top rake is insufficient in amount, though the fibrous character of the material may ensure cohesion, sufficient to prevent the shavings from breaking into chips, yet they will be curled round into smaller, shorter, tighter spirals. The test therefore of a true incisive tool having sufficient top rake is the production of large shavings of great length, and in the case of cast iron, where long shavings are impossible, the less of break there is in the chips, and the less sliding of the layers over one another, is the test of a proper amount of top rake. No shaving ever made in fibrous metals, measures, if straightened out, the full length of the surface from which it is severed, testifying to the fact that some crushing action always takes place. In order to the better understanding of the angles of clear¬ ance, and top rake, we take a hand tool, which may be a graver. or a roughing, or finishing tool made of triangular, or square bar. Such a tool becomes either a cutting instrument, or a scrape ac¬ cording to the way in which it is presented to the work ; the tool angle alone does not change. In Fig. i the tool is scraping, in Fig. 2 it is cutting. Fig. I. Fig. 2. But while in Fig. i the angle of relief is so large that the tool edge will soon be lost, in Fig. 2 it is just right for almost any material. A safe way, therefore, to go to work is this. Settle a minimum angle of front clearance, which may be as low as 5° and need not exceed 10°. Then make the top angle, or top rake, as large as is found consistent with durability, and easy cutting of the shavings. In other words, give as much of incisive angle, and TOOL ANGLES. 13 chisel-like action, as the tool will endure, with permanence of shape. A mean can thus be struck, and embodied in tool-holders, and in settings for grinding in shop systems. All the experimenting and theory in the world will not get beyond these simple rules. There is another aspect of this subject to which attention should be given. Returning to the plane iron, the rigidity produced by the screwing down of the top iron is as important a factor as its bend¬ ing of the shaving. This belief is borne out by the fact that any¬ thing which diminishes chatter produces better shavings, and leaves better cut surfaces. An iron plane works better than a wooden one, because its mass absorbs chatter; many iron-stocked planes have single irons which could not work so sweetly in wooden stocks. Also the closer the top iron is brought down to the edge of the cutting iron, the less the chatter. Again, an iron that beds best on its stock, and that is secured best, works sweet¬ est, i.e., with less chatter. So that the function of the top iron is just as much that of preventing or lessening vibration, as that of bending the shaving. In metal-turning tools also, we know that the more rigidly the tools are held, and the closer they are supported to the work, the less do they chatter, and the better is the cutting done. This is exemplified in many ways ; in tools gripped in the slide rest, some with little overhang, and some with an excessive amount, in tools gripped in holders, in overhanging boring tools held in the rest, and in bars, and in boring heads. The better the support afforded, the less chatter, and the sweeter, and smoother, and heavier the cutting possible. Tools of high quality have been used since the days of the Pyramid builders; and even long antecedent to that, the first flint chips were true cutting tools, the shapes of which embodied the same elementary principles of formation as the chisels and gouges used to-day. But during those thousands of intervening years no exact science of tools has been formulated, and so a great deal of what some would term empiricism still rules in the shops. There are no exact angles of cutting tools, and no exact formations of tool edges, of which one can say, confidently ; “ These are the best, and every departure therefrom is an error in practice.” It would seem desirable in these days of formuUe to be able to put the problem of tool edges into a nutshell; but neither the writers on the subject, nor the practical men in the shops have yet accomplished 14 TOOLS. this. Either would have done it if the task had been easy, but the difficulties have been too great. It is very easy to state the principles which underlie the forma¬ tion of cutting tools—no one calls these in question. In the whole range, from the razor, with a cutting angle of, say, 15°, to those for cutting cast iron and steel with angles of, say, 60° or 80°, we find that two matters have to be balanced, one of which compromises the other—the maintenance of the maximum keenness of the cutting angle, with the maximum endurance or capacity of the tool to resist the loss of its edge. That remains the fundamental fact or principle—the basis which underlies the essential design of all cutting tools whatsoever. Going a step farther, it is also true that as a rule the softer the material operated on, the more acute can the angles of the facets of the tool be made ; while, on the contrary, the harder the material the more obtuse must they be. But exactly what the angle should be to suit best any given material, apart from trial or previous experience, has not yet been made the subject . of exact determination. Quite as chaotic is the problem of what is termed the angle of presentation, and that of relief or clearance. We are prepared to find a considerable range possible to the latter, though there seems no good reason why it should ever exceed from 5° to 6°. But it very often does, and without any apparent detriment to the per¬ manence of the tool edge. With regard to the angle of presenta¬ tion, it seems as if some precise angle ought to be better than any others for a given class of material, both for effecting severance, and for clearing the stuff severed with the minimum of friction. Yet that has not been fixed, for those angles range within several degrees without appearing to be inconsistent with good practice. The case 'stands something like this to-day. Men work in grooves. They find certain results follow from the use of certain tool angles, and then they lay down theories which harmonise with those results, and think that in so doing they have formulated rules of universal application. That is just where the error comes in; for the rule deduced, if universally applied, does not square with universal facts. For there are several conditions which exercise important influences on the operation of cutting tools, chief among which are differences in the physical characteristics of materials nominally the same, the effect of cutting speeds and TOOL ANGLES. ^5 feeds, the support afforded to the tool, and, last, and equally impor¬ tant at least with the others, lubrication. With regard to the first set of conditions, the denominations— cast iron, wrought iron, steel, and brass—tell but little of the physical characteristics of the materials which are classified by those names. Cast iron may have a toughness and hardness closely approximating to that of the quality of cast steel, or it may flake off in soft powdery chips. Obviously the tool best suited for dealing with one quality cannot be the best for the other. The same remark applies to forgings in different qualities of steel, and in a lesser degree to wrought .iron. The gun-metals and brasses again range from tough, hard, and crystalline to soft qualities. Taking next the question of speed, a high rate of cutting speed will rapidly grind away a thin keen tool-edge, and, therefore, rate, and depth of cut are both limited by the durability of the tool itself. But lubricate in quantity, and the edge endures even at a higher speed, and takes a deeper cut or coarser feed than with¬ out the lubricant. In extreme instances we find examples of rapid and efficient tooling done with cutting angles that appear incorrect in theory, results superior to those obtained with correctly formed tools and ordinary methods. AVe find, therefore, that the subject of the angles of tools has in some degree been permitted to obscure other matters which are of equal importance. This does not 'imply that these angles should receive less attention, but that the other conditions should have more. Lubrication appears to be of equal value with angles, yet until recently it has not been studied and applied with one hundredth part of the interest and care that has been devoted to the former. A secondary condition also which is studied to a greater extent now than formerly, is that of affording support to the work in opposition to the action of the tool. In older shop practice if this was ill supported, the feed of the tool was generally lessened, so reducing its efficiency. Now, one of the most striking differences between the design of the lathe tools of a few years since, and those of the most advanced practice of the present day, lies less in tool forms and angles than in the better support afforded, in con¬ junction with more complete lubrication. We have probably not learned much more about tool angles than Willis and Babbage i6 TOOLS. taught; but we are better acquainted with other conditions that also make for efficiency. In the ordinary lathe there is but one way of opposing the action of the cutting-tool—that, namely, of a steady acting in the rear, or one encircling the work adjacent to the tool. Some few heavy lathes embody the duple.x system, in which one tool is diametrically opposed to the other—an excellent device, but one which is obviously limited in its application. The balancing of cutting forces, or of rendering support to the work is now exten¬ sively carried out in the various box tools fitted to modern turret lathes, and in the hollow mills (Fig. 3) and kindred forms. The adoption of the same principle in screwing-dies renders their opera¬ tion so much more rapid than that of cutting a thread in a lathe with a single pointed tool. It is not necessary for high efficiency that forces should be balanced by the cutting tools themselves. If adequate resistance is offered to the action of a single tool, that is sufficient. To fit two or more tools for simultaneous action introduces complica¬ tions which would for some work involve a too great expense. It is very often quite enough to use a single tool, and to support the work behind it with a vee’d guide (Fig. 4) following immediately after the cut,—our old friend the lathe- steady in a new and simpler guise. Supported thus, depths of cut of from ^ in. to f in. are constantly being taken with fine feeds. In the box the support is often more rigid than that of the lathe-steady, because both tool and guide are carried as closely together as pos¬ sible in the very stiff box attached to the turret, and from which all possibility of spring is eliminated. The tools used for roughing are similar to those in the ordinary lathe work, or they resemble what are termed “ knife tools ” (Fig. 5), Fig. 5- TOOL ANGLES. 17 and the box is their tool-holder. A small angle of clearance is given and an average cutting angle, and these tools are capable of removing broad shavings. In the most complete boxes, two, and sometimes three tools operate either simultaneously or suc¬ cessively on one piece, each tool having its own vee-support at the opposite side. The slogging done with these tools could not be accomplished without the assistance of floods of lubricant. While writers on tools have long emphasised the evil of the rapid generation of heat, and pointed out the obvious advantages which would result from an ample supply of cooling fluid, the problem has been solved by the adoption of entirely new methods, familiar to many because they are now adopted in many of the more advanced English shops. They differ from the drip-can device in the im¬ mensely greater volume of lubricant, pumped in such quantity that it partially or wholly conceals the work being cut from observation. In the case of reamers or boring-tools it is pumped into the interior of the reamer, or into the recess being bored. Instead of soapy water being employed, lard-oil is frequently used, which, though costly, is yet economical, because employed over and over again. The secret of heavy cutting must therefore be credited to lubrication and tool support equally with tool angles. Until within recent years machinists knew little of the possibilities that were hidden in these. Now they boldly attack large breadths of metal. Taken in conjunction with good average angles the tools feed with avidity, and that they are not being unduly stressed is apparent from the fact that they often retain their edges for several days, even though in constant use, without regrinding, showing in this respect also a far better record than common tools in lathe and planer operated under common conditions. This could not be the case but for the aids afforded by lubrication and support, however correctly the edges might be ground. It is now well understood that lubrication can only reach its fullest efflciency when it is proportioned to the heaviness of the duty of the cutting tool. The harder a tool is worked, the more profuse must it be. The fluid used must also be supplied right at the edge of the tool, and be allowed to flow away at once, to be replaced continually by fresh, cool liquid. The broader the work, and the more rapid the feed, the more heavily are the cooling properties of the liquid taxed. B i8 TOOLS. The advantages of lubrication are so great that in modern practice cast metals are sometimes so treated, brass quite commonly, and occasionally even cast iron, both of which are tooled dry in the ordinary practice of the lathe and machine shop. In conclusion, the balancing of cutting forces, the giving ample support to work and to tools, and floods of liquid are the later features noticeable in the operation of cutting tools, and these to some extent diminish the importance which has been hitherto accorded to exact tool angles. The necessity of observing good average angles for given conditions of working is not neglected; but the point is that this is only one factor in the economies and efficiencies of cutting tools, and that others which are of equal value are those noted above. A large number of tools that bear no external resemblance to the chisel, and the tools of this group used for cutting by lineal movements, possess the chisel action. But so many lie on the border line between cutting, scraping, abrasion, and shearing that we had better touch on these methods of operation at this stage. When the working face, or the top face of a tool stands at an angle of 90° or more with the face on which it is operating, or with the tangent to that face in circular work, it is not a cutting tool, but a scrape. Such tools are frequently used for turning brass, and for finishing smoothly the surfaces of iron and steel, which have been previously roughed out with cutting tools. The cabinetmaker’s toothing plane is an example of a scrape for wood. Final correction, and finish-frosting is put on metal work by scrapers, which remove extremely minute quantities of metal. But the chief interest centres round the action of the scrape in a larger variety of tools, represented by taps, dies, some saws, and files. Abrasion, so called, by the gritty points of grindstones and emery wheels, may seem a small matter, yet it looms large in present practice, and in fact we must consider it as a true cutting action. Shearing is an operation which takes place when a shaving or a sheet of metal is severed in detail, or diagonally, instead of by a straightforward, or sudden cut. The detrusive action of a punch may, or may not partake of a shearing character. In each case a tool angle may be present, or not. We begin to see how complicated the queston of tool angles may become. There are several tools to which it is difficult to assign an exact place, tools which are not true cutting instruments. TOOL ANGLES. 19 if measured by angle, but which nevertheless do operate in effect as such. In the attempt also to impart cutting angles to some, other evils are magnified. Shearing and cutting are sometimes combined, one to counteract the other, or both to operate in unison, and help each other. In saws we have examples of cutting, and of scraping teeth, the first for ripping soft woods, the second for ripping hard woods, and cross-cutting both kinds. The teeth of files are scrapes. The teeth of taps, and dies, and of milling cutters are generally scrapes, but some have a slight rake which brings them under the head of cutting tools. Some drills are scrapes, others are true cutting tools, with shearing action in combination. Mo-st tools for wood-boring cut, but not all, and of those which cut, many suffer by reason of the cutting forces being unbalanced. These and cognate problems will receive illustration in the various sections of this work devoted to particular groups of tools. SECTION L THE CHISEL GROUP. CHAPTER II. Chisels and Allied Forms for Woodworkers. tiquity of Chisels—Primitive Forms of Stone, Bronze, and Iron—Single and Double-bevelled Chisels—Cutting Action — Angle and Edge — The Wedge Principle — Splitting Action—Operation by Thrust or Pressure—and Per¬ cussion—Importance of Rigidity—Angles of Grinding and Sharpening— Skill required for Operation—Methods of Holding—and of Thrusting— Grain—Plane Surfaces—Paring and other Chisels compared—The Axes and Adzes—Control of—Draw-knife—Carvers’ Chisels—Lock Chisels— Turning Chisels—Sharpening Chisels—Permanence of Edges. The Gouges—Antiquity of—Outside and Inside Types—-Eirmer and Paring— Millwrights’ and Coachmakers’—Curves of Gouges—Value of Paring Gouge—Carvers’ Gouges — Their Varieties — Method of Operation — Turning Gouges—How to Use. T he chisels are the oldest tools, for Paleolithic men used them in the form of axes, roughly chipped from flint, while the severed flakes served as tips for javelins, and lances, and for the first rude drills used by man. The Neolithic men improved on these primitive tools by the practice of grinding and polishing their celts (Latin, celtis, a chisel), and in a crude fashion they seem to have differen¬ tiated true chisels and gouges from the axe-like celts, besides which many examples of hafting occur. But they at first hafted with a hole in the handle, into which the celt or other implement was secured, being easier than drilling a hole in the stone. To lessen risk of the handle splitting, the hole was made a considerable distance from the end (Fig. 6). The two were often secured with vegetable fibre. CHISELS FOR WOODWORKERS, 21 The older axes were of stone, and driven into their handles. The modern one is of steel, and the handle is driven into its eye— a most important difference. Apparently thousands of years passed before the present method of handling occurred to the minds of tool-users. The true chisel, handled for direct thrusting by the hand, is late in point of time. Apparently such tools were unknown until long after men cast tools in bronze. Then we find the true chisel, and the gouge. The axe, therefore, is the oldest of all tools—older than the adze, or the chisel, or the drill—and, except in the material, and the manner of handling, it resembles the modern one. While flint was chiefly used in the Paleolithic times, the Neolithic men also employed beside flint, basalt, greenstone, ser¬ pentine, porphyry, micaceous grit, for their celts. Not until men had acquired the art of casting in metals was any further advance possible. But the Bronze Period of human culture is exceedingly rich in chisels, axes, and allied forms, which bear unmistakable resemblances to those of the present time. Palstaves, tanged, and socketed chisels, and gouges are abundant, and many of the moulds in which they were cast have also