The present invention comprises a Grinding or sanding machine for grinding or sanding a surface of a workpiece (8), wherein the grinding or sanding machine has at least one transportation device for transporting a workpiece (8) in a transportation direction; at least one revolving grinding or sanding belt (2); and at least one pressure beam (12) for exerting a pressure in the direction of the transportation device on the grinding or sanding belt (2), wherein a plate (14) which is mounted so as to be movable in a plane that is perpendicular to the direction of the exertable pressure is disposed between the grinding or sanding belt (2) and the pressure beam (12).