William L. Ilgen

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 blow is 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.

Figure 22 shows 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 blow will lengthen the material more rapidly, because the hammer will cover more in length than in width.

46. The edge-to-edge blow is 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 at b, where the depressions are indicated by the broken lines.

In forming shoulders such as are required on the hasp exercise (page 64) the first pair may be formed as shown at b and the second pair as shown at c. 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 blow is delivered so that half the width of the hammer face extends over the edge of the anvil. (See Fig. 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 blows are 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. Figure 25 shows 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. (See Fig. 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 at A, Fig. 26. Then the hammer will not come in contact with the face of the anvil, as shown at B. If the hammer strikes the anvil, small chips of steel are liable to break off from the hammer at the place indicated by c, and cause serious injury.

Fig. 28.—Bending by Leverage Blows.

49. The leverage blows are 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 in Fig. 27. Note that the metal will bend at a, 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 in Fig. 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 (page 74), where upright blows are used with a leverage effect.

50. The backing-up blows are 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 in Fig. 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. The blows should be directed so that they will have an upsetting effect, as indicated in Fig. 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 (see Fig. 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. Seven specific 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. Figure 32 shows 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 four sides, 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.

Fig. 32.—Drawing with the Swages.

Fig. 33.—Drawing with the Flatter.

Drawing with the top and bottom fullers, in the manner shown with the swages (Fig. 32), ought to be done cautiously, as the metal decreases in size so rapidly that there is danger of its becoming too small at the fullered place before the operator is aware of it. When using the top fuller alone, in the same manner as the flatter (Fig. 33), similar precautions should be observed. If the metal is to be decreased between two shoulders, the top fuller may be used to rough it out; but the fuller marks should be distributed between the shoulders, until one of the set hammers or the flatter can be used.

If the metal is being drawn and is held crosswise on the anvil, as shown at a, Fig. 34, it will increase in length more rapidly than it will in width, and if held lengthwise as at b, it will increase more in width than in length. This is due to the fact that the anvil is slightly convex on its face, so that it has the effect of a large fuller.

Fig. 34.—Drawing with the Hand Hammer.

The most difficult drawing for the beginner is to form metal into a square or hexagonal shape. To draw it into a square form, the metal must always be turned either one quarter or one half of a revolution to prevent its becoming diamond-shaped, and the blows must be delivered equally on the four sides to prevent its becoming oblong. If it does become diamond-shaped, it can be made square by delivering blows at a slight angle on the corners and sides of its long diagonal as shown at A, B, and C, Fig. 35. If it is but slightly diamond-shaped, the method shown at B will prove satisfactory, but if badly out of square, the method at A will be the best.

Fig. 35.—Squaring up a Diamond-shaped Piece.

In drawing the hexagonal form, the metal should be turned by sixths of a revolution. If it becomes distorted, it may be forged with such blows as are shown at B and C; if held as at A, it would be marred by the edge e.

54. Bending is the operation of deflecting metal from a straight line or changing its form by increasing the deflection already present. Iron of any cross-sectional shape can be bent, but some shapes are much more difficult than others.

The easiest to bend is the round, the only difficulty being to prevent the hammer blows from showing. If the metal is to be round in section when finished, the work will not have a good appearance if the cross section is oval at some places and round at others, and unless the hammer blows are cautiously delivered this will be the result.

Bending metal of a square section at right angles with the sides is not very difficult, but bending such a section in line with the diagonal is quite difficult, because the edges are liable to be marred where they rest on the anvil and where the blows are delivered. The best method of making bends of this kind is to heat the metal only where the bend is to be, and then to bend it by pressure or pulling, while the work is held securely in the vise, hardy hole, or swage block. If the heating cannot be confined to the desired space, all excessively heated parts should be cooled.

Oval sections are easily bent through their short diameters, but in bending through the long diameters, the same method should be pursued as described above for bending the square section in the plane of its diagonal. Further explanations for bending are given on pages 118-121.

