Abstract: A milling cutter has a cutter body including one or more steps extending along the outer peripheral edge of the cutter body. Cartridges are detachably mounted on the step, each of the cartridges having a plurality of equally spaced cutting edges. Preferably, the cutter body has a radially outer step and a radially inner step close thereto, and the cartridges with roughly cutting edges are mounted on the radially outer step. Roughly cutting edges and finishing cutting edges may be attached to the outer and inner surfaces of a single cartridge. When the cartridges are mounted on the step, the cutting edges are equally spaced fully around the cutter body for successive milling operation on a workpiece.

Abstract: A holding device for a rotating body comprising a tubular member (1) which permits insertion therein of the rotating body, at least three support members (2) disposed along the inner periphery of the tubular member (1) so as to be movable in a substantially radial direction, and a locking arrangement (3a, 3b, 4a, 4b, 10a, 10b) capable of independently holding each of the support members (2) in a desired position. With such device, bodies which are rotatable about an axis not coaxial with the driving shaft thereof can be held in place without having any substantial influence upon their rotational shafts. Besides, it is not necessary to pay close attention to the clearance between moving members in the manufacture and use of the device, and thus the holding device is high in versatility and low in cost.