When grinding frame parts or other workpieces with different grain directions, grinding against the grain direction cannot be avoided. The abrasive marks created are clearly visible, especially when using dark stains. With the OSR, all sanding marks are effectively removed. DB-S planetary head units for breaking edges and sanding out deeper surfaces can be combined with orbital grinding units. The stationary, vibrating sanding belt of the OSR unit removes the sanding marks from the grinding machine located upstream. The result is an absolutely smooth surface.