Abstract: A rotating cutting tool has a clamping system that positively locks generally square or rectangular carbide cutters into position on the cutter head and extending outwardly from the head for spot facing or boring as the head is rotated. The head has backing supports that are raised above the head end surface for backing and securely holding the carbide inserts to prevent breakage or damage. The clamping system is very rapidly used, and particularly in the case of a spot facer, by having a proper diameter pilot pin member in the center, the carbide cutter inserts can be quickly adjusted for the desired cutting diameter. The unit has no flutes as normally required for high speed or sweated carbide spot facers.