@kiki0000 Might be best if you say what Duet you have, what firmware you have running (send M115, post reply), post your full config.g. You should be using either 2.05.1 or the latest 3.01 RC12. Then we'll have a better chance of getting this right.
How are you homing the 3 Z axes? Is it Z,U and V? You only need to split out Z and U if you're running RRF2, and are using endstops on each motor of Z for homing. If you're using a probe for homing, or using RRF3, you don't. Post your homez.g too.
Remove ALL Znnn:nnn entries in the motor settings, and just use Znnn; it doesn't work. At best, the second setting is ignored, at worst, the firmware (depending on version) will be trying to map this to another axis.
Send M669 and post what it reports. As you've used V rather than U to track Z, the M669 command may need to change.
Finally, axis visibility (the P3 parameter in M584). I'm not sure, but the extra axis may need to be visible, at least to home it.
Ian
