Elementary forge practice; a textbook for technical and vocational schools

Front matter

F0RG3E PRACTICE

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HARCOURT

Preface

to SECOND EDITION

While it is realized that a comprehensive knowledge of forge practice can be gained only thru contact with a commercial shop doing a wide variety of work, it is at the same time believed that an understanding of fundamental principles may be secured thru a carefully planned and conducted course of instruction in a technical school. This book is designed to assist the student in grasping fundamental principles. To this end a series of projects involving fundamental operations has been devised.

It may be unnecessary for some students to complete the entire set. Some of the earlier projects and occasionally others may be omitted if the student has had previous practice or if he shows great facility. On the other hand it will be readily seen that there is a logical order in the series and that some projects must be mastered before others are undertaken.

The whole set may require a longer time than is allotted to the subject in the average manual training course. In such case the instructor may easily select such work as will meet the peculiar conditions.

The criticism given an earlier edition by the technical press, and the reception by teachers of forge and machine-shop practice, have shown the need for a text-book of this type.

The author wishes to express his appreciation of the assistance rendered by Professor E. P. Lesley of Leland Stanford Junior University, Mr. W. L. Rifenberick, and Mr. H. P. Miller, Jr., in the preparation of this book.

R. H. HARCOURT.

Stanford University, November, 1919.

Contents

PAGE

Chapter I. Materials and Equipment 13

Materials; Wrought Iron, Norway or Swedish Iron, Machinery Steel, High-Carbon Steel, High-Speed Steel ; Emery- Wheel Test; Weight of Iron; Shrinkage; Bibliography ; Forge, Fire Tools, Coal, Building Fire, Coke, Making Coke, Clinker, Banking Fire, Cleaning Fire at End of Period; Anvil, Tool Rack; Hammer, Backing Hammer, Cross Peen Hammer, Sledges ; Tongs, Fitting Tongs to the Work; Measuring and Marking Tools; Flatter, Set- Hammer, Chisels, Grinding Chisels, Bob-Punch, Necking Tool, Fullers, Swages, Swage Block; Vise, Cone, Surface Plate, Shears.

Chapter II. Drawing-cut^ Bending and Twisting ... 30 Oxidizing Fire; To Prevent the Formation of Scale; Welding Heat, Indications of a Welding Heat; Burned Iron; Drawing-out, Squaring, or Truing-up, Work; Cutting Cold Stock, Cutting Hot Stock; Twisting, Punching.

Chapter VI. Annealing, Hardening and Tempering Steel . 101

Annealing, Box Annealing, Water Annealing; Hardening, Refining Heat, Recalescence, Tempering, Guide for Hardening, Tempering only the Cutting Edges of Tools, Hardening and Tempering Tools thruout. Methods of Cooling, Forging Heat of Tool Steel, Heating Steel for Hardening, Importance of Uniform Heating, Hardening at a Rising Heat, Restoring the Grain, Warping in Cooling, Hardening Thin Flat Articles, Tempering Taps, Tempering Carving Knives, Tempering Shear Blades, Tempering Springs, Case- Hardening, Pack-Hardening; Treatment of High-Speed Steel ; Cutting Stock, Forging Heat, the Fire, Heating for Hardening, Cooling, Annealing.

Chapter VII. Tool Forging 118

Selection of Steel for Tools, Lathe Tools, Cold Chisel, Cape Chisel, Round-Nose Cape Chisel, Center-Punch, Round-Nose Tool, Cutting-ofif Tool, Threading Tool, Side Tool, Boring Tool, Cross-Peen Hammer, Eye-Punch, Drift-Pin, Small Cross-Peen Hammer Ball-Peen Hammer, Hot Eye-Chisel, Cold Eye-Chisel, Geologist's Pick, Hand Rock-Drill, Machine Rock-Drill, V-FuUers, Wing Swage, Dolly, Hunting Axe, Hunting Knife.

