Patent ID: 6840717

Claim:
A rotatable tool comprising: a shaft defining a longitudinal axis of rotation and including: a chip removal passage for removing chips, and a longitudinal front end forming a seat, the seat including a first engagement surface extending generally longitudinally and facing generally radially with reference to the axis; a cutting head attached on the seat and including a cutting edge structure oriented to define a direction of rotation for performing a cutting operation, and a second engagement surface extending generally longitudinally and facing generally radially, the second engagement surface engaging the first engagement surface for longitudinally locking the cutting head to the shaft and for transmitting torque between the shaft and the cutting head; the first and second engagement surfaces including respective first and second support surfaces together forming a planar interface defining a contact line when viewed longitudinally toward a front end of the tool, the contact line intersecting an outer periphery of the cutting head at a point, wherein the contact line extends from the point in a direction forming an acute angle with a radius that intersects the point, the contact line disposed rotationally ahead of the radius with reference to the direction of rotation of the tool during a cutting operation, wherein the cutting head is positionable in an attached state in response to relative rotation between the cutting head and the shaft in one direction about the longitudinal axis, and positionable out of the attached state in response to relative rotation between the cutting head and the shaft in an opposite direction about the longitudinal axis; wherein the cutting end of the cutting head includes a forwardly facing front surface, and the second support surface extends to the front surface.