Patent ID: 6026918
Filing Date: 2000-02-22
Classification: E21B

Abstract:
A roof bolt bit arrangement, comprising:a spade drill body portion having a rotational axis, a forward end, a pair of spaced apart, opposite side surface portions and a generally planar spade cutter portion having generally planar side surfaces with a pair of oppositely directed cutting edges extending radially of said axis, and having a general plane containing said axis and said general plane substantially parallel to said planar side surfaces, said spade drill body portion having at least one opening exposing an interior conical bearing surface adjacent the maximum radial extent of each said cutting edge;a rotatable frusto conical cutter mounted on said drill body portion in said opening, said cutter having an exterior conical bearing surface in bearing relationship with said interior bearing surface; anda retainer for fixing said rotatable frusto conical cutter axially relative said spade cutter portion.