Raw data comes off a CD at something like 44kHz. The drive motor is in a servo loop such that the disc passes under the head at a constant rate, a process called constant linear velocity (CLV). When the read head is near the inside edge the disc spins fast (>300 rpm?), and when near the outside edge it is slow (~100 rpm?). Because there is only one track on a CD (similar to a phonograph record) there would have to be a way to step the head out each revolution.
If you could record a (very) constant tone so that there were a known number of wavelengths per revolution, couple the shaft to your cnc machine, and count wavelengths, the whole thing just might work.
I think the index step each revolution might be the big gotcha.
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