Abstract: A mold forming machine for the production of casting molds wherein molding sand is compressed within mold flasks is provided with stabilizing means for counteracting the effects of the compressive forces generated within the mold flask during compression of the molding sand tending to cause distortion of the flask. The stabilizing means include a movable frame which is adapted to extend about a molding flask placed in the machine with the frame being positioned relative to the flask by lifting gears which move the frame in accordance with the various stages of operation of the machine. A plurality of fluid pressure actuated tensioning elements are mounted on the frame to be movable therewith. The tensioning elements are adapted to apply compressive forces inwardly of the mold flasks during application of the molding sand compressing forces.