CHAPTER III
SHOP EQUIPMENT
(41) In equipping a shop for welding, in addition to the welding apparatus, the operators are many times undecided whether it is advisable to have a planed metal or a brick top table to use for welding purposes; each has its advantages, but were there a choice of one or the other, it is suggested that the brick-top table be used. The theory of having a planed metal top for lining up work does not prove as satisfactory in actual practice as might be expected, for the simple reason that the average welder generally places his metal in direct contact with this cold top, and much of the heat which is supposed to go into the weld is conducted away by the table top, producing a hard, brittle weld. In the case of cast iron, these welds are generally porous. Then too, the operator to a large extent depends upon the table top for lining up his work and does not study his contraction and expansion as thoroughly as he might. The result is that many of his pieces warp in cooling. To rectify the first objection it is advisable to cover the table top with asbestos paper as shown in [Fig. 28]. In the second place, sometimes clamps are used to hold the work in position. Preheating without a layer of bricks on a metal-topped table is not to be recommended.
Fig. 28.—Method of Holding Heat when Welding on Metal Top Tables.
Asbestos paper, P, is laid upon the metal top, M, and the pieces, A and B, placed upon P in such a manner that the weld can be made at C. The asbestos paper prevents too much heat escaping from the bottom of the weld.
Fig. 29.—A Fire-brick Table for Welding.
Angle iron measuring 2 by 2 by ¹⁄₄ inches is welded together in the manner shown and covered with fire-bricks which measure 2¹⁄₂ by 4¹⁄₄ by 9 inches.
(42) A fire-brick table, made up along the lines shown in [Fig. 29], is very easily constructed and can be used for all sorts of jobs. It is well to have everything clear around the legs and have no braces to cut the operator on the shins or to interfere in any way with his work. The best fire bricks obtainable should be used. A large number of extra bricks should always be on hand for they come in very handy in most of the welding operations, and in fact to conduct a welding shop without fire bricks could almost be likened to a blacksmith’s shop without an anvil. Besides being used for table tops, preheating furnaces of a temporary nature may be built and the bricks used to jack up and align many jobs which could not be handled otherwise.
(43) An emery wheel plays a very important part in a commercial welding shop, insomuch that rust, scale, and unnecessary metal can be removed in a very short time by its use. A flexible shaft attachment should be on hand, if possible, or a portable grinder of some kind, for in many cases where the casting, or the piece being worked upon is too heavy to bring to the emery wheel, the wheel can be brought to it and many places ground down by its use that would be impossible with a stationary grinder.