There seems to be a general agreement that Mastercam's post language, while powerful, is mysterious. Without going into another rant (it's what I do), I'll offer some advice for those who are struggling.

The older, V5 posts do not have the features of the latest MP language. But that is to your advantage if you are trying to tweak and learn at the same time. Start with a V5 post and work from there.

I would volunteer the 3-axis mill post I use but I haven't tested it since the latest round of fiddling. Will be glad to share it once it is verified again.

Doug