Here we go again . . . MK4

[routercnc]

Hi Trevor
Yes you can only use this to square up a mm or so otherwise there is too much tension. You need to make and assemble it as square as possible first. Depending on the design you might be able to slacken the gantry bolts and square it up using separate home switches then retighten as you suggest.

I had to be careful with mine as to do independent homing I needed to switch off slaved axes temporarily. This meant my Z motors were also no longer slaved (I have 2 on Z) so after homing X I switched slave back on and now usually just home off the left sensor with the motors slaved. I check each side with callipers to ensure they are still the same distance from the end plates.

Yes separate drives are required plus a spare axis on your break out board (usually A). You can’t do this trick from a single motor with belt coupling to the other ballscrew and would need a way of making tiny adjustments on one ballscrew relative to the other mechanically. Probably the grub screws holding the pulley onto one of the shafts