Quote Originally Posted by Neale View Post
With a bit of work, I'm sure that you could put some simple logic circuitry together to take the A and B quadrature outputs from the MPG and turn them into step/dir signals for the stepper, but that's a bit too complicated for me at this time of the morning!
The quadrature outputs *should* suit a direct coupling with the stepper driver, connect either A/B to Step, and the other to Dir - you use one of the two quad outputs as a clock and, depending on direction of travel, the alternate phase will either be 0 or 1 (and so provide the direction control).

OP suck it and see - just check the outputs from the MPG - sling a meter on and confirm that for each detent moved, each output changes from 0 to 5 volts (the first one that I had used an open collector drive - and so has to be used with the negative-side switching). All signal levels from the MPG will be low current, low voltage, and the input to the stepper driver will be via a current-limited opt-isolator designed to run off 5v signalling. There's not a lot to go wrong if you know one end of a bit of wire from the next.

All this will give you is an ability to rotate a stepper in response to the rotation of the MPG wheel. That's going to get awfully boring to use on a mill.