Credo Tool Company

Zane D Lockhart, Jr

Juergen Wiker

Gregory A Phillips

David H Byrley

Carl Shumaker

Debbie Ann Newhouse

Oscar H Miller

A double-ended drill bit having opposed cutting ends of different structural configurations is provided in combination with a sleeve or holder to be received within a drill chuck. The sleeve is provided with a cylindrical body having a top end with a pair of helically-shaped longitudinally extending members in spaced mating relation attached thereto. One cutting end of a drill bit is received within the cylindrical body and the spaced helically-shaped members.

Chuck sleeve insert for a drill

A carbide substrate including a binder prepared to receive a cutting material such as a diamond coating thereon. The substrate is immersed in an electrolyte solution with the substrate acting as the anode thereby providing for an electro-polished substrate surface. The electro-polished substrate surface is then etched to substantially remove the binder phase of the carbide substrate, the etching being to a depth of up to about 15 microns. The resulting surface is susceptible for receiving a coating of the diamond cutting material.

Method of making cemented carbide substrate

Growing community of inventors

Louisville, KY, United States of America

Zane D Lockhart, Jr