Abstract:
An improved twist drill sharpening machine for sharpening two lip twist drills having a base, a chuck for chucking a drill bit W to be sharpened, and a grinding wheel spindle supported on the base, a grinding wheel fast on the spindle, the grinding wheel having a concave grinding surface profile on its periphery, an arrangement for moving the chuck and grinding wheel relative to each other so that the grinding wheel carries out metal removal grinding operations on the drill bit W for sharpening same, and the drill bit W being incrementally in-fed to the grinding wheel on an axis parallel to the grinding wheel axis while held disposed at an acute angle to the in-feed axis, an arrangement for flip-flopping the chuck and drill bit W through 180. degree. rotational arcs of travel during in-feed of the drill bit W, an arrangement for cushioning the chuck and drill bit W at the ends of the 180. degree. rotational arcs of travel, and an arrangement for automatically controlling of said in-feed and flip-flopping of the drill W and for returning it to its in-feed starting position upon completion of the grinding operation thereon.