Steppers generate voltages that can be dangerous

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Every now and then someone comes out with the statement that running a stepper by hand by moving the table or gantry will generate a current that will fry your electronics in the printer. Most printers have a “disable steppers” switch somewhere just for this condition. A lot of us don’t seem to care and do it anyway.

Any motor can also be a generator even if it is inefficient. Yesterday I moved the table on the Franken-Ender, powered off, so I assumed it was safe and when I did the hotend fans started to turn. I repeated this again and the fans turned again.

Conclusion, if you move the table or other parts fast enough (moving it slowly didn’t do it) the stepper will generate a current and could possibly damage things in the printer.

Who knew!

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Yup, I’ve seen the similar on my ender 3s if I move the bed too fast. Hasn’t ever damaged anything, as far as I can tell, but I wouldn’t want to be touching any of the main board while moving the bed.

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It is quite hard to damage modern mainboards by doing this as there are usually over-voltage protections in place. But its not impossible…

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