I am in the process of upgrading my gantry router from a single stepper motor driving the gantry along the X axis, to two steppers slaved together.

The current router uses a single stepper to move the gantry along the X axis. I have an axle and chain drive system to drive the gantry from both ends using a single motor located in the middle of the gantry. To square the gantry I simply set up my reference jig and dial indicator and then loosen one of the set screws of the drive system and manually move one side of the gantry to square it up before re tightening the set screw.

The upgraded gantry will have a stepper at each end and a R&P drive system. How do I square the gantry with this drive system? Is there a function in Mach that I can use to bump one stepper of the slaved pair to adjust the gantry or do I need to do it at the drive system or by adjusting the rack back and forth?

Thanks
James

Put a home switch on each side, and when you home the machine, each side will home to their own switch. Adjust the position of one switch until it homes square.
Note that the switches need to each use a separate input pin.

What I used to do before I had home switches, was drive the machine into hard stops to square it up. Just adjust the stops so it's square.