PROJECTS

1. Drawing-out and Bending Ring

2. S-Hook

3. Staples ....

4. Beam Strap .

5. Twisted Gate-Hook .

6. Practice Welds — Fagot

7. Round Lap-Weld

8. Flat Lap-Weld .

9. Links of Chain .

10. iRing— Round Lap-Weld

11. Ring — Link Scarf

12. Forged Hook

13. Common Eye-Bolt

14. Common Hinge .

15. Flat Ring .

16. Band Ring .

17. Upset-Head Bolt

18. Welded-Head Bolt .

19. Forged Bolt

20. T-Weld

21. Angle Weld

22. Forged Open-End Wrench

23. Flat-Jawed Tongs

24. Link Tongs .

25. Hollow-Bit Tongs

26. Cold Chisel .

27. Cape Chisel .

28. Round-Nose Cape Chisel

29. Center-Punch

30. Round-Nose Tool

31. Cutting-Off Tool

32. Threading Tool .

33. Side Tool .

34. Boring Tool

35. Cross-Peen Hammer .

36. Small Cross-Peen Hammer

37. Ball-Peen Hammer .

38. Hot Eye-Chisel .

39. Cold Eye-Chisel .

40. Geologist's Pick .

41. Hand Rock-Drill

42. Machine Rock-Drill .

43. Hunting Axe

44. Hunting Knife .

I

X

XI XII and XIII

XIV

XV

XVI

XVII

XVIII

XIX

XIX

XX

XXI

XXII and XXIII

XXIV and XXV

XXVI and XXVII

XXVIII

XXIX

XXIX

XXX

XXX

XXXI

XXXI.

XXXII

XXXIII

XXXIV

XXXV

XXXVI

XXXVII

XXXVIII

XXXIX

XL

XLI

XLII

XLIII

XLIV

Introduction

The author has found that very good results may be obtained by the use of "Elementary Forge Practice" if the following methods are applied. Assemble the students and give them a talk and demonstration covering the following points:

i. The forge.

2. Coal, coke, and clinkers.

3. The anvil.

4. Forge tools, tongs, etc.

5. Building the fire, banking fire, making coke, care of the fire, etc.

6. Materials : Tool steel, machinery steel, and wrought iron. Their characteristics and the methods for distinguishing them.

7. A piece of machinery steel p^ or ^ of an inch in diameter should be heated and drawn out as described on page 32. Only a portion of the stock necessary to make the project is drawn out. The next step is to take a piece of stock Y^ an inch in diameter and 11 J^ inches long. This is heated and bent as described on page 36.

A piece of stock % or J^ an inch in diameter is pointed. A wedge for a hand-hammer is also made. This completes the first demonstration.

A demonstration should not be necessary for projects 2 and 3.

Experience has shown that where the first demonstration and explanations have been thoro, fewer demonstrations are required.

Demonstrations are given only when they are absolutely necessary. The difficult projects such as the Lap-weld, Link, Hook, Tongs, and a few others require them.

10 INTRODUCTION

Toward the end of the term, talks and demonstrations are given covering the making of crank shafts, drop forgings, special welds, and manufacturing methods.

Upon completion of the required number of projects, or work accepted in lieu of them, students are encouraged to make hunting knives, axes, or work which has a special interest for them.

Written examinations including questions of the following type are given about once a month:

1. Give a method for distinguishing wrought iron from machinery steel.

2. What percentage of carbon do tool steel, machinery steel, and wrought iron contain?

3. Why is a flux used when welding steel?

4. What is an oxidizing fire?

5. Give a method for finding the refining or hardening heat for tool steel.

6. What is the purpose of pack hardening?

7. Why is tool steel annealed?

8. Describe the process of water-annealing tool steel.

9. Describe one method of tempering a spring.

10. How is a cold chisel hardened and tempered?

11. What is the length of stock necessary for a ring of one-inch round iron, having an inside diameter of ten inches, allowing J^ an inch for upset and waste in welding?

12. How is high-speed steel hardened?

13. Describe one method of hardening and tempering a tap.

14. Draw a diagram of an anvil, designate the parts and give the material of which they are made.

15. What is meant by drawing the temper?

The use of this book has clearly demonstrated the following advantages :

INTRODUCTION 1 1

1. Taking of notes during a demonstration is partially eliminated, so that a student has the fullest opportunity for watching the entire demonstration. The text is a ready reference in case he does not remember a demonstrated point.

2. Students do better work and complete the projects in a shorter period of time.

3. Students are able to proceed with the projects without personal instruction. This eliminates a great waste of time.

4. The instructor is able to handle a large number of students efficiently and without confusion.

Note — The best results will be obtained if the student uses the book as a guide while at work.

Elementary Forge Practice

CHAPTER I. Materials and Equipment

The Materials most commonly used in forging are: wrought iron, Norway iron, machine steel, tool steel, and high-speed steel. Their main constituent is iron, as obtained from iron ore; but they differ in the amount of carbon and other elements that are mixed or alloyed with the iron.

