# Bipolar Stepper Motor, Does polarity matter?

I have an Easy Driver and a 4 wire bipolar stepper. I was wondering if the polarity of the AA, BB connections matter. What I mean by that, say I had four wires A1 A2 B1 B2

would switching A1 and A2 have any effect?

Swapping the ends of one winding will either stop the stepper from working or will change the direction of motion. I'm not sure which.

It will reverse the direction of motion.

Read this on why the order of the motor excitation matters:- http://www.thebox.myzen.co.uk/Workshop/Motors_4.html

Sure does, it matters in terms of direction.

So when setting up a mill or lathe you'll figure things out, just start in the middle of any axis that way you have travel in either direction to work with, once you decide what direction you want the axis to move on, "based on polarity", keep the wiring.

Half the fun in this stuff is problem solving, like you would with a mutli-piece puzzle.

Thanks for the explanation everyone. That makes sense since the phase shift would be equal but opposite when the wires are switched.

Could I also ask, would this be true for any 2 phase motor, even 2-2 phase unipolar motors in bipolar mode?

In Bipolar mode, for any bipolar motor, swapping any pair of leads will reverse the rotation. (meaning A+, A- or B+ B-)

Hey, my step motor does not work with A4988 driver. What is the problem ı could not solve it? please help me

johnwasser: Swapping the ends of one winding will either stop the stepper from working or will change the direction of motion. I'm not sure which.

No, swapping the ends on one winding simply reverses the direction. swapping the A pair and B pair over will also reverse the direction.

Swapping a single A wire for a B wire will stop it working. Might even blow up the driver.

The rule is one winding goes to the A terminals, the other goes to the B terminals. Check this with a multimeter before ever powering up. Always attach the wires securely - an intermittent connection will probably blow up the driver. Power down before rewiring always...