PURPOSE: To form grooves wider than the width of a cutter with a sawing machine or a milling machine by a method wherein the angle of the contact surfaces between a circular cutter blade and its clamping holders can be free to change.

CONSTITUTION: A circular cutter blade 1 is clamped by cutter holding disks 3, 4 and a pin 17, held by clamping disks 5, 6 and a pushing disks 7, 8 and mounted on the shaft 2 by a nut 10. The contact surfaces a, a' between the cutter holding disks 3, 4 and the clamping disks 5, 6 incline to the axis of a rotating shaft 2 at a specified angle. Any inclination angle of the cutter 1 is adjusted simply by inclining the said contact surfaces at any angle to the rotating axis by the relative revolution of them.