CHAPTER IIForging Operations

Fig. 8.—The Tongs.A, flat-jawed tongs;B, hollow bit tongs;C, pick-up tongs;D, side tongs;E, chisel tongs;F, link tongs;G, tool or box tongs.

12. The hollow bit tongs, shown atB,Fig. 8, are very handy for holding round iron or octagonal steel. They can be used also for holding square material, in which case the depressions in the jaws should be V-shaped.

13. The pick-up tongs(C,Fig. 8) are useful for picking up large or small pieces, as the points of the jaws are fitted closely together, and the two circular openings back of the point will securely grip larger pieces when seized from the side.

14. The side tongs(D,Fig. 8) are used for holding flat iron from the side. Tongs for holding round iron from the side can be made in this form with circular jaws.

15. The chisel tongsare shown atE,Fig. 8. One or more pairs of these are necessary in all forge shops. As the hot and cold cutters frequently get dull or broken, it will be necessary to draw them out and retemper them; and, as the heads of these cutters become battered considerably, they are difficult to hold without chisel tongs. The two projecting lugs at the ends of the jaws fit into the eye, and the circular bows back of them surround the battered head of the cutter, so that it can be held without any difficulty.

16. The link tongs(F,Fig. 8) are as essential as anything else required in making chains or rings of round material. They can be made to fit any size of stock.

17. The tool or box tongs(G,Fig. 8) should be made to fit the various sizes of lathe tool stock that are used. They should be made substantially and fit the steel perfectly so that it can be held securely and without danger of stinging the hand, while the tool is being forged. Another style of tool tongs is made with one jaw perfectly flat; on the other jaw, lugs are provided to hold the steel firmly. These are not illustrated.

Almost an unlimited number of different tongs could be explained and illustrated, but, from those given, any one should be able to add to or change the tongs he has so that his material can be securely held.

18. Anvil and Forging Tools.—If a complete set of these tools were to be illustrated and explained, a volume would be required. Even then, the worker would very often be compelled to devise some new tool to suit the particular work at hand. One advantage that the blacksmith has over all other mechanics is that when a special tool is required, if he is a thorough mechanic he can make it.

An almost unlimited number of tools might be required in a general smith shop; but only such tools as are essential in manual training or elementary smith work will be considered here.

Fig. 9.A, hardy;B, cold cutter;C, hot cutter.

19. The hardy(A,Fig. 9) should fit the hardy hole of the anvil loosely enough so that it will not stick or wedge fast. It is made of cast steel and should be tempered so that it will not chip or batter from severe use. It is an indispensable tool, especially to one who has to work without a helper, for with it iron can be cut either hot orcold, and steel when it is heated. The material should be held on the cutting edge of the hardy, then struck with the hammer. A deep cut should be made entirely around the material, round, square, or flat, so that it can be broken off by being held over the outer edge of the anvil and struck a few downward blows with the hammer.

Material should not be cut through from one side, for the cut would then be angular instead of square; furthermore, there would be the effect of dulling the hardy if the hammer should come in contact with it. The hardy is frequently used to mark iron where it is to be bent or forged, but it is not advisable to use it for such purposes, unless the subsequent operations would entirely remove the marks, for they might be made deep enough to weaken the metal, especially at a bending point.

20. The cold and hot cutters(BandC,Fig. 9) are made, as are all other top tools, with an eye for inserting a handle, and should be held by the workman while some one acting as his helper strikes on them with the sledge. The handles can be of any convenient length from eighteen inches to two feet. Cast steel should be used for making both these cutters, but their shapes differ somewhat. The cold cutterBis forged considerably heavier on the cutting end than is the hot cutter, in order to give it plenty of backing to withstand the heavy blows that it receives. The cutting edge is ground convex to prevent the possibility of the corners breaking off easily, and is ground more blunt than the hot cutter. It should be used only to nick the metal, which should then be broken off with the hammer or sledge, as described in cutting iron with the hardy.

