Jazz, nothing you say applies to lathe.
Lathe in Mach 3 or 4 just doesn't work.
Dan Malch has managed to get it working in M4 but he's lost 3 months of his life. Is that worth it ?

Me I can't even get M4 to run, error message after error message and not one reply to forum posts.



Error message at the bottom, Line 42: I word given for arc in YZ plane.

Now correct me please but in line 4 does it not say G18 ?

And according to Mach's published list of G-Code G18 is XZ plane for lathe.