A pump drill is a simple hand-powered device used to impart a rapid rotating motion to a rod (the ''spindle'' or ''drill shaft''). It can be used for

fire making Fire making, fire lighting or fire craft is the process of artificially starting a fire. It requires completing the fire triangle, usually by heating tinder above its autoignition temperature. Fire is an essential tool for human survival and ...

or as a drill to make holes in various materials. It consists of: the drill shaft, a narrow board with a hole through the center, a weight (usually a heavy disc) acting as a

flywheel A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, as ...

, and a length of

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. The weight is attached to the shaft, near the bottom end, and the hole board is slipped over the top. The cord is run through a hole or slot near the top of the shaft and attached to both ends of the hole board. The length of the cord is such that, at its lowest position, the board lies just above the weight. The end of the shaft usually has a slot or hole that can hold a hard bit that does the actual drilling, either by abrasion or by cutting. For wood, the bit may be an auger bits or a simple triangular blade, that can cut while rotating in either directions. To use, the shaft is first turned by hand so that the cord wraps around the top part, as much as possible, and the board is as the highest position. A smooth downward pressure is exerted on the board, causing the shaft to rapidly spin. Once the bottom is reached, the pressure is relieved. The weight then keeps the shaft spinning so that the cord wind again around it, in the opposite sense, pulling the board up to the starting position. The process then can be repeated.

References

Primitive Technology: Cord drill and Pump drill , You Tube , Jan 22, 2016
/ref> J. W. Powell (1884)
Annual report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution, 1881-1882
'. Plate XLII, page 583. {{Firelighting Mechanical hand tools Primitive technology Firelighting using friction

See also

References