Abstract: A rotating arbor in a sawing machine such as a table saw or radial saw or in a milling machine is provided with a pair of pressing members that are mounted on the arbor so as to be rotated in unison therewith, and a bearing sleeve which is provided on the arbor between the pressing members so as to be rotatable in unison therewith. A rotary blade for forming a groove is clamped from both sides thereof by a pair of clamping members which are mounted on the bearing sleeve in a tilted orientation for holding the rotary blade at an inclined angle with respect to the arbor, the clamping members being pressed between, and hence secured by the pair of pressing members. Turning both clamping members relative to the pressing members allows the clamping members to be tilted together with the rotary blade with respect to the central axis of the arbor.