sur¬ vived. A few similar forms in iron of a later date have escaped the ravages of rust. In the ancient Swiss lake dwellings iron axes, with holes for the wooden hafts, have been found. The bench chisel—^type of others—differs from the chisel used for turning, or the axe, in the fact that the wedge formation given to it is imparted by bevelling one face only. In this respect it resembles the adze. This distinguishes it from those tools in method of operation, inasmuch as the chisel will pare a fairly true surface by the control of the hand in conjunction with the flat face of the tool. But this also involves the necessity of keeping the cutting face perfectly level. The chisel having a single bevel only is late in point of time. It marked a great advance, because the unbevelled face became a guide to accurate work, differing from a doubly bevelled tool, such as a celt, or a cold-chisel type, of which numerous examples in bronze remain. A good deal of correction in the way of re¬ moving fine chips and scraping must have been necessary with such tools. The difficulty of cutting effectively with the ancient chisel of 22 TOOLS. stone, and even of bronze, seems to indicate that these tools were seldom if ever used otherwise than percussively, of which the axe and the hatchet are the modern representatives. In the case of the smaller chisels there is evidence of the use of the mallet in the burred-over heads. So that really three of the most important tools of the chisel type are operated by our carpenters to-day much as they were actuated many thousands of years ago. Chisels are used in all the woodworking, and in many other trades besides, yet each trade has some forms peculiarly its own. Among these are included carpenters, joiners, pattern-makers, millwrights, coach and waggon builders, turners, coopers, masons, slaters, bricklayers, sculptors, engravers, butchers, and so on. Most of these chisels are furnished with handles, and the handles differ also from one another in several respects, depending on the method of use of the tools. (See Chap. XVI.) The proportions of blades in respect of width, and length, and cross sections also vary widely. The action of this great family of chisel tools is that of cutting, the condition of which is that one face lies parallel or nearly so with the face being cut, and the bevel makes an angle therewith, which may range from lo to 30 degrees. The razor, the shoe¬ maker’s knife, and the table knives are chisel-like tools with the smallest angle, while axes have the largest angle among the true chisels. It is necessary to distinguish between angle, and edge. A keen angled tool will not cut shavings if the edge is dulled. Sharpen the edge on the hone, without altering the angle, and the tool cuts shavings sweetly. If the tool were acting as a wedge only, splitting by percussive blows, the state of the edge would have no influence, but the angle of the wedge only. But the degree of keenness of edge is related to angle, when materials of different kinds are being cut. A keen edge is equally desirable for cutting soft pine, hard oak, harder lignum vitte, or hardest iron and steel, but the tool angles have to be different in each, to back up the edge properly and by supporting it to its work, they prevent it from being crumbled or broken away. A chisel angle suitable for cutting wood, will cut lead, and copper easily, and tin with some difficulty. Very minute cuUings can even be taken off well-annealed malleable cast iron. But ordinary irons and steels cannot be touched except by adopting larger CHISELS FOR WOODWORKERS, 23 angles, and using percussion, as in the cold chisel, or by making the rotation of work effect much of the necessary pressure, as in hand turning, or by adopting the mechanical help of the slide rest to keep the tool up to its task. The mere thrust of a tool, sufficient in wood cutting, is impotent to sever hard metals, however keen the edge may be, and however wide the tool angle. The wedgelike action of a chisel is comparable with that of an inclined .plane, in which the labour of drawing a weight up the slant face is less than that of lifting it perpendicularly; in the pro¬ portion which the length of the inclined plane bears to the per¬ pendicular height. A wedge may be regarded as two inclined planes placed back to back. Tools of the chisel type embrace a very great number of forms, diverse in appearance, and in mode of application, yet having a common affinity to the wedge. A wedge may possess the splitting property merely, or it may divide by cutting, the difference depend¬ ing partly upon its degree of obtuseness, partly upon the manner in which it is presented to the material, partly also upon the nature of the material operated on. Thus, an axe if driven into the end of a piece of wood, in the direction of the grain fibres, will not actually cut, but will divide the wood by splitting alone. But if it be employed at the face of the wood, where the layer of fibres is so thin as to yield readily, the purely cutting action will pre¬ dominate. The same remarks will hold good of a chisel used in the same way. But if the wood is to be divided in a direction transversely to the fibres, neither axe nor chisel will operate by splitting, but the cutting action must of necessity be continuous throughout, and then the saw is used. The chisel, therefore, used as a splitting tool is the oldest type, its most familiar representative being the axe, which is a wedge pure and simple, no cutting action occurring after the first entrance of the edge. The line of cleavage then lies in advance of the edge, the fibres being forced asunder, and the edge does not cut at all. Such action is widely different from that of paring. It is only of value in splitting up fairly straight-grained stuff, its most familiar example being chopping wood, and rending builders’ laths. In crooked grain and across the grain it is of no value, nor for any substance but wood. Such action has little in common with the bench chisel, the edge of which is instrumental in removing a shaving, thick, or thin, away from the cut surface. The chisels 24 TOOLS. actuated by a direct thrust, and those in which the force expended takes place at right angles with the axis of the chisel, correspond with another classification. All the early chisels belonged to the latter, being furnished with handles or hafts, as our axes and adzes are to-day. As all the chisels are used in one of two ways, being either thrust to their work by simple pressure, or driven by percussive action, this distinction is embodied in the proportions of these tools, and to a slight degree in their cutting angles. Percussively acting chisels, which have to stand the mallet, like mortise chisels, or have to be driven by the swing of a lever, like the axe and adze, must be made stouter than the paring tools which are simply thrust, or they would become fractured by the severe con¬ cussions to which they are subject. Their cutting angle must also be slightly more obtuse, or the edge would be lost, either by simple dulness, or by the breaking out of fragments of metal, especially in tools that have been tempered rather highly. This difference is not so apparent in the simple action of paring, as it is when the tools are used more in the character of wedges, deeply buried in the wood, and acting partly by cutting, but often more largely by cleavage. The exact degree of cutting angle of chisels is generally disguised by the fact that the sharpened angle is greater than the ground one. But a wider angle is usually adopted for percussive work than for simple pressure, and for operating on hard, tough, stringy woods than on soft, open grained ones. It is always much less than the angle for metal-cutting chisels, e.g., the cold chisel, the turner’s and planer’s roughing tools, knife tools, and others that remove shavings from metal. Many tools of the chisel family are operated indif¬ ferently by pushing, or by percussion; as for example the firmer chisels, and those for millwrights, coachmakers, and others. But in the extreme types there is but one method of use adopted. I-ong, thin, paring chisels (Fig. 7) are seldom struck by a mallet. They are liable to fracture, and even if they do not break, they spring. Neither are draw-knives, or turning chisels ever struck. But the axe, and the adze group are always used percussively, and so are many others. Fig- 7- CHISELS FOR WOODWORKERS. 25 The efificiency of any chisel depends to a considerable extent on its rigidity. This is apparent when attempting to cut thick chips with a slender paring chisel. It springs, and would chatter, and jump away from its work if forced hard. In an extreme case, try to slog out a mortise with a paring chisel. To cut mortises properly, an extra stout chisel is made for the purpose (Fig. 8), which will neither spring, nor snap under the heaviest work. It is very thick—nearly square in cross section—while the paring tool is very thin, and often also has its top edges bevelled, as in Fig. 7. Then the handle in the latter is comparatively slender, while that of the former is massive. That of the paring tool is bellied, to be grasped easily in the hand; that of the mortise is of no particular shape, since it is simply steadied and controlled by one hand, while the blows of the mallet are delivered by the other. If paring chisels are struck by the mallet, as they are sometimes, the blow's must not be severe, or the jar is liable to snap them. To pare with a mortise chisel, on the other hand, is almost impossible. Midway between the extreme types are the firmer or short chisels, and the coachmakers’ chisels (Fig. 9), which have to stand some hard duty imposed by the con¬ cussion of the mallet; and the turning tools, which are fitted to withstand occasional concussion, besides the steady strain of deep cutting. The bevelled face includes the ground bevel, and the sharpening bevel, the first of which remains constant, the second always tends to increase the cutting angle, due to re¬ sharpening. On first sharpening a newly ground chisel, there will be little difference in the angle of the grinding and sharpening, and at that period the tool cuts most sweetly. When by re¬ sharpening the angle becomes thickened to such an extent that cutting is not sufficiently free, or re-sharpening takes a long time; then it is more economical to re-grind. The angles at which chisels and gauges are sharpened should vary a little with the work on which they are used, and also slightly with the known temper of the tools. Tools are sometimes so hard and brittle that it is impossible to grind them thin ; for contact pi O Fig. 8 . Fig. 9 . 26 TOOLS. with a knot, or a slight amount of malleting suffices to break pieces out of the keen cutting edges. But if ground more obtusely they form splendid tools, cutting sweetly, and keeping their edges good. Other conditions being equal, tools used on soft wood will bear, more acute grinding than for hard woods. This is no more than we should expect; but the error consists in supposing that a tool sharp€?ied “ thick ” must needs cut well on hard wood. It will not, since the edge has little penetrative power. We must not ignore the wedgelike action of the tool. A chisel will also cut more sweetly, if instead of being forced directly down¬ wards, or across, the wood as the case may be, it is moved in a slightly oblique direction. This combines the wedgelike, with the shearing action, and produces a clean cut face, even though the edge happens to be a little dulled. It will be found also that less muscular effort is required. The chisel in all its forms requires more skill in its manipula¬ tion than some other tools, such as the plane, or spoke-shave, because the degree of accuracy of its operation depends on the control afforded by the workman’s hands; it is also less easy to control the percussive chisels, as the axe and the adze, than the paring tools. In paring, the tool is set or placed against the face, or the line to be cut by, as in Fig. lo. In the axe and adze the eye determines the location of the blow delivered by the hand—a task requiring skill born of prac¬ tice. A man unaccustomed to the adze can do nothing accurate with it; one skilled in its use will control its action within a sixteenth of an inch. The training of the hand and eye is a mutual one. The direction and extent of a percussive cut cannot be altered after it is once started; that of a paring tool can. Thus the latter is capable of producing the more accurate results. In order to produce the best work with the axe, using it as a trimming tool, rather than as one for splitting, the single-grinding bevel should not be departed from in sharpening. If the bevel for sharpening is different from that of grinding, the power of control is lessened. The advantage which the adze possesses over the axe for correct work is due to the fact that all the bevel is on one face; the face in contact with the work being cut is not ground at all. It would be flat, but for the necessity of imparting a convexity to that face (Fig. 15, p. 30), Fig. 10. CHISELS FOR WOODWORKERS. 27 about equal to the radius through which the adze is swung. The difference between these tools and the chisel having one face quite flat is apparent, and the nearer they resemble the chisel the more accurate will the results be which they produce. The way in which a chisel should be held when in use depends on the position of the work. Most cutting is done with the tool held perpendicu¬ larly, the work lying on the bench. When paring vertically, the wrong way to hold the chisel is to elevate the elbow, and grip the handle at the end and press downwards with the palm of the hand. That is the method of the beginner. The right way is to clasp the body of the handle in the closed hand, with the elbow slightly depressed, and to exercise pressure downwards in the direction of the axis (Fig. ii). The chisel edge generally has to be set into lines scribed, or otherwise marked on the surface of the work. So that while the right hand is thrusting the chisel, the left is controlling its cutting edge by resting partly on the work and partly against the chisel. Of course, after the lines have been set in, the cut surfaces afford sufficient controlling influence. A fair amount of work is also held in the vice, and the chisel held horizontally. To cut thus, the wrong way is to grasp the body of the handle; the right is to grip Fig. 12. it at the end, and to thrust it forward with the palm of the right hand, steadying it, if need be, with the left (Fig. 12). To pare 28 TOOLS. small work held in the left hand, the chisel is grasped by the body of the handle (Fig. i.^). The direction of thrusting a chisel has much influence on the results. When cut¬ ting vertically above the bench as in Fig. ii, the effort is little more than that of the muscles of the arm. But when cutting horizontally by thrusting (Fig. 12), much of the weight of the body can be thrown into the work. One hand only can be con¬ veniently used in a vertical cut, but two may be frequently employed when shaving horizontally. The chisel is ill adapted for cutting along the grain with any great precision, though suitable for roughing-down in that direc¬ tion. If the grain is not very straight, the tool will follow it, and tear up the surface in those places where the fibre runs downwards or away from the cutting edge. Then the work must be reversed, and when that is not practicable, very thin and light cuttings only must be removed. A chisel working across the grain avoids these evils, but the surface left is not smooth—a shearing cut being required. The cutting of end grain is most satisfactory, since that can be left very clean and smooth and true, provided the chisel is quite sharp. The force required to operate a chisel varies with its width, and with the thickness of the chip, and therefore there comes a limit to its effective operation by hand. A width of i-|- in. is about as much as one can use in cutting chips of moderate thick¬ ness, combined with the production of a reasonably true face. To sever thick chips of such a width is hard work. To remove those of, say, ^ in. thick, even with a narrow mortise chisel, is beyond the power of the hand alone, and so here the mallet is brought in. No chisel possesses such perfect guidance as the planes do, and yet by practice, surfaces of three or four inches in width are constantly being finished by the chisel alone. Here the value of the paring tools over the firniers is apparent. A firmer chisel is a stumpy article to use for broad cuts. One has to work in a more CHISELS FOE WOODWORKERS 29 cramped posture with it than with a paring chisel. The latter, moreover, can be kept flat on the surface being cut for a length of several inches, provided the chisel has a nice straight face. It should never be tipped up on that face when sharpening. Frequently an end can be finished more neatly by holding the work in one hand, and taking very light cuts, as in Fig. 13, turning the wood about, and cutting first in one direction, and then in the other. Since a paring chisel is so slender that it springs in the longi¬ tudinal direction when the attempt is made to cut deeply with it, especially on end grain, here therefore the millwright’s or coachmaker’s chisel (Fig. 9) fills a valuable place. This is used both as a paring chisel in heavy cutting on hard woods, or for medium heavy malleting. In this respect it occupies a place between the firmers, the mortise chisels, and the paring tools. The chisels which are regularly driven by the mallet are much stiffer than the millwright’s and coachmaker’s. They include principally the tanged mortise, and the socket mortise chisels (Fig. 8), made in their several varieties to suit different trades. Though differing in length, all alike are characterised by a thickness approximately twice or three times as great as that of the firmer, and paring tools. They have a very marked_amount of 3° TOOLS. taper, so that they can be malleted, and also used as levers to push the chips back from the cut face, and to dig them out of their holes. Proportions vary, thus :— A cabinetmaker’s chisel is rather lighter than the carpenter’s. A sash chisel is made more slender than the carpenter’s. The chairmaker’s tool is shorter, and more stumpy than either. A mortise chisel used for locks is bent similarly to the carver’s in order to permit of scooping out the chips (Fig. 14). In the socket types, variations occur in length, and in substance. These will stand more punishment than the tanged chisels, the sockets lessening risk of splitting the handles by hard malleting, and in that their chief value lies. Except for cutting, and clearing away at the finish, these tools are invariably driven with the mallet. Fig. 16. Fig. 17. Many chisels have their back or upper edges bevelled (Fig. 7), to permit of cutting along within the edges of acute angles, as those of dovetails. An alternative to this form is a convex back, less used however than the bevelled. [ Fig. 18. Fig. 19. That large group of the chisel family which, though percussive, is not actuated by a mallet, but by the swing of a lever, includes the adze (Fig. 15) and the axe (Figs. 16 and 17), the various choppers (Fig. 18), and cleavers, the bill hook (Fig. 19), the CHISELS FOR WOODWORKERS 31 Fig. 20. chisel-pane hammers (Fig. 20), boiler scaling hammers, and allied forms. The width of blade in most of these considerably exceeds that of the chisels. There is no guidance at all for starting an operation, but cutting to a line is a work of skill on the part of the craftsman. And yet in the case of the axe and adze, very close results can be obtained. Cleavers, choppers, bill hooks, and the lath-hammer, or lath-render (Fig. 21), are employed as instruments for severance only, or chiefly, but the adze and axe are in a sense finishing as well as roughing tools. Within their sphere they are unapproachable by any tool whatever, that sphere being the shaping of rough balks and branches of timber into straight and curved outlines for various purposes. Adzes are used by shipwrights, carpenters, coopers, wheelers, platelayers. They differ in length of blade, in curvature, and in the formation of the head, which is generally finished to serve as a hammer. Axes or hatchets are made in many forms, each with its distinguishing name in the trade. The most marked difference occurs perhaps in the English, and Yankee pattern (Figs. 16 and 17 respectively). The efficiency of adze and axe depend to a large extent on the long swing of the handles, by which they are distinguished from most of the other chisel-like tools. In those which resemble them most nearly, the butcher’s cleavers, meat choppers, and bill hooks, the handles are much shorter; but the latter score in greater length and weight of blade. 