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.