Re: Gantry or Stepper issue?
I'm by no means an expert but:
You have some very high quality motion control hardware (Mesa 7i76) and you have Peter from Mesa (PCW_MESA) already offering to help but you have not posted your hal and in in files as he asked. You will be taking a step backwards if you go to Mach 3.
But in my view the way you have put your system together after the 7i76 motion control board is just crippling your system and I suspect your motors are just crying out for more voltage ad if you heed their cries for help, all your problems will go away. I have some 8 wire small Nema34's on my gantry machine (with a 48 volt power supply). In my experiments as I built my machine anything other than bipolar only parallel wiring just did not cut it. But when you adopt that wiring scheme, you need 4.2 amps per motor to drive them properly and your drives just cannot deliver that amount of current.
So i think to persevere with those motors, you really need to upgrade your system so that you can feed them 4.2 amps and preferably at 80 volts.
So that will not be a cheap exercise as it will require upgrading your power supply and your stepper controllers.
If you do that, just be aware that the 7i76 can step at up to 10 Mhz but I keep mine around 100 kHz max (at around 750 rpm) so there is plenty of scope to increase your microstepping beyond what controllers are capable of.
Alternatively, replace/downgrade your stepper motors so they are within the specs of your power supply and drivers.
Rod Webster
www.vehiclemods.net.au