Bow drill

A bow drill is a simple, ancient tool used to generate friction for various purposes, most commonly to start a fire. It consists of several key components:

• The bow: A flexible, typically curved piece of wood with a cord (often rawhide, sinew, or plant fiber) strung tightly between its ends. This acts as the driving force.
• The spindle: A straight, pointed shaft of wood that is rotated. One end of the spindle is the working end and is pressed onto the fireboard or other material.
• The handhold (bearing block/socket): A smooth, often lubricated object (wood, bone, or stone) held in the hand, used to apply downward pressure and stabilize the top of the spindle during rotation.
• The fireboard (hearth board): A flat piece of soft wood in which a small depression, or socket, has been carved to receive the pointed end of the spindle. A notch is cut from the edge of the depression to allow for the collection of tinder dust.

The bow is moved back and forth horizontally, causing the cord to rotate the spindle rapidly. The friction between the spindle and the fireboard generates heat. When used for fire-starting, the heat eventually produces fine, smoldering dust, which, with careful encouragement (such as blowing), can be coaxed into a flame when placed in a tinder bundle.

Beyond fire-starting, bow drills can be used for drilling holes in soft materials like wood, bone, or shell. The basic principle of friction-based rotation remains the same. The material being drilled replaces the fireboard.