Bow drill

Bow drill

The bow drill is an ancient tool. While it was usually used to make fire, it was also used for primitive woodworking and dentistry. It consists of a "bearing block" or "handhold", a "spindle" or "drill", a "hearth" or "fireboard", and a simple "bow". Related drills include the pump drill and the hand drill.

History

The bow drill appeared in Mehrgarh between the 4th-5th millennium BCE. This bow drill—used to drill holes into lapis lazuli and cornelian—was made of green jasper.Kulke, Hermann & Rothermund, Dietmar (2004). "A History of India". Routledge. 22. ISBN 0415329205.] Similar drills were found in other parts of the Indus Valley Civilization and Iran one millennium later.

Description

The spindle, carved to reduce friction at one end and maximize it at the other, is held at one end by the bearing block, and at the other by the hearth. The string of the bow is wrapped once around it, so that it is taut enough not to slip during operation. A variation on this called the "Egyptian Bow Drill" attaches the string by wrapping it around multiple times.

The usual position that a person assumes whilst operating the bow drill is as follows: the right knee is placed on the ground (assuming a right-handed operator) and the arch of the left foot is on the board, pinning it in place. The left wrist, holding the handhold, is hooked around the left shin so it can generate enough downward pressure and speed; achieved by pushing down with the handhold and spinning the drill. The heat of the friction between the hearth and the spindle both creates charred, fuzzy dust and causes it to ignite - forming a "coal" or "ember". The handhold is lubricated and the spindle is carved to about thumb thickness, usually six to eight inches long.

An indentation and a "v" notch into the center of the dent is made into the fireboard and the spindle is placed on it. The notch allows a place for the dust collect while it is being abraded off the spindle and the hearth. Eventually, the friction generates heat to ignite the dust, which can be used to light tinder.

Whilst a "v" is most common, other methods to create a cavity to contain the dust whilst it is being ignited can be used. For example: drilling part-way into a hearth made by lashing two sticks together from one side, and then drilling from the other side to meet this hole; or using the area where two branches separate. This is to keep the coal off wet or snow covered ground.

The hearth and spindle can both be soft woods; yucca, aspen, cedar, basswood, and most willows all work very well. Combinations such as hazel and poplar also work well. The bow should be stiff but slightly limber and around 30 inches long. The bearing block can be made of anything but bone, antler, and stone work the best as they can be easily greased, do not create as much friction, and do not burn.

This is by far the easiest method of producing a coal by primitive means and anyone can do it by using good materials and maintaining a calm mentality, concentrating only on working everything slowly and smoothly.

Pump Drill

A pump drill is a simple tool used to make holes in light materials by hand and has been in use for centuries. The drill itself is composed of: the drill shaft, a narrow board with a hole through the center, a weight (usually a heavy disc) acting as a fly wheel, and a length of cord. The weight is attached near the bottom of the shaft and the hole board is slipped over the top. The cordage is run through a hole near the top of the shaft and affixed to either end of the hole board so that it hangs just above the weight. The end of the shaft usually has a square hole made to fit certain sized auger bits or a simple triangular bit made to cut while rotating in both directions.

To use one hand is placed on the hole board while the other turns the shaft to wind the cord around its length thus raising the hole board to near the top where the cord becomes taut. Placing the tip against the material to be drilled and held upright, a smooth downward pressure is exerted on the board causing the drill to rapidly spin. Once the bottom is reached, the weight is relieved and the drill allowed to rebound re-winding the cord around the shaft and the process is repeated. It is a skill simple in concept but takes some practice to master and greatly speeds up the process of making small holes.

Hand Drills

The Hand Drill is a similar method: but uses a longer, thinner spindle; and instead of a bearing block and bow combination, the downward pressure and spinning is achieved by rubbing the hands together around the spindle. As the hands move downward to the base, where the drill is pinched and the hands are brought quickly to the top one at a time. This can be made unnecessary by cutting a nock at the top of the drill, tying a cord through this, and then putting your thumbs through loops in the cord. However, skilled operators can either maintain pressure with their hands almost stationary vertically; or, in a movement comparable to floating, can "float" their hands back to the top of the drill. There is a more limited choice of materials to use with this method, needing much softer materials, such as mullien, yucca, cattail, and root wood. This method requires more physical capabilities and thick calloused hands.

External links

* [http://www.motherearthnews.com/library/1982_January_February/A_Home_In_the_Wilderness__Part_III__Fire Friction method: the bow drill]


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