Z-Axis passes home position at end of job

[john.mcculloch]

Hi - I’ve having a “weird” problem in that I have a Z-Axis limit/home switch at the top of my Z-axis which works fine when homing my laser, but at the end of a job it overshoots the limit switch upwards and then moves down to the correct “pre-job” position following the overshoot. This isn’t great for the limit switch as it gets pushed further than it’s meant to go. I can implement “hard limits”, but this then alarms and I have to re-home again. I also notice that there is a “reverse Z direction” option in device settings - is this independent of GCode $3 ?

My controller settings are as follows:
$2=0
$3=5
$20=0
$21=0
$22=1
$23=3
$24=25.000
$25=800.000
$26=250
$27=1.000

Any ideas?

Thx John

[john.mcculloch]

I’ve just been testing and it looks like the Lightburn “reverse Z-direction” option in Device Settings stops this from happening.

[berainlb (PY)]

@john.mcculloch

reverse Z-direction

This is independent of $3 and simply flips if positive moves are up or down.

Another option potentially is to use Relative Z Moves only. That will have LightBurn only move Z for changes in Z position. It will not attempt to make absolute Z moves. This eliminates the ability to use Material height if you do that.