# Will this hurt steppers?



## Transformer (Jan 4, 2015)

I am in the process of converting my lathe to CNC.  I have installed the type of stepper motor that has a shaft at both ends.  On the sticking out, unused shaft, I installed a little hand wheel.  Now I am wondering if actually using this wheel to move the position of the cutters will harm the steppers.

Dennis


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## JimDawson (Jan 4, 2015)

Nope, you'll be fine.  From a safety perspective, don't put a crank handle on the stepper, just use a round hand wheel.  Mine have folding crank handles, and sometimes I forget to fold it up.  It hurts to get smacked in the wrist with a crank.:bitingnails:


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## mzayd3 (Jan 4, 2015)

If the stepper is still powered, it is holding position. So, you will not be able to turn it freely.  In order to turn it, you have to de-energize it.  Even so, unless the shaft on the side closest to the handwheel is well supported, I would hesitant to do what you are describing.  Even on a monster nema 34 frame, the shaft is really quite small.  Hand power isn't truly radial? Force, and it seems to me that there is a risk in inadvertently bend the shaft.


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## Wreck™Wreck (Jan 4, 2015)

A stepper will generate electricity when driven, I have no idea what if any effect this can have on a driver.

I have used BPort EZ Trak mills, if you power down the servos the cranks can be used manually, as noted if the wheels have handles attached they WILL hurt you when it rapids.  I often run a Trens 24" X 100" manual lathe that has a rapid feature for moving the axes around, the Z handle will easily break your wrist.


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## John Hasler (Jan 4, 2015)

Wreck™Wreck said:


> A stepper will generate electricity when driven, I have no idea what if any effect this can have on a driver.
> 
> I have used BPort EZ Trak mills, if you power down the servos the cranks can be used manually, as noted if the wheels have handles attached they WILL hurt you when it rapids.  I often run a Trens 24" X 100" manual lathe that has a rapid feature for moving the axes around, the Z handle will easily break your wrist.



It won't hurt either the motors or the drivers.


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## Rbeckett (Jan 4, 2015)

Nearly every driver on the market has a diode to prevent damage to the FET so you can turn the motor by hand with no concern other than losing your edge or center position.  It will be much easier to turn the motor of you de-energize it first, but you will still have moved it from the theoretical center you established when you mounted the part for machining  Just a thought  or two from the dark side....

Bob


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## Wreck™Wreck (Jan 4, 2015)

John Hasler said:


> It won't hurt either the motors or the drivers.


Thanks, I never thought about it until reading the above question.


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## ogberi (Jan 4, 2015)

Nope, won't hurt the steppers at all, nor a properly designed driver.   Not sure what the ones coming out of China are like, but in general, they shunt anything over their rated voltage to ground, or short it across the windings.  

I doubt you can spin the handwheels fast enough to generate enough voltage and power to harm the drivers.  But the handwheels won't turn easily. They "notch", as steppers do, especially if under power.   As was said above, the vibration of the off-axis handle weight can cause a problem, mostly in the form of mashed fingers and possibly broken bones.  A little machine may "whack" you, a big machine has the power of the stepper, plus the "umph" of inertia.  Broken bones *can* result.  After all, if it can snap off a 3/4" endmill, it'll make a meal of the dinky bones in your hand.

If I HAD to turn them by hand, I'd put a fairly well balanced handwheel on the, minus the handle, and stick the shank of a hex wrench in the hole to spin them by hand when necessary.  

But honestly, jogging in the CNC software is usually fast, easy, and easily different feed rates are easily selectable.   

The only use I could see in manually jogging via handwheels is touching off a tool.  And that I'd even do via the CNC controls.  Run it close by eye, jog careful until it squeaks or cuts. Either way, you've probably got enough stock to clean up without worrying about a .005 margin of error on the rough cuts.


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## Transformer (Jan 4, 2015)

Thank you all for expanding my comfort zone.

Dennis


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