CHAPTER II.
Electric Welding—Oxy-acetylene Gas Welding—The Fagot Weld—The Separate Heat Weld—Scarfing—Upsetting—Making the Weld—Lap Welding Without Scarfing—Jump Welding—Butt Weld—Split Welding—Corner Weld—T Weld.
A rapid blast on the start, not only heats the outer part of the metal first and not the center, but it also burns out the fire and makes it become hollow before the metal has the welding heat. There is a right and a wrong way of taking a welding heat from the fire to the anvil. The pieces must be lifted clear up out of the fire, and must not be dragged thru the dirt and cinders on the inner edge of the fire. Iron will not unite when dirty. It is very easy to get a clean heat if one will pay attention to having the fire clean. Do not attempt to get the welding heat in a dirty fire; this is one thing that must be impressed upon the mind of one working at the forge. The skillful worker in iron always pays particular attention to the fire, for he knows by experience that it must be clean, in order to do good work.
Welding is also done with an electric welding machine. The pieces to be welded are clamped and held in bronze clamps. The clamps are adjusted so that the ends of the pieces to be welded touch. They can be moved so as to bring the pieces into close contact or separate them. When the pieces are in close contact, the current is turned on. The pieces are then separated a little so that the current jumps across the space between them, forming an electric arc. This heats the ends to a welding heat, and by forcing them together they are welded.
Another form of welding is by the oxy-acetylene gas method. It is being used extensively at present, and has been found very valuable and economical in making the lighter welds. It is possible to weld steel, iron, cast-iron, copper, brass and aluminum by this process. The apparatus consists of a specially designed blow pipe, an acetylene tank and an oxygen tank under pressure.
The method of welding is to heat the pieces to be welded with the blow pipe until they reach the fusion point. For instance, in welding cast-iron, the pieces are clamped together, a V shape is cut nearly thru the joint, the metal is heated to the fusion point, and a feeder, which is a small cast-iron rod, is melted into it. In welding steel, the feeder is a steel rod; for copper or brass welding, a rod of copper or brass is used. Nowadays this method is extensively used in automobile work, in repairing cracked cylinders.
Fig. 21.
A very simple weld to make by heating in the forge, is what is known as the fagot weld. In doing this, two or three pieces are welded by simply laying one piece on top of the other, or a bundle of pieces of iron of various sizes and shapes are bound together, heated and welded. For example, if a bar of flat iron is heated and cut half thru in several places, doubled over and over, one piece on top of the other and then welded in order to make a large piece of stock this would be called a fagot weld.
In [Figure 21], the pieces are represented ready to make a fagot weld.
The welding of two pieces of stock by scarfing and lapping is known as a separate-heat-weld, so called because the pieces are detached while the heat is taken. In making any kind of a weld there is more or less stock wasted in the raising of the welding heat, therefore the parts to be lapped and welded are always upset or thickened and then scarfed. The word “scarfed” means the shaping of the ends of the bars so that when heated and lapped one on top of the other, they will fit and make a splice, leaving the stock when hammered about its original size.
The method of upsetting is to heat the ends of the bar, then set the hot end on the anvil with the bar vertical and hammer on the other end. This thickens the heated end. If it is a long heavy bar, the worker churns the bar up and down striking the hot end on the anvil. A bar may also be heated on the end, then fastened in a vise and the hot part hammered to thicken it. In upsetting, the bar must be kept straight as hammering will bend it where heated; if not kept straight, it will not thicken.
Fig. 22. Fig. 23.
When a piece is upset about one inch in diameter for a three-quarter inch, round bar, it is scarfed by setting the hot end on and near the outer edge of the anvil. It is then driven back on a bevel by hammering. See [Figure 22]. It is also turned on the side and beveled on both sides to nearly a point. See [Figure 23]. The scarf must not be hammered when the piece is held in the center of the anvil, ([Figure 24]), for the reason that the edge of the hammer comes in contact with the anvil, pecking dents in it or breaking out pieces from the hammer.
Fig. 24. Fig. 25.
Another method of scarfing is to hammer the end partly back as previously explained, then set the piece on the inner edge of the anvil and hammer it as shown in [Figure 25]. After each blow, it is drawn away from the edge of the anvil just a little; this tapers it with a series of little steps, not for the purpose of making notches in the scarfs to fit together and hold while hammering, but simply because the edge of the anvil leaves it in this condition when tapered. It is also drawn pointed by hammering on the outer edge of the anvil.