Wrought Iron is made by the Puddling Process, and differs from other kinds of iron mainly because of the slag seams introduced during its manufacture. These seams cause the stringy, fibrous appearance of the iron when it is broken or cut cold. They are helpful when welding, since the slag acts as a flux; but they also weaken the iron, and make it liable to crack. Wrought iron is much easier to weld than machine steel, because the range of temperature thru which it may be heated without injury is much greater. It may not be hardened to any appreciable extent. If hammered too much when cold it will burst thru the slag seams.

The percentage of carbon in common wrought iron is very low, being about .04%.

Norway or Swedish Iron, as imported from Norway and Sweden, is made in a charcoal furnace. It is the purest soft iron on the market, as the ore from which it is made is practically free from phosphorus and sulphur. It is used mainly for intricate work involving much bending and, since it rusts very slowly, for forgings that are exposed to the weather. The best grades of crucible steel produced in this country are also made from this kind of iron.

Machinery Steel, also known as machine steel, low-carbon steel, and mild steel, contains from about .05% to .5% of carbon, and is made by the Open-Hearth or Bessemer Process. It may be easily welded with the aid of a flux, and can be welded without one. Being stronger, more homogeneous and cheaper than wrought iron, it is well adapted for f orgings. It cannot be hardened to any very great extent. A piece of good grade %-inch thick may be bent cold 180° flat on itself without rupture. In general it is found that increasing the carbon content will increase the strength, elasticity and hardening quality, and decrease the ductility and weldability.

This grade of steel differs from wrought iron in that it does not become soft and plastic at the welding heat. It burns or wastes away at a lower temperature than wrought iron, making it more difficult to weld. The crystalline, or granular, appearance of the fracture, the absence of slag seams, and the emery-wheel test described later, are used to distinguish it from wrought iron.

High-Carbon Steel, or tool steel, the best grades of which are made by the Crucible Process, contains carbon in amounts varying from .5% to 1.6%. Steel with a higher carbon content is seldom used. High-carbon steel is generally distinguished from low-carbon steel by the fact that it becomes very hard when heated to a red heat and suddenly cooled. It snaps off when cut cold, on account of the hardness of the ordinary commercial stock. As with mild, or low-carbon steel, the hardening quality varies directly with the carbon content. There are, however, some brands of steel containing less than .5% carbon which harden considerably when heated and cooled quickly; so there is no well marked division between the two classes. High-carbon ste'el is most difficult to weld.

High-Speed Steel is of special importance in the machine shop on account of its red hardness, or property of retaining a cutting edge at a visible red heat. Tools made from ordinary high-carbon steel, if heated by friction or otherwise to a

IRON AND STEEL 15

temperature of about 400° F., begin to lose their hardness; while high-speed steel tools may be heated up to about 1200° F. before they break doWn from softening.

This property is due to the presence in the steel of from 13% to 19% tungsten. Other elements are present in approximately the percentages given :

The Emery-Wheel Test. — The most satisfactory shop method for distinguishing between the different kinds and grades of iron and steel consists in observing the sparks given off when a bar of the material is brought in contact with a rapidly revolving emery-wheel. In general it is found that the more carbon there is present the brighter the sparks will be.

Sparks obtained from wrought iron are light-straw color, and follow straight lines. Machine steel gives off sparks that are much the same in character except that they explode, or fork, to some extent. White sparks which explode much more frequently are obtained from high-carbon steel. Those given off by high-speed steel follow straight lines, similarly to sparks from wrought iron, but give off much less light, and end abruptly in a chrome-yellow, pear-shaped flame.

Weight of Iron. — It is often necessary to know the weight of material used in an iron or steel forging. This can be computed if it is remembered that a cubic foot of steel weighs about 490 pounds, or that a 1-inch square bar 1 foot long weighs 3.40 pounds and a 1-inch round bar of the same length weighs 2.67 pounds.

Shrinkage. — When iron or steel is heated, it expands in direct proportion to the change in temperature. A bar heated to a good forging heat will have each of its linear dimensions increased about % inch to the foot. Upon cooling it will contract about the same amount.

Bibliography. — For a complete description of the various processes employed in making iron and steel, the student is referred to the following books :

Stoughton: The Metallurgy of Iron and Steel.

