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-   -   taking back part of Stepper motor (http://www.mechmate.com/forums/showthread.php?t=4143)

Fox Wed 10 July 2013 04:10

taking back part of Stepper motor
 
Question;

When you disassemble a stepper motor, but only to the part that you loosen the screws so you can remove the the back, and take the back part of the motor, ( so without sliding out the axle/rotor).... will this already damage the performance of the stepper ?

I know/read from Geralds experiments when you completely disassemble them, you will loose (some) performance, because the rotor is magnetized after assembly and the magnetic fields are sliding past each other when you remove the rotor. When I remove only the back, it could be that the rotor makes contact with the body ? Would that hurt performance ?

I just want to take of the back cover of it for trying out a crazy little idea on neater wiring and extending an stepper axle, but i don't want to ruin a perfect stepper by merely opening it to find out.

MetalHead Wed 10 July 2013 10:26

http://www.ducttapeeng.com/smd/smd1.htm

This may tell you what you need to know without taking yours apart.

What are you thinking about shaft extentions? Some steppers have the shaft out the back for encoders and such.

As far as wire management, the output wires are about as neat as they are going to get because they quickly turn to windings inside the motor.

danilom Wed 10 July 2013 10:34

For nema23 you got back covers like this

http://www.soigeneris.com/Images/Products/NEMA23_1.jpg

http://www.dyengineering.com/index_html_files/74.jpg

I would not try to open it, the axle is pushed into the bearing in back cover, in a perfect situation you should unscrew it and push the bearing out the back or push the axle out of a back bearing, all without moving the rotor out the case, seems too much for just cable management

Make the machine, and then design the back covers, there is just a little bit of thread on the back so you can screw them into existing back plate.

Fox Wed 10 July 2013 11:06

Thanks Mike & Danilom,

was aware of both suggestions ( googled a bit on the subject already before I posted), neither one tells me though if it's indeed bad for your engine to open only the back. Found a topic by Gerald on the shopbot forum that tells he opens an motor all the way and lost some performance. He then also wonders if it would have been the same if he only took of the back instead of the whole thing apart.

The Nema 23 cover is nice, already had e-mailed them for a 34 version...they don't intend to make nema 34 ( well they intend to for a few years that is ) Machining a cover like that out of some layers was my next option. Not too much work either, was just looking for the quickest solution ( If i could open the cover with no issues, cutting the thread would be a 5 minute job and quicker then the backcover )

Was just being curious, as some of the more expensive stepper have strain reliefs on them if I could cut some thread in the back cover. Was thinking into a quick peek before I start wiring, when I thought mayeb somebody knew already.

Extending the stepper axis was even more of a longshot, since I already have the motors without extended shafts and Deitechs supplier does not want to make me a single motor with extended shaft. I thought if I can easily open it, I might be able to whip something up instead of buying another stepper elsewhere.

Gerald D Wed 10 July 2013 23:23

Looking back today, I am not sure that I lost any performance when changing bearings without pulling the magnets out of the housing. I think you will be okay . . . . but there is no guarantee! :)

Fox Thu 11 July 2013 02:26

Good insight, I think I will and give it a try with my spare motor when my kitchen table project is running.

Yesterday I noticed a center mark on the axle and thought up a 100 % safe solution to have a peek: I could bolt the stepper on the L block on my lathe and support the axle from the back with a thin center and pull the cover over that. That way the rotor won't even know I opened the stepper :D


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