3.0Nm stepper from Zapp stopped working / faulty

[Jonathan]

One of these stepper motors that I have is not working properly:

http://www.slidesandballscrews.com/sy60sth883008-nema-stepper-motor-p-118.html?cPath=45_81

The max rpm has suddenly decreased greatly - won't go above 620 rpm with no load. It just misses steps, or just stalls whilst accelerating. :thumbdown:

I've tried it on to other identical, PM752, drivers running on 70v and get the same symptoms - so it's not the driver that's the problem.

My other 3 of these steppers are all fine...

Any ideas what could be wrong / where to go from here?

[Jonathan]

Ok well that was weird ... it's suddenly started working just fine!
Still, I'd like to know what might have caused it so it can't happen whilst the machine is running.

[Robin Hewitt]

Is it possible you overheated the rotor and it eventually cooled down?

[Jonathan]

No, the motor had only been on a few seconds, and off for about a month. Not warm at all. It happened just after I'd installed 4th stepper driver and cleaned out all the dust from the computer.

[Desertboy]

Maybe dodgy connections since you rewired it several times if it is a dodgy connection I would think it inside the stepper motor.

You can split steppers to check have a look on you tube.

I wouldn't trust a motor that had done that to me unless I traced the reason it happened because it'll cost a lot more than a new motor would if it starts skipping steps on a work piece.

[Clive S]

You do realise this post is 7 years old. Also it is not a good idea to open a stepper motor.

[Desertboy]

No I didn't lol, I would think as long as you de-energized the coil you have nothing to lose going inside. I'm going to rip one open to see what's inside but it's a scrap one.

[Jonathan]

I have no recollection of this incident, though I can say that 7 years later all the 3Nm motors I have from Zapp and CNC4You are still working well.

I agree with Clive on not dismantling without good reason - apparently this can result in demagnetisation.

[Gary]

If you remove the rotor from a stepper motor it will demagnetise very quickly and then when you re assemble, it will not have the rated torque that it had before you stripped it down.