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.
[Illustration: 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.]
[Illustration: 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.
[Illustration: FIG. 30.--One Shop in which Instruction in Steel is being Given, at the Ordnance Welding School.
Note the construction of the welding tables. Two or more may be placed together, to give as large a surface as desired.]
(=44=) Many times when working near a hole which may be threaded, the welder has much difficulty in keeping his metal from entering the hole. At other times it is necessary to back up preheated work such as aluminum, to prevent its collapsing. Ordinary clay or putty cannot be used for this purpose. The simple reason being that when metal is heated it expands and the clay or putty in giving off its moisture contracts, showing two opposite reactions. Retort cement is a name given furnace cement mixed with shredded asbestos, this, as well as carbon flour, has been found to be very satisfactory for filling in holes and backing up pre-heated work. Retort cement is purchased in airtight containers, hardening very quickly when brought in contact with the air, so at all times it should be kept in containers similar to those in which it is purchased. It cannot be reclaimed once it is hardened.
(=45=) A blacksmith forge will be the medium of saving much valuable gas and time in a welding shop. It will heat up parts to be welded in very short order and while in this condition they may be welded and then thrown back into the forge and allowed to cool very slowly.
(=46=) Several pails of water should always be located where welding is being done to prevent fire from flying sparks; to cool the torch tips and filler-rods, when working on large jobs; to keep certain parts of work being welded cool, and to harden or temper other parts.
(=47=) A simple and efficient manner of handling flux in the welding shop has puzzled many welders, on account of the flux containers being easily upset, their inaccessibility and the action of the air upon large quantities of flux. A simple method of overcoming this is to cut in two, a two and one-half or three-inch pipe coupling and mount it by welding on a square piece of one-eighth inch plate, as shown in Fig. 31. This type of container is very hard to upset; may be used when working on preheated jobs; is easy to get at on account of its shallow nature, and, as it only holds a small amount of flux, it can be cleaned out frequently and a fresh flux will always be available.
[Illustration: FIG. 31.--A Good Flux Container for the Welding Table.]
(=48=) Additional equipment beneficial to the welder will be a quantity of various sized carbon rods and blocks; asbestos paper; goggles; V-blocks for lining up shafts and an assortment of mechanics’ tools, such as wrenches, hammers, chisels, hack-saws, and other things which might be used in dissembling or assembling various kinds of machinery.
(=49=) Another important item which is generally overlooked in the average welding shop is the question of ventilation. Although the welding flame itself contains no objectionable gases, those from fresh charcoal preheating fires, those given off when some of the alloys of the filler-rods are melted when brass, copper, and other metals are being worked on, and from gas engine exhausts are not desirable. At times they will give the operators violent headaches unless means are taken to carry them off. The ventilation should be such that it will not directly affect the work. Drafts are to be avoided as much as possible, for many times they will warp pieces being preheated if allowed to come in direct contact with them. It is a good thing to remember that indirect ventilation and plenty of it is a prime requisite in a good welding shop.