Buffing and grinding machines finish, shape, and remove excess material from workpieces. Bench grinders have abrasive wheels or belts that smooth rough surfaces and hone sharp edges. Bench buffers have cloth wheels that polish items. Combo wheel and belt grinders have a stone grinding wheel on one side and an abrasive belt on the other. OD grinders (outside-diameter grinders) have a grinding wheel that rotates to remove material from a spinning cylindrical workpiece. Surface grinders are large tables with a grinding wheel, and they produce a smooth finish on flat surfaces.