Abstract: A paper folding machine is improved by grooving the fold rollers. Grooves in the fold rollers extend along a curved path, from one end of the roller and terminating adjacent to the center of the roller. Complementary grooves extend from the opposite end of the roller towards the center of the roller. The surface of the roller is rubber or the like, and has a durometer hardness in the range of 65 to 72 Shore A. The grooves are shallow enough that the paper is not crimped or wrinkled by the grooves.

Abstract: The feed table of a paper folder is provided with a downward step at the discharge end of the feed table. The downward step provides a discharge area so that the leading edge of a sheet can be pulled forward and down for a positive feed without wrinkling the leading edge through contact with the feed table. A vacuum wheel engages and holds the paper to effect the feed, and the vacuum wheel has an increased number of holes for a stronger grip. The rear ends of paper guides are movable by screws for carefully controlled skewing of the paper with respect to the feed table.

Abstract: A sheet folder is convertible to a booklet maker by mounting a stapling and sheet guide unit at the inlet side of the folder. The stapling and sheet guide unit has a pair of laterally aligned staplers above a sheet guide which includes holders for engaging the stack of sheets along their opposite side edges and a retractable front stop engaging the leading edge of the stack of sheets to be stapled. A vibratory jogger on one of the holders aligns the edges of the sheets in the stack. After the stack of sheets is stapled, the front stop is retracted and a kicker plate strikes the stapled set of sheets from below, causing the stapled set of sheets to slide down into the folder. The folder has rollers which advance the leading edge of the stapled set of sheets against a stop and then continue to pull the stapled set of sheets, causing its stapled centerline to fold into a fold gap between rollers. The size of this fold gap is selectively adjustable.