A fly press is a type of screw press in which the screw shaft is driven by a flywheel or a pair of fly weights at the ends of a bar. The wheel can either be cranked by hand or driven by a motor using a friction coupling. The wheel is weighted so its momentum will maintain the motion of the shaft. A fly press which is operated by hand is the simplest of all presses, it consists of mass, handle, body, arm, screw, ram, stop collar, treads, and guides.