55. Upsetting is the operation of enlarging metal at some desired point or place. It is done by hammering, ramming, or jarring. When a piece of metal is too long it can be shortened by upsetting, or when it is too thin at a certain place it can be thickened by the same method. This is done by having the metal hot only at the point or place where the upsetting is required. It is frequently necessary to cool the metal where the heat is not needed in order to confine the upsetting to the desired place.

Upsetting is not a very difficult operation as long as the metal is kept perfectly straight; otherwise the task will prove tedious and the metal may break from the constant bending back and forth. Bending will always take place, but breaking generally can be prevented by having the metal hot when it is straightened. The greatest difficulty in this respect will be experienced when operating on common wrought iron.

Upsetting by hammering is done by holding the metal perpendicularly on the anvil or something solid enough to withstand the blows which will be delivered upon it. Figure 36 shows this method.

Fig. 36.—Upsetting by Hammering.

If the end of a bar is being upset, and the upsetting is supposed to extend up through the bar for some distance, the heated end should be placed on the anvil as shown in the figure, because the anvil will slightly chill the end of the bar, and the upsetting will continue much farther than if the blows were delivered on the hot end. Striking the hot end with the hammer increases the diameter of the end excessively, because the contact of the hammer does not have a tendency to cool the metal.

Another method of upsetting with the hammer, which is called “backing up” the metal, is shown in Fig. 37. This method does not upset the metal so rapidly, because the force of the hammer blows jars the hand and arm which hold the bar.

Upsetting by ramming or jarring is thrusting the metal forcibly against some heavy object like the surface plate, the swage block, or the anvil. Figure 38 shows upsetting by this process. This method is very effective and is used mostly when the metal is long enough to be held with the hands, as shown.

56. Forming is a term generally applied to the making of a forging with special tools, dies, or forms. This process may include bending, punching, and other operations.

Swages are used for forming. A block of steel with a depression of a special design is known as a forming die; a number of other tools and appliances may be used for forming, but it is needless to mention them here.

57. Straightening is one of the most frequent operations. When metal is being forged, the various blows have a tendency to make it crooked, and if the work is supposed to be straight when finished, it should be so.

There is as much skill required to straighten properly a piece of metal as there is to bend it. The most common method (A, Fig. 39) is to hold the metal lengthwise on the anvil with the bowed side or edge upwards, then to deliver the blows at the highest point of the bow. The blows will be most effective at the point where they are delivered, so they should be distributed in order to get the object perfectly straight and to avoid making unsightly hammer marks.

If the metal to be straightened is round, or if it is flat with round edges, it is best to use a top swage of the proper size and deliver the blows on the swage as shown at B, Fig. 39. Then the surface of the round or the edges of the flat stock will not show any marks. The flatter or round-edged set hammer may be used in the same manner on flat or square material.

When wide pieces of flat metal are to be straightened edgewise, and such blows as are shown at A, Fig. 39, are not effective, then the blows should be delivered along the concave edge as shown in Fig. 40, and distributed as indicated by the dotted circular lines. Blows delivered in this manner will stretch or lengthen the metal on the concave edge and straighten it.

58. Twisting is the operation of rotating metal to give it a spiral appearance. It may be done either hot or cold, as the dimensions of the material may require. It is done by holding the material in the vise, the hardy hole, or the swage block, and turning one end of it with a pair of tongs or a monkey wrench as many times as may be required. The twisting will be confined between the places where it is held with the vise, and where it is seized by the tongs or wrench.

If the material to be twisted is heavy enough to require heating, a uniform heat is necessary or the twist will be irregular, and, as an artistic appearance is usually desired, this operation should be carried out with that result in view.

A, Fig. 41, illustrates a piece of ¹/₂-inch square stock that has been twisted while hot. B shows a piece of ¹/₂ × ¹/₈-inch material that has been twisted cold.

