Abstract: A sharpener having a clam-shell housing in which a motor is mounted for driving a grinding wheel disposed adjacent one end of the housing, a chuck which holds either twist drills or a diamond dresser, the chuck being indexable 180.degree. about its axis, and structure for mounting the chuck relative to the grinding wheel so that either the twist drill can be moved in a prescribed manner across the grinding periphery of the grinding wheel, or so that the diamond dresser can be moved across the grinding wheel in order to dress the wheel to a form suitable for sharpening twist drills or the like, and also means for moving the twist drills or the like or diamond dresser towards the grinding wheel.