Temporary layer shifting?  

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imre.b
(@imre-b)
Active Member

Hi, Any of you Fine Folks have an idea what might cause this thing on the pics below?
My print is as large as the bed diagonal but I've seen something similar with smaller parts as well. My printer worked flawlessly for over a year then I broke a nozzle, rebuilt the hotend and I'm struggling ever since. 
The shift seems to be in the X direction but what's weird is that it sorta fixes itself after a while. I didn't see any difference between stealth and normal mode in this regard.

Interestingly I can see this happening for the very first line of the brim it prints, then before the end of the first loop it realigns itself, then goes on ok for some layers but the end result is what you see on the pictures. I thought it might be some crazy g-code interpolation issue. I tries multiple versions of prusaslicer and the printer fw, but didn't seem to have any difference.

Tips?

Best Answer by joan.t:

That is usually something like a loose steppermotor pulley.    one screw should be tightened  against the Flat on the Motor shaft, and then the second screw should be tightened against the curve of the shaft...

 

regards Joan

Posted : 01/10/2019 3:25 pm
joan.t
(@joantabb)
Veteran Member Moderator

That is usually something like a loose steppermotor pulley.    one screw should be tightened  against the Flat on the Motor shaft, and then the second screw should be tightened against the curve of the shaft...

 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 01/10/2019 6:24 pm
imre.b
(@imre-b)
Active Member

@joantabb

Thanks Joan! Have you ever seen to correct itself though? That is what's bugging me. If it were just shifted gradually and stayed there I'd understand that something is slipping but I don't get it how it eventually gets back kinda on the right track.

Posted : 01/10/2019 6:35 pm
joan.t
(@joantabb)
Veteran Member Moderator

Yes, 
Let's assume your printer has been working for a while with a screw loose and jammed against one side of the flat on the shaft, but not had a snag on anything

then it suddenly catches  on something causing the pully to move so far that the screw catches on the other side of the flat on the shaft... 
this lasts a couple of layers and then the same happens in reverse..    the ammount of slip is constrained by the limit of the slack in the screw against the flat on the shaft...   this is why it moved one way thn the other, by the same amount!   regards Joan 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 01/10/2019 7:09 pm
imre.b liked
imre.b
(@imre-b)
Active Member

@joantabb

Oh wow. That makes so much sense. I shall look at it as soon as I get home. Thanks Joan.

Posted : 01/10/2019 7:24 pm
imre.b
(@imre-b)
Active Member

@joantabb

Thank you Joan, that was it. Works like a charm.

 

Posted : 02/10/2019 1:39 am
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