Abstract: An existing box-making machine is retrofitted by first removing the pull rolls and impression cylinder and other associated parts and cross-ties. However, the heavy duty side frames and drums, including the print cylinder are left intact in the box-making machine. A vacuum transfer machine is then inserted in the box-making machine and mounted to the existing frame to replace the pull rolls that were removed. The vacuum transfer machine includes a hood enclosure having an impression cylinder for printing, and transport rolls on opposite sides of the impression cylinder for conveying the corrugated boards through the impression and print cylinders and to the die cutter. The boards are held against the transport rolls and the impression cylinder by vacuum generated in a vacuum chamber in the hood which also contains the transport rolls and the impression cylinder. The vacuum chamber contains a plurality of vacuum dampers for controlling the vacuum area in accordance with the size of the boards being processed.