Fig. 2373.
As a guide when fitting the bottom brass in the strap, place the strap on the rod as in [Fig. 2373], and take the measure of the strap at a a, the strap overlapping the rod to admit the calipers or gauge. Each time the brass is driven in the strap to try the fit, the calipers so set should be tried in the strap (the brass being in the strap), as in the figure, and when the calipers very nearly touch the strap jaws, the strap with the back brass still in should be tried on the rod end, or in the case of a very heavy strap the caliper measurement minutely taken may be relied on to show that the brass does not spring the strap jaws too wide open. It is better, however, to leave the brasses a little too tight in the strap as they close slightly in the boring, becoming easier in the strap.
Fig. 2374.
Fig. 2375.
After the brass has been tried in the strap, and before it is filed again, it should be tried with a square, using a straight-edge also if the square back is too short to cross both faces of the brass. The method of testing is shown in [Fig. 2374], in which b represents the brass, s the square, and t the straight-edge. The inside face of the flange should also be tried as in [Fig. 2375], in which p represents the surface plate, s the square, and b the brass. This will insure that the brass face joint is square as it should be, and is further necessary because the bearing marks on the brass are not to be altogether relied upon.