Abstract: A paper folder has folding rollers spring urged against the complementary rollers so the rollers touch at the nip when no paper is present. A light spring allows the rollers to open when a piece of paper is to be received therebetween; but, the light spring completely closes after a short movement to limit the gap between the rollers. A heavy spring allows further spacing of the rollers under great force. The resulting folder will fold a range of thicknesses of paper, and including groups of several sheets of paper, without adjustment of the rollers.

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.