21. The hot cutter(C,Fig. 9) is drawn down, taperingfrom two depressions or shoulders near the eye to an edge about1⁄8inch thick, which is ground equally from both sides to form a cutting edge parallel with the eye. It should be used exclusively for cutting hot metal, because the shape and temper will not stand the cutting of cold iron. In order to avoid dulling the cutter and the possibility of injuring some one with the piece of hot metal that is being cut off, the cut should be held over the outside edge of the anvil when the final blows are being struck; the operation will then have a shearing action, and the piece of metal will drop downward instead of flying upward.

Great care should be taken in hardening and tempering each of these cutters to prevent possible injury from small particles of steel that might fly from them if they were tempered too hard. The cold cutter should be hard enough to cut steel or iron without being broken or battered on its cutting edge. The hot cutter should not be quite so hard and should be dipped in water frequently when it is being used to prevent the temper from being drawn.

22. The flatter(A,Fig. 10) is as useful and as essential for the production of smooth and nicely finished work as the finishing coat of varnish on a beautiful piece of furniture. Any work that is worth doing is certainly worth doing well, and in order to make forge work present a finished appearance the smith should use the flatter freely. With it the rough markings of the various forging tools or hammer can be entirely removed. By using it while the work is at a dull red heat, and by occasionally dipping the flatter in water before it is applied, all the rough scale can be removed, thus leaving the work with a smooth, finished appearance.

There are various sizes of this tool, but one with a 2-inchface is convenient for use on light forgings. The edges of the face may be made slightly round, so that markings will not be left on the work, but frequently the edges are left perfectly square.

Fig. 10.A, flatter;B, square-edged set hammer;C, round-edged set hammer.

It is not necessary to temper this tool; in fact, the constant hammering on it has a tendency to crystallize the steel, often causing it to break off at the eye. As the constant hammering on the head of the flatter will also cause the head to become battered, it is good practice frequently to draw out the head and lay the flatter aside to cool. This will anneal the steel and prevent crystallization, at least for some time.

23. The square-and round-edged set hammers(BandC,Fig. 10) are employed for various purposes. The former is used for making square shoulders or depressions such as could not be produced with the hand hammer alone, or for drawing metal between two shoulders or projections. The latter is used for the same purposes, with the exception that it produces a rounded fillet instead of a square corner. It is also convenient for use in small places where the flatter cannot be employed.

The sizes of these tools vary according to the requirements of the work, but it is advisable to have about three sizes of the square-edged one. A good outfit of set hammers consists of one5⁄8-inch, one3⁄4-inch, one 1-inch, all square-edged; and one round-edged set with a 11⁄4-inch face. These four should fulfill all requirements for light forgings. These tools need not be tempered, for the reason explained in connection with the flatter.

24. The punches(A,B, andC,Fig. 11) are merely samples of the multitude of such tools that may be required. They may be of various sizes, depending upon the requirements of the work, and either round, square, or oval in shape at the end. The hand punchAis held with one hand while blows are delivered with the other. It is convenient for punching holes in light pieces; but when the work is heavy the intense heat from the metal makes it impossible to hold a punch of this kind.

Fig. 11.—The Punches.

In such cases the handle punchesBandCare employed. They eliminate the danger of burning the hand, but it is necessary to have some one act as helper and do the striking. The proper way to use a punch on hot metal is to drive it partly through, or until an impression can beseen on the opposite side after the punch has been removed; then the punch is placed on the impression and driven through the metal while it is held over the pritchel hole, the hardy hole, or anything that will allow the punch to project through without causing the end to be battered. If heavy pieces of metal are to be punched, it is a great advantage to withdraw the tool, drop a small piece of coal into the hole, and cool the punch before again inserting it. The coal prevents the tool from sticking fast, and the operation can be repeated as often as necessary.

Punches need not be tempered, because the strength of the steel from which they should be made will withstand the force of the blows, and also because the metal is generally hot when the punches are used; therefore the temper would be quickly drawn out of them. If sheet metal or light material is to be punched cold, it is advisable to harden the punch slightly; then the hole may be punched through from one side, while the metal is held on something containing a hole slightly larger than the punch. This method has the effect of producing a smoothly cut hole, provided the metal is properly placed.

Fig. 12.—The Top and Bottom Swages.

