A workpiece has two cylindrical workpiece surfaces centered on respective parallel axes and each flanked by a pair of arcuately rounded and annular corners also centered on the respective axes. Some of the corners have a small radius of curvature and others of the corners have a large radius of curvature. The workpiece is held and rotated about a main axis parallel to the axis of one of the workpiece surfaces. A pair of grinders have wheels generally diametrally flanking the workpiece and each having a central cylindrical outer wheel surface centered on the respective wheel axis and a pair of arcuately rounded edge and surfaces also centered on the respective wheel axis. Two of the edge surfaces are the large radius and the other two of the small radius.