In using a Fire Bow it is the friction of a hardwood spindle rotated on a softwood base that produces wood dust tinder which then becomes heat.
MAKING A FIRE BOW :
Make a small depression close to the end of baseboard.
You should make sure to shape the spindle evenly.
Make a bow from twine, shoelace, shoot or hide.
Use a hollow piece of wood or stone to steady the top and exert downward pressure.
Winde the bowstring once around the spindle.
Kneel with one foot on baseboard.
Then place the spindle in the depression, bear down lightly on the steadying piece while moving the bow backwards and forwards so the spindle spins.
Continue bowing till a glowing tip drops on to the tinder, then gently blow till it ignites.
Wilderness Survival