Strange layer shift  

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guillaume.lucas-garra
(@guillaume-lucas-garra)
New Member

Hi everyone !

I have a weird problem that popped up on my MK3S lately. ( It has the MMU2 on it but the problem, for once, doesn't seem related to it, si I post here).

I have this strange layer shift on almost all my prints. It does not look like a belt issue, as the shift dissapear progressively after a few layers. My bed sheet il also placed correctly. The shift often appears on the first centimeter of the print. It happens regardless of the filament I use..

It's hard to see here, but the shift is both on the X and Y axis.

Any Idea of what could be causing that ? 

Edit : Sorry I just can't insert  that picture properly.

Best Answer by Neophyl:

With a step like that it looks like the grub screws on your motor pulleys are loose.  Its the single most common cause of layer shifts like that.  They must be tightened parallel to the flat on the shaft and its worth checking them regularly as part of maintenance checks.

Also what I do is once aligned and tightened properly is draw a line in sharpie marker on to the motor shaft and pully so that you can see if it ever moves as the line will be offset.

If its not the pulleys and it always happens at the same height then that would suggest a break in one of the wires to the motor(s).  Basically when the wires are in certain positions the break occurs.  Unfortunately that type is issue is very difficult to track down and needs something like a digital multi meter at minimum to check wire continuity.

This topic was modified 7 months ago 4 times by guillaume.lucas-garra
Posted : 13/02/2020 2:31 pm
Knickohr
(@knickohr)
Member Moderator

Is it really a shift ?  It's shrinking. Show us the other side of the thing.

I suggest it is a cooling problem. You print the first few layers with less cooling because there is 100% infill and more layer printing time. And after that point your fan speeds up because of less layer printing time.

Please check.

Thomas

Posted : 14/02/2020 8:13 am
Neophyl
(@neophyl)
Noble Member

With a step like that it looks like the grub screws on your motor pulleys are loose.  Its the single most common cause of layer shifts like that.  They must be tightened parallel to the flat on the shaft and its worth checking them regularly as part of maintenance checks.

Also what I do is once aligned and tightened properly is draw a line in sharpie marker on to the motor shaft and pully so that you can see if it ever moves as the line will be offset.

If its not the pulleys and it always happens at the same height then that would suggest a break in one of the wires to the motor(s).  Basically when the wires are in certain positions the break occurs.  Unfortunately that type is issue is very difficult to track down and needs something like a digital multi meter at minimum to check wire continuity.

This post was modified 7 months ago 2 times by Neophyl
Posted : 14/02/2020 8:25 am
guillaume.lucas-garra
(@guillaume-lucas-garra)
New Member

@knickohr

Tanks for your answer, it's true that on the picture it does look like shrinking, but I'm pretty sure it's not. Here's the full view of the part :

@neophyl

I'll check that right away, see if that's the source of the problem.

Posted : 17/02/2020 10:44 am
Knickohr
(@knickohr)
Member Moderator

Yes correct, this is shifting, not shrinking 😉

Try neophyl solution.

Thomas

Posted : 17/02/2020 10:50 am
guillaume.lucas-garra
(@guillaume-lucas-garra)
New Member

Thanks everyone !

One of my grub screw was indeed slighly loose, I tightened it and started printing again. So far, no shifting, so it seems that was the problem.

Guillaume

Posted : 18/02/2020 10:58 am
Robert-mm200
(@robert-rmm200)
Noble Member
Posted by: @guillaume-lucas-garra

Thanks everyone !

One of my grub screw was indeed slighly loose, I tightened it and started printing again. So far, no shifting, so it seems that was the problem.

Guillaume

You have set yourself up to have it fail again...

Loosen both grub screws.

Align one with the flat - and fully tighten that one.

Finally, fully tighten the second grub screw.

On those screws, what you do and the order you do it in actually does matter.

Posted : 18/02/2020 3:58 pm
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