A rotatable chuck for clamping a shank portion of a rotatably operating machining tool includes a rotatable chuck body provided with a cylindrical bore concentric with a rotation axis of the chuck body. The circumferential surfaces of a clamping portion of the bore are arranged to apply a clamping force around the circumference of the shank portion of the tool when it is mounted in the chuck to fixate the tool in the chuck. The chuck is provided with auxiliary pull out preventing means for preventing inadvertent pull out of the tool in the axial direction of the bore during machining operation, as well as auxiliary rotary preventing means for preventing inadvertent rotation in at least one direction in relation to the chuck during machining operation. The auxiliary pull out and rotary preventing means include an attachment member positionable in an inner portion of the bore and attachable to the shank portion to be clamped, such that the tool and the attachment member will be prevented from being pulled apart in the axial direction and from being rotated in at least one direction in relation to each other.

A device for enlarging a hole with a frustoconical base body that can be inserted into a hole of a workpiece, and has an insertion opening for inserting a pilot drill of a hole saw. The frustoconical shell surface of the base body has a self-tapping thread, which can engage into the wall of the hole to be enlarged. A screwdriver is provided to apply the correspondingly large torque.

The invention relates to a screw-in tool (1) and to a tool holder (2) for such a screw-in tool. The screw-in tool (1) contains a tool head (3) and a tool shank (4) having an outer thread (5) and a supporting region arranged between the tool head (3) and the outer thread (5). According to the invention, the supporting region is formed by two conical bearing faces (6, 8) having different cone angles.

A replaceable cutting head includes a forward cutting portion and a rearward mounting portion. The mounting portion includes a male coupling member that protrudes rearwardly from a head base surface. The male coupling member includes forward and rearward bearing portions and an external thread located therebetween. The forward and rearward bearing portions include respective conically shaped forward and rearward head abutment surface. The forward and rearward head abutment surfaces have the same cone angle. When a cutting tool, including said cutting head and a tool holder having a female coupling member, is in a locked position, the external thread is threadingly engaged in the female coupling member and the forward and rearward head abutment surfaces conically abut corresponding conical shaped surfaces in the female coupling member.

A replaceable cutting head includes a forward cutting portion and a rearward mounting portion. The mounting portion includes a male coupling member that protrudes rearwardly from a head base surface. The male coupling member includes forward and rearward bearing portions and an external thread located therebetween. The forward and rearward bearing portions include respective conically shaped forward and rearward head abutment surface. The forward and rearward head abutment surfaces have the same cone angle. When a cutting tool, including said cutting head and a tool holder having a female coupling member, is in a locked position, the external thread is threadingly engaged in the female coupling member and the forward and rearward head abutment surfaces conically abut corresponding conical shaped surfaces in the female coupling member.