Abstract: 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.

Abstract: A cutting plate carrier insertable in a holder of a machine tool, in particular a lathe tool. The carrier has a plane base surface and a substantially circular plan, the axis of which coincides with the axis of a central screw thread. The cutting plate carrier is provided with a recess for a polygonal cutting plate having a central bore. The cutting plate can be fixed in the recess by means of a clamping screw which can be screwed into the central screw thread. For the cutting plate, the recess has a plane supporting surface arranged parallel to the base surface and a number of bearing surfaces corresponding to the number of lateral surfaces of the cutting plate and extending parallel thereto. These bearing surfaces are arranged at the same distance (a) from the central screw thread. A second screw thread for screwing in a retaining screw inserted into the holder from below is provided parallel to the central screw thread.

Abstract: A tool insert for boring operations, particularly for a boring bar, comprising a housing which can be inserted in a recess in a toolholder, for example the boring bar, and which has a cutting tip support slidably mounted in a longitudinal bore therein, the said cutting tip support having a cylindrical shank, the outer end of the support bearing in a recess a replaceable cutting tip which is staggered laterally relative to the shank axis and the rear end having a thread which is engaged by the thread of an adjusting element rotatably mounted free of play in the housing between axially loaded ball bearings.

Abstract: The shaft (1) of the drilling tool has a support (3) fixed in a cylindrical blind hole (2) by means of a fixing screw (10). The support has a rear cylindrical portion (3a) and a forward half-cylindrical portion (3b). The forward portion has a replaceable cutting insert (4) fixed in it by means of a clamping screw (8). This is screwed into a first thread (9) of the support, and this thread extends perpendicularly to the seating (5) provided for the replaceable cutting insert. The support has a second thread (9) running parallel to the first thread and this locates the fixing screw which is screwed into the support from below passing through an oblong hole (11) in the shaft. The base (2a) of the blind hole is provided with an adjusting screw (12) which is arranged so as to be displaced from its axil.