View Full Version : disassembly of stepper motors

06-12-2003, 06:08 PM

I was just wondering if anyone can tell me why the manufacturers of stepper motors are so careful to warn people not to disassemble the stepper motors? One stepper motor I have even has a label on it advising that disassembly will alter the motor characteristics (I assume they mean disassembly and re-assembly since I would be very surprised to see a disassembled motor work at all!). Somewhere inside me there's still the curious kid who wants to see how things are put together...

How about it - has anyone disassembled a stepper motor and lived to tell the tale? Did the motor survive - for better or worse?
Should I keep my screwdrivers and stepper motors in separate rooms?


06-12-2003, 07:17 PM
All I know is if you that them apart they will not work again.

06-12-2003, 07:25 PM
It likely has to do with the magnets. The magnets are "magnetised" with the motor assembled, and pulling it apart (pulling the magnetic fields across one another) likely scrambles the individual poles on the particles enough that it weakens the magnets. That's my guess :)

I know the same thing happens with a magnetic dial indicator base. Disassemble the magnet and it becomes weak as hell.

In the case of the motor, you might be able to take the endbells off ( if it is built that way), leaving the rotor in place inside the stator, and you might live to tell us about it :D

06-12-2003, 10:15 PM
I cut graphite on an extended z axis router. It took a while to get everything dust "proof", removing all lubricant from ball screws to run them dry and sealing the motors.

I had to take two pac-sci motors apart at different times because dust had entered the motors through the end shaft. They were packed with graphite dust and had stopped running.

Didn't read any warning labels, took them completely apart, put them back together and they are still running two years later.

06-13-2003, 12:32 AM
Extremely cool mold Keith- Can you tell us what material you are molding? I assume that you are pouring a liquid in, sloshing it around, and pouring it out?


06-13-2003, 01:14 AM
The molds are for blown glass. A video of this mold being used in a factory is at www.skeelsglass.com 22MB file size, so you should have high speed access.

06-13-2003, 01:14 AM
...yeah, way cool mold! Is the mold graphite? And if so, why?


06-13-2003, 01:45 PM
Thanks, I'll pull that one down tonight.

Any tips on how to get that perfect finish? Is there a lot of hand work?


Mariss Freimanis
06-25-2003, 08:09 PM
This topic came up in another group. The stator acts as a magnetic "keeper" for the rotor.

Nothing like running an experiment to know if something is true or not.

I had a motor I didn't care for (MO62-FD04), so I ran dyno tests on it that showed 112 in-oz low-speed torque. I removed the rotor for 5 seconds, then replaced it and re-ran the dyno test.

The low-speed torque now was 70 in-oz, or only 62% of what it was before disassemby.

You may not notice the loss in torque but it is real and it is there.