Book Co., New York.

McGraw-Hill

Forge. — One of the commonest types of forge used in universities and technical schools is shown in Fig. 1. It consists of a cast-iron hearth (A) mounted on a suitable base (H) and having at its center a fire-pot (B). This fire-pot is made in various shapes and sizes, and is sometimes lined with firebrick. At the bottom of the fire-pot is an opening,

Fig. 1. The Forge.

A, hearth; 5, fire-pot; C, tuyere lever; D, blast-gate lever; E, adjustable hood; F, adjusting lever; G, exhaust pipe; H, base; /, coal-box; /, coke-box.

FIRE 17

called the tuyere, thru which the blast is forced. Tuyeres are constructed so as to admit the air readily and at the same time prevent coal from dropping thru therti. Some are arranged so that the coal and ashes which do drop thru can be shaken out by means of the tuyere lever (C). The air blast is controlled by means of the blast-gate lever (D).

The forge shown is of the down-draft type, the smoke and gases from the fire being drawn under the adjustable hood (£) and down thru the exhaust pipe (G). The position of the hood can be changed by means of the adjusting lever (F). The boxes (/) and (/) should be used for holding coal and coke respectively, a separate tank for water being advisable.

In commercial shops the forges are generally circular and made of light sheet steel.

Fire Tools. — The tools required at each forge in order to take proper care of the fire are : coal shovel, fire rake, dipper, and poker.

Coal. — ^The best "blacksmith's" coal for use in a forge is a high grade of soft or bituminous coal. It can in general be distinguished by the crumbling of the lumps when hit with a hammer, but the most reliable test is to note its characteristics in actual use. When dampened and put on a fire it should cake up, forming good coke and leaving very little clinker when burned. Ordinary soft coal, or steam-coal, makes a very dirty fire, giving off much smoke and leaving a great deal of clinker. It is very disagreeable to work with, on account both of the smoke and the hot gases given oflf.

Coal containing either sulphur or phosphorus is to be avoided, as these elements are absorbed by the iron. Sulphur makes the iron hot-short, i. e., brittle while hot; and phosphorus makes it cold-short, or brittle when cold.

Building Fire. — The success of welding and forging depends, to a large extent, on the building and care of the fire. When a fresh fire is to be built, make a hole about 8 inches in diameter at the center of the hearth, removing enough of the dirt and ashes to expose the tuyere. Place some shavings in this hole and on top of them some small lumps of coke. After lighting the shavings, turn the blast on a little and wait until the coke has become red hot. More coke should then be added, forming a cone, and the space around it banked, or filled in, vi^ith moist coal. Care must be taken in dampening the coal not to get it too wet, or the water will seep out and run over the tuyere, thereby spoiling the fire. When enough coal has been placed around the fire, it should be leveled off and packed down hard with the back of a shovel. This is done to prevent the air-blast from coming thru at the outer edges of the fire, spreading it over too large an area.

Coke. — It is found that packing also helps materially in the production of coke, which is formed by the caking of the coal after the fire has burned for some time. Coke should be saved when cleaning out the fire or hearth at the end of a period, or when building a second fire. The center of the fire burns out somewhat like a crater, and has to be constantly refilled with extra coke. If it is necessary to have a small fire, the coke should be broken into small pieces.

Making Coke. — When extra coke is required, it can be made by placing some large lumps, or wet coal, on top of the fire and allowing it to burn slowly for some time. It should not be disturbed with a poker until it has caked well.

Caution. — Do not continually poke or disturb the fire, but keep the center full of small pieces of coke.

Clinker. — Dirt and dross in the coal form clinker directly above the tuyere. This is a detriment when welding, since it prevents air from coming thru the tuyere and causes a deposit of dirt on the pieces in the fire. For this reason the fire should be cleaned out every half-hour, when welding, by removing the clinker with a poker. Care must be taken to prevent lead and babbitt metal from getting into the fire, as thev oxidize and prevent welding.

FIRE

Banking Fire. — By placing a piece of wood on end in the fire and covering it with coke and coal, the fire will last for some time without air-blast.

Cleaning Fire at End of Period. — When the fire is no longer needed, the coal should be removed and placed in the coal-tank. The coke should then be loosened with the poker, moistened with water, and placed in the coke-tank. The clinker and ashes are dug out and thrown into the ash-box. The forge is then clean and ready for future use.

