Drill and surface insensitive starting drill for difficult materials and deep holes

摘要: A fluteless pyramid point drill for spotting holes drills having an included angle from 90-160°. The preferred tool is double ended. Another embodiment features the on back end of a penetrating drill. An enhanced geometry enables construction technical ceramics. These embodiments notched pyramid, dual beveled and eccentric pyramid. utilizes grooved-body hollow reaming holes. Geometries single sided drilling hardened materials include limited flute with depth ⅓ diameter. Point 0-20° primary cutting edge steeper relief negative rake along edge, radial steep this edge. Additionally may be superimposed superior centering guidance.