I have a strange problem with Z-axis controle.
When I load in the G-code file everything looks normal, Z-range is between +12 and -18.29 as expected.
When Mach runs the file, Z-axix goes deeper than -18.29, it goes down to -19.********* so I stopped the machine in order not to damage the fixture.
The indication on the Z dro is consistent withZ-axix positions, so it indicates -19.********* as well, so no calibrating problem.
All offsets are 0.
It's a fresh installation ( a few weeks) and the tool is a straight MDF one with square edges.
X and Y seems to be normal.
The same problem occurs with another G-file where it goes over 2mm deeper than it should, again I stopped the machine.
Again DRO indication and Z position are consistent. Retracts are too low so the tool hits allready milled areas on aproaching the end of the job.

It seems like there is a scale factor involved but all scaling is set to 1. There is no G50 or G51 in the file.

Seems to be no explanation for this he.
It's a HSR file from solidcam and I have run several dummy runs of it. I can see during the run that the Z-axis goes deeper than the line with the Z-instruction coming by.
In other words the machine doesn't follow the Z-instruction and does it's own way so to speek. I don't see any possible way such thing can happen and according the
massive respons on this no one does.
Only Z-axis, the other 2 behave correct.
DRO  is consistent with position and not with the instruction.
Manual z-position inputs behave correct (z50 z0 z50 z0 z50 z30 z0....)

Hi Wadero,

If it would be of any help to you - zip and post a copy of the Gcode which has the problem I will run it and see if the problem occurs here.

DRO  is consistent with position and not with the instruction.

One possible explanation is that you are mixing G90 / G91 commands in an incorrect manner.

Tweakie.

I've been able to solve the problem by making a clean installation AND configuration of Mach 3.....for now.
The problem was not in the file I believe because the problem appeared with several files.
Probably some configuration bit that got out of the corner.

Thanks for offering your help anyway, I hope it stays on it's feet.