Abstract: A sanding machine (1; 300) comprising a support structure (2; 302) for the piece (3) to be processed and a sanding unit (4) for the piece (3) itself. The sanding unit (4) comprises a frame (40) that supports a winding element (8) cooperating with kinematic means (9) suitable for setting it in motion according to a closed ring configuration on a plane (?1) substantially parallel to the plane (?2) defined by the support structure (2; 302) and a plurality of abrasive elements (10) combined with the winding element (8) spaced from one another and provided with an abrasive surface (16; 416) that comes in contact with the piece (3) during the movement of the winding element (8).