Shorting stepper coils to dampen movement when powered off

Hello. I am using 3D printing hardware to do some testing, not for 3D printing. I had to use a belt-driven z axis for speed. As you'd expect, the z axis falls when steppers are powered off.

If I use a relay (or maybe a diode) to short z axis stepper coils as soon as I power down, it would really dampen the fall. So, I'm considering trying this.

Any thoughts on this?

I can't imagine I'm generating 1.7A as the axis falls, the current limit of the coils, but that could be an issue. Also, I may need a few ms delay before activating relays in case the DRV8825 are still powered up by some capacitor.

I'm hoping those of you with more stepper motor knowledge could weigh in.

Thanks!

... this is normally done by a mechanical brake, activated when the power goes off ...

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Viktor
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With electromagnetic braking, the braking force will be proportional to speed, like viscosity. So you won't be able to hold your plate in place without applying external currents or using a mechanical brake, but you can certainly slow the falling. Extra style points if you use the generated currents to charge a battery.

Use a DPDT relay (2 switches, 6 terminals) for each motor.

Relay connected as:
Common 1 - motor terminal A+
NC1 - motor A-
NO1 - driver A+
Common 2 - motor B+
NC2 - motor B-
NO2 - driver B+

A- and B- are connected directly to the driver.