Make your hearth the same as you did for the hand drill method. You drill a hole through it about half an inch in from the end and that's where the ends of the cord are attached. Try heavy leather boot lacing for the cord or you can make your own from sinew or a piece of heavy leather. The cord is looped around the drill as shown above. The bearing block is placed atop the drill.
Heavy pressure is applied to the drill.
The bow is then sawed back and forth continously to spin the drill until the glowing coal is produced as in the hand drill method. It is the old one. The constant metaphor for great beginnings. Long ago the ability to create and make use of hot sparks to make fire was discovered. We can recreate these methods easily today with just a little practice.