[basskitcase]

I have a g540 that i want to connect to an existing stepper in bipolar parallel. the motor is rated at 4.2V 2.8A 305oz on the data plate (8 wire motor). I know if i wire it in bipolar parallel, the current goes up a lot. what happens if the driver is set to limit current below what the motor wants to draw? Is the net result just lower torque?

The problem i ultiamtely am trying to solve with this setup is shifting my torque curve to deliver a little more high end torque and hopefully higher speed, though i know those don't always go together. right now, with my motors wired unipolar is i have too much low end torque but not enough high end. i can get acceptable speed but it isn't as reliable at the higher speed settings, presumably due to limited torque. If I push against my gantry lightly at high speed, it stalls.

[ger21]

what happens if the driver is set to limit current below what the motor wants to draw? Is the net result just lower torque?

Yes

[James Newton]

It you want more speed, worry less about amps, or bipolar/unipolar and more about voltage. Actually, unipolar will typically spin faster all else being the same, but voltage is more important. And watch out for mid band resonance, which is where the motors will run fine at high speeds (under light load) but then randomly stall and lock up at mid range speeds. To avoid that, use microstepping modes and add mass or resonance dampers. (e.g. a hockey puck with a hole in it on the shaft.)