'I'he utilities of the chisel family are not confined to the obvious one of removing shavings or splitting. A bricklayer’s axe for example is a broad knife by means of which a nick is produced around the brick, after which a blow of the hammer severs it. The slater’s saxe (Fig. 22) acts in a similar fashion by nicking, and other examples occur to the mind. The pick in its various forms is a chisel in which the point takes the place of an edge. It does not sever, but splits. It is a cleaving, not a shaving tool. The coal pick, and the navvy’s pick 32 TOOLS. are tools in common. Somewhat similar is the marline spike used for forcing the strands of rope apart when splicing. A miner’s, or rock drill (Fig. 23), is a percussive tool;—in effect two chisel points at right angles, which is turned upon its ■4 Fig. 23. Fig. 24. axis, and thrust to the rock which it breaks up. A quarry jumper is a single chisel edge (Fig. 24), operated similarly. Only in a slight degree do any of these tools possess guidance in themselves, even after a cut or a split is started, for they have no flat faces like the firmer, and paring chisels possess, but are either doubly bevelled as in the axes, or the cutting face has considerable curvature as in the adzes (Fig. 15). After the cutting of a face has commenced, the portions first cut help to control the move¬ ments of these tools, which are arrested by the cut faces. The surfaces left are short facets, each one formed independently of the more of the wedge, and less than of shaving. In using others, differing in this aspect from the face left by a chisel, which lies flat upon its work. The degree of control exer¬ cised upon the axe and adze makes all the difference be¬ tween good and poor results, and this has to be acquired; the tool formation rendering no aid as it does in the chisel, or in a more complete manner in the planes. Both axe and adze tend either to “ strike off” from the work, or to stick fast in it. The first happens when fine cutting is attempted, the second when slogging is being done. Cut¬ ting of the latter class partakes the chisel action, of splitting more hatchet, a little support can be CHISELS FOR WOODWORKERS. 33 Fig. 26. derived by keeping the right arm close to the body, but in using an adze, support is obtained by resting the elbows and arms close against the ribs. After considerable practice a man may become more ex¬ pert with the adze, than with the axe. A chisel is often used as a roughing tool on the bench in place of the axe. Pieces of wood that have to be turned down between centres have their keen angles cut off with a chisel, as being more rapid in action than the plane, with the stuff laid in an angle board. Chips are cut off with the chisel face next the piece, the work being pressed against the bench stop. Or often the back of the chisel is employed to rough down an edge preparatory to planing, the stuff being held vertically (Fig. 25), the mode of cutting then resembling that of the axe. The draw-knife (Fig. 26) owes much of its value to its two handles, which enable both hands to be utilised, so that very thick chips can be cut off the edges of boards held in the vice, being almost as stout as those which an axe would cut. And the draw-knife is simply a very broad chisel fitted with two handles, by which the tool is pulled or drawn towards the workman. Draw-knives occur in several patterns, and sizes, straight and curved in the blade, and with handles parallel, or divergent. Carpenters, joiners, mastmakers, wheelers, and coopers use them. The intricacies of wood carvers’ work are reflected in a number of tools, all of small size, but greatly varied in outline. There are straight chisels, square across the cutting edge, and skew, or on a bevel. There are also spade chisels, both square, and skew. The vee tools, or parting tools (Fig. 27), are in effect two chisels set at various angles, acute, and obtuse, for cutting angular grooves of corresponding shapes, and these are both straight and curved longi¬ tudinally. The dog-leg chisel comprises a narrow chisel formed at the end of a long cranked shank. The turning chisel (Fig. 28) is an example of a mixed character. c Fig. 28. 34 TOOLS. Its guidance does not depend on the sharpened faces, since it has a double bevel in the style of the axe. Yet it is not a percussive tool, and it is not thrust with much force to its work. It is held, controlled, and guided by the hands, in combination with the support afforded by the rest (Fig. 29). It does not cut over its entire width, but only over one-third or one-fourth of the same. Its action is so keen that it will cut with or across the grain, or on end grain with almost equal facility. The gouges are true chisels, curved in cross section. The remarks that have been made about the difference between firmer and paring tools, of chisels yjg 29. Fig. 30. operated by thrust and by percussion, apply to gouges. The latter, however, do not occur in so large a range of sub-types, neither are the adze and axe-like tools represented among the gouges. Gouges of bronze occurred in great numbers in the Neolithic Age, some being of the tanged, others of socketed types (Fig. 30). The idea of curving the chisel to enable it to form concave pro¬ files is therefore some two or three thousand years old. There are two great groups of gouges, the outside and the inside, the terms denoting the method of grinding; the outside gouge having its bevel for grinding and sharpening on the convex or outer face, the inside gouge being ground on the inner or concave face. The former group are also firmer or short gouges, the latter are paring or long gouges, the relative lengths of which have their analogies in the firmer and paring chisels. The paring gouges were developed by the necessities of the millwrights and patternmakers, and they are, like the chisels, made stout and heavy, and thin and light. The firmer and paring gouges are used like the chisels of the same name, the firmer chiefly with the mallet, and the latter by hand thrust or pressure almost wholly. Exceptions occur in the millwright’s or coachmaker’s paring gouges, which are made stiff enough to endure malleting, and in a small group of firmer gouges, which is ground inside instead of, as usual, on the outside. CHISELS FOR WOODWORKERS. 35 The curves of the paring and firmer gouges are divided between groups, so that a gouge of any one width can be obtained in either one' of six different curvatures. Formerly there were three available, quick, flat, and middle ffat, but now a range of six is obtainable, designated as A, B, C, D, E, F groups. Two of these, the extremes, are shown in Figs. 31 and 32 for gouges up to i ^ ^ inch in width. Gouges are made from ^ to 2 inches wide, but the generally useful sizes are included between and i| inch. The paring gouge is very valuable not only -- as a finishing tool but as a roughing-out tool. There is k great deal of work which cannot be - put under the band saw, and for this a broad quick gouge is the best possible slogger.- What are termed the “ trowel shank ” or “ spoon gouges ” are excellent forms for this, ^ _ because the knuckles do not come in contact yjg. ^i. with the work. As in chisels, the working face of a paring gouge must be true, if true cutting is to be done. A great group of gouges is that used by carvers. They include straight gouges in numerous sweeps, and gouges curved in the longitudinal direction, capable therefore of cutting concave shapes in two directions;—that corresponding with the curve of gouge section, and the other variable, but to k some extent controlled by the longi- I tudinal curve of the gouge. ' The carver’s gouges may be ranked as firmer gouges, being all short, but they form a class alone, since, though some are straight lengthwise, the great majority of them are curved or “ bent ” in that direction, the object of which is to permit of their cutting into curves ) of very small radius, in the longitudinal direction of movement of the gouge. They are “front bent,” and they are “bent back”; made also with long curves, and with short quick ones, or “ spoon bit ” (Fig. 33) and “ spade ” type, and each in a 36 TOOLS. Fig- 34 - wide range of sizes, from extremely flat forms to “ quick,” up to half circles. The widest of these tools do not exceed about | in. in breadth. Extreme sectional curves are shown in Fig. 34 - Patternmakers use some of the carver’s tools, chiefly the curved, and front bent gouges, for cutting the interiors of core boxes, especially for the “ hollow ” portions, or radii of recessed, or chambered, or shouldered parts of boxes. The carver’s tools are driven by the mallet in roughing out, but in finer cutting they are more often thrust by the ball of the right hand, concussively, and in finishing cuts they are simply held in, and thrust by the hand. The turning gouge is shown in Fig. 35. In the hands of a professional wood-turner a simple gouge is a marvellous tool, producing hollows, ogees, and mouldings of various shapes with swift dexterity, aided only by the chisel where sharp corners are concerned. Those who handle the gouge with confidence and skill can turn out their work quicker, cleaner, and better than those, who, dreading a disastrous “kick,” or “catch,” scrape away cautiously with the round nose, and chisel, and diamond point. An inch gouge, that is i in. wide, is the largest that can be well used with a light treadle lathe, and to use that effectively means hard leg work. A ^ in., | in., or ^ in. will be more generally useful by far. The gouges should be well Fig. 35. rounded in grinding (Fig. 36), so that the point, and not the corners shall be used for cutting, and they, in common with most of the other tools, should be furnished with long handles, to afford adequate leverage and control. In turning straight along, either between centres, or on the face plate, the gouge may be held flat on its back without any danger of its catching in the wood; but, in turning mouldings, and in boring holes with the cup chuck, the tool must be held sideways, and the corner of the gouge which is lowest, or rather some portion of that half the gouge which is lowest, is the one which will be used for cutting, the higher corner being kept carefully away from the revolving Fig. 36. CHISELS FOR WOODWORKERS. 37 wood to prevent a catch. Even, however, in rapidly roughing down plain straight surfaces, it is advantageous to handle the gouge in this fashion, using both sides alternately, since it cuts the wood cleaner, quicker, and with less friction than when used on the flat. This is a lesson only to be learned by practice. The great thing is to feel the work. Thus, if turning down a moulding, or a ball at the end of a curtain pole, from circum¬ ference towards the centre, there is the centrifugal force very sensibly tending to thrust the gouge outwards, and this, of course, is the force wTich must be resisted. The point of the gouge, or a portion just below the point, will be used, as offering least friction, and the tool must be grasped very firmly. In turning a flat surface, no such force exists, and the gouge may be held indiffer¬ ently in any position, and comparatively slack. Always the end of the gouge handle is held in the right hand, while the three last fingers of the left grasp the lower portion of the gouge itself. The requisite guidance is imparted to the tool by the thumb of the left hand, while the opposite forefinger passes underneath the rest, in opposition to the thumb, thus gripping the tool as in a vice. Lastly the rest must be kept close up to the work. CHAPTER III. Planes. Great Variety in—Setting of Chisel or Iron in its Stock—Fastening of the Iron—Convexity of Same—Choking—Utility of Top Iron—The Question of Angles, as affected by Re-sharpening—Linear Guidance— Related to Length of Stock—Preservation of Truth of Face—Planes for Concave Sweeps—The Profiles of Planes—Drawbacks to the Moulding Planes—Iron Planes—Gripping of Planes—Pressure on—-Guidance of— Aids derived from Shooting, and Angle Boards—The Aid of Strips— Checking the Truth of Planed Surfaces—Details of Planing—Faces— Ends—Setting Irons in Slocks—Removal of Irons—Good and Bad Timber—Sharpening Moulding Planes—Wear and Tear of Planes— Shooting—Mouthpieces—Selection—and Preservation of Planes—Tooth¬ ing Planes. A CHISEL, to possess linear guidance, must have its flat face coincident with the surface being cut. Thus, it would be impossible to cut the surface a. Fig. 37, truly with the chisel held at an angle, as there shown. But if it is inserted at an angle in a stock, it becomes a plane, which pro¬ duces true surfaces beyond the capacity of a mere chisel to operate upon. The mechanic who first put a chisel in a wooden stock to supplement the un- Fig- 37- certain control of the hand led the way to an infinite line of inventions, of a similar character. This device involved the distinction between the chip and the shaving, between the uncertain and the precise, the slow and the expeditious, and finally in its later developments, between the puny weakness of the human arm and the practically unlimited giant power of machinery. Specifically we confine our attention here to the common planes, leaving alone the vast number of applications of the principle of guidance that are embodied in the tools which are controlled in machines. The different kinds of planes now made number hundreds. PLANES. 39 Almost any form of cutter can be put in a stock, while the shape of the latter can be so modified as to suit work corresponding with the sectional shapes of the cutting irons, as in the moulding planes, and the proportions or relations can be made adjustable, as in the ploughs. The old woman’s tooth, or “ router,” is used for planing out the bottoms of recesses, the depth to which the iron stands out from the face of the stock being adjustable. It is therefore an exception to the general plane design, in which the iron stands but very slightly out from the face of the stock, inch, inch, or less. There are so many different kinds of planes that, though they have a family resemblance, the various groups require to be operated differently, if the best results are to be secured. Actually there are only two instances in which a plane iron is employed in the same fashion as a chisel is used in paring—that is, with the flat face in exact coincidence with the face of the work. One of these is the familiar spokeshave, the other is the rounder plane, used for rounding up rulers, broom handles, and other long circular rods, the iron cutting tangentially. In all other cases the chisel is set in its stock, neither parallel nor tangentially, but in such a way that its cutting face makes a large angle ■with the face of the work. And it does not matter in the least which face lies next the work, whether the flat, or the bevelled one, since the power of control no longer lies with the chisel itself, but is trans¬ ferred to its stock. The flat face may be downwards, next the stuff, as in many of the iron planes, or it may be uppermost, as is the usual practice. In the first, the angle of setting the chisel in its stock is low, or acute; in the second, it is steep. The first important point is the secure fastening of the iron, so that it becomes practically one with its stock. It must not rock 40 TOOLS. in the slightest degree on its seating Fig. 38, and the wedge must bed closely down at h, all over it. In this way the tendency to chattering and vibration is eliminated, and these are the principal causes of choking. Other points are, to see that the corners are removed on the hone, and that the iron is either sharpened straight across, or with the slightest possible convexity, which is tested by standing the edge of the iron lengthwise on the face of the stock, and noting the light underneath. An iron must not be in the slightest degree concave. When one begins to handle planes, the first trouble that arises is that the shavings choke in the mouth, between the iron and the stock. This is more apparent in the trying, and smooth¬ ing plane, than in the jack plane. The first impression is, there¬ fore, that the mouth is too narrow to permit the shavings to get away, and an apprentice will not infrequently, unless checked, cut the mouth wider, and so lose two or three years of wear. But the fact is soon discovered that better results are obtained if the amount of convexity given across the edge of the iron is increased, and thus another error is committed—that of making the irons of trying and smoothing planes nearly as convex as those of the Jack plane. Then, of course, they are unfit for producing true surfaces. For if those irons be sharpened straight across, and only just the corners rubbed off, they will operate as freely as though well rounded, pro¬ vided other matters are attended to. The rigidity of the iron a, is increased by the addition of the top iron B. The difference between single and double iron planes is most marked, and this is due largely to the fact that the screwing-down of the top iron tightly on the cutting- Fig. 39. Fig. 40. iron stiffens the latter so much that all chance of chatter is absorbed thereby. How important this is may be observed by noting the difference in the working of a plane when the top iron is set back from to yV ioch (Fig. 39), and when it is brought down quite close to the cutting edge (Fig. 40). The first is incompatible with PLANES. 4T the production of the finest results ; the latter is essential thereto. In working on soft pine the coarse setting has scarcely any evil results; but it becomes most marked when attempting to plane crooked grain, knots, and hard, harsh wood, and end-grain, on which it is impossible to produce smooth surfaces except with a finely-set top iron. The setting of the top iron also has a secondary influence. It coerces the severed shaving immediately behind the cutting edge, and compels it to bend over at the instant of severance. We re¬ marked (p. 23) on the distinction between the axe that cleaves the wood a little way beyond the cutting edge and the paring chisel that removes and cuts up a fine shaving, the first action being percussive, and the second purely cutting. A similar distinction occurs, but in a less marked degree, between the single and the double iron. Take a .single-iron jack plane (Fig. 41) set coarsely, and note the kind of shavings removed. They are not curled off regularly, but appear to have been split off in a succession of jerks, the stuff being divided in front of the actual cutting edge. But, using a finely- set double iron (Fig. 42), such an action is not apparent, for the shaving appears to be quite unbroken. Fig. 42. Anything that interferes with the perfect controlling action of the top iron lessens the efficiency of the plane. If the bedding of the top iron is not perfect on the other, the plane will choke, or chatter. If its edge is not parallel with the cutting edge the same evils will be induced. Even the greasy dirt that accumulates on the top iron will tend the same way, and it should therefore be rubbed off with glass-paper. As yet these remarks have had reference only to the good or bad action of those planes which are designed for, and are appro¬ priate to, the class of work upon which they are commonly used. But the question of the appropriateness or otherwise of a plane to its work raises many points of detail. To be concise, the problem may^be considered from three points of view—the question of angles, of linear guidance, and of profiles. 