Hi Gang:
I help rebuild a machine for drilling valves for gasoline injectors. To keep the holes centered the machine spun both the valve seat and the drills. I don't know why but it kept the drill from wandering and also maintained a good cutting speed. It was quite a machine: twelve chucks holding the parts vertical, one load station, one unload station and ten working stations. Flood coolant for all, the machine was in a Plexiglas case to keep the operator dry.
Carl.