Abstract: An apparatus and method for on-site dressing and truing of rubber-covered cylinders mounted within sanding machines. The grinding apparatus comprises a base having a pneumatic cylinder mounted thereon for imparting oscillating or reciprocating movement to an abrasive plate which extends back and forth along the length of the rubber-covered cylinder during the dressing and truing procedure. The grinding apparatus removes the necessary amount of rubber compound from the rubber-covered cylinder upon which it acts until the rubber-covered cylinder is perfectly round, and the grinding apparatus is then removed from the sanding machine. In this fashion, the apparatus and method of the invention provide for on-site dressing and truing of rubber-covered cylinders of sanding machines without the necessity for conventional removal of the rubber-covered cylinders for dressing and truing.