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Prusa i3 MK3i layer shifting issue  

New Member
Prusa i3 MK3i layer shifting issue

I’ve been encountering a problem with one of our prusa i3 MK3i’s for …like a year now, in which there’s rather horrible layer shifting. Some examples:

(I rotated the prints 180deg in the fourth image)

PLA, default settings for print speeds, in normal mode

Things we’ve tried:

- rebuilding the hotend
- adjusting belt tension both up and down
- rebuilding the x axis
- adding lubricant
- replacing the bearings
It hasn’t gone away.

Some interesting things of note is that it always seems to happen around the same spot ~15 layers up or so, always in the same direction. I've also watched the printer while it was layer shifting, and it didn't appear that anything was immediately wrong physically (aside from the layer shifting).

however, i’ve also ran a test print of a really small pillar that went up past the z-level it typically happened with no issues.

The smooth rods appear fine, no scuffs or anything. This issue has happened (in slightly different ways) on both cura and prusaslicer.

Posted : 01/02/2023 12:53 am
Famed Member
RE: Prusa i3 MK3i layer shifting issue

You don't mention if you have checked the grub/set screws that attach the pulley to the motor shafts.  That's a very common cause of small shifts like that.  If they are not tightened properly (in the correct order and places) then they can loosen over time, they allows them to wiggle on the motor shaft.  

When assembled the first set screw MUST be perpendicular to the flat on the motor shaft.  It has to be flat to it.  Then the second is tightened, this is sometimes called a jam screw or set screw as it locks the first in place.  

Posted : 01/02/2023 7:07 am
New Member
Topic starter answered:
RE: Prusa i3 MK3i layer shifting issue

Yes, I have checked the set screws. I will check again tomorrow, for they may have loosened over time. 

Posted : 01/02/2023 8:47 am