25. The top and bottom swages(Fig. 12) are made with semicircular grooves of different sizes to fit the various diameters of round material. The former has an eye for the insertion of a handle bywhich it is held when in use. The eye should be crosswise to the groove in the face. The bottom swage is made with a square projecting shank to fit loosely into the hardy hole of the anvil. It should be placed in position for use with the groove crosswise to the length of the anvil, unless the form of the forging should require otherwise. Swages are conveniently used for smoothing round material after it has been welded, or for swaging parts of a forging after they have been roughly hammered out. By dipping the top swage in water occasionally while in use, the work can be made much smoother and the scale of oxide removed; this is called water swaging.

Fig. 13.—The Top and Bottom Fullers.

26. The top and bottom fullers(Fig. 13) are made in pairs with convex semicircular projections or working faces, whose diameters should correspond, if intended to be used together. As the former is quite frequently used alone, it may be made of any desired size. The top fuller, like the top swage, is made to be used with a handle; the bottom fuller, fitted to the anvil like a bottom swage, generally is placed for use with the length of its face parallel to the length of the anvil.

They are used together for forming depressions or shoulders on opposite sides of the material; from the shoulders thus formed, the metal may be forged without disturbing them. They are used also for rapidly drawing out metal between shoulders or projections which may have been previouslymade and are to be left undisturbed. The top fuller is used singly in making scarfs for welding, in forming grooves, in smoothing fillets and semicircular depressions, or in forming shoulders on only one side of metal.

27. The button head set or snap(A,Fig. 14) as it is sometimes called, has a hemispherical depression on its face. It is used for making heads of rivets or finishing the heads of bolts. Only a few different sizes are required, unless considerable riveting or bolt making is to be done.

Fig. 14.A, the button head set;B, the heading tool.

28. The heading tool(B,Fig. 14) is used exclusively for forming the heads of bolts or rivets. Formerly a very large assortment of these tools was required in a general shop; but as bolts can now be made so cheaply by modern machinery, there are not many made by hand. It would be advisable to have a few general sizes, however, because they are sometimes convenient in making other forgings, and bolt making affords an instructive exercise.

29. The swage block(A,Fig. 15) rests on a cast-iron baseB. It is a very useful tool in any smith shop and does away with the necessity of having a large assortment of bottom swages, as only top swages will be required for large-sized material. The block is made of cast iron and of different thicknesses. The depressions on the edges include a graduated series of semicircular grooves that can be used in place of bottomswages; a large segment of a circle, which is handy in bending hoops or bands; graduated grooves for forming hexagonal boltheads or nuts; and sometimes a V-shaped and a right-angled space used for forming forgings.

Fig. 15.—The Swage Block.

The holes through the blocks are round, square, or oblong. The round ones can be used in place of heading tools for large sized bolts, or in breaking off octagon or round steel after it has been nicked with the cold cutter. The square holes may be used either for making and shaping the face of a flatter or a round-edged set hammer, or in place of a heading tool, when a square shoulder is required under the head. They may be used, also, for breaking square steel. The oblong holes are convenient for breaking lathe tool material. Some swage blocks have in addition a hemispherical depression on the side, convenient for forming dippers or melting ladles.

The base upon which the swage block rests is constructed with lugs on the inner side, as indicated by the broken lines on the sketch. Upon these it is supported, either flat or on any of its four edges. These lugs prevent the swage block from tipping sidewise.

30. The surface plate(C,Fig. 16) is generally made of cast iron about 11⁄2to 2 inches thick, from 20 to 24 inches wide,and from 3 to 4 feet long. It should be planed perfectly smooth and straight on its face, the edges slightly round. It should be supported on a strong wooden benchDand placed somewhere in the middle of the shop so that it is accessible to all the workmen. On it work is tested to see whether it is straight, perpendicular, or if projections are parallel. The anvil is sometimes used for this purpose, but as it is subjected to such severe use, the face becomes untrue and therefore cannot be depended upon. A true surface plate is always reliable and convenient for testing work.

Fig. 16.—The Surface Plate.

