Blacksmithing
by C.T. Schaefer
from Farm Mechanics, October & November 1928
The Tools of the Trade
There is, of course, some equipment and a few tools that are absolutely essential if one would turn out good workmanship. The more important tools are mentioned, however, others may be added to meet individual requirements.
While the tools are the most important, it should not be amiss to consider the equipment first, as without equipment it is useless to prepare for the work. The tools are useless without the other equipment, such as the forge and the anvil, and these must be in position before the tools can be brought into use. Fig. 1 depicts two types of geared forges ordinarily recommended for the farm shop. The hearth is large enough for general use and coal, coke or charcoal may be burned. It is made with half or full hood, as illustrated, and the blower is gear driven, the ratio between blast wheel and crank being such as to provide a steady, high-pressure blast with minimum effort. The blower is attached directly to the forge and being gear driven does not require any attention outside of an occasional oiling. The hood which is used to conduct the smoke and gases out of the shop is not absolutely essential, although for certain types of work it will prevent cold drafts of air from striking the work. This feature is, of course, important in tempering tools.
Forges are of such variety and style that it is extremely difficult to say that any one type or make is superior to others. However, be sure to select one with the blower tube as free from bends as possible; also be sure the blower is powerful and easy running, that the hearth is of generous size and if a hood is used, that it overhangs well. In the matter of height, a forge as high as your hip-bones is the most comfortable to work at. The general recommendation for locating the forge in the shop is in a shadow, reserving the strong light for the anvil where light is more essential, as the actual work is done on the anvil and not in the forge.
The shape of the ordinary anvil has remained unchanged for hundreds of years. Though any block of metal upon which the work is placed for hammering may be called an anvil, the shape shown at “1”, Fig. 2, is the conventional one and best serves the purpose for all classes of work. As it may frequently be necessary to handle large pieces it is best to select an anvil of suitable proportions, the weight preferably should be around 150 to 175 pounds, although the 100-pound size may suffice. It is also of advantage to select a long tapering horn and far overhanging heel.
The anvil must be conveniently located with respect to the forge and the height of the working surface should be such as to avoid fatigue. A good rule is to mount the anvil so that the knuckles of the clinched hand will just touch the working face of the anvil when the workman stands erect. For mounting the anvil select a solid timber or stump with bottom and top squared off parallel and cut to a height after mounting which will give the proportions mentioned above. In positioning the anvil, the block should preferably be sunk into the ground and when facing the anvil, the horn should point to the workman’s left hand. It is also well to have the width and breadth of the block of such proportion that space will be provided for resting tools which it may be necessary to bring into use quickly. The anvil can be fastened to its supporting block with strap iron, but the method shown in illustration “2”, Fig. 2, will be found more durable and will more rigidly hold the anvil in position. The timber should be notched on two sides for the end straps and then drawing up on the nuts evenly will keep the anvil centered on its mounting block. The square hole at the end of the face of the anvil is known as the hardie hole and is used to hold the stems of swedges, hardies and blocks. The other hole is called the spud hole.
One who has had experience will generally revise the position of the anvil to meet his preference, however, the inexperienced will do well to mount it about one long pace from the front end of the forge. It is also necessary for the individual to determine whether he can produce the best results with the anvil setting parallel to the forge or at a slight angle. Both locations are successfully employed.
Among the tools required some will be found as part of the equipment of the shop. Several sizes of ballpein hammers should be available. In addition, tools will be needed for cutting, forming and swaging stock as well as several sledges of varying weights. Three tools for cutting off stock are commonly used. These are the hot cutter, the cold cutter and the hardie depicted by illustrations 3, 4 and 11, respectively. Note the difference in the shape of the two cutters which must be used for the purpose intended or they will quickly be ruined.
As the name implies, the hot cutter is for cutting heated material and the cold cutter is used only for cold cuts. Both of these tools follow the construction of the hammer head being provided with a hole for mounting on a handle and a striking face to which the sledge can be applied. It will be noted that the cold cutter is made with a thicker blade than the hot cutters which has a rather thin cutting edge. Both tools are tempered when new but the hot cutter, from repeated use on hot material, soon loses its temper and becomes soft. For this reason neither of the tools should be used to do the work of the other. It will be noted that the hardie is also made with a cutting edge on its upper end and a stem that fits the hardie hole in the anvil. Stock is cut with this tool by placing it on the cutting edge of the tool and striking with a hammer or sledge. The hardie may be used in place of the hot cutter and is primarily drawn into use when a helper is not available. The hot and cold cutters require a helper to strike with the sledge as the workman holds the cutter with one hand and the tongs which give him a grip on the work with the other hand.
