NOTES ON CHAIN CABLES. 169 



Electric welding is practiced commercially on small chain up to 3/2 inch, the 

 Standard Chain Company having quite a large plant. It is extremely rapid and 

 cheap, but the material is somewhat damaged in the vicinity of the weld, due to 

 the very high local heat, which tends to burn the iron and to set up internal stresses. 

 This latter defect is somewhat lessened by working under a hammer or annealing 

 subsequent to welding. However, the process is generally considered to be not 

 capable of extension to larger sizes of chain, because of the uncertainty of the 

 results. Aside from this it can well be imagined that the design of a suitable elec- 

 tric welding machine for 3-inch chain would be a very difficult undertaking in that 

 the ends to be welded will require to be squeezed together so as to upset them 

 slightly when the heat is taken, which operation will require considerable force 

 with a cold link. ; 



Press welds have been tried from time to time. So far as I know the 

 welds made thus far have not been successful and have not stood the required 

 tests, but I have been informed that the fault was with the heat and not with the 

 press. However, it is the general opinion among experienced smiths that a weld 

 should be hammered and not pressed. This seems reasonable, because of the more 

 rapid action of the hammer, of the tendency of the blow to expel the dirt and slag 

 and of the press action to confine it. It is possible, too, that the kneading effect 

 of the light hammer blows rapidly repeated is to produce a finer structure and bet- 

 ter arrangement of crystals. Considered as a shop equipment proposition the 

 press will cost about $10,000 to install and this represents a rather heavy overhead 

 charge for a chain fire. It would seem, therefore, that the hammer can be accepted 

 as preferable to the press. 



The selection of a power hammer for the welding of large chain links is diffi- 

 cult, and before a decision can be reached in this matter, it is necessary to consider 

 the various types. 



A helve hammer of the Standish type would, no doubt, prove excellent, but as 

 this hammer is not made commercially in large sizes, a special hammer would re- 

 quire to be built. 



It is maintained by experienced smiths and chain workers that a weld should 

 be made with a type of hammer that will give an elastic blow and a succession of 

 light repeated blows rather than a few heavy blows. In other words, the idea is to 

 approach as nearly as possible to the kind of blows struck by a hand sledge. 



The Bradlee hammer with rubber-cushioned helve most nearly meets these 

 requirements. Considerable experimenting has been done with this type of ham- 

 mer at the Boston Navy Yard, and some very satisfactory results obtained. 

 These experiments provided for a double set of dies, one set of the cup form for 

 starting the weld, and the other merely a horn projecting from the side of the an- 

 vil similar to that used by hand chainmakers. The objections to this type of ham- 

 mer were that it required considerable working and moving of the link, that its 

 form prevented the men working around it, and that its rapid action was difficult 

 to control, and its stroke was so short that it gave scarcely room enough to enter 

 the link into the dies. 