42 TOOLS. The remark has already been made that the sweet working of planes is less a question of angles than of keeping them in good order. Thus the iron of a common plane, Fig. 38, is set at an angle r, of 45° in its stock. The ground bevel makes one of about 20° to 25'" or 30°, with the face of the stock, depending on the work of the plane, and when newly ground the sharpening angle e is not very sensibly divergent therefrom. Yet the plane continues to work sweetly after successive re-sharpenings until at last the angle will be reduced to 5° or with the stock. The only thing that remains constant is the angle of top rake—namely, 45°. Though the cutting angle is always increasing as the plane-iron thickens, and the clearance angle is always being reduced, yet the tool works sweetly. On the other hand, in an iron plane in which the iron is set face downwards at an angle of about 15° with the face of the stock, the clearance never changes ; but that of top rake and of cutting always increases with sharpening. And the cutting angle of the latter usually becomes thicker with re-sharpening than is practicable in the case of the irons of the wooden planes, for with a face angle of 15“, and a grinding angle of, say, 20°, if this is gradually increased by 10° to 15° by sharpening, the total angle will be greater than that which is possible in the wooden planes. The foregoing facts, taken as a whole, explain why the same planes can be readily used for the hard and soft woods, unlike the cutting tools for metals, which are generally shaped differently for different metals. But though a 45° of angle in a plane iron is used for both classes of timber, the workman makes slight differences, as experience dictates when working in one or the other. The differences lie chiefly in the degree of setting of the top iron, which is finest for the hardest and harshest woods, and in the coarse or fine setting outwards of the cutting iron, for removing coarse or fine shavings respectively. In the moulding planes a difference is made in angle for hard and soft woods, the irons in the former being set at 55° or 60° instead of 45°. But the forms of these planes are much less favourable to sweet cutting than are those of the bench planes, for reasons which will be noted directly. The angles of plane irons are compared with the action of the chisel in Figs. 43-45, between which there is much analogy. Shavings are coarse or fine, one difference consisting in the fact that the coarse shavings are broken, while the fine ones are not perceptibly so. If we consider the action of a chisel PLANES. 43 when removing coarse and fine parings, we shall see a marked difference. In the first case the parings will be like Fig. 43, broken in polygonal forms; in the second, Fig. 44, they will be continuous, and regularly curved. The same effect is observable in planes, the coarsely set single iron of Fig. 41 breaking up the shaving, the finely set double iron of Fig. 42 removing it as a continuous ribbon. But the iron in Fig. 41, if set ever so finely, would not remove such fine shavings as Fig. 42 ; neither if the latter were set very coarsely would it chatter so much as the former. Hence, in planes the addition of the top iron is necessary in order to counteract the influence of the angular setting in the stock, which setting being a departure from the chisel principle, tends to cause chattering. An important function of the top iron therefore consists in the diminution of vibration of the cutting iron, effected by increasing the rigidity of that portion of the plane. That rigidity is the main essential, rather than the mere breaking of the shaving, is borne out by the fact that iron planes are the Fig- 43 - most rigid of all, and that in these, single irons (see P'ig. 45) can be used without chatter, or choking, even when cutting against the grain, and on harsh stuff. In Fig. 42, showing the iron of an ordinary plane, whose face c, is set at an angle of 45° with the face of the stock; 45° does not represent the cutting angle, for a is the angle of presentment of the tool to the work. It is that included between the narrow sharpened facet of the iron, and the face of the material, ranging between about 5° and 10° only—just an angle of relief, and no more. The other, is that formed by the first grinding of the basil, and is the reserve, so to speak, which is drawn upon for sharpening. The top face r, answers to the bevel therefore of a chisel, and the sharpened facet, or rather the sole of the stock, to its face. In Fig. 45, which represents the mouth of an iron plane in section, the bottom angle a, is increased, being about 20°, and the top b., on which the sharpening takes place is not very different from that of the first example. But in these apparently 44 TOOLS. diverse cases, that which renders the plane so valuable is the guidance afforded by the stock, without which it would not be possible to remove shavings of uniform thickness, that is, with chisels alone, held at the same angles as the plane irons. Our second point—that of linear guidance—is the feature that is most obvious in planes; in all its degrees, from the tiny thumb- plane of 4 in. to 6 in. long, to the cooper’s planes, measuring as many feet. In another form we have the planes controllable in sweeps, known as compass planes, the elementary type of which is the spokeshave. Since the control of the iron depends on the linear guidance exercised by the face of a plane, this is proportionate to the character of the work done. Hence the reasons why the planes which are used for making close joints, whether glued or not, are always the longest. The common jack plane is never employed for this purpose, and its length is limited to from 14 in. to 17 in. But the trying plane ranges between 22 in. and 26 in., and when specially long joints have to be made, jointers are used from 28 in. to 30 in. long, while the cooper’s jointer of 5 ft. to 6 ft. is an extreme instance of specialisation. Smoothing planes, rebates, moulding planes In all cases measure less than 12 in. in length, for there is no question of very accurate jointing in most of these— that is, not in the same degree in which it applies to the trying planes. However accurate the face of a* plane, it wears with service, and therefore it is periodically “shot” with a trying plane in good order. Jack, trying, and smoothing planes are treated thus, twice or thrice in a twelvemonth, and every care is taken, by the assistance of straight-edges and winding strips, to restore the faces to perfect accuracy. To maintain permanence of form is the principal reason for the employment, first of iron-soled planes, and then of planes with iron stocks. The latter may be of the skeleton form, or a skeleton may be filled in with blockings of hard wood. But there is the other advantage derived from iron planes, due to their rigidity, and by virtue of which they work more sweetly in hard, harsh, cross-grained, and stringy woods than those having stocks of wood. The circular, or compass planes, are used for concave sweeps. The simplest form is a smoothing plane with a sole cut convex lengthwise. But such a plane is not well adapted for any sweeps PLANES. 45 which are of much flatter radius than the radius of the sole. The next advance is to insert a sliding piece in the front, by the adjustment of which the range of utility is increased. In American forms the sole is made flexible, consisting of a thin strip of elastic steel, which is adjusted to any required curve by means of a thumb-screw. Compass rebate planes are also employed, and in some cases both the face and one side are sweeped. The third point of view from which we have to consider the planes is that of their profiles, or the sectional forms of their cutting edges. These are the counterparts of the work which they have to do. In the trying plane we have seen that the edge has to be as straight as possible if close joints have to be produced by it. In the jack plane a good deal of convexity (Fig. 46) is imparted to produce a penetrative and shearing cut, in which its primary value lies. But the con¬ trolling power and co-relation of the plane to its work is seen in its greatest development in the numerous moulding planes. The labour of cutting a strip of wood into any moulded form by means of chisels and gouges is so great that the develop¬ ment of these planes was an early necessity. Possi¬ bly the “ hollows ” and “ rounds ” preceded the numerous moulding planes, which are mostly com¬ binations of hollows, rounds, and flats. Though these are superseded in modern shops by the moulding machines, they are yet used in the small country shops, and on jobbing work. Knack is required to handle some of these planes nicely— such as some of the ogees, quirk ovolos, torus, beads, and sashes —because the combinations of curves and flats are such that some portions of the irons are in the worst possible position for cutting—in fact, in some localities they stand perpendicularly to the work instead of at an angle, as all irons should do. To a slight extent this is counteracted in some planes by setting the stock at an angle to the work, or at a “ spring,” in order to lessen these drawbacks by a principle of averaging. But good working mainly depends on the careful way in which they are sharpened, set, and used. Particular care must be exercised to keep the angles keen enough, and the edge profiles of the iron exactly co- Fig. 46. 46 TOOLS. incident with those of its wooden stock. These planes also suffer from the disadvantage that they have single irons only, and are therefore liable to chatter. For this reason the bedding of the iron on its stock, and the close fitting of the wedge are very important points. The planes are also rather hard to work, and drag somewhat, especially in wide and deep mouldings. Some of these planes, like the plough, are used for cutting deep grooves. and though perpendicular edges are present, they are not actually cut by the iron, and here friction and dragging occur. Some of the profiles of these planes are grouped in Figs. 47 to 50. Figs. 47 are the irons of rounds, and hollows, the sections of which, going by numbers, are shown in Fig. 48. Fig. 49 is the iron of the plough for grooving—eight irons of different widths forming a set for a plane. Fig. 50 is the iron of one form of beading plane. Besides these there are planes to correspond with various mouldings for sash bars, and strips, to enume¬ rate which would be hardly possible here. Ovolos, quirk ovolos, ogees, astra¬ gals, reeding tools, sash tools, air-tight planes for making tongued and grooved joints, blisters, and others. Rebate planes occur in various types, straight, and skew mouthed (Fig. 51), Fig. 51- PLANES. 47 and side rebates. Chamfer planes form another group, and so do chariot, and bull-nose planes, for cutting up close to a shoulder. The iron planes have, to a large extent, invaded the pro¬ vince of those with wooden stocks, some firms making a speciality of their manufacture. They occur in the following groups: jack, trying, and smoothing; the latter being commonly termed block planes;—bull-nose, rebate, circular-soled, tonguing and grooving, routers, hollows, and rounds, beading, ploughs, universal, and spokeshaves. Fig. 52 shows a lever block plane. The lever a takes the place of the usual wedge. It is pivoted at a, and turning the milled head and screw b, pinches it on the top of the iron at b. Instead of tapping the iron inwards or outwards, it is moved slightly by the lever c, hinged at c, and having serrations on its upper face to engage with serrations on the lower face of the iron at d. /4 Fig. 53 - Fig. 52. A different type of iron plane is shown in Fig. 53. a is the base into which the handle b is screwed. The iron c is double, and the cap d holds the iron down. The adjustment of the latter is effected by the milled head e operating a lever entering into a slot in the iron. The portion f, the frog, can be adjusted to close up the opening of the mouth if wear occurs. No plane is easily handled by the beginner. The art con¬ sists first in exercising the most perfect control over the tool, instead of allowing it to wabble about all over the stuff. It is true that the workman appears to hold it very slackly and easily; but he has, nevertheless, a perfect grip on it, so that it does not tip up at the beginning and termination of every stroke, nor slip over the knots, nor remove shavings from the wrong places. All planes, except the tiny thumb planes, require to be gripped in both hands. The trying and the jack planes are grasped by their handles with the right hand, while the left is spread over 8 TOOLS. the top of the body of the plane near the front end, slightly gripping the sides also. The smoothing planes and all the rebates and moulding planes and their cognate forms, which have no handles, are gripped in the rear with the right hand, the heel of the hand exercising a thrust on the stock downwards and forwards, while the left hand steadies the plane in front. The degree of pressure transferred from the body to a plane varies much, being very considerable when roughing down. Most planing, like sawing, taxes the muscles, though, when accustomed to it, one can occupy a whole day in either task without feeling unusually tired ; but it exhausts the beginner. The muscles of the arms, and a portion of the weight of the body are both brought to bear upon the plane, and the proper degree of force exercised is graduated in a nearly unconscious and instinctive manner. The guidance of the planes usually depends on the skill of Fig. 55 - Fig. 54. the operator. All those in which the edges of the irons lie inside the stock, as in the jack, trying, and smoothing planes, require no control save that of the workman, except when used on a shooting board (Fig. 54), or a mitre board (Fig. 55), for planing edges and ends. But when the irons come out flush with edges, as in the rebates, or when they project, as in the plough, or when a planed edge has to be worked by, as in the beads and kindred forms of moulding planes, they are coerced, either by the edge of a strip of wood tacked upon the face of the work, in the exact position where a shouldered portion is to be formed, as when rebating, or by a fence, which is adjustable, as in the plough, or by a fixed fence, as in the beads, fili.sters, &c. In planing narrow strips, with rounds, or hollows, the angle board (Fig. 56) coerces the stuff sideways, preventing it from slipping about. The rounds, and hollows, and many others are controlled only by the fingers of the left hand. Tools of PLANES. 49 these classes are only suitable for cutting with the grain. Some are used also for cutting across, but then a saw-kerf must be made to sever the grain, as in rebating. Another point is, that the skilful man does not need to check the results of his work nearly so often, or so much, as one who is unskilled. When planing a level surface, the latter timidly resorts to straight-edge and winding-strips long before the surface is approaching completion; the other feels by the nature of the contact between the plane and the wood how the work is pro¬ gressing, and uses the edge of the plane itself as a rough straight-edge—tipping the tool to a slight angle, and glancing under the edge in the intervals of every few strokes. And yet he arrives at the desired result quickly. If he has much to slog off, he does not plane in an unvarying, straightforward fashion, but alternates these cuts between cross and diagonal ones, which are of the nature of shearing; so not only reducing material with the minimum of labour, but also getting close Fig- 56. approximation to truth across the board. As also the jack plane removes stuff most rapidly, its employment is continued until the fine finishing of the trying plane becomes quite necessary. A beginner will commence working with the trying plane too soon, and so waste time in removing a quantity of material that could have been taken off in one-fourth the time with the jack plane. Further, with a view to preserve the edges as long as possible, and so avoid the need of too frequent sharpening, the experienced man relieves the cutting-iron of the weight of the plane on its backward stroke, so preventing friction between it and the face of the board. The harsher and more gritty the stuff, the more desirable is this instinctive precaution. Before roughing-down dirty stuff with the jack plane, too, the careful man brushes the outside with card wire, to remove the dirt and grit before using the plane on it, and then he sets the iron coarsely in order to get well beneath the surface in the first cuts, instead of allowing the D 5° TOOLS. dirt to grind the edge off the plane, just as the iron-turner and machinist get below the skin at once. When testing the truth of planed faces, both straight-edges, and winding-strips are requisitioned. A straight-edge alone will serve the functions of both, because when held diagonally across a board, if the straight-edge shows true faces in both diagonal directions the face is out of winding, the result being the same as though tested with parallel winding-strips at the ends. But this method, though quite suitable for short pieces of stuff, say not exceeding 2 ft. to 3 ft. in length, is not so suitable as the other for long wide boards, because the strips magnify any error due to their length, the latter being considerably longer than the width of a board. Of course, in trying the truth of boards it is not enough to lay the straight-edge on them. That is good enough during the earlier stages, but later, chalk must be rubbed on the straight¬ edge, and transferred by very slight pressure and slight endlong movement to the face being planed. This visibly indicates by its transference or not, what portions of the face are high or low, and where the material requires removal. The straight-edge is tried crossways at intervals of every few inches, and a long straight-edge is also tried lengthwise; besides which, the winding-strips are tried on. Sighting down the latter, the edge of the farther one is more clearly seen if the face that lies next the edge is whitened with chalk. Always the first step is to plane one face perfectly true, and gauge the thickness from that by which to plane the second face. As a board is seldom quite straight across when taken from the rack, the concave face is better to begin work on than the convex, because the latter would be pressed down, and sprung by the weight of the plane. But it is always better to “jack” over both sides before beginning to finish either face; or if this can be done a few days, or even a few hours, before planing to thick¬ ness, it is better, because there is less risk of the board warping subsequently. When planing end grain, the expert workman does not let the plane tip over the end and split the stuff out; but he either chamfers the extreme end with a chisel, or else planes a few strokes from each end alternately, relieving the plane just as it comes to the termination of its cut. When practicable, he will plane ends and edges on the shooting-board (Fig. 54, p. 48), rather PLANES. 