Various forms of sledges are available, a good shape being depicted by illustration “5”. A light sledge is convenient when finishing a surface with a flatter “10” or when shaping heavy work with the assistance of a helper. Some of the lighter sledges are similar to the ballpein hammer, but a double faced sledge may also be had. The weight of the sledge will depend somewhat upon the work and the ability of the helper, for an average recommendation the twelve-pound size is suggested.
The hammer is the most important tool and upon its use the quality of the work depends. The face of the tool should be nearly flat with unchipped edges, as chipped edges will make the work rough. A ballpein hammer weighing about two pounds will be found to give about the right proportion, the handle length varying according to the requirements of the workman. A workman with a short arm will require a shorter handle than one with a longer arm to permit striking the hardest blow and oftenest without fatigue. The ballpein hammer is recommended, as this has a large face to be used for ordinary work and a ball on the other end. This rounded end is used for scarfing and riveting, these operations being covered in articles which are to follow.
The flatter, it will be noted from the illustration, is a tool with a smooth, square face and is used for smoothing flat surfaces after they have been hammered into shape. The bottom fuller, illustration “9”, has a shank similar to that of the hardie which is used for the same purpose, but has a semi-rounded cutting face. The top fuller “8” has a similar face, a striking face, with an eye for a handle and is used with the bottom fuller. These tools are used for making round bottom notches and flutes. Swedges “6” and “7” are similar to fullers but with a semi-rounded groove instead of semi-rounded surface. Swedges are primarily used for making smooth, true surfaces on rods after these have been hammered to approximate size.
A point to bear in mind in connection with safety in the use of striking tools such as hammers, sledges, flatters, fullers and swedges is to avoid allowing these to grow mushroom heads. If this is not done chips are apt to fly from the head, doing damage where they strike. These surfaces should be ground down as fast as they form.
Cold chisels are no doubt part of the shop equipment, if not they can be made, as will be explained later. Tongs vary in size and shape and usually shaped to fit the work at hand. In this connection, the usual practice is to heat the tongjaws red, grip the work, and then hammering until they fit. The conventional flat jaw tongs are depicted by illustration “12”, Fig. 3, while a variety of shapes to which these may be formed are shown in the other illustrations. Twenty-inch tongs provide a good length, the flat jaw being used for general purposes. The type depicted by illustration “13” can be used for square stock, “14” for gripping round stock endwise and “15” for holding round stock at right angles to the axis.
When it is necessary to securely hold the work, the tongs should be carefully fitted so that they will grip the full length of the jaws. If the jaws are too close or too far apart, they will hold the work at but one point and will not provide a grip sufficiently strong for good work. In fitting the tongs to the work by heating and hammering care must be taken or the handles will be brought too close together.
Simple Forging Operations and Figuring Stock to be Used
Successful forging depends greatly on the proper heating of the work and this means the fire is an important feature. In this respect, don’t try to use any coal available as it will pay to buy selected smithing coal which can be secured in hundred-pound sacks. Common coals are too full of foreign matter and chemical impurities. Also keep the coal damp if you want a hot fire. Dry coal gives off its gases constantly.
The object should be to get the best heat possible and this is obtained by converting the coal to coke and maintaining a supply of coke as you work. Building and maintaining the fire should follow this routine: First, get some shavings if possible, if not paper will do, also a few sticks of pine wood. Use the shavings as you would paper and place the pine sticks over the tuyere as shown in Fig. 1 (of Fig. 4). Then pile a ring of dry coal around them. Light the shavings turning the blower crank slowly to get a light draft as you heap on the coal. Get the coal to glowing and when this is accomplished, keep a ring of wet coal around it, gradually covering the fire with wet coal as you apply more draft. Punch a hole in the top of the heap directly over the center of the tuyere and reduce the draft until the blue flames break through the sides of the coal heap. This indicates the coal underneath is turning to coke, then by keeping the outer surface of the fire wet and adding wet coal as heeded, maintain the coke supply. It is best to have the fire concentrated over the tuyere and small, as that is the place you want to get action so that you can control the volume of the metal to be heated. The fire can be kept small by quenching the outer edges occasionally.
