When done, turn power off, plug in the stepper motor cables, turn power back on and test motor movement.
Don't tune digital stepper drivers with the motors plugged in, if you accidentally set current too high you can fry the motor or the stepper.
Don't plug or unplug stepper motors closed loop with the power on.
Measure DC voltage between the stepper trimpot and 12V ground. The ground at the 12V supply to the control board is fine to use.
Look up the correct current for your motor part number. If you have cheap Chinese motors with no part number, assume they have a max of 1.25A to be safe.
Look up the proper formula for your stepper drivers below, and find the voltage which corresponds with the current you want to set.
Pro tip: Get slip-on alligator clips for your multimeter. Clamp ground to a 12V ground wire and clamp positive to your screwdriver. This way you'll measure the voltage as you adjust and don't need three hands.
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