Abstract: A bottom vacuum corrugation feeder includes a vacuum chamber with a bi-level support surface that support a plurality of apertured belts. The bi-level support surface has a series of raised members on a portion of its surface that corrugate the bottom sheet of a stack of sheets that are supported on a stacking tray. The stacking tray inclues raised members on its stack support surface that allow the venting of air from an air knife positioned in front of the sheet stack for separating the bottom sheet in the stack from the remainder of the stack. Recesses are included in the stack support surface of the stacking tray in order to reduce vacuum leak around the front edge of the sheet stack.