31. The tapered mandrels(Fig. 17) are made of cast iron, and are used for truing rings, hoops, bands, or anything that is supposed to have a perfectly circular form. The height ranges from 21⁄2to 5 feet; the largest diameter varies from 8 to 18 inches. They are cone-shaped with a smooth surface, and should be used with caution. The blows should be delivered on the metal where it does not come in contact with the mandrel; when bands of flat material are to be trued, the best method is to place them on the mandrel from each side alternately. Unless this precaution is observed, the band will be found tapered the same as the mandrel. Alternating is not so necessary when bands or rings of round material are handled.

Mandrels are sometimes made in two sections, as shown atBandC. AsBis made to fit into the top ofC, the two parts become continuous; the smaller one can also be held in the vise or swage block and thus used separately. They are frequently made with a groove running lengthwise, which allows work to be held with tongs and provides a recess for any eyebolt or chain that may be attached to the ring.

Fig. 17.—The Tapered Mandrels.

It should not be supposed that all mandrels are of this particular form; any shape of bar, block, or rod of iron that is used for the purpose of forming or welding a special shape is called a mandrel.

32. Bench and Measuring Tools.—Another set of blacksmith appliances includes the bench vise, chisels, center punch, rule, dividers, calipers, scriber, square, bevel, hack saw, and files.

Fig. 18.—The Bench Vise.

33. The bench or box vise(Fig. 18) is not ordinarily used in general blacksmithing. The back jaw of a general smith’s vise extends to the floor, forming a leg, and is held in position on thefloor by a gudgeon on its end. This vise is not illustrated, because the bench or box vise is preferable for manual training work.

The vise should be set so that the tops of the jaws are at the height of the elbows,—a position convenient in filing. It is used for holding the work for filing, chipping, twisting, and sometimes for bending. But when it is used for bending, especially when bending a right angle, the operation should be performed cautiously, for the sharp edges of the jaws are very liable to cut the inner corner of the angle and cause a gall which will weaken the metal at the bend.

34. The chisels(AandB,Fig. 19) are very familiar, yet, though they are so common, they are the most abused tools used by both skilled and unskilled workmen. The mere name “cold chisel” seems to convey the impression to most people that with it they ought to be able to cut anything. But that impression is wrong; chisels ought to be made of a certain grade of steel and drawn for either rough or smooth work, as may be required. Then they should be properly tempered to cut the material for which they are intended.

A chisel for rough, heavy work should not be drawn too thin or too broad at the cutting edge. If it is flattened out into a fan-shaped cutting edge, there should be no surprise if it breaks, for, in order to make a chisel stand rough usage, it should have sufficient metal to back up the corners. On the other hand, a chisel for smooth finishing work can safely be drawn thin but not fan-shaped, as the cuts that ought to be required of such a chisel should not be heavy.Achisel for ordinary work ought to be ground so that the two faces form an angleof 60 degrees; if the work is heavy, it should be ground even more blunt.

Fig. 19.A, cold chisel;B, cape chisel;C, center punch;D, rule.

The chisel illustrated atArepresents a common cold chisel, which can be used for various purposes. The chiselBis called a cape chisel and is used for cutting and trimming narrow grooves and slots. It is indispensable for cutting key seats in shafting or work of that kind. On account of its being used in such narrow places it is necessary to make the cutting edge somewhat fan-shaped to prevent the chisel from sticking fast; but for additional strength the metal is allowed to spread, as shown. When using the cape chisel, it is a good practice occasionally to dip the cutting edge in some oily waste, which will tend to prevent its wearing away or sticking.

35. The center punch(C,Fig. 19) should be made of the same quality of material as the cold chisel. It can bemade of steel from1⁄4to5⁄8of an inch in diameter; octagon steel is preferable. After it has been roughly drawn out, it is ground to a smooth round point, then it is tempered as hard as it will stand without breaking. It is used for marking centers of holes to be drilled, or for marking metal where it is to be bent, twisted, or forged. When used for marking hot metal, it is frequently made with an eyehole in the body, so that a small handle can be inserted; this will prevent burning the hands.

36. The rule(D,Fig. 19) should be of good quality. The one best adapted for forge work is the 2-foot rule, which is jointed in the center. It is3⁄4inch wide and is made of either tempered spring steel or hard rolled brass.

Fig. 20.A, dividers;B, calipers;C, scriber;D, square;E, bevel.

