[kevinmccarthy]

Hi, I've had my CNC table for a while and was working fine until I decided to change the THC min in mach3 and that is where the problem started, first I couldn't change the THC min to a negative value but then I figured it out; when I started to cut something, Z axis goes straight to THC min value and drags the torch all over the material. Already made THC test and works fine. Am I missing a setting that might have changed when I changed THC min?

[Mike 1948]

Is your torch supposed lower to touch off, then raise up a certain amount to the pierce height and then fire. If so maybe your post processor needs fixing or your zero switch is not set correctly.

Mike

[Torchhead]

All THC Min and MAX in the Corrections do is keep the Z from moving past those two points when cutting with the THC active. Its sorta like soft limits but with material that is not perfectly flat the numbers are just set to something that keeps it turned off. So once you told it it could go down to a negative number it is doing just that...at least it thinks the Z is below Z . If you have no way to tell the system where Z zero (top of the material) is to it may dive down. The problem has always been there it was just masked by having the min set positive.

It time to review your touch off and make sure it working properly and uses the correct switch offset to set the top of material zero accurately. Load some code with the touch offs and go to Single Step and run a line at time and watch it in stop motion YOu can see what each line of the code does