Abstract: Sheets of paperboard or the like are gripped along one end by a plurality of grippers and are drawn by the grippers along a predetermined path for processing. An array of stripper tools mounted at the end of the path strips the body of the sheet free from a waste strip which remains gripped by the grippers. The waste strip is carried away from the stripper tools by the grippers and is subsequently released at another station. The stripper blades are driven by a reciprocating drive mechanism which includes a reciprocating slide, a spring urging the slide in one direction, a rotating arcuate cam flange which periodically blocks movement of the slide and periodically frees it for movement, and another rotating cam which reciprocates the slide through one cycle each time it is free to move.