98. Yoke. The best way of making this, of course, is to cut a piece of bar-iron the right size. For 5⁄16 bolts the strip of wrought iron should be about ¾ in. wide and 3⁄16 or ¼ in. thick. Any blacksmith can make this and punch or drill the holes. If taps and dies (tools) are at hand, the hole may be drilled and tapped to fit the thread on the bolt. It is very easy to make good looking apparatus if you have, and can use, a whole machine shop full of tools. The lengths of yokes will depend upon the special uses to be made of them.
99. Yoke. Fig. 47. The yoke, Y, is a part of a carriage. This can be bought at a blacksmith's. The holes are already in, but it may require some filing before the nuts of the bolt magnets will fit down firmly.
Fig. 47.
100. Tin Armatures may be made by bending together 5 or 6 thicknesses of tin. Different forms of tin armatures are shown under telegraph sounders; these should have a hole punched at the center; through this is put a screw. The length of the armature will depend upon the distance the magnets are placed apart; they should be about ¾ in. wide.