A screw capper includes a capping head which comprises a chuck for holding a cap, a motor for driving the chuck for rotation, a cam mechanism for elevating the chuck, and an air cylinder for imparting a load to the chuck. Each of the actuators is mounted in said actuation holding plate by a support collar threaded into said actuator holding plate. A second, smaller disc fits within the rim on the first disc, the second disc includes a centrally located slotted hole and multi-lobed holes.