Ger21
You're right. I have to take back my last post. You were right the first time.
Somewhere along the line I reversed the A motor.
When I connected both the X and the A to gearing I had the horrible grinding during jogging.
I corrected this by getting the motors configured so A was reverse of X and then jogging was fine.
I set up homing negative for both X and A, as you said previously.
I checked motor tuning: My A motor tuning was considerably different from X,
I copied and pasted the X motor tuning settings for steps, speed and acceleration to A and homing is now working smoothly.
So, I assume that Mach 3 will send the same step and Dir commands to the motor and its slave during normal operation but this is not the case during homing? (i.e. homing is not slaved?)