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I have read that you can wire a unipolar stepper to a bipolar driver, which I have, by ignoring the two extra wires. One concern I have is whether connecting a unipolar stepper to a bipolar driver will cause it to lose torque (holding or operating)?

Will it be the same? Increase?

I've read that bipolars are more bang for your buck energy-wise, and since you can "transform" a unipolar stepper to a bipolar good enough that the driver will still work right, I would think that it might run more efficiently. Is this true?

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  • $\begingroup$ Did you find any limitation/caveats for using bipolar drives for 6-wire unipolars? $\endgroup$ – Zeta.Investigator Jul 29 '18 at 17:18
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From wikipedia http://en.wikipedia.org/wiki/Stepper_motor

Because windings are better utilized, they are more powerful than a unipolar motor of the
same weight. This is due to the physical space occupied by the windings. A unipolar motor has twice the amount of wire in the same space, but only half used at any point in time, hence is 50% efficient (or approximately 70% of the torque output available). Though a bipolar stepper motor is more complicated to drive, the abundance of driver chips means this is much less difficult to achieve.

If you read specifications for a stepper motor that can be wired as unipolar/bipolar, you will confirm this.

But if you have a 5 wire unipolar, the central one is common to the center tap of both coils. You need to remove this connection to use it as bipolar. If you have a 6 wire, yes it is meant for that, just ignore the two other wires (some motors have connectors so you can disconnect the wires), and run it as bipolar.

stepper motor wiring
From http://www.esuli.it/2011/10/11/converting-an-unipolar-stepper-to-bipolar/

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