# Will This Hurt Steppers



## Transformer (Nov 7, 2015)

The stepper motors I used on my lathe have the shaft coming out both ends.  More to dress things up than for any other reason I installed some ribbed knobs from Ebay on the ends of the exposed shafts.  Recently for a small job, rather than write a program, I ran the mill in manual mode, just hand turning the knobs on the stepper shafts to move the tool.  Now I am wondering if hand turning the stepper motors, with no power going to them, will damage the motors.  Thanks.


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## Eddyde (Nov 8, 2015)

No it won't harm them.


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## kd4gij (Nov 8, 2015)

As said won't heart the stepper. But I have read that you can take out the driver board if the motor isn't isolated. A dc motor acts like a generator when you spin it by hand. Some one else should come along  with more info.


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## stupoty (Nov 8, 2015)

Wont hurt the stepper but as kd4gij says it might be bad for the driver board with back emf .

Probably depends how the output stage of the drivers is designed.

Stuart


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## Transformer (Nov 9, 2015)

Thanks.  I think when I have to do this I will unplug the motors to eliminate feedback.

Dennis


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## lindse34 (Nov 9, 2015)

Turning by hand probably won't generate enough EMF to damage stepper drivers (unless you are quite excellent at turning the knobs). In testing some stepper drives I have fried drivers when using a Brushed DC motor as a constant torque load and the DC motor overran the stepper drive. In that case though the stepper was being driven at 3x the stepping frequency once it ran away. After that incident I made a traditional brake arrangement with a load cell to measure performance.


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## kevinpg (Nov 20, 2015)

the sherline stepper motors have this specifically to turn manually. if you are concerned, why not add a diode to prevent that?  it's a thought.


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