pompboorThe pumpdrill(improved bowdrill: see firearc) consists of a long, straight shaft with a hard point that is wider than the shaft. A bar or stick with in the middle a hole, slightly wider than the shaft, is pushed over the shank (shank through the hole). Both ends of this stick are connected to a rope which runs over a deep notch at the top of the shaft. It then looks like a bow and arrow with a too weak tendon. Between the point and the 'arc' you make a flywheel on the shaft: a heavy disc or block (wood, stone, clay). Can also with some 8 spokes with ballast (stone, clay) at the end.

If you rotate the shaft with one hand, the slack rope will doubly rotated around the shaft.
To drill press the bow down. By the flywheel the shaft then turns reverse, and the rope rolls back up so the arch comes back up. So you can in a smooth movement continue pumping up and down and drill. The principle is also used as a fire bow, to make fire.

A small pump drill you can operate with one hand. But you can also make a big you serve as a fitness device with two hands. Then, of course, also use heavier flywheels (several blocks above each other).
It is a very simple and efficient device for drilling horizontally.