Stepper motors working as generators

Just finished my 1000mm Xcarve build and am working on tuning. I noticed that when the machine is unpowered (unplugged or off) and I move an axis the lights on the Gshield and fan come on. Not sure if this is normal, or potentially damaging. Seem that back feeding current into electronics might not be good.

It is perfectly normal, motors are generators. If you move an axis really fast by hand you can produce a potentially damaging voltage to the GRBL controller. Although in practice I have not heard of anyone actually damaging anything. If you move the axis slowly you will be fine.

If you connect two stepper motors together, turning one will actually turn the other one, Something I’ve always thought was neat, but I’ve never found a use for…

Yeah, same here ,cool but sorta useless. Well not quite, used the motor/generator or is it generator/motor, as a great visual hands on learning opportunity with my kids. Was just concerned that the backwards flowing current might be damaging.

Now that is a build that I would love to see!! Even if the exoskeleton motors were larger and the robot arm and motors were smaller it would be a cool project.

Or, you could just do this:

Check out the video.