Chuck adapter sleeve for a twist drill

摘要

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.