Another difficulty met with in twisting a piece of metal is that of its becoming crooked. It can be straightened by laying the twisted portion on a wooden block and striking it with a wooden mallet. This will prevent the corners from becoming marred. A good method of avoiding this trouble is to twist the metal inside of a piece of pipe whose inside diameter is equal to the diameter of the metal.

59. Welding, the most difficult operation in the art of forging, is the process of joining two or more pieces of metal into one solid mass.

All the previous operations allow some time for thought; in welding, the worker must determine instantly where each blow is to be delivered, as the welding heat of the metal vanishes rapidly; therefore, he is compelled to think and act very quickly.

A scientific analysis of a perfect weld shows that it consists of several processes, and that each one must be perfectly executed. If any of these operations are improperly done, the result will be a partial failure; if they are essential ones, the weld may readily be considered as totally unfit.

60. The Material for Welding.—This must be considered, because there are different qualities in each metal to be operated upon, and some metals can be worked more easily than others.

A cross section of a bar of iron viewed through the microscope is seen to be made up of a great number of layers or fibers, called laminÆ, resembling the grain or fiber in wood. These were cemented together in the process of rolling or welding in the mill where the iron was manufactured, and are continuous through its length. This makes the bar of uniform quality throughout.

In welding, these fibers are joined diagonally at the ends, consequently the strength of the weld depends entirely on how closely or perfectly this cohesion is made. Careful hammering at the proper heat brings the fibers in as close contact as possible, squeezes out the slag and scale, and therefore greatly assists in strengthening the weld.

Iron is an easy metal to weld. To prove this, place two pieces of iron in a clean, non-oxidizing fire, allowing them to attain a white or welding heat; then place them in contact and notice how readily they stick together, proving that iron is easily welded at the proper temperature. But in order to make the contact thorough, the pieces must be hammered. This shows that hammering is a secondary operation, and that iron cannot be joined by either heating or hammering alone.

By a similar experiment with soft steel, you will notice that the pieces do not adhere like iron. If borax is applied while they are heating, then slight indications of adhesion will be noticeable. This shows that borax, sand, or something of a like nature must be used in welding steel. In this case hammering is not a secondary operation, but an essential one.

A higher carbon or tool steel may be experimented upon, with nearly the same result. The noticeable difference between the lower and higher qualities of steel proves that the greater the quantity of carbon, the harder will be the welding, and if the experiments were extended to still higher carbon steels, it would be discovered that they could not be joined except by the use of a specially prepared flux. There are indeed some high carbon steels that cannot be welded.

If a forging is to be made of a special quality of material, it is frequently advisable to avoid welds, because two pieces that are welded can hardly be considered so strong as a piece of the same material that has not been welded.

The weldings which are alluded to here are such as are used by practical blacksmiths in their general work without any special appliances or apparatus whatever. The majority of the exercises on welding in this book require the use of iron; for this reason this preliminary consideration of metals need not have any further special attention.

61. Heating.—When the word “fuel” is used here, either coal or coke may be meant. Coal is the original in either case, for coke is formed from it by the removal of gaseous substances. It is better that the coal first be converted into coke, and that only the coke should come in direct contact with the heating metals.

Figure 42 shows a sectional view of a blacksmithing fire: d is the bed of hot coke; c is the dampened and unburned coal which surrounds the fire, continually forming more coke as it is needed and also holding the fire in a compact form; a shows the proper way of placing the metal in the fire, b, the improper way because the metal is too near the entrance of the blast. As heating is such an important operation, a thorough understanding of what causes imperfect heats, as well as how to prevent them, is necessary.

The best fire for perfect heating is a reducing one, that is, one in which the combustion of the fuel is rapid enough to use entirely the oxygen in the air which is supplied. An oxidizing fire is one that does not use all the oxygen in the blast for the combustion of the fuel. The surplus oxygen will produce, on the surface of the metal, oxide of iron, or a black scale, which is extremely injurious. This scale will prevent welding, so all possible precautions should be taken to avoid its forming.

