what I have done since my last reply, I purchase a used traditional Gantry Mill, travel: x 1.2m, y: 2.8m, Z: within 1 m (will check), there are 3 AC motors with chain and gears to each axis, very large BACK -LASH!.

Currently there are 3 Fagor Linear encoder + 1 DRO came with machine, will have a Mach3 controller ready for this machine.

I'm looking for a solution to reduce back lash without replacing the leadscrew to a ballscrew, what have in mind:

1: Use a stepper card with Linear encoder input form Mbot, need a longer magnetic strip for all 3 axis.

2: DC Motor attached to each axis, then use an encoder interface to read Fagor Linear encoder's signal and feedback to the Dc Motor.

any oter ideas?

thakns