Y Axis knocking sound  

RE: Y Axis knocking sound

I have got exactly same sound from y axis motor recently... I tried removing y axis motor and holding it in hand, it feels like it is pulsing somehow, also if I press it hard to frame I start hearing some kind of hissing from it.

I will contact support about this issue.

RE: Y Axis knocking sound

In my case I have also tried connect Y motor to X motor`s slot and X motor to Y motor`s slot, that moved the sound from Y motor to X motor, so it is probably not motor issue.

RE: Y Axis knocking sound

@esminis

Thank you for your feedback.

I would be grateful if you give me feedback on a possible response.

I am thinking to do the same.

RE: Y Axis knocking sound

Factory reset did not help also 🙂

RE: Y Axis knocking sound

I also tried a MR105 5x10x4mm Bearing with a modified Y-Axis Motor Mount to take some stress coming from the belt from the motors axis.

https://www.thingiverse.com/thing:3811614

Also no positive results. Maybe the damage already occured, and it would have helped prevent that.....

RE: Y Axis knocking sound

After more talking to support, they offered to replace board, and take in mine for testing, but I have offered to test disconnecting mmu2 (as I have printer with it) and then check if issue goes away (I will do it probably only on weekend), if it won`t I will send board for replacement. So solution from me will probably be only next week. You can try contacting support yourself if you want faster results 😉

RE: Y Axis knocking sound

I dont think the MMU is connected to the problem - at least I don't have a MMU.

The board? That's odd. How unfortunate, I wouldn't have guessed that.

I'm not in a hurry. If you get results please let me know!

RE: Y Axis knocking sound

@manfred-schwiebert

at least in my case it seems to be not motors fault, something in board probably or wires (as I have changed connection and this sound moved to x axis motor).

RE: Y Axis knocking sound

Swapping Axes for diagnosis reasons is something I could try, that's not a bad idea.

I'll see if I find the time this weekend to do that.
Please keep me updated if you get your problem solved.

RE: Y Axis knocking sound

This sounds very much like the micro adjustments on Z for MBL as the print progresses. I hear similar on my printer, and I heard it more before I did the nylock conversion and dialled in the bed level, afterwards it was far less frequent (i.e. tic-tic-tic-tic vs tic.........tic........tic)

Easy to verify - if you get the angle of a light just right you can see the facets on the z motor dust caps and it will be relatively easy to see if they are turning even a minute amount. 

RE: Y Axis knocking sound

@vintagepc

At least in my case I doubt it is Z axis micro movements because:

• If I remove Y from frame sound dissapears
• If I hold Y motor in hand I feel as it is pulsing (seems that pulsing an creates the sound)
• If I have switched X / Y motors, sound moved to other motor

RE: Y Axis knocking sound

• Still @todo - try disconnecting MMU2S
• Btw I have printed same 3D prints several days before issue appeared and there were no such sound
• Tried downgrading MK3S firmware to 3.8.0 - did not help
• Seems the issue is happening when it is moving on X and Y
• Also I am attaching .gcode I was testing on (it is generated by Prusa Slicer, for model https://www.thingiverse.com/thing:2981230), and it seems issue is happening on for example movements like:

G1 X24.630 Y204.130 E0.01716
G1 X6.370 Y185.870 E0.82023

RE: Y Axis knocking sound

Last update before sending board to Prusa as I am out of ideas:

• MMU2S disconnect did not help
• Interestingly if I change to 90° lines where there were 45° lines sound dissapears, so it is somehow related to X and Y motors moving together

RE: Y Axis knocking sound

Update - just got replacement board, connected it and sound still the same...

So will need to debug further when I will have some more free time 

RE: Y Axis knocking sound

I actually encountered this recently on my printer after doing some service. In my case, it was the mount holding the motor within touching distance of the back plate. When the motor changes direction, it torqued a bit which would cause it to tap the rear printer frame and make a loud knock. In your case, it might very well just be the normal stepping action vibrations that are being amplified by the frame.

I mitigated it (in my case) with a very thin spacer between the motor mount and rear plate of the printer frame. e.g. a layer of electrical tape or 2-3 layers of kapton tape to move the motor far enough away it no longer touches on direction changes.

RE: Y Axis knocking sound

@vintagepc

I could dampen at least a bit, but it would be better to solve root cause. As without solving root cause it might become worse and worse and then dampening will not help at all.

Plus this is already seems to be affecting at least 3 different people and it started happening recently for all of us

RE: Y Axis knocking sound

I don't fall into that category; I'd unintentionally removed my previous damping when doing service, causing me to notice the problem and remember I'd removed it. 

PETG and PLA can warp a bit over time if they are under continual stress, it's quite possible your motor mount is not sitting flush against the rear plate anymore or has shifted slightly due to belt tension changes. Keep in mind the belt is on the opposite side of the mounting screws from the motor body, so your belt tension is causing it to cantilever into a position where it is being pulled askew and closer to the frame. 

You should at least test to see if this is indeed the same cause for your sounds. Try just shimming something between the motor body and rear backplate. Does the sound go away or change?

RE: Y Axis knocking sound

@vintagepc

I have tried different solution earlier - I have flipped X and Y motor connections on board - sound moved to other motor. Also I held it in hand and I feel strong pulsing in motor when it is doing long straight ~45 degree movements (if it is doing 90 degree movements there is no sound / pulsing)

RE: Y Axis knocking sound

OK, I'll back out and shut up now 🙂 I clearly have nothing further to offer.  ( and I don't mean that sarcastically)