Fig. 2. The Anvil.

A, body; B, horn; C, base of horn; D, face; E, hardie hole; F, pritchel hole ; G, rounded edges.

Anvil. — The type of anvil generally used is shown in Fig. 2. The body {A) is usually made of wrought iron or a special grade of steel, but for light work it is sometimes of cast iron. The horn (5) must be tough in order to withstand heavy pounding and is usually of the same material as the body. The base of the horn (C) has a flat top which is used in preference to the face when cutting stock with a chisel, because it is not so hard and will not dull the chisel. The face {D) is a tool-steel plate J^-inch thick which is welded to the body. It is carefully hardened and has a smoothly ground top. The square hardie hole (£) is used for holding the shanks of tools, while the pritchel hole (F) is very convenient in making small bolts, as it allows their stems, or shanks, to extend thru. The two side edges of the face (G) are rounded for about 4 inches near the horn, to facilitate the bending of stock. If intended for small work, like the projects in this book, an anvil should weigh about 150 pounds.

The anvil should be placed with the 'horn at the left of the worker and the face 26 inches above the floor, the outer edge being about J4 inch lower than the inner one. It is therefore necessary to provide a base. This is generally of cast iron, as shown in Fig. 2, but may consist of a large wooden block.

Fig. 3. Tool-Rack.

Tool-Rack. — To have the blacksmith tools within easy reach while working at the forge, they should be kept on some sort of a tool-rack. A very good type is shown in Fig. 3. It consists of an iron top cast on one end of a piece of large pipe." The other end of the pipe is imbedded in the floor. Slots for holding tools are provided on each side of the top, which acts as a table for pieces of stock, supplies, etc.

HAMMER

These racks are sometimes made of wood, but such are easily burned by hot materialsj and, since they usually have four legs and a bottom shelf, it is rather hard to clean under them.

The Hammer used most commonly by blacksmiths is a ball-peen hammer weighing from Ij^ to 2>^ pounds and similar to the one shown in Fig. 4. The face, or large end, is for ordinary work ; and the ball end, or peen, for scarfing, riveting, etc. The face should be convex, in order not to mark hot material, and its edges rounded off, to keep them from breaking. The edge of the face nearest the worker is called the heel, and the front edge the toe.

Fig. 4.

Hand-Hammer.

Fig. S.

Cross-peen.

Fig. 6.

Sledge.

A Backing Hammer generally has the same shape as the common ball peen hammer, but it weighs about 5 pounds. It is used by a helper when light quick blows are necessary, and also when backing up, or starting, the heel of a scarf.

A Cross-peen Hammer, Fig. 5, weighing "about 3j^ pounds, is needed for each two forges. This hammer is particularly valuable in welding steel on account of the heavier blows which can be delivered. It is also useful when making a pair of tongs, and in almost any work where one student needs the help of another.

Sledges. — Fig. 6 shows a sledge of the straight-peen type, which is ordinarily used in a blacksmith shop. The weight of such sledges varies from 8 to 13 pounds.

Tongs vary in form, depending on the size and shape of the stock handled. Those frequently used in the forge shop are shown in Fig. 7.

E

Fig. 7.

A, flat-jawed; B, hollow-bits; C, link; D, pick-ups; E, chisel.

The Flat-Jawred Tongs, shown at A in Fig. 7, are used for holdmg flat stock.

The Hollow-Bit Tongs (B, Fig. 7) are employed in handlmg round, square, or flat material.

TONGS 23

Link Tongs are shown at C, Fig. 7, and are very convenient for holding links or rings.

Pick-up Tongs {D, Fig. 7) are intended mainly for picking up large and small pieces of different sizes of stock.

The Eye Tongs, or eye-chisel tongs, shown at E in Fig. 7, are used in dressing an eye-chisel. The projections are made to fit into the eye, while the jaws are bent so as to avoid contact with the burred head of the chisel.

Fitting Tongs to the Work. — Tongs should alv^ays be fitted to the work which they are intended to hold. The poorly fitted tongs shown at A, Fig. 8, should be changed so that the jaws touch the stock for their entire length, as in B, Fig. 8. Their form at A affords a poor grip, which is a serious drawback when forging or welding.

B £

Fig. 8.

To fit tongs to a piece of work the jaws should be heated red hot, the stock placed between them, and the jaws hammered down tight around it. In order to prevent the handles, or reins, from coming too close together while doing this, a piece of iron should be placed between them directly behind the jaws. If the handles are too far apart, give them several blows a short distance back of the eye.

