Abstract: A production line, continuous feed, high volume output apparatus for cutting, grinding, and/or polishing concrete or fired masonry units into finished masonry building materials. A conveyor belt moves the masonry units from an input station through a processing station where the masonry units are subjected to abrasion treatment by a rotating working head. The working head may take the form of saw blades or one or more horizontal cylindrical drums disposed above the conveyor path with the axis of the horizontal cylindrical drums normal to the conveyor path. The height of the working head above the conveyor path is adjustable. In the drum form of the working head, an abrasive, such as synthetic diamonds is mounted in a matrix in a spiral array. Lateral movement of the masonry units off of the conveyor path is restrained by adjustable guide rails.