Abstract: A positioning apparatus includes a guide frame with a mounting assembly for mounting the frame on the end face of a tool holder so that it projects transversely away from the holder. A levelling or positioning member is slidably mounted in the frame for movement in a first direction towards and away from the tool holder, and a locking device locks the levelling member in a selected position. A key indent at one end of the member locates a cutting edge at the end of a cutting tool mounted in the tool holder. The key indent is adjustable in position in a second direction perpendicular to the first.