5 ^ than in the vice, because with the use of the shooting-board there is no necessity to try the truth of the edge with the square, re¬ latively to the face of the board. A good workman will not allow one plane to usurp the functions of another, nor expect the smoothing plane to produce a true surface like the trying plane, nor use the latter merely to dress off joints flush, or to clean a dirty surface previous to glass-papering, or to round-up an edge. Nor will he attempt to round-up any con¬ siderable quantity of work with a smoothing plane when hollow planes are available. To set an iron in its stock suitably for different classes of work is not quite so easy as it appears. Beginners knock their planes about sadly in getting the irons in and out, and in correcting their setting. No very hard blows need ever be dealt. The most trying work to a plane is the presence of hard knots in soft wood—those in spruce, for example; and contact with these will often cause a loosely fitting iron to start backwards, so that in such cases the wedge should be driven more tightly than under normal conditions; but to drive a wedge habitually tight only springs the stock, without holding the iron any better. The setting of an iron is accomplished by bringing the face of the plane in line with the ey« in a good light, and sighting down, when the exact projection of the iron beyond the face of the stock is readily detected by the eye, and also whether it is parallel cross- ways. If it projects to a greater distance towards one side than the other, the edge of the iron beside the wedge is tapped with the hammer on the side where the projection is too full. If it stands out too far all across, the top of the plane stock is lightly tapped with the hammer, in jack and trying planes, to start the iron upwards by reaction. In the smoothing and moulding planes, the rear end is struck. A tap on the top end of the iron sets it out. When adjustments are all completed, a final tap or two is given on the wedge. Damage to planes is caused by the hammering of the stock to effect the removal of the iron. In trying, and jack planes, this is done on the top front face with the hammer held in the right hand, the left grasping the side of the plane, and the thumb being inserted in the hollow of the wedge, to steady it, and con¬ trol the results. In smoothing planes a sharp blow is delivered at the hinder end; in the moulding planes under the knob of the 52 TOOLS. wedge. As these blows are repeated so frequently, they must be delivered quite flat and dead, in order not to bruise and damage the wood overmuch. A little knob is often glued into a centre- bit hole in the top of jack and trying planes to receive these blows. When wedges are being driven in, they should not be bruised and burred over; partly with a view to prevent this, their edges are chamfered. To maintain planes in good order, fit for producing clean and smooth surfaces on soft straight-grained woods, is not so difficult as when they have to work against the grain, and over knots, and on stringy harsh stuff. In some of these cases it is better to have an iron sharpened rather thickly than thin, and it will usually have to be set very finely to remove a mere scrape; in fact, in such cases the plane, though sharp, will do better if its action approximates to scraping, because it will not then have so great a tendency to tear up the harsh, coarse grain. When planing sappy stuff the mouth is very liable to choke, and the tool works with much friction. A liberal application of sweet oil to the sole of the plane is very helpful in this case. In sharpening moulding planes much care is necessary in order to preserve their profiles exactly. The irons should be ground on very small emery wheels, or they are filed sometimes with new finely-cut files; they are sharpened with gouge slips. In using any of these planes it is difficult to start properly. Some, like the sash fibsters, have adjustable guides or fences to be held against the side of the work. So have the beads, the ploughs, the chamfer planes, and others. In the rounds, and hollows the workman’s hands afford the only control. In the rebate planes it is usual to nail or clamp a strip down to the work as a guide. In depth gauging there are stops, as those used for sash fibsters and for the ploughs, and these are adjustable with screws, so that we get a good many complications in moulding planes. But in a large degree interest in these has diminished since mouldings are stuck by machinery, and there are many younger joiners who have * never had a chance to use such planes, and have had no need to add them to their kit. The wear and tear of planes is due to the wearing of the iron, of the sole, and of the removal, and resetting of the iron. The first-named has the effect, in most cases, of increasing the width of the mouth, the exception being in the case of those irons which PLANES. 53 are parallel. In the tapered iron, the wearing-down, due to regrinding, brings the thinner portion down to the mouth, and so increases the width of the latter. But the chief wear to planes is that due to the constant friction of the face, which causes it to get out of truth, to correct which the face has to be “ shot,” or planed afresh, so widening the mouth. After several years this width becomes so great that a mouth-piece has to be fitted across. In selecting planes, the grain of the wood is a matter of much importance. Straight grain of course is looked for; and heart wood must be rejected. A hard quality of timber, cut from the outer layers of the tree, is the best; the latter being apparent by the ring segments having scarcely any convexity. The silver grain also must run perpendicularly to the face of the plane, and not diagonally. A stock selected thus has the best wearing quality, and is less liable to warp than one in which the contrary conditions are present. All plane stocks are made of beech, excepting the smallest thumb planes, and spokeshaves, and the quirks, and fences of some of the moulding planes, ploughs, &c., which being subject to much wear are of box. To preserve a new plane, a good plan is to harden its face by saturating it for two or three days in raw linseed oil, and rubbing oil'all over elsewhere, applying it thickly and afresh as it sinks into the grain. Also after shooting a plane, the face must be saturated with oil to harden it, and to cause it to work more sweetly. CHAPTER IV. Hand Chisels and Allied Forms for Metal Working. The Cold Chisel—Cutting Angles—Shape—Breadth—Method of Use—The Cross-cut Chisel—Diamond Point—Cold and Hot Setts—and Gouges— Setts for the Steam Hammer—Nicking Chisel—Drifts or Broaches. T hese chisels are not nearly so numerous as those of the wood worker. They are simple in character, and yet a very slight difference, not to be appreciated save by those who know them well, will make all the difference in their effective, or non-effective action. The roughing-out tool par excellence of the fitter, is the cold chisel in its various types. The cutting edge of the typical “chipping” or “cold” chisel (Fig. 57, a) gives 60° n 1 fl . 1 D A ' li I \ 1 J Fig- 57- cutting angle, but it may, and does vary several degrees on each side of this, not only for different materials, but for materials of the same character. The practical rule to lay down is, that the harder the material, the more obtuse the cutting angle; the softer the material, the more acute will it be. This of course is a neces¬ sary modification, not alone in the case of chisels, but also of all cutting tools, not because an obtuse edge cuts better than an acute one, but simply because it endures better. HAND CHISELS FOR METAL WORKING. 55 A little practice soon demonstrates the best angle for a chisel for any particular kind, or grade of metal. Hard, harsh metal will rapidly spoil the chisel edge, and then the remedy is obvious— grind it thicker. But a moderately thin chisel will cut soft iron rapidly, and without losing its edge, and one thinner still will work gun metal, and brass with ease. This is really the ultimate test, the cutting of the largest quantity of any given material with the least expenditure of labour, and the most lasting permanence of edge. The tool is held approximately at the angle in which one facet comes nearly parallel with the face of the material being operated upon, giving the smallest possible angle of relief. A slight round¬ ing is imparted to the edge in the transverse direction, the object of which is to prevent risk of the corners catching in the material, which would draw the chisel out of parallel. Most wide chisels are ground thus more or less rounding, though sometimes straight, but never hollow; not much rounding, however, is given, else the chipped surface would present a series of furrows. The breadth of the chisel has an influence upon its action. For steel, and wrought iron, a narrow chisel is preferable to a wide one, because they are of a close solid texture, and require a considerable application of force to effect the removal of chips therefrom. But the more crystalline cast iron and brass are more suitably attacked with wider chisels, which have less tendency to dig in, and to tear up the material than the narrower ones. This again is not a hard-and-fast rule, since both wide and narrow chisels are used indiscriminately on all grades of metal. But the principle laid down is nevertheless a correct one. A good deal will depend on the force of the blows, the depth of cut, and the amount of material attempted to be removed. To use the chisel, hold it near its head in order to afford steadiness of grasp, stand in an easy, unconstrained posture, not hugging the chisel too closely, and deliver the blows from the shoulder. The cutting edge of the chisel is to be kept pressed against the cut, and the surface is to be reduced as evenly as possible, to lessen the subsequent labour of the file. Finishing cuts will be taken with quicker and lighter blows than the roughing cuts. When reducing a surface of large area, the labour can be lessened, and better results obtained by first cross-cutting the 56 TOOLS. surface all over with the cape, or cross-cut chisel (Fig. 57, b). A series of narrow grooves parallel with each other is cut with this over the surface, and the material removed from between with the ordinary chisel. The same chisel is used as a “ sett ” for nicking pipes, or plates preparatory to severance. i The economic importance of chip¬ ping has considerably diminished in I the workshops during the present generation, owing to the wider em¬ ployment of planing, shaping, and milling machines. There is, com¬ paratively speaking, little call now for skill in chipping, except in the case of repairs, and of work too bulky to be put under the machines. To many, therefore, the chip¬ ping and filing of a large surface true, especially if that surface be awkardly situated, as for instance a slide valve face enclosed within the sides of its steam chest, presents a not too easy task. Fig- 57) c, is a diamond point, one of the setts, used for nicking metal which has to be severed, and also for cutting grooves. Its re¬ semblance to the vee chisels of the carver (p. 33) will be apparent, the difference between the two being one of thick, and thin cutting angles. Fig. 57, d, is a narrow round nose, also one of the setts, corre¬ sponding with the wood¬ worker’s gouge; while Fig. 57, E, is a wider gouge, con¬ cave on the face, also termed a cow-mouthed chisel. These tools are used in several metal-working trades, by fitters chiefly, but also by smiths, and boilermakers, on forgings and plated work, as well as on castings. The next group is for forged, and plated work, the cold and hot chisels or setts being held to the work, and struck with sledges. A ^ — 8 -V_ Lj C Fig. 59- Fig. 58 . ITAN'D CHISELS FOR METAL WORKING. 57 I Fig. 58, A, is the cold, and Fig. 58, b, the hot sett, the difference between the two being that of angle only, the latter being thinner than the former, a would entail unnecessary labour in severing hot metal, while b would not retain its edge long in cold metal. Fig. 58, c, is the gouge, or hollow sett, made also for hot and cold metal, and in various curvatures, and singly as well as doubly bevelled. These are handled with rigid rods of ash. The next group fulfils similar functions, but they are used chiefly with power hammer work. Fig. 59, a, is a sett made thick, and thin, for cold, and hot metal. Fig. 59, B, is a hot gouge sett handled like the previous one. Its function is severing or dressing ends w^hich are to be bossed, instead of cutting facets to produce polygonal outlines. Fig. 59, c, is a very obtuse-angled chisel which operates as a nicker only, setting in round a rod under the hammer preparatory to severance. It is used on hot, or cold bars. Drifts are true chisels. Some operate by their ends only, but most are serrated (Fig. 60). They both cut, and shear, and are used to finish holes that have been roughed out with drills, or chisels. They are employed both in blind, and thoroughfare holes, finishing accurately and to uniform dimensions. They are used by hand, or in a machine. In America they are termed broaches. Fig. 60. CHAPTER V. Chisel-like Tools for Cutting Metal by Turning, Planing, &c. Roughing and Finishing Type—Roughing Tools—Finishing Tools—Parting Tools—Inside Tools—Tools for Planer and Shaper—Cranking—Overhang — Stiffness of Tool and Support — Roughing and Finishing Tools — Straightforward Tools — Cranked Tools — Broad Finishing — Slotting Tools. T ''HE principal types of these tools are shown in Figs. 6i to 65. They are mainly divisible in two groups—roughing, and finishing. On some kinds of work there is but one type practicable—the finishing, which combines the two functions. The angles of tools that operate on the same materials are varied according to whether they are employed for removing material in quantity, or for finishing by scraping. In the latter case they have little or no top rake, the top face being normal, or nearly so, to the surface of the work. It is also essential to the highest smoothness of finish that the edge be broad, and straight. The angles of scraping tools are nearly alike for all metals and alloys, differing in this respect from the roughing tools. Fig. 61 is the commonest kind of roughing tool for lathe, planer, or shaper, and if clamped in a bar, for the slotting machine also. A tool used for the same work is prismatic in form, instead of being round-nosed, being slightly easier to grinds As a rule, to which there are numerous exceptions, the roughing tools are round-nosed, the advantage being that they possess penetrative capacity in a large degree. And because the correct cutting angle only occurs at that portion of the tool d, which TOOLS FOR CUTTING METAL. 59 projects most, and in a diminishing degree round the curve, until at E E there would be no top rake at all, this limits the useful work done when deep cutting is attempted, and explains the advantage possessed by right and left handed roughing tools, in which the point of highest projection and greatest rake corre¬ sponds with that portion of the work being cut where the pene¬ tration is deepest. Four such tools are shown in Fig. 62, in pairs. The right, and left hand tools at a differ from straight¬ forward ones in the method of grinding the top rake—top side rake in these cases. Those at b differ in being bent round, the grinding of the top faces being then normal to the centre line of Fig- 63. the bent part. The arrows indicate the direction of movement of the tools, and c c shows the direction of the top side rake. Fig. 63, A, shows a broad finishing tool in plan, which is used with coarse sliding feeds, but only for removing shallow chips. The amount of top rake in these is variable, but is generally slight, ranging from zero to 10° or 15°. Fig. 63, b, is the spring tool, used for fine finishing, with a mere scrape. The action of this tool can be better understood by a reference to the planer tool (Fig. 64), the point of which is brought back somewhere about in line with the back of the tool shank, in order to prevent risk of the cutting edge digging in, in consequence of the spring of the planer rail, or of the overhanging of the end of the tool. But 6o TOOLS. Fig. 64. for the inconvenience of the arrangement, it would be better to mount the planer tool behind, instead of several inches in front of the rail. With the tool shaped as in Fig. 64, it cannot dig in, even though it should spring back, because the point would be immediately thrown olf the work. For the same reason a turning tool should not be set above the centre of the work, but level, as in Fig. 61. So, too, if the spring tool, Fig. 63, b, meets with an obstacle, it yields, and will not dig in. The cut becomes analogous to a drawing cut, as distin¬ guished from a pushing cut. But spring tools are not suitable for working to fine-gauged dimensions ; they simply impart a smooth finish, serviceable in work of an average character. Tools for parting off (Fig. 63, c) have clearance both behind and below. Being generally very thin at the cutting end, this is commonly reduced from a bar of greater width, in order to afford sufficient width and rigidity for clamping in the tool-holder. Such tools are also in some cases required to be right and left handed. The same tool generally serves for roughing and finishing, but knife-edge or side tools (Fig. 65, a), right and left handed, straightforward, as shown, or bent, are used for facing an end, following the parting tool before a piece is actually cut off, as in facing the ends of spindles. As the metal removed by the parting tool is slight, and leaves little room for the knife tool, the latter is there¬ fore made narrow and nearly pointed. The same kind of tool is also much used in turret lathes for turning down bars, using a very deep cut and a fine traverse feed. Tools having their cutting edges corresponding with the J' B Fig. 65. contour of portions of the work are made to requirements. The commonest are the convex and concave shapes, in various radii. Inside tools resemble in the main those used for outside turning, comprising roughing, which can be fed inwards or out- TOOLS FOR CUTTING METAL. 6i wards for roughing (Fig. 65, b), or for finishing, or for parting off (c). Besides this, there are the internal screw-threading tools for vee, or square threads, which are like Fig. 65, c, but suitably shaped and ground at the cutting end; and those for worms of the sectional form in Fig. 66, the clearances of which have to be regulated accord¬ ing to the slope of the thread to be cut. The question of the best forms of tools to use on planing and shaping machines is complicated by the conditions under which the tools are used. 