Because woods of different hardnesses are used in bow making, the sanding machine must be able to sand at different speeds. It is not feasible to vary the drum speed, so it is necessary to vary the head speed as it moves across the sanding bed. The machine, as it was configured (see above photo), did not allow the head speed to be changed so it could only be used on one type of wood.
The motor that is used to drive the head is a single phase AC motor with a start winding, so it was not possible modify it to run at different speeds.
We purchased and installed a Vari-Cone(tm) pulley system on the motor and the all thread. This system automatically changes the pulley ratio when the motor is moved closer or further away from the shaft. The ratio is variable from 1:1 to 2:1. Currently, the motor must be loosened on the bracket and slid up or down to vary to ratio. Because this is somewhat clumsy, we are hoping that a mean speed can be used for most types of wood and then adjust the machine for extremely hard or extremely soft woods.