37. The dividers(A,Fig. 20) are used for measuring distances and for describing circles. The points are clamped in a rigid position with the small thumbscrew, which comes in contact with the segmental arc. Close adjustments can be made with the milled-edge nut on the end of the segmental arc. When metal is to be bent to a circular form, a good method is to rub chalk on the surface plate and describe the desired curve on this chalk. Asthe markings thus made are not easily removed, this plan is much better than drawing upon a board.

38. The calipers(B,Fig. 20) are used for measuring diameters, widths, and thicknesses. Those illustrated are the kind generally used in forge work. They are called double calipers and are the most convenient because two dimensions can be determined by them. As the accuracy of the work depends on them, they should be well made. In the illustration here given, each bow is held securely by an individual rivet. Sometimes they are secured with one; if so, the rivet should be square in the straight central part and tightly fitted. The projecting ends of the rivet should be filed round, and the holes in the bowed sides should be made to fit the round ends of the rivet; then the sides should be riveted on tight so that each bow may be moved independently of the other.

39. The scriber or scratch awl(C,Fig. 20) is used in marking holes, sawing, chipping, or in laying out distances, which can afterward be marked with a center punch if required. It should be made of a good quality of steel, and the point should be well hardened so that it will cut through the surface scale of the metal. A suitable-sized steel for making a scriber is3⁄16inch round and the length over all about 6 inches.

40. The square(D,Fig. 20) is another indispensable tool when accurate work is to be produced. Convenient sizes for manual training work are the 8 × 12-inch, with a 16 × 24-inch for general use.

41. The bevel(E,Fig. 20) should be used when bending and laying out angles of various degrees. When metal is to be bent to a given angle, the pupil should set and use the bevel.

42. The hack saw(Fig. 21) is at present considered a necessary part of any forge shop equipment. It is used for sawing iron or untempered steel, and when a power shear is not included in the equipment, considerable filing can be saved by sawing. The frame illustrated is adjustable so that the blades can be made of different lengths and be set at right angles to the frame, which is sometimes convenient.

When using the hack saw, make slow, full-swing strokes; when drawing back for another stroke, it will prolong the efficiency of the blades if the saw is raised up to prevent the teeth from bearing on the metal, as the backward stroke is more destructive to the teeth than the forward or cutting stroke. The blades are made from 8 to 12 inches in length,1⁄2inch in width, and with from 14 to 25 teeth to the inch. They are tempered so hard that they cannot be filed, but are so inexpensive that when they cease to be efficient they may be thrown away.

Fig. 21.—The Hack Saw and Files.

43. The files(Fig. 21) are illustrated merely to show that they are to be used for special purposes. As finishing orfiling is almost a trade in itself, the file should not be used in blacksmithing, unless it is especially necessary. A piece of smith’s work that has been roughly forged is much more admirable than a highly polished piece that has been filed into elegance.

Files are round, flat, square, half round, and of numerous other shapes, and vary in lengths and cuts for rough or smooth filing. Any of them may be used as required, but it should be remembered that filing is not blacksmithing.

Questions for Review

What is the main difference between the old type of smithing forge and a modern one? How is the air supplied for each? What is a tuyère iron? Describe the hearth. What kind of coal is used for forging? Is coal the best fuel for heating all metals? Why is charcoal the best fuel for heating carbon steel? How should the fire be built to prevent making excess smoke? What other fuel is used in forging? What kind of work is it used for? Describe the different parts of the anvil. How is a cast-iron anvil hardened? How is a wrought-iron anvil hardened? Name and describe the different kinds of hammers. Why should the tongs fit properly the iron to be handled? Name and describe the different tongs you have been made familiar with. How would you secure the tongs to relieve the hand?What is a hardy? What is it used for? Explain the proper method of using it. Is it always good practice to use a hardy for marking the iron? Why? What is the difference between a cold and a hot cutter? What is the general use for a flatter? Should it be tempered? Why? What are set hammers? What is a punch used for? Explain the difference between a hand punch and a handle punch. When punching a heavy piece of metal, how is the tool prevented from sticking fast? Are all punches tempered? Why? Describe and explain the use of top and bottom swages. How should the bottom swage be placed for use? What is meant by water swaging? State the effect it has on the iron. What are top and bottom fullers used for? Are they always used in pairs? How is the bottom oneplaced for use? What are the button head set and heading tool used for? What is the special advantage of having a swage block? Explain some of the different uses of that tool. What is the special use of the surface plate? What is the tapered mandrel used for? Are all mandrels of this particular kind? Explain others. Is it good practice to use the vise for bending? Why? Describe the cold chisel. Should all cold chisels be made alike? What is the center punch used for? Describe the other bench and measuring tools mentioned. What is the special objection to using the files?