A reducing fire can be maintained, and an oxidizing one avoided, by having plenty of fuel surrounding the metal, equally, and allowing the entrance of only sufficient air or blast to provide the necessary heating.

If a piece of metal is left in a fixed position while heating, the lower side will become the hottest. For that reason, all metals to be welded are placed with scarfs downward. If the required heat is to be a penetrating and thorough one, the metal is turned frequently to bring all surfaces in contact with the most intense point of heat.

Even though every possible precaution is taken in all other steps of the welding, the pieces cannot be joined perfectly if the heating is carelessly done.

62. Scarfing.—This is the operation of preparing or shaping metal for welding. There are five general kinds of welds, the distinct form of each depending either on the quality of the material or on the shape of the desired forging. They are called the lap weld, the cleft weld, the butt weld, the jump weld, and the V weld.

63. The lap weld (Fig. 43) is so called because the pieces lap over each other when placed in contact. It is most commonly used in general practice, and all welds formed in a similar manner belong to this class, regardless of the sectional form of the material or the shape of the completed weld.

The pieces should always be upset where the scarfs are to be formed, to provide excess metal for welding. They should be formed with their end surfaces convex, and at an angle of about 45 degrees, which would not make the joining surfaces too long.

When the fire and all tools are ready, place both scarfs face down in the fire; when they are removed to the anvil, the piece held in the right hand should be turned face up and rest on the anvil, in order that the other may be placed in position on top of it.

The left-hand scarf should be placed carefully, with its point meeting the heel of the other. If placed too high and overlapping, it will increase the surface to be welded and perhaps decrease the dimensions of the material where the points are welded down upon the exterior. If placed too low, in all probability the surplus metal provided by upsetting will not be sufficient to form the weld to a uniform dimension. A little practice with the scarfs before heating is advisable to prevent this difficulty.

The hand hammer should be placed conveniently on the anvil, with the handle projecting sufficiently over the heel so that it can be grasped quickly with the right hand as soon as the two pieces are in position. If this precaution is not taken, the welding heat may disappear before any blows can be struck.

The first blows after the pieces are placed should be directed toward the center of the scarfs; when the center has been thoroughly united, the blows should be directed toward the points to complete the operation, if this can possibly be done in one heating.

It is impossible to give an invariable routine of blows; those given are sufficient for the beginning, the rest must be left to the observation and skill of the operator. Practice and judgment will determine where the blows should be delivered, and when they should cease.

As the welding heat vanishes very rapidly, it requires careful judgment to determine when the pieces cease to unite. All blows delivered after this will reduce the dimensions of the metal; if reheating is necessary, there should be no metal sacrificed by unnecessary hammering. Welds are generally weaker than the metal from which they are made; consequently if the stock is made smaller at the weld, its strength is greatly decreased.

The old adage “Haste makes waste” does not always apply. If you hasten the operation of welding while the pieces are sufficiently hot, you will not waste the metal. If through want of haste you are compelled to reheat, you will waste metal, for every time a piece is heated it loses a fractional part of its area, regardless of any hammering.

Welds made with scarfs of this kind are considered to be nearly as strong as the metal itself, because they allow of a more thorough lamination by hammering than other welds, consequently they are frequently used on various qualities of metal when strength is considered a chief requirement.

64. The cleft weld (A, Fig. 44) is so called because one piece of metal is split to receive the other. It is used for welding iron to iron or steel to iron (the inserted portion being the steel). Whatever the metal, the inserted portion is usually roughened with a hot cutter on the pointed surfaces and the cleft hammered down and securely fitted before the whole is heated. The pieces should not be placed in the fire separately, but together, as they have been fitted.

When a welding heat appears, if possible, light blows should be delivered on the end of the inserted portion while the two are in the fire; these blows will partly join the pieces and make them secure before removal. If this cannot be done, the first blows after removal from the fire should be on the end. When a final and thorough welding heat has been attained, they should be removed to the anvil and securely joined. If heavy pieces are being operated upon, they may be welded with the steam hammer.

