Sheetcam gcode command over soft limit?

[ROTM]

Good day.
Running some test yesterday cutting some holes to dial the machine in.
I get z commanded over soft limit.
In Mach4 it stopped at this line N170 G31.0 Z-100 F500.0

weird part it does not do it all the time ...with the same sheetcam file.
I lowered the Plasma torch and the physiscal range from 0 (from the limit switch) to and inch below the plate is 6".
set in Mach4 soft limit 0 to -6.

Still does it time to time. funny thing is I cut more than 300pcs already and this just comes out of the blue.
So I am thinking the gcode that sheetcam create try to drive it outside its limits....if yes how can I fix this.

Thank you!

[Les Newell]

Sorry I'm a bit late replying. Is it possible your Z axis is losing steps? If you have a Z probe touch-off switch you probably wouldn't notice any cut height issues. If re-homing the Z axis fixes the issue for a while you are probably losing steps on the Z axis.