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By F. G. Coburn Naval Constructor, U. S. N. HAIN CABLES for vessels of the United States navy are now being manufactured at the Boston navy yard under steam hammers. The process has been developed to a point where its success as a rapid and high-grade producer is unquestionable: For many years, all chain cables for naval vessels of all kinds and sizes were made at the Boston yard, with only an occasional purchase of chain under exceptional con- ditions. Until comparatively recently, the old-fashioned methods of chain-making were accepted and followed; but about five or six years ago a movement was begun to improve these old methods. The trade of hand-chain-making is a fairly old one, and as the industry is not large, the trade has not received much attention. The chain fires look much as they did a hundred years ago; and the chain- makers go through the same motions that their great-great-grandfathers did. Machine processes of manufacturing small chain have been invented, and are in actual use; but the quality of the product is not always equal to that of the hand- welded product—and the latter is by no means perfect. In the hand process, the scarf is formed by peening with the back of the sledge; this results in a rough, irregular faying surface, frequently. with fairly large pockets. These pockets retain slag, and the unevenness of the faying surfaces brings about a separation of the surfaces which is not reduced by the hammer- ing during welding, particularly in the large sizes. The result is that the weld is not complete; and the danger lies in this, that the edges of the scarfs are perfectly welded and smoothly finished, completely masking the bad weld. The writer has seen a link of old chain break in the test pit—chain that had been in service for several years—the break occurring along the scarf and showing both slag pockets and sledge marks. It was perfectly welded around the edges, but the inside, probably 75 per cent of the faying surface, was absolutely ‘not welded at all. The link had never parted in service, because end-welded chain has a high measure of strength due to its form, and the additional strength, due to the welded area, was sufficient to make it stand the stresses of service, which, for- tunately, were not high. Hand-welded chain is usual- ly irregular in shape and dimensions, an important deficiency if the chain is to be veered and hove over a wild cat. Hand welders are a bit careless in this the scarfs come together truly, and could not, on respect, as a rule, but when impressed with the neces- account of the limitations of their tools, make a. fair, sity of uniformity and equipped with gages it must round section at the weld. Finally, the problem of Hammer-Welded 3-inch Chain Which Broke Well Above Re- quired Pull. Chain is uniform in shape and size Hand - Welded 3.-inch Chain Which Failed in Test. Chain is Irregular in shape and size be said for them that they will turn out very uniform chain. But whatever may be the comparative advan- tages and disadvantages existing between hand- welded and machine-welded chain in the small sizes, there is no question at all about the shortcomings of © the hand process when applied to large chain. Large chain may be defined as chain of 234 inches diameter and upward. The hand welders do fairly well up to 2% inches, although there are plants which make hard work of anything over 2 inches; above these sizes they run into difficulties. At the Boston yard, by dint of close attention to inspection and tests, no great diffi- culty was had, until the 27-inch and 3-inch sizes were reached, in the gradual increase of chain sizes, which accompanied battleship development. This 3-inch chain is so large that the hand welders made‘very hard work of it. In addition, they were actually unable to make making the 3%4-inch cables for the battleship PENN- SYLVANIA was faced. When the iron for these cables was delivered, two sample triplets were made for testing, one triplet by one gang, the other by another gang. Each gang took a whole day to make its three links, and then stayed out all the next day to rest from its arduous labor. One and one-half links per gang per day. At that rate it would have taken one gang more than seven years to make that one set of cables. With all the capacity available in the shop for large chain work concentrated on that one order, it would have required more than a year. With the steam hammers, one gang produces 20 links of this size chain per day, every day. There seems to be no need for argument as to the advisa- bility of going to the use of hammers. Cost “would be no consideration, because the chain must be made, 105