There have been times when it's nessacary to know and control the speed of cutters, etc. like on a drill press or lathe. There is a simple way of determining the speed if you know the speed of the motor and the diameter of the drive pulley and the driven pulley. You simply take the motor speed, or RPMs (revolutions per minute) and multily that by the diameter of the pulley mounted on the motor, or "drive pulley". Then divide the product by the diameter of the cutter pulley, or "driven pulley":

 Speed of drive pulley    X   Diameter of drive pulley

~or~