Hi,
I have kinda asked this question before but in a different way. Lets say you leave your machine on all night and you come in to do a job. You set all the zeros and the machine starts fine but with each pass it loses z height and starts to air cut. I have no issues with mechanical. What could be the culprit of this? If I shut everything down and reload Mach, and power down the control panel I come back to life and all is well.
What could I look for to stop this as its becoming more of an issue even when powering up in the morning?
Would I need to look at the Smooth Stepper Board??

Just an update:

I loaded material to do the exact same job. Around 10ish lines of code in it started doing the same exact thing (losing Z height). This time I just rebooted Mach4 and it is working fine now. What am I missing on this? I cannot imagine anything wrong with gantry. This is running this job now for 30 minutes with no issues and worked fine all day yesterday.

If restarting Mach4 resolved the issue, a temporary software glitch could have been the cause. Verify the latest version of your Mach4 software and confirm the correct setup of any plugins or configurations. After that, check your machine's calibration settings to ensure they are accurate. Because incorrect calibration can also lead to unexpected movements and inaccurate positioning.