'I'hus results depend on overhang, and depth of cut nearly or quite as much as on correct formation. The typical roughing tool occurs indifferently in all forms, very much cranked (Fig. 64), or scarcely cranked at all (Figs. 67 and 68). The first is theoretically correct, the second incorrect, yet both work well under suitable conditions. The essential difference between the two is this, that under given conditions Fig. 64 will not dig into the work, or chatter, and Figs. 67 and 68 will. But the latter are used more extensively than the former, and the reasons for this seeming contradiction are not obscure. In the first place, solid tools are made of steel ranging from, say, f in. square to 2 in. square, depending on the nature of the work which they are designed to do, and they are, therefore, very rigid under ordinary conditions of duty. Another matter is that the machinist invari¬ ably endeavours to give the least amount of overhang possible to the tool, by bringing the tool-box as close to the work as the con¬ ditions of the work will permit of. In this way the spring of the tool is reduced to a practically unappreciable amount. So that in Fig. 68, if the edge of the tool-box is brought to the line c — the heaviest cutting can be performed without the tool-point digging into the work, or breaking off. c—d would be possible in the majority of cases, a—b being exceptionally high up. Figs. 67 and 68 represent the roughing tools commonly used on planer and shaper for cast and wrought metals respectively. The differences are that the first is broader at the cutting point, and that the cutting-angle is greater than that in the second. Ca.st metals, being more crystalline, do not offer so great resistance to the tool as wrought metals, nor is so much heat generated during cutting. So that broader cuts are, as a rule, practicable with the former than with the latter. Experience has also demonstrated 62 TOOLS. the necessity for making a difference in the cutting angles for cast and wrought metals. Usually a difference of about io° is made, the tools for wrought metals being the keener. The dif- erence is made on the top or cutting face, there being no necessity to make any in the clearance angle. Often, however, though not necessary, there is such a difference made, the clearance angle being slightly greater in the tools for wrought than in those for cast metals. Though the term “ cast metals,” is employed, brass, and gun-metal are excepted. The tool commonly used for these is shown in Fig. 69. There is no front rake, and the clearance angle is in practice very variable, often being much greater than that indicated. The resistance to cutting is so slight, that a large clearance angle is possible without seriously affecting the dura¬ bility of the tool point. But brass and gun-metal are very com- Fig. 67. monly planed, and shaped with the same tools that are employed for cast iron and steel, both for light and heavy cutting. If the tools are stiff, and held firmly, there is no perceptible tendency to “ draw in,” or to chatter apparent. The three forms illustrated in Figs. 67, 68, and 69, are the types upon which numerous cutting tools used in planer and shaper are based. Each of these is of the straightforward class— that is, it is usually presented perpendicularly, or normal to the surface of the work, and the traverse feed takes place at right angles with the tool shank. But these forms of tools, and methods of presentation by no means cover the whole range of work which has to be done. Since the surfaces which have to be machined in planer or shaper occur in many positions, they necessitate correspondingly varied methods of presentation of the tools. It is always desirable to machine the whole, or as large a portion of TOOLS FOR CUTTING I^LETAL. 63 a job at one setting as possible, because the risk of error due to inaccurate subsequent setting is prevented. The swivel tool¬ boxes permit of a great deal of variation in methods of presenta¬ tion of tools. But, apart from this, it is often necessary to use tools cranked to right, or left hand, and both roughing, and finishing tools occur in these forms. The reason is that it is frequently not possible to set a tool at an angle in the tool-box, as, for example, when it has to pass down between adjacent ver¬ tical parts to plane some portions which are undercut, or which lie at an angle. The following figures illustrate the principal forms, shown operating on surfaces of work typical of those for which they are generally best adapted. In Fig. 70, A and b illustrate the application of a straight- Fig. 71. forward tool in the two positions in which it can be used most favourably, a is the position suitable for horizontal surfaces, and this is how the bulk of planing and shaping is done, b represents it as on vertical surfaces. But the method of presentation shown at B is only possible when there is a supplementary tool-box on one of the vertical sides of the planing machine, or on a supple¬ mentary standard by the side. And it is not possible at all to use it so on the shaper, so that many vertical faces have to be planed with a tool set diagonally, as at c or d. c is not of a form quite so favourable to cutting in this direction as d, though both are employed indiscriminately. It would be a troublesome job to cut down an angular face except with a cranked tool, as indicated at E. And for cutting down vertical faces in confined positions in which there is no room to set the tools at an angle, as in Fig. 71, 64 TOOLS. the use of cranked tools is absolutely necessary to-the production of accurate results. The straightforward and cranked tools, there¬ fore, each being kept in forms suitably ground for cast, and wrought metals, constitute the most extensive equipment of planing and shaping machines. The tool grooves left on the surface of the work are always visible as distinct grooves, but so shallow that the surface is suffi¬ ciently accurate for very many purposes. For a large quantity of work, the practice is to take two cuts with the same roughing tool; the first with a deep cut, and coarse feed, which leaves the surface much ridged or grooved, and the second with a shallow cut, and fine feed, which reduces the work to the finished dimen¬ sions required, and leaves the tool marks visible, but scarcely perceptible to the touch as distinct ridges. For the finest work, however, this is neither true enough, nor is it finished sufficiently. Then the broad-finishing, or broad-cutting, tool (Fig. 72) is employed. The depth of cut effected with this is almost imperceptible—a mere surface cutting, or scraping of fine shavings or dust—but the traverse feed is large. From a | in. to f in. is a common amount of traverse for average work; but on large surfaces | in. or i in. is often given, and in some cases even this is exceeded. The width of tool is greater than the feed imparted to it, say, ^ in. more at least, and the extreme corners are rubbed off on a hone. The marks of these tools remain visible on the surface of the finished work, corresponding in width with amount of feed given. It is to remove these, and to impart a still higher degree of accuracy, that scraping is resorted to. But for all except the highest class of work broad finishing is practically true, unless, indeed, the machine slides, or the mode of setting the work produces inaccuracy. These are the typical tools, but others of varied forms 'are derived from them, the difference being in outlines, and not in cutting, and other angles. It is not necessary to illustrate all these, since tools are frequently devised for special jobs of work. Thus, broad-cutting tools like Fig. 72 are commonly made right, and left handed for side cutting, or cutting at angles, similarly to the roughing tools in Figs. 70, 71. Tools of similar type, straight¬ forward, are used for cutting or finishing grooves, as in Fig. 73. Round-nosed tools of various radii are also used in planer and shaper; while for recesses, cranked tools are employed. TOOLS FOR CUTTING METAL. 65 There are three movements of planer and shaper tools, and each has various rates, depending on quality of metal, condition, and shape of the tools used, and the nature of the cutting being done. The movements are the travel, or forward movement of the tool, or of the work; the cutting feed, or depth to which the tool penetrates in a single cutting movement; and the traverse feed, or width of cut taken by the tool during a single cutting or return movement. The rate of forward movement varies from about 15 ft. to 40 ft. per minute respectively in the case of the hardest materials, and heavy cuts; and of the softer materials, and lighter cuts. 20 ft. a minute is a good average speed for cutting cast iron. The maxi¬ mum speed for cutting wrought iron with a single tool is about 40 ft. per minute ; a very usual rate is 30 ft. But so much depends on feed, depth of cut, and quality of metal, that those are simply averages. Using high speed steels for tools, these rates are easily trebled. The cutting feed or depth of cut varies from an almost unappreciable amount up to f in. and | in. deep. The traverse feed or width of cut varies from, say, in. to i in., or more, in broad cutting, or finishing cuts. The Armstrong “gang” planing tool (Figs. 74 and 75) com¬ prises a holder carrying four tools, each successive tool being set laterally a little in advance of the preceding one. Each there¬ fore cuts deeper than its predecessor, and the result is that a greater aggregate amount of cut is taken than would be possible with a single tool point. The advantage of this is very apparent on large surfaces, which are thus planed more quickly than in the ordinary way. The holder comprises a shank, upon which the E 66 TOOLS. • Ip *(<> Fig. 76. tool head is fitted with a projecting stud. Two set screws, passing through slots in the head, attach it firmly to the shank, while allowing of circular swivelling taking place. This latter provides the means for setting the tools in successively deeper, the swivel of the holder being graduated, so that an exact and known amount of swivel can be imparted. This slewing naturally alters the side clearance of the tools somewhat, but the amount is insufficient to be noticeable. The diagram. Fig. 76, shows the effect of this, the left hand side cutting -deeply, and so having less clearance than the one on the right, which is cutting finely and therefore has not been swivelled so much in the holder. The arrow shows the direction of motion of the planer table. In the slotting machine, no feed whatever can be given to the tool. In this respect it differs from both planer and shaper. All feeds are imparted to the table on which the work is bolted. Heavy feeds can be utilised, because the cutting force passes mainly through the longitudinal axis of the tool, which is in line with the ram, and the latter is always massive, and moves in long slides. The tool always tends to spring backwards under the stress of cutting; but this is diminished by using a stiff shank, and reducing the amount of its projection to a minimum for each job. To permit of this, the height of the ram above the table is rendered adjustable. For some work, a tool like a planer tool is used, and set at right angles with the axis of the ram (Fig. 78); but it is mostly employed when the ordinary straightforward type is not suitable. An objection to the usual form of tool is that it cannot be lifted clear of the work during the up, or non-cutting stroke. Arrangements for lifting the tool have been devised, but are not to be seen on one out of a hundred machines. In practice, the friction during the up stroke is not very detrimental, because the cutting-edge is not ground acutely, and does not soon suffer. Neither have tool-holders met with much favour in slotting machines, notwithstanding that there are one or two good ones offered for sale. A few useful solid slotting tools are grouped together in Figs. 77 and 78. In the first three figures the tool is shown in side elevation, and in inverted plan—that is, the bottom figures repre- TOOLS FOR CUTTING METAL. 67 sent the cutting edges looked at from below. In each instance the cutting point or edge is to the left hand. In Fig. 77 the first tool to the left is of the diamond point type, and is used both for fine cutting, and for finishing right into the corners of angular work. The second and third are round¬ nosed tools, used for roughing out, and also for finishing concave work. The fourth, seen in side and front views, is a common tool, used both for roughing, and finish¬ ing, and generally for completing work at one cut, and specially for key-way grooving, being tapered backwards from the cutting edge. Although the essential forms of the tools used on slotting machines are not numerous, yet each occurs in so many dimen¬ sions, that the total numbers run up rapidly. There may very well be 15 or 16 key-waying tools at a machine, all of precisely the same form, but of different widths. And so of other tools. Hence the equipment of an ordinary slotting machine will run up to 70, 80, or 100 separate tools. There are two ways in which the amount of metal in slotting tools is reduced. One is by making the tools double-ended—a very common practice—as in the key-grooving tool to the right of Fig. 77. The other is by using several detachable tool points in one shank, as seen in side and front views to the left of Fig. 78. The latter has other advantages besides the economy of metal; it often saves time— the time occupied in changing and setting the solid tools. It also furnishes the lighter tools with a substantial shank, by which they are enabled to operate more steadily and sweetly than if forged on a solid shank of light proportions. In one example the tool point is held with one, or with both of the set screv^'s shown; in the other a wedge only is used. Two tools are often used at one time for cutting either on external or internal surfaces, an example being a horn block for a locomotive, which is machined for the vertical movements of the axle-boxes. A single block only, or two or more, are often 68 TOOLS. superimposed and machined at once. The tools are not only clamped, but a stretcher of hard wood is inserted to keep them from being sprung inwards through the stress of cutting. The reason is that the manner in which the tools are set deprives them of the support of the face of the ram during cutting, and the pinching of the clips might not be sufficient to prevent springing or working back of the tools. There are many jobs where the inner faces which have to be slotted are situated too closely to¬ gether to permit of the convenient employment of two separate tools. To avoid the waste of time involved in the use of a single tool operating in succession on the two faces, one formed like that to the right of Fig. 78 in front and edge views is used, when the number of pieces to be slotted will permit of the cost of making such a special tool. The width of the tool is precisely the same as the finished width between the faces of the bosses, and there is but one cut taken over them. The hollow is simply imparted for facility of grinding the cutting faces. CHAPTER VI. The Shearing Action, and Shearing Tools. Shearing, a detailed operation—Diagonal Cutting with Chisel—Fox Trimmer —Square and Skew mouthed Rebate Plane—Turning Chisel—Reamers and Milling Cutters—Roughing Tools—Walker Planer Tool—Profiled Tools—Shear Blades—Necessity for Support to the substance being Shorn—Staggered Cutting in Mills—Flat Drill—Combination of Shearing with Staggering. T he labour involved in cutting hard materials is so great that various devices are adopted in order to lessen it as far as practicable. One of these is to remove the shavings or chips by a detailed action —a successive, but unbroken method of cutting, which is termed shearing; the other is similar in its results, though different in its operation, and embodies an action that breaks up the continuity of the chips. In a few instances the two devices are combined—namely, the shearing, and the staggering cut. The first is applied in the case of tools operated both by hand, and by machine, on timber, and on metal. When great resist¬ ance is offered to cutting with a chisel, the hand instinctively slides it along diagonally, and so applies the muscular effort to greater advantage. It comes more naturally on hard, than on soft wood, for it is nearly impossible to take a fair cut across the end grain of the hard woods, if a chisel is actuated straightforward. The labour of planing straightforward over a considerable width is great, being evident in the work of a coarsely set trying plane. As an extreme case take the power planing machines. A common panel planer, having parallel knives, say 24 in. in length, will absorb something like 3 H.P., and then will pull up its engine if forced to take exceptionally deep cuts. One of the most useful of the modern tools in the pattern shop, and joinery is the Fox trimmer, and its great value lies in 70 TOOLS. the nature of its shearing cutting. The blades a a, Fig. 79, are screwed to their backing at an angle of 45°. Being actuated by a long lever, pinion, and rack, they are slid longitudinally for right, and left handed cutting. The work rests on the table b, and adjustable wings at the ends permit of setting the work either square across, or to any angle. The trimmer shears off thick or thin chips at one traverse across the entire area of an end pre¬ sented to it, and wkh perfect truth, and as clean as though planed, due mainly to the shearing action of the blades. Since the shearing cut produces a clean surface, that affords another reason why it is sometimes adopted in preference to the straightforward cut. The difference is very marked—for example, in a square-mouthed rebate plane working across coarse grain in soft wood, and a skew-mouthed one. The latter not only operates with less labour, but it cuts much more sweetly, taking off curling shavings, and leaving a sleek, polished surface. Or plane a rebate lengthwise with the two types of planes; and not only will the labour required in the first be bound to be greater, but the surface which is cut will not be left so smooth, for a slight chatter will be found to have left its marks in places. Examples of this kind might be multiplied, but one more may suffice—the turning chisel. The action here is always that of shearing; the scraping chisels are not in the running for re¬ moving material rapidly, or for leaving clean, smooth surfaces. The difference which we note in the rebate planes, and in turning and scraping chisels is perfectly paralleled in the edge types of reamers and milling cutters. Few of these of over an inch in width have their teeth set parallel with the axis, but they are placed at an angle therewith (see Fig. 117, p. 99), to take a series of shearing cuts, 'fhe tendency to chatter is thus lessened, SHEARING TOOLS. 