Theory teaches that the scarf should be made with the beveled part convexed. However, in practice, it is made to look like the drawing in [Figure 26]. Note the raised parts at “D”. This is forced up when the scarf is first driven back with the hammer as shown at “B”.
The reason that the high part should be on the scarf, is, that when lapped it gives an additional amount of stock at this part of the laps to be hammered. If the scarfs are made flat, when hammered, they are not liable to finish up without having the pieces thin, or the point of the lap exposed. If the scarfs are made concave, it is claimed by some workers of iron that dirt will deposit there and result in a poor weld. This is true to some extent. However, dirt will deposit on any scarf unless the fire is clear. With a concaved scarf when lapped, there is not stock enough to be hammered without leaving the pieces thin, or the lapping too long when welded. Scarfs should not be made concave.
Fig. 26.
Fig. 27. Fig. 28.
Notice in [Figure 27], the incorrect way of scarfing and in [Figure 28], the correct way.
The scarfs must not be made too long; this is a common fault with all beginners and one to avoid. The scarfs should be made a little longer than the thickness of the iron, perhaps 1½ times the thickness.
In raising the welding heat, the pieces must be placed in the fire with the scarfs, or beveled part, down. The fire must be a clean one. A well burned fire is best. A new fire is not a good one to raise the welding heat in, as there is too much smoke and green coal that comes in contact with the metal. The hammer should be placed on the anvil about over the square hole, so it will be handy to reach when making the weld. The anvil should also be clean. A heavy hammer should be used in welding. The proper way to hold the hand hammer is with the fingers around the handle and the thumb protruding along the side and near the top. The thumb should never grip around the handle, but lie along the side to guide and direct the blows. When using the sledge hammer, stand in front of the anvil and not at its side, and let the first blow be a light one.
In heating a slow blast is maintained. When the pieces begin to get about yellow, more blast is used. The pieces can be watched without removing them from the fire. They should be turned over occasionally, moving them nearer to the surface of fire to see how the heat is progressing, and then under the coke again. Care must be taken to get both pieces heated alike. If one piece should get hotter than the other, it can be moved over in the fire a little, and the cool one put in its place. Perhaps the fire is hotter in one spot than another. If one piece is heating much faster than the other, lift it clear up and out of the fire for a few seconds to cool and give the other piece a chance to become hotter. If the points of the scarf are heating too fast for the body, the pieces must be pushed thru the fire a little farther.
It is a good plan sometimes, when the pieces are about a yellow heat to shut off the wind for a moment, to let the pieces and fire even up and give the heat a chance to soak thru them. As the pieces become nearly white, the blast is increased. Welding heat is about 1900°-2000° Fahrenheit, and can only be determined by experience. When the temperature of the pieces reaches the welding heat, they are lifted up and out of the fire and taken by the smith to the anvil, without the aid of a helper. The smith raps them against one another or against the anvil to dislodge any dirt that may be on the scarfs. The piece in the left hand is set against the inner edge of the anvil. The piece in the right hand is now moved across the anvil until it comes under the top one. See [Figure 29]. The piece in the left hand is then placed on the under one, by simply raising the hand, teetering the piece on the edge of the anvil, and holding it firmly by pressing down. This is important. The smith lets go of the piece in his right hand, and taking the hammer strikes lightly until the two are stuck, after which he welds them together with solid blows, first on one side, then on the other and finally on the corners.
Fig. 29.
It requires some practice to be able to take two pieces from the fire and place them in position on the anvil to be welded. This should be practiced by the pupil under the eye of the teacher, perhaps a dozen or more times, with the cold pieces before he undertakes to get the welding heat. If one cannot take the pieces out and place them in position, he cannot make a weld of this kind.
Two boys should not be allowed to work together on this weld. One can do it much better than two. It is a one-man job. There is nothing difficult about it, after the method is learned by deliberate and persistent practice with the cold iron. There is no need of hurrying when taking the pieces out of the fire to the anvil.
If the scarfs are too long, they will overlap one another too far and cannot be welded down quickly enough. If too short, they hammer down too quickly to make a good job, and the weld will be thin.
If the scarfs are the right length and about the same size, which is important, the weld will finish down in good shape and make a smooth job, providing the ends are clean. When the pieces being heated, look as tho they are covered with grease, you may be sure the fire is dirty, or is too new.
Lap Welding Without Scarfing.
