The bow drill consists of five component parts only two of which must be combustible. These parts are the spindle, the fireboard or hearth, the bearing block, the bow, and the ash pan.
Step 2: Spindle
The spindle is a straight, narrow stick with a diameter of up to 2 inches. This piece will go between the fire board and the hearth.
Step 3: Fire Board Or Hearth
This piece is a long flat board essentially. The spindle is laid upon it in a carved round divet. Then pressure is applied by the bearing block an motion is set in by the spinning of the bow. Once you have the spindle and hearth "mated" or fitted onto each other you will carve a inward v shape into the board in between the burnt in divet, this allows the coal to fall between.
Step 4: The Bow
This is the part which gives the method it's very name. This is nothing more than literally a sturdy of rather flexible but not brittle stick in the shape of a bow. In fact, I doesn't even have to be a stick. It can be anything from a cow rib, to a bent piece of metal, or anything in the shape of a bow. Once you have found something which suits this position you must take string and tie it to it both ends, then wrap it around the spindle once. After this you place the spindle onto the fire board and under the bearing block and start pushing an pulling the bow increasingly faster.