Abstract: Cutting mechanism for cutting sheet material comprising a disc blade which is adapted to engage a pressure roller and which is mounted for rotation in a carrier which is slidably mounted within vertical guide grooves which are formed on the inner surfaces of a pair of guide plates. Each guide plate has a horizontal bottom edge, a vertical side edge, a sloped edge and an inclined groove which extends from the vertical guide groove to an opening at the sloped edge of the plate. The plates are connected at several locations and stiffering means are provided near the intersection of the side and sloped edges.