The rotary disk for a lathe has near the circumference thereof a plurality of insert-receiving recesses (5) which are circumferentially spaced apart. For each insert-receiving recess (5) there is provided an insert disk (6) which can be removably inserted therein and within which a receiving bore is concentrically arranged. Each insert disk (6) has in the region of the cylindrical receiving bore (8) two diametrically opposite, radially extending screw-threaded bores (9, 10), a clamping screw (11) with a conical recess (12) being screwed into the screw-threaded bore (9) which is located more inwardly with respect to the axis of the rotary disk and a clamping screw (13) with a conical end part (14) being screwed into the screw-threaded bore (10) which is located more outwardly with respect to the said axis. Each tool holder shank (17) which can be inserted into the receiving bore (8) has a transverse bore (18) with a clamping bolt (19) arranged for radial sliding movement therein and is provided at one of its ends with a conical end part (20) and at its other end with a conical recess (21).