Abstract: A grinder for polishing the outer surface of a work piece, comprising a power unit set in a machine base to carry a centrifugal disc to a centrifugalize grinding solution contained in a container for polishing work pieces therein. Elongated stop bars are longitudinally arranged on the inner wall surface of the container to stop the grinding solution centrifugalized by the centrifugal disc. Stirring bars are on the cap of the container for stirring the centrifugalized grinding solution. Stirring blades are provided on a rotary wheel, which is revolvably attached to the inner bottom of the cap, for agitating the centrifugalized grinding solution into turbulent flow so as to achieve better grinding performance.

Abstract: A grinder of the type comprising a grinding cylinder for containing liquid grinding compound and a centrifugal disc to centrifugalize said liquid grinding compound for performing grinding operation, the improvement including a grinding cylinder automatic lifting mechanism controlled by a timer to automatically drive a motor to drive a linkage to automatically lift said grinding cylinder from said centrifugal disc for discharging liquid grinding compound and processed working pieces out of said grinding cylinder. A water circulation system is provided to circulate clean water through said grinding cylinder for cleaning purpose.