Fig. 2421.
To test the alignment of the jaws at end f, press a straightedge against the outside face of the hub and measure the distance j, [Fig. 2420], then apply it on the other side and measure distance k, [Fig. 2421], and when distances j and k are equal and the width l between the jaws is correct, end f is in line in one direction. To test it in the other direction, apply a pair of parallel strips, placing one on end e as in [Fig. 2417], and the other across the face of the hub of end f to see if there is any twist.
Suppose, however, that distances j k are unequal, then if distance l is too narrow (when tested by the piece that fits between the jaws) then the jaw at f that gives the widest distance at e is the one that requires correction, or if distance l is too wide, the jaw that shows the least distance at end e is the one requiring correction.
The link should be warmed to about 300°, or nearly black hot, and pieces of sheet copper placed between the work and the anvil, and between the blacksmith’s tools and the work, so that the latter may not be bruised by the blows delivered to effect the straightening.
After the process has been performed at each end individually the testing should be repeated, because setting the end f may have impaired the setting of end e, in the alignment to f.
It is obvious that the same setting or aligning process would be required in the case of a large link, where the ends were forged separately and welded to the body after the machine work and fitting had been done to them.
Fig. 2422.