Oxy-acetylene welding manual

by Lorn Campbell

Part Three.—STEEL WELDING

(97) Aside from the difficulties already mentioned in steel welding, there are many others. A few of these will be taken up in order to let the beginner know how to approach the various problems which may confront him. But in no wise is this to be considered to be a treatise on advanced work. Ofttimes the question arises, Can springs be successfully welded? Now, while springs have been welded, and they have been tested out thoroughly, yet the practice of spring welding with the oxy-acetylene flame is not to be recommended. There are those who will weld leaf springs, such as are found on automobiles, and will apply rapid blows with the hammer, while their weld is still in a heated condition and then plunge the spring in water or oil to harden it and the weld. A close observer will readily see why this procedure is not correct. Springs of this nature are made up of metal which takes a uniform hardening, and were it not so they could not be considered springs. Now, if there is a fracture and a foreign metal, which under no circumstances can be expected to take the same hardening as the rest of the spring, is introduced into the weld, it can easily be seen why a fusion of this kind is not to be relied upon. If it were possible to diagnose or take an analysis of the metal in the spring and use a filler-rod which, after being acted upon by the flame, would come out the same as the metal in the spring, then some success might be expected, but until that time, welding of springs will not be encouraged. Unless perchance the break is of such a nature that it can be reinforced readily and is in such a position that a resilient quality is not necessary.

Fig. 65.—Building Up Worn Shafts.

(98) Work on crank-shafts often causes perplexity on the part of the beginner, for he usually hears this matter discussed pro and con. Crank-shafts of four inches in diameter can be successfully welded with the oxy-acetylene flame, and even larger, if correct methods are employed. There are many points which the welder considers before deciding whether a weld of this nature is advisable. Of course the usability of the piece after it has been welded is the main issue when executing any kind of a repair job. Now, a crank-shaft will generally break in either of two ways; by some external force, such as a connecting rod breaking loose, or by crystallization, which is usually due to fatigue. Now, in the latter case, ofttimes the shaft will break in the cheek of the “offset,” and possibly no part of the shaft is thrown out of alignment. When such is the case, welding is usually recommended and the shaft may be brought back to a useful state in very quick order. However, in the former case, the shaft is apt to be sprung, and while it could be welded, the machine work necessary to restore it to normal requires much time, and it has been known, where after spending a matter of days in trying to get proper alignments, work was scrapped as useless. So it is entirely up to the welder in work of this kind to determine whether the job is worth while or not. There are certain parts of a crank-shaft upon which welding work can be done with a marked degree of success, such as building up worn bearings and the like. In doing work of this kind it is recommended that the welder fuse his metal in a line parallel to the center line of the bearing, seeing to it that he has a perfect fusion between the surface of the bearing and the metal he is fusing and adding plenty of metal, to insure enough being used, so that no low spots will show up when it is machined. It is considered that by adding the metal as suggested the welder will hold his heat much better than if he attempted revolving the shaft continually. [Fig. 65] will show the method here outlined in a very clear way.

Fig. 66.—Shaft Broken at End of Square Shank, its Weakest Point.

Fig. 67.—Broken Part of Shaft Removed and New Piece Added, thereby Moving the Weld away from the Weak Part.

(99) When working on shafts the welder will encounter such articles as automobile propeller shafts and rear axles, which generally break adjoining the square ends. He will no doubt wonder whether it is advisable to weld this square end back on, or whether to try and build up the shaft the desired length. Undoubtedly the point of fracture is the weakest portion of the entire shaft, else it would not break there. The execution of a weld at this point where no additional metal can be added or any means of reinforcing used is not to be recommended. [Fig. 66] will show the problem which confronts the welder, and [Fig. 67] the suggested means of overcoming the difficulty. By removing about four inches from the broken end of the shaft and adding a new piece, about ten inches long, of the same diameter, the weld will be removed from the weak point; a heavier weld can be made, and the end can be machined off to the desired size. This procedure is recommended on all jobs of like nature.

(100) Occasionally case-hardened ring gears are brought to the welder to have teeth built up or new ones added, and although the welder must realize that the hardening is destroyed by the action of the flame, yet he does not understand why it is necessary to reharden the gear. A little thought on this subject will make him appreciate the fact that if he destroys certain properties in metal which have been introduced for a reason, these must be replaced if he would bring the job back to normal. It would be like heating up a tempered lathe tool, or cold chisel for that matter, and trying to use it before it had been retempered. Therefore if hardening or temper is destroyed by the flame it must be restored.

Fig. 68.—When Welding a Small Section to a Larger One, the Flame of the Torch is Directed toward the Heavier of the Two.

(101) If a weld were to break, it would be necessary for the welder to remove all metal added in the first weld before attempting to reweld. This is true of his own work as well as that of others which he may be called upon to do. For no matter how good the surface may appear, without a solid foundation no weld is of any value, and unless he clears out all of the old metal he cannot be sure of the work. This will apply not only to steel work, but to all metals, and it is a point which should be borne in mind.

(102) At times there are jobs come up in which one piece of work is to be fused to another which is much larger, and will absorb much more heat during the weld. When handling such work, it will be necessary to play the torch upon the larger piece most of the time, as shown in [Fig. 68], in order to bring both pieces to a fusion point at the same time and keep them in that condition.

(103) Once in a while it will be necessary for a welder to fuse cast iron to steel or vice versa, and the question will arise as to which filler-rod he will use. It has been found that a cast-iron filler-rod can be used with success and of course when using a cast-iron filler-rod, a cast-iron flux will be necessary. Work of this nature is not very frequent.