The grinding machines covered by this specification are intended for use in reconditioning intake and exhaust valves of internal combustion engines. The type I, style A, grinding machine is designed for bench mounting, and has a valve stem capacity of 9/32 to 11/16 inch and a valve head capacity of one to four inches. The type I, style B, grinding machine is the same as style A except that it is mounted on a metal cabinet. The type II grinding machine is a heavy duty, floor-mounted unit capable of grinding valves with stem diameters of 9/32 to 1-¼ inches and head diameters of 1 to 5-⅜ inches.