Abstract: A plastic bag making machine of the type consisting of opposing vertically aligned upper and lower machine sections which move in unison toward and away from each other to cut and seal plastic film being conveyed between the two machine sections on a horizontal path possesses three main features. The first feature is a simplified holding and feeding mechanism on each machine section for advancing periodically worn out teflon film without the necessity for manipulating large numbers of screws and other devices. The second feature is that the cutting/sealing device can act on plastic film either in premolded tube form or longitudinally folded form while passing through the machine to produce plastic bags by cutting and sealing either form of film repeatedly. A third feature of the device is the provision of mechanism to prevent and compensate for buckling in two planes of heating and sealing bars on the upper and lower machine sections.