Pump drill: A superb device for converting translational motion into high-speed rotation

Pump drill is an easily constructed ancient device that has been used for centuries to start fires and bore holes. It can effectively transfer rhythmic translational motions into vibratory, bi-directional rotary insertions. Here we explore, both experimentally and theoretically, the kinematics, dynamics, and potential applications of pump drills. The theoretical model, validated by experimental measurements, enables us to obtain the optimal structural geometries (e.g., the thread length and the crossbar span) of pump drills that maximize the mechanical responses such as the winding angle of the threads. Furthermore, the dependence of its rotational speed and piercing force on the loading conditions is investigated. Finally, manually powered devices, including an electric generator and a centrifugal separator, are developed based on the pump drill. This study paves a way towards promising applications of the pump drill in, for instance, energy harvesting and centrifugation.