Abstract: A honing tool having a mandrel with longitudinal grooves each of which has an inclined bottom slidably engaged by a correspondingly wedge-shaped honing stone. The honing stones partially project through windows in a sleeve and by these windows are held stationary in their longitudinal direction while being able to move radially with regard to the sleeve when the mandrel moves in either longitudinal direction. The longitudinal adjustment of the mandrel relative to the sleeve is effected by a spindle which threadedly engages the mandrel in its axial direction and is rotatable by hand in either direction to thereby either move the spindle in one or the other longitudinal directions. In response to such longitudinal movement of the mandrel, the honing stones are adjusted radially either outwardly or inwardly, to increase or decrease the honing diameter.