What is a hardy? What is it used for? Explain the proper method of using it. Is it always good practice to use a hardy for marking the iron? Why? What is the difference between a cold and a hot cutter? What is the general use for a flatter? Should it be tempered? Why? What are set hammers? What is a punch used for? Explain the difference between a hand punch and a handle punch. When punching a heavy piece of metal, how is the tool prevented from sticking fast? Are all punches tempered? Why? Describe and explain the use of top and bottom swages. How should the bottom swage be placed for use? What is meant by water swaging? State the effect it has on the iron. What are top and bottom fullers used for? Are they always used in pairs? How is the bottom oneplaced for use? What are the button head set and heading tool used for? What is the special advantage of having a swage block? Explain some of the different uses of that tool. What is the special use of the surface plate? What is the tapered mandrel used for? Are all mandrels of this particular kind? Explain others. Is it good practice to use the vise for bending? Why? Describe the cold chisel. Should all cold chisels be made alike? What is the center punch used for? Describe the other bench and measuring tools mentioned. What is the special objection to using the files?

44. The Hammer Blows.—Metal can be forced into desired shapes or forms by delivering the hammer blows in different ways. All hammer blows are not alike; some will have one effect and others will produce an entirely different result.

45. The upright blowis delivered so that the hammer strikes the metal in an upright position and fully on the anvil. Such blows force the metal equally in all directions, providing the surrounding dimensions are equal. They will also reduce the thickness of the metal in the direction in which they are delivered, the reduction depending upon the amount of force put into the blows. They are used for drawing where the metal is supposed to spread equally in all directions and for making smooth surfaces.

Fig. 22.—The Upright Blow.

Figure22shows an upright blow as delivered on a piece of flat material. If the material is as wide as the face of the hammer, or wider, the force of the blow will spread the metal equally, but if it is narrower, the blowwill lengthen the material more rapidly, because the hammer will cover more in length than in width.

46. The edge-to-edge blowis delivered so that the edge or side of the hammer face will be directly above the edge or side of the anvil. When blows are delivered in this manner (a,Fig. 23), the hammer forms a depression on the upper side of the metal and the anvil forms one on the bottom.

Fig. 23.—The Edge-to-edge Blow.

When a piece of metal is to be drawn to a smaller dimension, with shoulders opposite each other, on either two or four sides, these blows will produce the required result to the best advantage. They are more effective if the metal is held at a slight angle across the edge of the anvil face, but then the hammer blows must be delivered a little beyond the anvil edge, so that the upper and lower depressions in the metal will be formed exactly opposite each other, as shown atb, where the depressions are indicated by the broken lines.

In forming shoulders such as are required on the hasp exercise (page64) the first pair may be formed as shownatband the second pair as shown atc. In the latter case the metal is held across the nearer edge of the anvil face and the blows delivered in a manner similar to that described in the preceding paragraph. Hammer blows of this class may be used on any edge of the anvil as required.

47. The overhanging blowis delivered so that half the width of the hammer face extends over the edge of the anvil. (SeeFig. 24.)

Fig. 24.—The Overhanging Blow.

It is used for forming shoulders on one side of the metal and for drawling out points of scarfs. When blows are delivered in this manner, the anvil will form a depression or shoulder on the lower side of the metal, and the hammer will keep the metal straight on the upper side.

This blow also will be more effective if the metal is held at a slight angle across the edge of the anvil face, but the blows must always be delivered squarely on the upper side of the metal to keep it straight.

48. The beveling or angle blowsare delivered at any angle that the form of the work may require. When the metal is to be drawn with a taper on one side, it must be held level on the anvil and the blows delivered at an angle determined by the amount of taper required. Figure25shows the manner of holding the metal and the way the blows are to be delivered.

