Excerpt from How to Build: An One-Half Horse Power Motor or Dynamo Provided with the castings, the holes for the core should be bored out smoothly to two inches in diameter. For doing this the castings may be either bolted to the traveling carriage of a lathe, and a boring bar inserted, or to a face plate, using a rigid inside boring tool. If possible finish with a reamer. Drill, tap and counter-bore for the seven-sixteenths inch screw a on the bolt and screw list, Figure 4. The slots at the bottom, which may well have been cored part way, can w be extended through with a hack saw. The core is to be of wrought iron, seven and three-sixteenths inches long, smoothly turned to two inches in diameter. If what commonly kwn as cold rolled steel is available, turning will be necessary. This quality of steel is very soft and quite as good as wrought iron for magnetic purposes. Put one pole piece on the core, tighten the clamping screw; drill a one-fourth inch hole through the cast-iron into the steel and drive in a steel pin about three-fourths inch long. These two parts will then be permanently attached. Slip on the other pole piece, see that the protruding arms are parallel, tighten in place, and drill a one-fourth inch hole in the end, so as to be half in the core and half in the pole piece, in the location as shown, and drive in ather pin. This method locates the two parts definitely, but allows easy removal of one pole piece for placing the field spool. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art techlogy to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.