Ashes will be the result of the combustion of the coal and you will also find some clinkers. These should be pulled out each time you p?t the work into the fire, replacing with preheated coke which you knock to the center of the fire. The air coming up through the center of the tuyere must be heated thoroughly and you accomplish this by keeping the center of your fire deep. The object is to have the fire of such nature as to heat up the work quickly with little draft or effort at the blower. This is accomplished if you have just a spot of white heat coming up through the center of the fire.
As you will necessarily be limited in the amount of stock you will have on hand for emergency repairs, most of your work will have to include cutting off, drawing, bending, tapering, etc. The meaning of the first operation is readily understood, this is also true of the others with the exception of drawing. Drawing out might be explained as lengthening a bar of stock and reducing its thickness or width by hammering.
The cutting off operation is illustrated in Figs. 2 and 3 (of Fig. 4). The first step being to make a punch or chisel mark on one side to locate the cutting point. Put the work into the fire so that mark will just be in the center of the fire and the greatest heat concentrated at this point. Cover the work and blow, but avoid getting the work too deep in the fire. It will take about five minutes perhaps less if you have the right sort of fire to bring the stock to a light orange color. When checking the heat, always slide the work out of the fire lengthwise to keep it clean and also to avoid breaking up the fire.
Cutting off can be done with the hardie which should be set in the square hole at the heel of the anvil and the punch mark on the stock directly above the cutting surface of the hardie. With the ball pein hammer, strike a light blow or two, just enough to cut half way through the stock. Then turn the work over and repeat until you have just a thin ribbon of stock holding the two pieces together. The finishing cut can be taken by holding the work over the hardie and striking the end to be removed with the hammer or it may be done on the edge of the anvil as illustrated. The latter method is recommended for the inexperienced as this avoids damage to the cutting edge of the tool.
Here it is well to impart a few words of caution on the use of the anvil, to maintain it in proper condition. Be careful not to chip the anvil more than you can help as a chipped edge makes square bends hard to make especially a sharp square bend. It is best to reserve a short length of the anvil surface outside the heel for making these bends, doing all other work requiring the edge of the anvil elsewhere so that chips broken out to do the least harm.
In heating the work it must not only be brought to the proper temperature, but one must also have uniformity in the heat. Uneven heating causes strains which may appear in the form of cracks, especially if the part requires hardening. The heating should not be rushed, but should be slow enough so that the outside fibres of the stock will be no hotter than the inside fibres. The work should be forged immediately upon its removal from the fire otherwise the same effect as uneven heating might result. This is due to the fact that the outer portion of the stock cools more rapidly and the inner portion does not heat as rapidly and in either case, the cooler section will not be as plastic as the hotter sections and cannot yield so readily to the hammer. If cracks in the surface appear, these are usually the result of one of the above conditions.
Drawing can be done a great deal easier and faster if the stock is heated as high as possible without injury to it. Some of the old timers will recommend using the horn of the anvil for this operation as there is not so much danger of the stock spreading and most of the force of the blow will go toward lengthening the stock. Heavy pieces, however, will require the use of the sledge and in this case drawing will have to be done as shown in Fig. 4 (of Fig. 4), having the helper strike where you direct him to and following up the blow, back and forth, as indicated by the arrows. The work is also turned on its side at intervals and blows delivered to retain its width as it is being drawn.
If the work is to be drawn down to a thin section, located over the center of the stock, drawing is done from both sides and then finished with the ballpein hammer as illustrated in Fig. 5 (of Fig. 4). If this section is to be tapered the same general routine is followed, alternating working as shown in Figs. 7 and 8 (of Fig. 5), gradually drawing down to the taper in both directions, taking care to keep the work parallel with the face of the anvil. It is best to use light blows and gradually shape the surface rather than attempting to do the work too fast.
In making a square bend such as the one shown in Fig. 6 (of Fig. 4), first mark the location of the bend with a punch or chisel. Heat the work with the mark in the center of the fire, then place the stock with the mark over the edge of the anvil and facing up, then strike half way between the mark and the end of the stock with the full face of the hammer. It will be necessary to follow the work around as it bends striking alternately against the face of the anvil and the side until the work lies close to these surfaces. At this time the work will require reheating to work down the curve formed and thus affect a sharp corner.
