Abstract: A chucking reamer has a flattened section on its head, with a crescent-shaped recess. A crescent-shaped body which retains a cutter device is held in the cresent-shaped recess by a fixing screw and a pair of headless screws are threaded into the head to adjust the position of the crescent-shaped body and the cutting device. The carbide cutter device and the steel crescent-shaped body are in one piece. The fixing screw has a conical head which fits into a conical recess in the crescent-shaped body. An inner threaded hole is provided through the head, running perpendicularly from the bottom face of the crescent-shaped recess, for receiving the shank of the fixing screw.