I have a harbor freight 33686 mill that I am in the process of converting. I have a 3 axis hobby cnc driver and 3 steppers from kelinginc.net. The steppers are rated at 304 oz/in unipolar, 425 bi-polar. My power supply is 28V@18 Amps. My ballscrews are all 5mm pitch. Are these steppers going to be strong enough? Do I need to spring for a bi-polar controller? I don't plan on milling anything more than aluminum/brass.
Link to stepper specs
Link to mill specs