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Issue with Z axis, looking for help.


Jul 21, 2021
Hello guys, I am a new mill programmer and I've ran into an issue that has me stumped.

I have have a 4th axis simple set up and program that is just putting a couple flats and one hole on the part. Seemingly out of nowhere my Z axis seems to be a quarter inch off. I've double checked my set up, I've touched off my tools multiple times, I've checked both my work and tool offset pages, Ive double checked the program, and my tools are still coming down a quarter inch above my part.

Is there perhaps any modal G codes that somehow magically got activated, or perhaps is there some issues with parameters? I am dumbfounded as I just ran a part on this machine hours ago. I ran to re program my part (Gibbscam) because I didn't like the way the old programmer did it and when I loaded my program and went to run thats when the issues occured. The old program has the same issues I've tried switching back to that and still tools coming off a quarter inch above the part. G43 H#'s are correct. Completely stumped.

any ideas?


Feb 5, 2008
I can think of several things.

1: a positive z value in G53

2: you accidentally hit the "z axis neglect" or "axis neglect" button and the machine was commanded to move in Z a bit before you turned it off.

3: Tool pushed up into the holder (although you say you re-touched off tooling)

4: you accidentally adjusted your work offset.

5: the z axis didn't home out properly.

If it was #1, just setting it back to 0 would be sufficient.

If it was #2, re-homing z would fix it. Not just sending it back to G28, do an actual z axis reference return.

#3 and 4, self explanatory

#5 would be a possibility if you also have a problem when trying to do an automatic tool change. I'd also expect it to be a precise amount off (for example, 8 or 10mm exactly)