RINGVORMIGE GATENBOOR.

摘要

An annular hole cutter having an inverted cup-shaped body provided with a plurality of circumferentially spaced teeth around its lower edge. Helical flutes extend upwardly between successive teeth and form around the outer periphery of the cutter a plurality of radially relieved lands, each having a circle ground narrow margin at the leading edge thereof. Each tooth has a plurality of radially and axially staggered cutting edges thereon.