Abstract: A drive apparatus for a simultaneous operation machine includes a plurality of pulleys and drive belts in a unique orientation to simultaneously drive a plurality of spindles. A first outer spindle is driven about a first axis of rotation to perform a first operation such as machining. An inner spindle is disposed within the outer spindle and is driven about a second axis which is offset from and parallel to the first axis to simultaneously perform a second operation, such as grinding. Additionally, the drive apparatus is capable of rotating the second spindle about the second axis while orbiting about the first axis, and simultaneously rotating of the first spindle about the first axis. Preferably, a single motor is provided for driving both of the outer and inner spindles.