Staff Length Gauge
Another form of staff gauge, which is very simple, and which any watchmaker can manufacture is made as follows: Procure a small tube of steel, or make one from steel wire, thread it on the inside, and screw into each end a small steel plug as shown in Fig. 147, until the ends of the plug meet, cut off the outer end of plugs so as to leave the total length that of a short staff; harden, draw to a blue, place in a split chuck, plugs and all, and turn a pivot of good length on each plug. Flatten the sides of the plugs at the base of the pivots, so that they may be readily turned in or out by the aid of tweezers. By inserting this tool in the place of the balance, and screwing the plugs to the right position, screwing bridge down, and adjusting until the right endshake is obtained, you can ascertain in a moment the exact length that the staff should be over all, which can easily be transferred to calipers and thence to the new staff.