Fig. 1701.
Fig. 1702.
Fig. 1703.
In [Figs. 1701] and [1702] we have a jig or fixture for holding the link during the drilling process. It consists of two parts, c and d, between which the link is held by the screws e and f. The two hubs, g and h, are provided with hardened steel bushes, i and j, which are pierced with holes to receive and guide the drilling tool or reamer, and it is evident that in time the bore of these bushes will wear, and if they wear on one side more than on another they may wear longer or shorter between the centres or axis; hence we require gauges such as shown in [Fig. 1703], one being longer between centres and the other shorter, in each case to the amount of the prescribed limit. In this case, so long as the holes are kept within the prescribed limit of diameter, the distance apart of the two holes will be within the limit so long as neither of the limit gauges will enter; and when they will enter the bushes i j must be restored.