After reheating and cooling in water all but one inch of the short section, strike with the hammer so that with the tip of the short end on the anvil and the centerline of the hammer blow will be a continuance of the centerline of the short end of the bend. Do the same in the direction of the longer end as indicated by the arrows, alternating the blows. It will be necessary to work carefully so as to avoid getting the bend smaller than the rest of the section. Each blow should be placed exactly and too much hammering avoided.
When estimating the length of stock to be used in making a forging several factors must be taken into consideration. When making a sharp bend such as the one just described and dimensioned in Fig. 9 (of Fig. 6), it is obvious the outside measurement will be greater than the inside measurement. In this case, the outside will measure 12 inches and the inside 10 inches. Experiment will show that a straight piece of stock bent to the shape shown will have its outside edge lengthened and its inside edge shortened. However, a line drawn through the center of the piece which we call the centerline will remain unaltered in length. In our example, the dotted line which represents the centerline in both directions will be 5½ inches long. The correct length of the stock to be cut for forming to any shape may therefore be obtained by measuring the length of the center line. In the example shown this will be 11 inches.
In the case of a circle or a ring as shown in Fig. 10 (of Fig. 6), the circumference of the circle representing the centerline is taken as the correct length of the stock. The circumference of the circle is found by multiplying the diameter by 3-1/7 or more exactly 3.1416. In this case the inside diameter is 4 inches, the stock is 1 inch wide and the mean diameter or centerline is therefore 5 inches in diameter. The length of the stock required therefore will be 5 times 3.1416 or 15.708 inch which is equivalent to 15-45/64 inches.
Odd shapes such as the link shown in Fig. 11 (of Fig. 6) require dividing the piece into easily measured parts. This link consists of two half circles and two straight sections, the measurements of which are easily calculated and then added together. The straight sections are 8 inches long and therefore require 16 inches of stock. The two half circles are equivalent to a circle having a mean or centerline diameter of 5 inches, as in the previous case. The length of the stock necessary then is 5 times 3.1416 plus 16 or 31.708 inches; in fractions 31-45/64 inches. Irregular shapes can be measured by forming a piece of wire to correspond to the centerline of the part to be made. Straightening the wire then permits measuring the length. In these examples, one inch stock has been used for simplicity, however, it may be necessary to take into consideration the volume of the part and that of the stock to be used. One who has had little experience will do well to use a much greater length of stock and cut off the wastage after the part has been forged.
If it is necessary to estimate the stock remember volume is based on the area times the length and that the part will always have the same volume, regardless of the proportions of the stock from which it is made. The cross section of the parts in the above examples is one inch. The area of a circle is found by the formula : diameter times diameter times 0.7854 or one-half the diameter squared times 3-1/7. The area of the cross section therefore is 1 by 1 by 0.7854 or 0.7854 square inches. For the part shown in Fig. 9, we need 11 by 0.7854 or 8.53 cubic inches of stock plus whatever may be allowed for wastage due to scaling. Suppose we have a piece of 1 by ½ inch stock available for this forging. The area of this stock is 1 by 1-½ or 1-½ square inches. The volume of the part is 8.53 cubic inches, therefore we need 8.53 divided by 1-½ or 5.69; in fractions 5-45/64 inches of stock. Allowing for wastage, we estimate the length as 5¾ inch.
In the case of the ring we also have an area of 1 by 1 by 0.7854 or 0.7854 square inches and the length as previously calculated 15.708 inches, therefore the estimated volume is 0.7854 by 15.708 or 12.337 cubic inches. To forge this from 1 by 1-½ stock we need 12.337 divided by 1-½ to 8.225 inches of this size stock. This is approximately 8-¼ inches. In a similar manner we find the volume of the link to be 0.7854 by 31.708 or 24.9 cubic inches and using the same size stock we need 24.9 divided by 1-½ or 16.6 inches; in fractions, 16-5/8 inches.
The stock for any forging may be computed in similar manner, however, allowance must be made for wastage due to scaling. No definite rule can be given for the loss due to scaling as this will depend upon how many times the work is heated and how well one judges the proper forging heat.