Fig. 25.—The Beveling or Angle Blow.

When the metal is to be drawn tapering on two opposite sides, it should be held to the proper angle on the anvil to establish the taper desired on the bottom, while the hammer blows are delivered so as to form a similar taper on the upper side. (SeeFig. 25.)

Fig. 26.—Drawing Metal to a Point by Beveling or Angle Blows.A, correct position;B, incorrect position.

Fig. 27.—The Leverage Blow.

Blows of this kind are used for chamfering corners or edges, and may be delivered at any required angle. They are also used when drawing metal to a point, either square, round, hexagonal, or octagonal, but the metal should be held on the anvil, as shown atA,Fig. 26. Then the hammer will not come in contact with the face of the anvil, as shown atB. If the hammer strikes the anvil, small chips of steel are liable to break off from the hammer at the place indicated byc, and cause serious injury.

Fig. 28.—Bending by Leverage Blows.

49. The leverage blowsare used mostly for bending, as they will not leave marks where the bending occurs. For instance, when a ring is to be formed, the metal is first held in the tongs and rested on the horn of the anvil, as shown inFig. 27. Notethat the metal will bend ata, providing the heat is uniform. If, therefore, bending is required at a certain place, that place should rest on the anvil and the blows should be delivered beyond it.

After the first end has been bent to the required radius, the other should be bent by holding it in the manner shown inFig. 28, because the joint of the tongs will prevent its being struck out of them while the blow is being delivered. When both ends have been bent to the proper radius, the ring should be finished as described in the ring exercise (page74), where upright blows are used with a leverage effect.

50. The backing-up blowsare used to upset metal when it is impossible to upset it in the usual manner, and in backing up the heel of a scarf.

Fig. 29.—The Backing-up Blow, for Upsetting.

Upsetting with backing-up blows is done in the manner shown inFig. 29. The metal should be extended over the anvil and thrust forward as the blow is being delivered, to get the best results. This will also prevent jarring the hand. The metal should be as hot as possible when being upset in this manner.

The heel of a scarf is formed with backing-up blows after the metal has been upset in the usual manner. Theblows should be directed so that they will have an upsetting effect, as indicated inFig. 30, and not a drawing one. After a few blows have been delivered with the face of the hammer, they should then be delivered with the ball to form the heel better and more rapidly.

Fig. 30.—Backing-up Blows used for Scarfing.

51. The shearing blow(seeFig. 31) is conveniently used for cutting off small portions of metal instead of employing the hardy. It is delivered so that the side or edge of the hammer will pass by and nearly against the side or edge of the anvil. A blow so delivered will have a shearing effect and cut the metal. It is perfectly proper to use this blow for its intended purpose, but it should not be used when the edge-to-edge blow is the one really required.

52. Forging.—Forging is the operation of hammering or compressing metals into a desired shape. Sevenspecific operations are used. Sometimes a piece of work or forging requires two, three, or even all of them to complete it. These operations are designated by the following names: drawing, bending, upsetting, forming, straightening, twisting, and welding.

Fig. 31.—The Shearing Blow.

53. Drawing, the process of spreading or extending metal in a desired direction, is accomplished by hammering or by pressing the metal between such tools as the swages and fullers, or by holding it on the anvil and using either of the set hammers, the flatter, or the fuller. When using any of these pressing tools for drawing, a helper is supposed to use the sledge to deliver the blows upon them.

It is always best to draw round metal with the swages, as it will be smoother when finished than if it were done with the hammer; it should be rolled in the swage a little after each blow of the sledge, and after a complete revolution in one direction it should be turned in the opposite direction, and so alternately continued until finished. Especially if iron is being drawn, this will prevent twisting of the fiber, which, if prolonged, would cause the metal to crack. Figure32shows the method of drawing with the swages.

When drawing any shape or size of metal to a smaller round diameter, it is best first to draw it square to about the required size, delivering the blows by turns on all foursides, then to make it octagonal, and finally round. The finishing should be done with the swages, if those of proper size are at hand; if not, light blows should be used, and the metal revolved constantly in alternate directions, to make an acceptable shape.

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