Abstract: A device for sharpening a single flute countersink in which a threaded shaft is mounted in an enlarged opening formed at the upper end portion of an upstanding post. One end of the threaded shaft mounts a countersink to-be-sharpened, while the other end has a knurled portion to allow for the manual rotation of the shaft. A collar is provided adjacent to the knurled end of the shaft which collar has a projecting pin that cooperates with a projecting pin from the side of the upstanding post, to thereby limit the arcuate rotation of the shaft and attached countersink to less than 360.degree., in accordance with the arcuate extent of the cutting surface of the single flute countersink. Upon sharpening of the countersink, it is simultaneously rotated and translated in one direction, in accordance with the geometry of a single flute countersink.