65. The butt weld (B, Fig. 44) is so called because the pieces are butted together and almost thoroughly joined by ramming or backing-up blows before any blows are delivered on the exterior surface. The scarfs are easily formed. The outer edges of the pieces are backed up to form a rounded or convex end to insure their being joined at the center first. As the blows are delivered on the end, the metal will upset and the pieces will be joined from the center to the outer edges. After they have been quite thoroughly joined with these blows, they should be hammered on their exterior to weld them securely.

When scarfed in this manner, the pieces are frequently placed in the fire for heating with the ends in contact, then partly joined while in the fire and removed to the anvil or the steam hammer for final welding.

66. The jump weld is shown in Fig. 45. The scarfs require perfect forming, because the opportunity for hammering is limited, as blows can be delivered only at certain places: on the end of the scarf 1 driving it into the concave groove 3; on a fuller which is held in the fillet 4; and on both the edges indicated at 3.

The groove at 3 should be formed with sufficient metal at points 0, to meet the projections X, and form a fillet. The convex scarf 1 should first come in contact at 3, so that welding will proceed from that place.

Welds made in this way are considered the weakest of those here described, on account of the limited assistance which can be provided by hammering. Still they are frequently used to avoid the laborious operations required to make such forgings out of solid metal.

67. The V weld (Fig. 46) is a very important but difficult one. It is generally used on extremely heavy work, such as locomotive frames (Fig. 47), beam straps, rudder stems, and all cumbersome forgings.

The process is as follows: Pieces 5 and 6 are to be welded. They are held in a rigid position with heavy straps and bolts, as shown on the locomotive frame in Fig. 47, sometimes while the V-shaped opening is being formed; however, they must always be held secure while the welding heat is being obtained. The V-shaped opening formed by the scarfs on 5 and 6 should penetrate about two thirds of their thickness and form an angle of about 50 degrees, with sufficient metal at 9 to provide for the waste which will occur while a welding heat is being procured.

The wedge 7 is formed with some surplus metal for filling the V-shaped opening. It is handled by a bar which is welded to it. The angle of the wedge should be not less than 5 degrees smaller than the angle of the opening. This will insure that the welding proceeds from the apex or point of the wedge outward.

Two fires are required; 5 and 6, securely strapped and bolted together, are placed in one with the V-shaped opening turned downward. Plenty of coke is placed around this opening, completely covered with moistened coal, and securely packed with a shovel; then two openings or vents are made through the coal with a poker, one on each side of the metal and leading to the scarfs. This is called a covered fire. The blast is now turned on and slowly increased until the proper heat is attained. The progress of heating can be observed through the openings thus made, and the fire replenished with coke when necessary.

These operations are supervised by the smith who has the work in charge, with two or more helpers or assistants, according to the size of the forging. The wedge 7 also is heated in a covered fire with only one opening on the workman’s side of the forge; the wedge is inserted in that opening, and is attended and handled by another smith, who watches its progress in heating.

When the supervising and attending smiths have signaled to each other that the heats are ready, 5 and 6 are removed, turned over, and placed on the anvil or on the steam hammer die to receive the wedge which is placed in position by the attending smith. After the wedge has been thoroughly welded into place with either sledges or steam hammer, the handle and all surplus metal surrounding the openings are removed by the aid of hot cutters and sledges.

This procedure must now be repeated and another wedge welded into place on the opposite side indicated by the broken lines. With these two wedges 5 and 6 will be securely joined.

To insure a perfect weld, a good quality of material should be selected for the wedges. It should be thoroughly hammered to produce good texture, and if iron is operated upon, the fiber of the wedges should run parallel to the fiber of the piece to be welded. As this is not generally observed, welds of this character often break through the centers of the two wedges.

The broken locomotive frame shown in Fig. 47 would be repaired by the above method. The irregular line at A shows where the break has occurred. The straps and bolts at B indicate the method of holding the parts in alignment. Two tie rods at C prevent the parts from separating.

Questions for Review