Layer shifting during print  

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danieldanielnova
(@danieldanielnova)
Active Member

Hi,

I am experiencing layer shifting during printing and wondering what the cause is. The belts are tight, or from what I can tell. I just built this printer, other prints have come out fine. It mainly seems to have issues when there are thin walls in the part it seems. This is my second Prusa MK3S in my print farm. 

Thanks,

Daniel

 

Posted : 26/10/2019 12:51 am
Tim
(@tim-m30)
Illustrious Member

Friction. Did you grease the bearings before installation?  

It is always wise to get more than one opinion......
Posted : 26/10/2019 1:20 am
danieldanielnova
(@danieldanielnova)
Active Member

It mentioned the bearings were already greased in the MK3S instructions. I just now tightened the belts and I am re-running though, just to be sure on that statement.

Posted : 26/10/2019 1:29 am
joan.t
(@joantabb)
Veteran Member Moderator

Hi Daniel, 

it looks like you have regular layer slips,  of equal lengths... on various layers, 

I would suspect the belt drive pulley being a little loose on the shaft. when the extruder meets a little resistance, whilst travelling in the appropriate direction the drive pulley moves until the grub screw bumps into the flat on the shaft, slightly off centre 

the proint continues with the drive gear in the slightly offset position until the extruder again meets a little resistnce when the shaft rotates in the opposite direction relative to the displaced pulley, and again comes to a stop when the grub screw touches the motor shaft flat in the opposite direction..   
the ammount of layer shift is limited by the looseness of the grub screws on the belt drive pulley

to resolve, first identify which direction the problem is occurring in, (X or Y) then  loosen both screws on that pulley, rotate the pullley so that one of the grub screws in exactly in the middle of the flat on the motor shaft and tighten it. 

then tighten the other grub screw against the motor 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 : 26/10/2019 8:59 am
Tim
(@tim-m30)
Illustrious Member

Joan's comments about a loose belt drive gear are probably the cause.

But, if properly tightening the gears doesn't help, despite Prusa's claim about their bearings, the linear bearings come packed in a preserving/anti-rust oil that is not intended for lubrication.  Once out of the bag, the oil begins evaporating and the bearings are soon dry. A good grease is needed to keep friction low and help the bearings last more than a couple months (depending on use, of course).  Lubriplate, Lithese, Superlube are common greases available at most hardware or autoparts store. Even the small tube that Prusa now ships will work in a pinch.

It is always wise to get more than one opinion......
Posted : 26/10/2019 4:48 pm
danieldanielnova
(@danieldanielnova)
Active Member

Hey guys. 

Sorry for not getting back to this post. I tightened the belts as much as a could and it ended up fixing the issue. So I guess never hurts to crank up your belts more!

Posted : 02/11/2019 6:51 am
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