Improvements in the drilling devices, trends to the realization of polygonal drills (Machine-translation by Google Translate, not legally binding)

摘要

Perfections in the drilling devices, aimed at the realization of polygonal holes, characterized by establishing a handle, finished in a cone, which is surrounded by a pair of flat friction bearings each constituted by a bronze bushing and a ring, threaded upper to the box of the tool and the lower one, which is internal, to the bushing at the end of the handle. (Machine-translation by Google Translate, not legally binding)