well, I have done lots of preliminary cuts that were successful. did a dust boot -a few times actually, did a spoil board 2x, did some circles in the form of coasters... did some engraving. planed my materials using it, did my mounting holes - all went swell. honestly each part of this guitar is broken down into simple steps... and even the body shape went fine.
the reason gecko is of focus is that it is very much recommended for this machine. lots of folks have had success with it. further the implementation is very simple. it has the drivers right on the control board which simplifies things a bit. as I understand I can always add a motion controller to it later and go out via usb or ethernet. It is quite popular and as such has a lot of support. That is also the reason I chose mach3 - there is lots of support/threads regarding it. In my mind these are all good places to start.
I realize there are lots of other solutions out there ucnc, etc. My thoughts are that if I could start with something simple... I can continue to learn and perhaps learn why one might go the ucnc rout other than just to get usb or ethernet.
I know your advice was to not use center-line - but I can't help it - that's what makes the most sense to me. Everything I've done apart from the neck pocket has worked great using that. It would seem that using ctr line is not an option when tiling but other than that... I don't see a down side to it. that is indeed what I'm picking for my x0/yo. then we come to machine coordinates... perhaps I need to learn something there but machine coordinates seem irrelevant in that they don't really matter if you just disregard them once you have workpiece coordinates (and assuming you don't have limit switches setup).
Either way... I'm gonna keep throwing things at this... build a new pc today, rewire the steppers/vfd next week, perhaps build a new controller - until it makes sense and runs the way I expect. Perhaps along the way I'll stumble into what is causing issue here but so far it sure doesn't seem like it's anything I'm doing.
Any chance you could run my g-code and see if you have the sm issue? If you don't: doesn't tell me much... but if you do - then it's def something in the g-code. I don't want to lean on you too much, so totally fine if you don't want to.
Either way - I very much appreciate the help from both of you - I've actually learned a lot just troubleshooting this so... I think I would probably have learned less if things just went w/o issue. Please forgive if I don't always take your advice verbatim - it's not that I doubt you... it's just that I have to learn and that means sometimes not blindly following but picking the wrong path and making mistakes, and finding out why something isn't a good idea.