A lap weld is sometimes made without scarfing the ends. For instance, pieces of 1″ × ¼″ iron are to be welded by the lap method. They are brought to a welding heat without upsetting; taken to the anvil as previously explained for the scarf weld, lapped about ⁵⁄₁₆-inch, as shown in [Figure 30], and welded. This form of welding is used in a hurry-up job where there is no great amount of strain on the work. It is impossible to make a strong weld this way. Very thin stock, either iron or steel, can be welded to advantage in this manner by hammering on the flat sides. The edges, instead of being hammered, are cut off with a chisel, then ground or filed smooth. In welding very thin stock, a little flux is used. Always weld by separate heats, and do not rivet or split the stock to hold both ends in place. This is not necessary. Try to make the weld with one heat. All good welds are made in one heat.
Fig. 30.
Jump Welding.
Fig. 31. Fig. 32.
For example, a piece like the one shown in [Figure 31], is to be made by welding. The pieces should be prepared as shown in [Figure 32]. The square piece is 1″ by 1″ by 6″, the flat one 1½″ by ½″ by 8″. The square piece is heated directly on one end. If the heat cannot be taken short enough, it may be cooled in water so as to upset it with a lip or projection, as shown. This lip can be worked out afterwards with a fuller, or it may be driven into a heading tool which has the top corners of the hole rounded. This will leave the corners of the lip round as shown. The bar at the end should also be made slightly convex, so that the center part comes in contact with the flat piece first. The flat piece is also upset in the center.
In welding, separate heats are taken. With the square bar, handled with the right hand, the pieces are brought to the anvil by the smith. The square bar is set on top of the flat one, and a helper strikes the top piece with the sledge, driving it down into the bottom one. The edge of the lip is then welded fast with a hand-hammer; or a fuller or set hammer is used, the helper striking with a sledge.
Butt Weld.
Fig. 33.
Iron may be welded by butting the ends together. In doing this, the bars must be long enough so that they can be handled without tongs. For instance, two bars of one-inch round stock, one five feet long and the other shorter are to be welded. This size is about as light as can be welded with this method. The ends are heated and upset a little making them a little high in the center so that when they are placed together, the contact is in the center. A short heat is taken on the end of each bar. The smith takes out the long bar and the helper the short one, butting the ends together on the anvil, as shown in [Figure 33]. The helper hammers on the end of the short piece with a heavy hammer while the smith holds the long one firmly, and hammers on the joint, at the same time turning the bar so as to hammer the joint all around. In welding heavier stock, a sledge should be used requiring more helpers. This method makes a good weld, providing the heats are clean.
Split Welding.
[Figure 34] shows a drawing of round stock prepared for a split weld. In making this weld, one piece is heated on the end, caught in a vise and split with a thin chisel. See [Figure 35].
These prongs are then spread and scarfed on the inside with the ball of the hammer letting them become fan shape and as wide as possible. See [Figure 36]. The other piece is upset and both pieces are caught in the vise. The scarf is then hammered tight and the ends are cut so as not to have them too long. See [Figure 37]. The cutting of the scarf, and partly into the bar, helps to bind the pieces firmly while the heat is being taken. See drawing of piece ready to be welded, [Figure 38].
Fig. 34. Fig. 35.
Fig. 36. Fig. 37.
Fig. 38. Fig. 39. Fig. 40.
A heat is now taken, using a little sand or welding flux, if the stock is very small. In welding, the first blow is struck on the end of the split piece to drive it down tight and weld it in the center. See [Figure 39]. The sides are next hammered to weld the laps. It is then finished. On heavy work, the heats are taken separately and placed on the anvil by the smith, in the same manner as described for a jump weld. Another form of split welding is shown in [Figure 40]. This method is used in welding heavy iron and steel, such as picks and drills. Notice the little beards cut with a chisel to help hold the pieces in position when heating. Heavy tool steel is also welded with this form of splitting. The first blow struck with the hammer on this weld, is on the end, forcing the pieces together; then on the flat part.
Corner Weld.
In [Figure 41] is shown an angle made by welding on the corner; this is called a corner weld. It is generally made by using square or flat stock. [Figure 42] shows the scarfs prepared for a corner weld, using 1″ by ½″ stock. The piece at “A” is scarfed with the ball of the hammer. The one at B, with the face of the hammer. Separate heats are taken and the pieces lapped and welded.
Fig. 41. Fig. 42.
T-Weld.
The scarfs for T-welds are made in just the same manner as for the corner weld, excepting that one scarf is in the center of the bar. See [Figure 43].
In taking the pieces from the fire to the anvil, the one scarfed in the center is handled with the tongs in the left hand. The one scarfed on the end is handled with the right hand, letting it under the other, and then hammered. Notice how wide the scarf is made on the end piece at “A”. This is done to cover the other scarf. All flat “T” scarfs are made in this manner.
Fig. 43.