Why do my offset automatically change?!?

[vossman]

I am currently trying to set up a Leadwell cnc lathe with Fanuc controls to run a proven program. It is an older machine, with gang tooling instead of a turret. When I get each point close to the part zero, enter the X and Z values in, and run a part, it makes ONE part successfully. HOWEVER, when I go to run the next part, it is suddenly pushing the tools 1" to 2" deeper than it did previously, even though I changed NOTHING. What is going on here? I have ran a HAAS lathe successfully for some time, so I am not a newbie, but I am feeling pretty stupid right now. Does anyone know why the tool geometry Z offsets (but not the X) are changing on me? (WEAR offsets and the work offset are both zeroed out)

[cncwhiz]

Post the program. Sounds like somewhere the program has an incremental movew thats giving the headache. Also if your program is not cancaling the offset that could be another problem.

[vossman]

Can't post till Monday, when I am @ work again.

[dcoupar]

Are there any G10 blocks in your program? Any G50 X Z blocks?

[vossman]

No G10 as I recall, but I will need to double check on Monday. What do you mean by G50 X and Z codes? G50 is a speed clamp...

[dcoupar]

Back in the "old" days (before G54), G50 was used to set X and Z zero coordinates (in addition to the max RPM) at the start of each tool operation.

[neilw20]

Any G92 blocks?
Maybe try single stepping to find where the numbers abruptly change.

[dcoupar]

My guess is that G92 on vossman's machine is a threading canned cycle. Good suggestion about the single step.

[ronfournier]

can you post a copy of the prgram for me to see I have 2 leadwells maybe I can help