If I power my board off the USB and supply the motor 5V from the arduino, it runs.
If I give it Vin, it doesn't run.
If I power my board off a regulated 12V wall adapter and supply it Vin, the motor takes about 3 steps and then starts to shudder back and forth.
If I give it 5V, it takes about 16 steps and then starts shuddering.
If I supply it 3.3V, it runs fine but the arduino heats up to blazing hot. I get that this low voltage means I'm drawing a lot of current.
No, wrong driver, that's not for low impedance bipolars at all, it is for a high impedance
You won't get any decent speed/torque out of the thing without a chopper driver run from a decentsupply voltage
I'm starting to think that maybe I should just scrap the bipolar motor and go with a unipolar one like the 42BY48H05 or 42BY48B03 sold by Jameco. Of course, that's assuming that I can run them on either the L293D or sn754410NE chips that I now own.