Never leave tongs on a piece of work while it is in the fire if there is danger of their becoming hot. When removed from the fire they will not hold the work firmly, because the handles will come together under the pressure of the hand.

Measuring and Marking Tools. — In forging it is often required to work to a given size, or to duplicate another forging. For this reason it is necessary to have on hand a rule, a pair of calipers, and a try-square, as shown in Fig. &.

Rule

Square

Center Punches-

Fig. 9. Measuring and Marking Tools.

The rule should be of brass in order to withstand the heat, and should have a 12-inch scale with enough extra room for a hand-hold. The calipers are generally made of steel, and are used mainly for work done under the trip-hammer. The try-square need only be a small one.

For marking stock a center-punch is generally employed,

Fig. 10. The Flatter. Fig. 11. The Set-Ha;hmer.

since the mark made by a chisel will start a crack if the stock is bent. A chisel should be used only when the stock is to be

It of? at the point marked.

The Flatter, Fig. 10, is used for flattening and smoothing

CHISELS straight surfaces. Its face is generally about 3 inches square, and should be smooth with rounded edges.

The Set-Hammer, shown in Fig. 11, is used in finishing corners and parts that cannot be reached with the flatter. The sizes vary, but for small work the face should be about 1J4 inches square. It also should be smooth and flat. The one illustrated is commonly called the square-edge set-hammer, to distinguish it from the round-edge set-hammer.

Chisels. — ^Two kinds of chisels are commonly used in the forge shop: one for cutting cold material, and the other for cutting hot material. These are called cold and hot chisels.

The cold chisel, Fig. 12, is made thicker in the blade than the hot chisel, Fig. 13, which has a rather thin edge. The

Fig. 12.

Cold Chisel.

Fig. 13.

Hot Chisel

Fig. 14.

Hardie.

hardie, shown in Fig. 14, is used for cutting hot material. It has a square shank to fit the hardie hole in the anvil. Hardies are also made to cut cold stock.

The hot chisel should never be used on cold material, as its edge will be turned and ruined; nor should the cold chisel be used for cutting hot stock, as the heat will soften its edge, making it unfit for cutting cold stock.

Grinding Chisels. — The sides of a cold chisel should be ground to an angle of about 60 degrees with each other, as shown at A in Fig. 15. This forms a good cutting edge. jV' the edge is too thin it will bend.

The cutting edge should also be ground convex, as shown slightly exaggerated at B. This prevents the corners from breaking off too readily, as they would if it were ground as at C.

Hot chisels are ground somewhat thinner than cold chisels, and with the sides at an angle of about 30°.

Fig. IS.

The Bob-Punch, shown in Fig. 16, is used in place of the peen of a hammer for hollowing out stock. Examples of its application are given in several of the special welds described in Chapter IV. It is hit with a heavy hammer, in the same manner as the flatter. If a hand hammer were used in place of the bob-punch its hardened face might break when struck.

Fig. 16.

Bob-punch.

Fig. 17.

Necking Tool.

Necking Tool. — In certain cases, such as welding an eye-bolt, finishing the inside of the eye of a forged hook, and making a T-weld, a necking tool (Fig. 17) is very convenient, but not absolutely necessary.

Fullers. — Fig. 18 shows top and bottom fullers, which are

FULLERS AND SWAGES used in forming grooves and filleted corners. They are made in a number of sizes, depending upon the radius of the circular edge. On a %-inch fuller this radius would be }i inch. The top fuller, A, is made with a handle, while the bottom fuller, B, has a square shank, like the hardie.

Fig. 18 Top and Bottom Fuller.

Fig. 19.

Top and Bottom Swage.

Swages. — A top and a bottom swage are shown at A and B in Fig. 19. They are used for a wide variety of purposes, but mainly for finishing round material. The sizes vary accord-

Fig. 20. The Swage Block.

ing to the diameter of the round stock for which they are made. Thus a 2-inch swage is used on 2-inch round stock.

A Swage Block is shown in Fig. 20. These blocks are usually made of cast iron, and, owing to their wide range of utility, in various shapes and sizes. They are of special importance in small shops, as they can be made to take the place of numerous swages and special tools. A cast-iron base is generally provided, as shown, on which they can be placed in either a flat or an upright position.