71 and the cut surface is left smooth. It is partly due to their shear¬ ing action that these cutters, with little or no top rake, act so efficiently. Latterly the tendency has been to increase this in amount, until on mills of considerable length the spiral twist becomes very marked. In some few mills the angle is found to measure as much as 50° with the axis of the cutter. Fig. 118, on p. 99, illustrates a French cutter, and some of the Pratt & Whitney mills have angles as great. Again, in built-up mills each separate piece is often set with its teeth in the opposite direction to that one adjacent (Fig. 119, p. 99). Each shears, but the endlong stress of one is counteracted by that of the other. By such devices work of from 24 in. to 30 in. in width is tooled readily. When the action of most metal-cutting tools is considered, few are found in which the action of the shearing cut does not occur, and this, without regarding those which are commonly known as shearing tools. Even the common roughing tools act partly by shearing, since sloping sides and edges take a share in cutting. The entire absence of such an action in parting-off tools, and in broad finishing tools, whether straight, or curved in profile, ex¬ plains why they are so hard to operate, and so liable to chatter. A familiar example of the shearing cut occurs in the knife tools used for facing ends. These are often bevelled so that the edges slope. The same formation is adopted in some roughing tools of the knife class used in turret lathes. The Walker planer tool shown in Fig. 80, is designed for taking broad finishing cuts. Its value lies in its shearing action, which not only renders the cutting easy, but prevents the breaking out of the metal at the edges of iron castings. The angle of the slope—namely 60°—is seen in plan. Amongst the most remarkable tools of recent years are those of the forming type, used for brass finishers’ work. Whatever the shape of a brass casting, provided it admits of turning a profile, a tool can be made to the profile, and slid tangentially thereto, cut¬ ting and finishing over the whole breadth at one traverse, and pro¬ ducing any number of pieces all exactly alike. One of these tools is shown in Fig. 81, with the piece of work it is designed to finish 72 TOOLS. beneath. The tools are milled to the section required, and never lose their form, because they are ground at the end only. The end is bevelled to an angle of 30°, and it is remarkable how very sweetly the cutting action is performed, as the cutter goes gradually through its work. There is no limit to the sectional shapes that can be formed in this way, and one movement of a lever is all that the attendant has to give to operate the tool. The shearing cut, therefore, is a power in the rapid removal of metal, just as it is in the side chisel for wood, and in the diagonal movement of the common chisel, instinctively imparted when paring the end of a piece of timber. Just as it is also in the skew¬ mouthed rebate plane, and in the little spill plane, which shears off the curling shavings that wrap tightly round it into a conical spill, with which to light your pipe. Without the diagonal cut, the ma¬ jority of the shearing tools would be nearly inoperative. Only by their gradual action (see the diagram, Fig. 82, which represents the angles of a pair of shear-blades) can they be made to sever materials. It would be clearly impossible with any amount of power to close, .say, the 4 ft. blade of a shearing-macbine instantly on a thick plate without damaging the blade, and plate. The question of tool angles here seems to be of much less importance than that of the thickness Fig. 82. of plate shorn, and of the degree of support afforded to it. There is no parallel between the removal of a shaving of metal with a cutting tool, and the separation'of a mass of metal SHEA/^/NG TOOLS. 73 through a considerable thickness. A shaving is curled off or broken immediately it is severed, but a plate in course of severance is backed up and rigidly supported by the mass of metal behind. Hence the action of the tool is only slightly cutting, and more largely squeezing—detrusive, a violent forcing of the material apart—and in a plane parallel with the faces of the shears. The diagonal severance occurs in the common scissors, and garden shears, sheep shears, and allied tools, though in a much reduced degree. The humble lawn mower is fitted with shear blades. The diagonal punch. Fig. 230, p. 160, embodies the same principle. It is essential to the successful opera¬ tion of all the shearing class of tools that the work be properly supported between the blades, or between the edge, and a bolster. If there is an open space between which the work can become squeezed, it will be bent, and distorted (see Fig. 83, a). What is seen to happen in loosely-jointed scissors would also occur in engineers’ shears if the blades were not in opposition in the plane of cutting (Fig. 83, b). But instead of the metal getting'squeezed be¬ tween, it would be bent somewhat at the severed edges and distorted, and the work of the shears would be interfered with, and increased by reason of the want of adequate support, and would probably become blocked and injured. The staggering of teeth is variously done. Fig. 154, p. 117, illustrates a common practice. Mills are built up thus on the hit-and-miss style, so that the teeth shall come into action in quick succession, instead of continuously, along a considerable length. The penetrative power is increased, and wide profile work is tooled with comparative ease. Fig. 199, p. 143, is another illustration of staggering, seen in the flat drill used in screw-machines for roughing-out a tapered hole rapidly. This is followed by the smooth tapered reamer in Fig. 200, p. 143. The last advance to be noted is the combined shearing and Fig. 83. 74 TOOLS. staggering of cutting edges, by which their penetrative power is still further increased, and in this way wide work is milled with increase in depth of cut. Either the mill is formed in the usual way by cutting the spirals on a universal machine, and the length of a spiral is broken up into short teeth subsequently, or the separate teeth are inserted into the body of the mill in diagonal lines. In each the effect is practically the same. In some cases the mill is made hollow, so that the teeth shall be flooded with lubricant during cutting. SECTION 11. SCRAPING TOOLS. CHAPTER VII. Examples of Scraping Tools. The Nature of the Operation—The Metal Worker’s Scrape—Some Wood- Turner’s Finishing Tools—Arboring Tools—Fly Cutters. S CRAPING tools form a large group, and they are also of much importance, because many tools occur on the border line, where it is often difficult to classify them either as cutting or scraping. Scraping is an operation which is not incisive, that is, the wedge formation of the tool is absent, and therefore practically it has no penetrative power, and cannot remove either shavings, or chips. A scraping tool used in lathe, or planer is usually held and operated with its axis normally to the surface of the work. But a hand scrape is generally held at an angle therewith. Scrapes are used only as corrective tools for fine processes, since they cannot remove material in quantity, but only in the form of dust, or minute particles. But their great value lies mainly in the minute precision of results attainable by their use, and in a lesser degree in the fact that they can be used on very hard material, which incisive tools will not touch. The scraping tools include the following:— Those used by metal-workers, in lathe, planer, and other machine tools ; those employed by wood-turners, the toothing plane of the cabinetmaker, for preparing veneering surfaces for gluing, the scrape made of a bit of broken saw blade for smoothing planed surfaces, preparatory to glasspapering, the scrape of the 76 TOOLS. metal-worker, employed either as a corrective tool, or for fine frosting. The common scrape of the metal-worker is shown in its more usual form in Fig. 84. It is pushed forward in short strokes, while held at a low angle with the face of the work. The cabinetmaker’s scrape Fig. 84. is held a few degrees over from the perpendicular. Figs. 85 illustrate tools used by wood-turners, which act purely by scraping. They are the round nose a, the right, and left hand fl Fig. 85. c side tools b, and the diamond point c, which is a union of the two forms B. The firmer chisel is also used as a scrape by the wood- n b ■ 1 Fig. 86. fi turner. The metal-turner employs scrapes in the form of finishing tools for all metals and alloys, including straight-edged tools, and SCRAPING TOOLS. 77 B those with convex and concave edges, parting tools, and others (see Chap, V.). Many facing tools are purely scrapes. Figs. 86 illustrate facing tools which act by scraping only. Fig. 86, a, is used for cutting faces on the inner side of cylinder covers, &c., to receive the bolts. The cutter a is wedged in the arbor d, which just fits the drilled bolt hole. In Fig. 86, b, a cutter is shown operating in turn on inside faces of bosses. Fig. 87 is a hand facing arbor, in which the cutter a is fed to its work by tightening the nut b. It is rotated by a wrench on the square neck c. Other ex¬ amples of facing cutters are given in Chap. XII., p. 127. Another type of scraping tool is the fly cutter (Fig. 88), used to a moderate ex¬ tent in some light operations, notably that of cutting wheel teeth of small r?.ii L J Fig. 87. dimensions, and the teeth of mortise wheels. Its advan¬ tage lies in the ease with which profiles can be produced without the trouble and expense of making a complete circular cutter. It is necessary to distinguish between the scrape, and the cutting tool, otherwise one is apt sometimes to confound the two. These, with the shearing action, are often all represented in the groups of tools to be noticed in subsequent chapters. Fig. 88. SECTION III. TOOLS RELATED TO BOTH CHISELS AND SCRAPES. CHAPTER VIII. Saws. * Wide Scope of the Subject—Saw Teeth, Scrapes and Chisels—Shapes varied to suit Materials—Examples —Spacing—-Types of Saws—Reciprocating— Continuous—Variations in Speeds—Tension of Blades—Thickness of Blades—Stiffening of Blades—Back Saws—Wear of Teeth—Degree of Set—Keeping Saws in Order—Set—Its Amount and Regularity—Methods of Setting—by Bending—by Hammering—Test of—Sharpening Saws— Topping the Teeth—by Stoning—by Filing—Files for sharpening— Angles for Filing—Gulleting—The Use of Saws—Forcing—-Buckle — Packing—The Place of Coarse and Fine Teeth—Plolding Work—Cutting to a Line. points to be considered in the economical working of I saws would never be remotely realised, apart from a considerable experience in their use. Are they scrapes, or chisels? What is the reason of the vast differences which exist in the shapes of their teeth, in their spacing, and their degree of set? Neither of these admit of a reply which would not be open to some criticism. And the devices for keeping these teeth in order, and maintaining them in full efficiency, admit of much discussion and differences of opinion. It will assist us in understanding the action of saws if we con¬ sider each tooth as a distinct tool. It will then be apparent that the teeth of all saws, except cross-cuts and those used for metal, are chisels, and mostly, too, with shearing action included. The cross¬ cut tears the fibres, the ripping does not, but each tooth severs a minute particle of the wood. The cross-cut operates in both direc¬ tions, the ripping saws in one direction only. The hardness, soft- SAWS. 79 ness, or stringiness of the ^tood also govern the forms of teeth, apart from that of their scraping, or cutting action. Thus, the shapes of saw teeth used for ripping, rake in various degrees, a selection of which is given in Figs. 89, 107, 108, those having the more obtuse angles being used for hard, and stringy, and knotty stuff, and those with acute angles for soft, clean materials. On these leading forms the changes are rung in various de¬ grees, in various shades of difference. A rip, or half-rip saw is the proper tool for cutting down thick plank¬ ing of soft wood wiVA the grain, and it has the least amount of set of any saw, proportional to its size, of course. But a saw having smaller teeth, called distinctively a “hand-saw” (Fig. 90), is that in com¬ monest use, and is generally used as a “cross-cut,” that is, for cutting planks, and boards across the fibres, and then it contains the greatest amount of set, and most of all for soft, wet woods. Fig. 89, A, shows the teeth of a rip saw to full size; Fig. 89, b, that of a half-rip; and c that of a hand-saw for cross-cutting. N^v/^/s/sAv/VVNv/\A C Fig. 89. Below, at d and e, are shown the teeth of a tenon, and a dovetail saw. A rip contains about two and a half teeth to the inch, a half-rip three and a half, a hand-saw four and a half to five and a half, a panel saw seven or more, a tenon saw ten, a dovetail saw sixteen to twenty. The degrees of coarseness and fineness in saws are also expressed in “ points.” The number of “ points ” is one more 8o TOOLS. than the number of teeth in the inch; an 8 point saw has but seven teeth. This is the American style. The type of tooth shown in Fig. 89, but with either more or less hook, and triangular, or gulleted, is universal in all saws that have to cut in one direction, such as ripping, hand, panel, tenon, dovetail, band, and circular. But when a saw has to cut alternately in two directions, as the cross-cut, the teeth are formed differently. The common hand-saw, set especially for cross-cutting, is an exception. Cross-cut saws are generally two- handled, so that two men can operate them; short ones, however, are made one-handled, and as they cut in both directions, equal pressure is exercised both ways, whereas with a hand, or tenon saw the workman instinctively relieves the weight of the saw from the cut on the back stroke, and bears harder on the forward or cutting one. It follows^that a saw cutting both ways must be a compromise in respect to the shape and method of action of the teeth. In a cross-cut saw the typical teeth are shaped as equilateral triangles, with the slopes equal on both sides (Fig. 91). That is how most English cross-cuts have been made for generations. But these are open to two objections: first that the retreating faces of the teeth are not favourable to good cutting action—the rake of the teeth being 30° back from the perpendicular, and second that there is little room for the sawdust to get clear of the teeth. Both faults are much more objectionable in soft SA WS. 8 i stringy woods than in hard powdery stuff. The M teeth (Fig. 92), in their various modifications, are designed to obviate these evils. This is an old form that fell into disuse in England, was revived in America, and is now sold extensively here. It is modified in several ways, both in the shapes of the M teeth, and in their alter¬ nation with teeth of other forms. Gulleting (Fig. 93) is an important feature in the teeth of saws working regu¬ larly in soft woods, as giving more clearance to the dust. It is especially applied to circular saws, which are most rapid in action, and to pit saws. Gulleting is much more important in saws running at high speeds than in other types. Hence circular saws generally have their teeth thus, and the larger the saw, and coarser the teeth, the deeper is the gulleting. The spacing of saw teeth is a matter of more importance than Fig. 94. Fig. 95 - it might seem to be on first thoughts. The case is one that has its parallel in the pitch of milling cutters. These were formerly pitched too finely, which caused the cuttings to choke, just as wood dust will choke the teeth of a saw having small spacings. But there is no universal rule for this, since some woods choke more quickly than others. Yellow pine, for instance, will work better with more spacing than stringy spruce will require. There are four broad types of saws—the reciprocating, the Fig, g6. circular, the band, and the cylin¬ drical. The latter is restricted to surgical operations on the cranium. The reciprocating saws include all hand (Fig. 90), back (Fig. 94), and turning, or sweep-cutting saws (Figs. 95 and 96), including the bow saws, the frame or gang saws, the fret saws, or F 82 TOOLS. jiggers, used for sweep-cutting, the hack saws, pit saws, and the cross-cuts. The circulars include but one class, though varied immensely in size, forms of teeth, precise functions, and arrange¬ ments, and including those both for operating on metal, and wood. The band or ribbon saws are continuous in action, like the circulars, and like those, are used for metal and timber. They are made in widths ranging from about ^ in. to 6 in., or 8 in. In all the reciprocating saws except the cross-cuts, the back stroke is lost, as is that of the metal planer, shaper, and slotter among machine tools. But in the circular and band saws the cutting proceeds uninterruptedly, as does that of the lathe, the milling cutter, and the grinding-wheel. As too there are certain speeds in lathe, milling machine, and grinder, which, though varying with the materials cut, are nearly constant for the same kinds, so there are certain best speeds for continuously cutting saws. Saws are not run at the same speeds for all woods, any more than lathe tools, milling cutters, and grinding wheels are. They can be run too slowly, or too fast; in either case the teeth get dull. In the first instance they lose their edges by mere friction, in the second by friction also; but in both cases the point is that the proper amount of dust is not removed in proportion to the speed of the saws, and the wear upon the teeth. There is waste involved in one case as there is in the other. An experienced saw hand will avoid both, by ascertaining the best rates, meaning the most efficient ones, for different materials, after which the thing is to feed regularly. The metal-cutting saws operate at a high speed in the thin- bladed “hot iron saws,” and very slowly in the thick-bladed “cold iron saws.” Other important differences in saws are those which arise from their tension, from the amount of support afforded to their blades, and from the direction in which they are operated. If a saw is thrust to its work, and nothing but the natural rigidity of the plate is utilised, then the latter cannot be so thin as when the opposite conditions exist. But a thin plate is always more economical than a thick one, because it causes less waste in dust, and this is a very important point where large quantities of material are being converted, as in sawmills. A thin blade also takes less power to operate it, hence one reason of the workman’s preference for a thin hand-saw. SAWS. 83 Thin blades are stiffened in various ways, in different kinds of saws. One is to strain them tightly, as in frame, or gang saws, in which case the tendency to bend under thrust is taken up by the tension of the blades. In the band saws, rigidity is secured by straining them over their pulleys with a weight, or spring. Another method is to fit a back to the blade, as in tenon (Fig. 94), and dovetail saws, hence termed back saws, the only objection to which is that the blade cannot pass right through, and into stuff thicker than its own depth, and is therefore unsuitable for cutting down boards. In the hand-saws, cross¬ cuts, turning-saws, and circulars, rigidity is obtained by thicken¬ ing the blades sufficiently, but making them no thicker than is actually necessary, and as a thick blade works heavily, and is productive of much friction, this is lessened by reducing the thickness from the cutting edges backw^ards, or in the circular saws, from circumference to centre. The grinding of a saw blade is an important matter, the ease and rapidity of working depending very much on this. The thick¬ ness of the blade must taper back from the teeth towards the back, and also from the end towards the handle. Fig. 97 shows the varying thicknesses under this system, the measurements being indicated at various locations, a, b, c, d. The measurements w’ere taken by Messrs Chas. Strelinger & Co. with a micrometer caliper, and are given as representative of a high grade saw. Saws, as supplied by the makers, are generally sent suitable for a given class of timber. But repeated re-sharpenings, in the case of circular saws, make the teeth, or the tooth spaces smaller, because the same number of teeth remain around a reduced diameter. Then it is better to use the saw's for some other kind of work. Or, every alternative tooth can be knocked out, or ground out. The degree of set of saw teeth varies from almost nothing, in the case of saws used for ripping in dry, hard woods, to larger 84 TOOLS. amounts in those cutting soft, wet logs, and in most that are used for cross-cutting. No rule can be laid down, but varying amounts of set are given, and saws selected for the duties which they have to perform. Saw teeth are kept in order by re-sharpening, and re-setting, and here good tools often get spoiled. Minute inaccuracies affect the working of saws, and these become cumulative. Slight varia¬ tions in the sizes of the teeth do not matter, though they look unsightly, but minute differences in their heights, and in the amount of their set soon show themselves in bad work. There may be little apparent difference between a saw that works well and one that does not. A sharp tool may work badly, for no saw will cut sweetly if the set is irregular, no matter how sharp it is. On the regularity and the amount of this the best results depend. Badly set saws cannot be prevented from hitching in the stuff, and this evil is more pronounced in cutting across, than with the grain, and in cutting harsh and hard woods than straight-grained soft kinds. The amount of set which is imparted to teeth is varied to suit different conditions. In a tool used for general service an average is struck. But two saws at least are required when regular work is being performed—one for ripping with the grain, and one for cross-cutting. Another may be well added for cross-cutting very wet and thick wood ; this one having the maximum amount of set. Irregular setting is of two kinds: in one it is variable from tooth to tooth ; in the other it is in excess all on one side, and insufficient all on the other, though regular for each one side. Both are common errors. The effect of the first is to throw more work on the high teeth than on the others, and dull them sooner* SAWS. 85 The effect of the second is to cause the saw to “ run ” sideways in the direction of the largest amount of set. This, in fact, is some¬ times done purposely, when the blade of a circular saw is per¬ manently buckled, in order to counteract the effect of the latter. Setting is done either by the hammer and set-block, or with a bending appliance. Besides these there are some special articles sold for the purpose. A professional saw-sharpener almost invari¬ ably employs the first named, an amateur and many workmen the second. The strong objection to the latter (Fig. 98 showing one of the commonest types) is that it is impossible to regulate the amount for each separate tooth with exact precision by bending it with the set. Much practice is necessary to handle this so as to produce a fair approximation to uniformity in the teeth, unless a sliding guide is used. Another objection is that the setting is done by a gradual bending of the tooth, instead of a sharp deflection, starting from the root. Using the hammer (Fig. 99), these evils are avoided. The saw blade being held in one hand at an angle which must not vary materially, the setting of the teeth, each by a single sharp hammer-blow, will be practically uniform (Fig. 100), and the bending will start sharply from the root. The whole of the setting down one side— t.e., of every alternate tooth —is done first, and then that of the other side, both to save time and secure uniformity of results. Fig. 100. 