Abstract: A centering and chucking system for fixing an interchangeable element to a carrier body. The carrier body is provided with guide elements whose guide surfaces are arranged along a coordinate system through the center of which extends the reference axis, e.g. the axis of a spindle. Due to the arrangement of two centering means along one axis of the coordinate system and of at least another centering means along the other axis, the reference axes of both parts are not displaced relative to each other by changes of temperature. Although the centering means are provided outside the reference axis, the system in said reference axis is determined by them.

Abstract: The machine tool comprises a vertical post (14) on which a head changer (19) is mounted for changing the tool head (17) provided at a head carrier (16). The head changer (19) is rotatable about a vertical axis. It carries at least one head gripper (22) which is adapted to grip from the top the tool head (17) and to rotate it from a front working position to a rear changing position. The post (14) being nonrotational (about any axis) and preferably unadjustable in height (the Y axis), is simple and low cost. The machine tool is readily adaptable to sophisticated design modifications, particularly including tool exchange in plural multi-tool tool heads and interchange with tool and/or tool head storage magazines.