Servo motor noise

[Hidden]

Hi folks, I installed a generic 750W servo motor (https://www.vevor.de/servomotor-c_11222/naehmaschine-servomotor-naehmotor-justierbar-befestigung-kupplungsmotor-750w-p_010611078687) on my Pfaff 545 H3 6/01 CLPMN a while ago, but it makes an irritating noise (I only found out it was the motor after presuming it was the machine itself and cleaning every part I could take off...).

Here's an example without the belt (it sounds louder in the video than it really is):

And here is the noise it makes with the (old) belt. New belt sounds roughly the same.

The noise I mean is the CHWUNKWUNKWUNKWUNKWUNK sound. I'm fine with a bit of a whirr from the motor, but this doesn't sound good.

Things I've already done:
- cleaned and lubricated the whole machine
- aligned the wheels of the motor and the machine
- tried a different (75mm) pulley instead of the 50mm pulley
- replaced the belt
- varied the belt tension

Alas, it still makes the noise. Does anyone know what could be the cause of this? I found this other thread but

but his videos are not available anymore, and there is no solution posted.

Thanks!

- Hidde

[MtlBiker]

Just a shot in the dark, but have you tried running the motor without the pulley attached to the shaft?  It's not unusual for a pulley to be out of round (not perfectly balanced) and that can cause quite a noise.  I ran into that myself about a year ago and became so convinced it was the motor that I ordered a new one.  Once I had it installed I was shocked to find the same noise was there.  And only by luck I found it was actually the out of round pulley.  I'd changed to a smaller motor pulley in order to slow the machine down and the one I got online wasn't perfect.  I ordered a replacement pulley from a dealer who knew about this issue and the new pulley was perfect... no more noise.

And I've now got a spare servo motor just waiting until I find a nice used machine with clutch motor.

 

[Hidden]

Thanks for that suggestion! I did run it without a pulley, sounds roughly the same (it sounds quieter in this video because I filmed it from farther away). I replaced the old clutch motor on the Pfaff with the servo, unfortunately the clutch motor's pulley doesn't fit on the shaft of the servo, or I would've tried that one. That one feels very solid. The pulleys that came with the servo motor feel very cheap. It makes the noise with both of them (75mm and 50mm). I may try ordering a new, better pulley!

 

[Northmount]

@Hidden  It sounds like electrical switching noise being amplified by the motor housing.  Sort of like a stepper motor/actuator which are a type of servo.

Some cordless drills sound similar, usually just not as loud.

[Gump]

I would suggest looking for a refund. That noise is mechanical, like the armature is out of round, and is hitting something inside the motor. I don't think it will cure itself until whatever is hitting breaks off or grinds away.

[Hidden]

Just took apart the servo, cleaned whatever I could and put it back together again. Same noise

One thing to note is that the sound you hear is in sync with the machine (one CHWUNK per stitch). I'm not sure if that matters.

[Northmount]

3 hours ago, Hidden said:

One thing to note is that the sound you hear is in sync with the machine (one CHWUNK per stitch). I'm not sure if that matters.

But you get the same sound whether it is driving the machine or not, so that would appear to be a misleader.

Check with the seller/manufacturer about the noise the motor makes.  Exchange it for another, same model and see if it makes the same noise.

[dikman]

Bearing noise?

[Hidden]

1 hour ago, Northmount said:

But you get the same sound whether it is driving the machine or not, so that would appear to be a misleader.

Check with the seller/manufacturer about the noise the motor makes.  Exchange it for another, same model and see if it makes the same noise.

The noise I mean is the noise you hear in the video with the belt attached. Not the whirring noise without the belt. That doesn’t bother me too much. Is the whirring also a red flag? I’m not sure what these things are supposed to sound like! Dead quiet?

[fibersport]

Is your belt too tight?  A sightly loose belt with help absorb shock and vibration.  How about a bad bearing in the motor?