86 TOOLS. Another method which is often practised for fine-toothed tenon, and dovetail saws, is to lay the blade flat on a block of hard wood, end grain up, and set the teeth with a common brad punch ; the wood yields sufficiently to allow the teeth to take their set, and without the slightest elasticity, the latter being a frequent cause of fracture when bending with a saw-set. Although the block affords no guide for the amount of set imparted, it becomes easy to regulate the force of each blow with sufficient uniformity to produce uniform setting. Another plan is to bevel the edge of a block of iron, and lay the saw on it, with the teeth just over the bevelled edge, and strike the teeth with a setting hammer. This ensures uniformity. A single square block may have its four edges bevelled differently, to suit saws having different degrees of set, and height of tooth. Another device is shown in Figs. loi and 102 , where a is a block of hard wood, b a plate of steel grooved for four different sets, &c.; c a steel punch dropping loosely into a hole, in the bottom of which is an indiarubber cube, which keeps the punch just above the saw teeth, which cube, however, yields readily to the pressure of the punch when it is tapped smartly with a hammer. The punch is brought down on the saw teeth, instead of the hammer direct, an advantage which is apparent to those who have experienced how a falsely directed blow will knock two consecutive teeth, instead of alternate ones, in the same direction. Here the tooth is brought close under the punch before the latter is struck, so that it is impossible to mistake one’s aim. The four faces of the punch being bevelled to correspond with their SAWS. 87 respective set angles, and being duly proportioned in size for larger or smaller saws, simply bend the teeth without thinning them down at the points, and are capable of setting band saws, hand-saws, small circular, panel, and tenon saws. For those who are afraid to trust to the eye and hand in exact setting, there are various handy devices and tools made, one only of which need be noticed, the Morrill saw set (Fig. 103). Pressure on the handle a pushes the plunger b against the tooth, and the spring pulls it back again on the release of the hand. The amount of set to be imparted is adjusted by the anvil c, which can be moved up and down by its screw. The chief advantage of the set shown is the uniformity of its results. The test of regular setting is to hold the saw, end-on to the eye, and on casting the latter down the teeth, it will be readily seen whether any of them stand out beyond the rest. A more accurate test is to lay a fine needle in the groove formed by the laying over of the teeth, and incline the saw. If the needle runs down, the set is pretty regular; if not, some teeth block the way. \ Before sharpening saws, the teeth are topped, circular saws by stoning, other kinds by filing. The stone—any piece of hard material, as millstone, or pennant —is held in the hands before the revolving- saw, and brought in contact with the tips. No more is taken off than just suffices to reduce the highest teeth to the level of the lowest. The reduced teeth will be left with little bright facets, which are the guides to which filing has to be done. In hand-saws, pit, frame, and cross-cut saws, a file is used, a three-square file, or a flat gulleting file, passed down the teeth, or in the direction of hook, a few times, until the topping is com¬ plete. There is just the slight risk of the file canting over, and taking more off the teeth on the one side than on the other. To prevent this a file can be mounted and kept for this work—Fig. 88 TOOLS. 104), A being the file, b a packing piece, the file being too hard to drill for screws, c the screws for pinching a and b on the block d, of about 11 in. square, by 6 in. or 8 in. long. The vertical face lies against the plate of the saw. With regard to the height of teeth, it is obvious that the case is like that of milling cutters, uniformity in height of which is essential if all the teeth are to be operative. If they are irregular, and one-fourth of the number are below the rest, they will be doing only a part of their work, or be absolutely idle, according to the depth of cut. In frame saws, hand-saws, and cross-cuts, this is just as true as in circulars. The forms of the various teeth involve differences in sharpening them. The triangular, or three-square file can only be used pro¬ perly on those teeth the adjacent faces of which make angles of 60° with each other. For other teeth the various mill-saw files are provided. Fig. 105. Fig. 106. The files used are tapered, and parallel, single, and double cut, according to the work they have to do. Most of them are single cut, the double cut being used chiefly for the smaller saws. For purely triangular teeth the three-square files are employed, tapered for small saws, parallel or blunt for large ones. When a saw is gulleted it is generally necessary to use a round or gulleting file for the roots, and one of the flat or mill-saw files for the backs and fronts. In some cases, however, a flat file with one edge or with both convex is employed to file flat and gullet at once. A SA WS. ' 89 half-round file—the pit-saw file—is also used for teeth with gullets. Saws used for cutting timber must not be filed straight across, or they would work heavily and slowly. Only a keen corner is left standing up on the outside of each tooth (see the enlarged section, Fig. 105), and this is produced by setting the file at a double angle. One of these is an angle departing from the square- Fig. 107. across position; the other from the horizontal, so that the file is held askew in two directions. The first is the principal angle, and it varies in saws for cutting hard and soft woods, the greater angle being given for the latter. One does not measure these angles—the eye is sole guide; but if tested, they will be found to average about 70" from the saw-blade, or 20° from the square-across position, and about 10° from the horizontal. The effect on the shape of the teeth Fig. 108. is seen in Figs. 105, 106, 107, and 108. Only the back of each tooth receives the pressure of the file in Fig. 106, though a trifle unavoidably comes off the front also. The fronts of teeth are only specially reduced if the pitch happens to have got irregular. All the teeth that lean away from the file are treated at once, and then the saw is reversed in the vice, and the alternate ones are done. That uniformity of angle is thus secured which conduces 90 TOOLS. to sweetness of cutting. In each tooth the shearing principle is embodied, the slope of the tooth edge producing a diagonal cut, instead of one straight across. The difference in sweetness of working is similar to that between a square mouth and a skew mouth rebate plane. In these views it is seen that the outer points of the teeth (a, a. Fig. 105 ), enter and sever the grain before the sloping edges follow to remove the dust. Fig. 106 shows the teeth of a hand-saw. Figs. 107 and 108 show the difference in the teeth of circular saws for hard, and soft wood respectively; Fig. 109 is a band saw blade. When a hand-saw is thus set and sharpened regularly it will not hitch, if handled with reasonable precision, excepting for an instant at the com¬ mencement of a cut, and that may be easily prevented by holding the saw lightly just at the start. Of late years a number of machines have been introduced for the automatic sharpening of machine saws, both band and circu¬ lar, using emery wheels in place of files. Absolute uniformity is thus secured. Inseparable from sharpening is the work of gulleting (Fig. 93, p. 81, and Figs. 107, 108). To continue topping and sharpening without gulleting results in short teeth, and insufficient clearance for sawdust. So that after a saw has been resharpened from three to half-a-dozen times, the teeth are deepened in the gullets. This of course applies to teeth that are not triangular in shape, but have concave, or flat roots. A hand-saw for instance, or a triangular toothed cross-cut is deepened by the same filing which sharpens. But even in these it is not unusual to find teeth become shallower in time, due to the unconscious harder pressure exercised when filing towards the upper portions of the teeth, done to expedite sharpening. In hollow gulleting, the half-round edge of a gulleting file is used, or a blunt pointed parallel round file. This is the method where gulleting machines are not available. Many shops have these, and then an emery wheel with convex edge reduces the metal with much greater rapidity than any filing is capable of. Forcing a saw, or forcing the work to a saw does positive damage, besides that of lost energy. It makes the saw hot, and that produces buckle in a circular saw, and overstrain in band saws, and inaccurate cutting in both. Fig. 109. SAWS. 91 The first makes itself apparent in a wabbling motion, and a loud disagreeable clanging sound "when the stuff leaves the saw free, and it may, or may not leave permanent buckle after the saw has cooled. The best plan if this happens, is to let the saw run awhile until the heat has become equalised, and then dissipated. If the buckle remains, the plate must be hammered by a qualified man. Frequently the buckle can be got out by pressing the end of a piece of wood hard against the blade of the saw in the vicinity of the spindle, and thence outwards slowly towards the teeth, but stopping short of them. The object of this is to expand the saw around the spindle, and so equalise the temperature there with that of the teeth, and parts adjacent. A strained band saw ceases to run like a fine line, wabbling in a more or less wavy fashion. Too rough setting will buckle a saw next the teeth. Buckle is often magnified by an attempt to take out a slight amount, by careless hammering. The way to remove it is to hammer, and spread the metal in the vicinity of the buckle, allowing the latter to spread itself out. Any machine saw, whether circular, or band, requires to be packed close to the portion that is cutting. A circular, if of large size, is also packed in the rear. Without this precaution, it would be impossible to use the thin blades that are necessary to the economical conversion of timber. A thin blade with a moderate amount of set is the ideal tool. With regard to the adaptability of saws to their work, the one with the coarsest teeth that is suitable for a job should be used as a matter of economy. To employ a fine saw, excepting for fine work, is wasteful of time. It is not economical to cross-cut thick stuff with a common hand-saw, while a rip saw is quite unfit for such work. It is wasteful to cross-cut thick stuff with a small tenon saw, or to use a dovetail saw for ordinary bench work. In proportion as the teeth become finer and more numerous, their capacity for removing dust is lessened. And although fine teeth are wanted for thin stuff, and exact sawing to line, they are not to be employed for the opposite conditions, simply because they happen to be so easily operated. With respect to the methods of using hand and bench saws, the first point is to have the wood secure. The sawing stool or trestle is used to lay the board on for the ordinary work of ripping 92 TOOLS. and cross-cutting, two stools being used for long pieces, one for short ones, and the workman lays his right knee, or his left hand on the board to prevent it from rising. The saw is held at an angle of about 65“ with the face of the board. Short pieces can often be cut closer to lines when held perpendicularly in the bench vice, as in sawing down the shoulders of tenons. The same position is adopted when using the compass, keyhole, or bow saws. The work is held steadily, the lines are seen better, and both hands are left free to operate the saws. The tenon and dovetail saws are employed on the bench mostly, the work being laid thereon. But resistance to the saw is generally afforded by the bench hook, or the shooting board, or by the vice, or in some cases by the angle board. A difficulty which unskilled amateurs and clumsy work¬ men encounter is that of sawing exactly to a line, and plumb. You see a cut started all wobbly, in the attempt to guide the saw straight, and to the line. This will also occur most readily in the case of a saw having too much set for its work, as, for instance, a hand-saw set coarsely to cross-cut but used for ripping. This difficulty can be avoided by sighting the saw correctly before be¬ ginning to cut. To saw plumb comes by practice. Apprentices may set a square on the board and up the blade of the saw; but they must soon discard that unless they want to be laughed at. Figs, no and in show two forms of mitre blocks, in wood, and metal respectively, by which the movement of tenon saws is controlled at an angle of 45°. When any large amount of sawing has to be done either to length, or angle, by hand or machine, mechanical aids are utilised. CHAPTER IX. Files. The Forms of the Teeth—Mode of Action—General Employment of Files- Sections—Derivations of—Longitudinal Forms—Degrees of Coarseness of Cut—Terms—Special Files—Length—Special Handling. F iles and rasps must be classed with the scrapes, as a glance at the enlarged sectional form of the teeth (Fig. 112) will show. A keen file tooth will not retain its cutting capacity long, the tips becoming broken off almost immediately. A file is therefore a collection of scrapes, just as the ordinary saw is a series of chisels. A file possesses a shearing action, because the rows of teeth are arranged diagonally, besides which the workman often gives a diagonal traverse to the tool in use. The teeth of files are cut by hand, and by machine, .^t one time the prejudice against the latter was very strong, but they are gradually ousting their rivals from the market. Files and rasps number probably from two to three thousand different sizes. They are employed in nearly all trades, both for metal, and woodworking. The largest are used by the engineer, and the smallest by watchmakers, and locksmiths. Cabinetmakers and carvers employ them, and saw sharpeners, and farriers. The principal points about any file or rasp are : The manner in which its teeth are cut, their degree of coarseness, the longi¬ tudinal shape, the section, and the length. The figures illustrate these cardinal points. With regard to the sections, we see that files are in many cases the counterpart of the forms which they have to produce. Fig. 112. 94 TOOLS. The flat files are obviously intended for flat surfaces. But they will of course produce convexities. If concavities have to be filed, the half-round, and similar tools are used, while in some cases longitudinal concavities are produced, as in the case of riffler files, besides which, engineers bend or crank their files for special purposes. In other cases files are used to impart exact angles. Looking at Fig. 113, we see that sections derived from the rectangle are the square files a, the flat files b, which occur in various thicknesses, and longitudinal outlines. A special flat file is the mill file c, which is thinner for a given width than the flat file B. A very thick flat file d is a pillar file, while a very thin one E is a warding file. Often flat files have both, or one edge rounding, as at f, g. Rasps are made in similar sections to the files. Sections derived from the circle include the round files h, the frame saw, or pit-saw file j, the half-round k, the cabinet files L, M, the double half-rounds n, o, whieh contain different curva¬ tures on opposite faces. Sections derived from the triangle are the three-cornered, or three-square file p, the cant file Q, the slitting, or feather-edge file r, and the knife file s. Compounded FILES. 95 of the square and triangle are the swaged reaper files t and u, and the reaper knife files v, w. ABC D E F Q H j Fig. 114. Coming to the longitudinal forms of files, we have in Fig, 114 first, A, B, c. A is a hand file, which may be nearly, or quite parallel. When a file is parallel throughout its length it is termed blunt pointed, to distinguish it from the ordinary equalling file, which always has a slight curvature lengthwise, b is a tapered file. It may be nearly straight-tapered, or of a bellied form, as in the figure. But any such file is always considerably smaller at the point than it is next the tang, differing therefore from a. The square file c is tapered in the figure and bellied. It is also made parallel, or blunt, d and e represent respec¬ tively the three-square file, and the three-square blunt saw file, one being tapered and bellied, the other parallel, f and g are round files, the first being commonly termed a rat-tail, the second a gulleting, being used by sawyers, for filing the roots or gullets of large saws, h is a common half-round, and bellied file; j is a parallel half-round, also termed a pit-saw, or frame-saw file. Most of these can be had single, or double cut, and also as rasps, the difference of which is shown in Fig. 115, Fig. 115.