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Prusa i3 mk3s+ Y layer shifting  

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The Astrononeer
(@the-astrononeer)
Active Member
Prusa i3 mk3s+ Y layer shifting

 

So I recently installed the MMU2 on my i3 mk3s+, all was going well, before filament got stuck in the extruder and the MMU seemed to pull quite hard on the extruder. Now every print I do has layer shifting in the first 5mm or so, and is fine everywhere else. I have been going in circles trying to figure out what's causing this. I tightened all the belts and recalibrate all axes before the benchy shown above. It was printed using the .15mm file that came with the printer and hatchbox white PLA. Any ideas? Thanks.

 

 

Posted : 28/10/2022 4:48 pm
cwbullet
(@cwbullet)
Member
RE: Prusa i3 mk3s+ Y layer shifting

Check your grub screws, also.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 03/11/2022 12:21 pm
Robin
(@robin)
Prominent Member
RE: Prusa i3 mk3s+ Y layer shifting

Mh, if the tip is stuck in the extruder and the MMU2 is pulling the force is transferred via the PTFE tube to the mounting on top of the extruder. So the MMU2 can not "pull the extruder" it can just pull the filament inside the extruder. The lower part of the PTFE inside the extruder is the only part the filament can get stuck on (since it's 1,85mm ID, everything else has a bigger ID). If this gets pulled up you can expect all kinds of trouble (loading, unloading, extrusion, see "hook of death" thread) but no layer shifts. 

Difficult to see this shift you are talking about on your pic. Just slice and print a simple cube with default settings and see how it looks... (Always generate your own gcode, you never know what settings have been used by others)

If at first you don't succeed, skydiving is not for you.

Posted : 04/11/2022 4:30 pm
The Astrononeer
(@the-astrononeer)
Active Member
Topic starter answered:
RE: Prusa i3 mk3s+ Y layer shifting

After some disassembly and snooping around, I noticed the belt drive gear for the Y axis was but up against the Y stepper. I took it off to find that the shaft had developed marks, as if the gear was pulled with great force towards the Y stepper. I re-aligned it to be a little bit away from the stepper, and it has been printing perfectly ever since. I am a little concerned that the gear worked itself loose, but I am keeping an eye on it now. My only thought is too much belt tension or a misassembled belt anchor point under the bed. Pictures below is the rubbing pattern that emerged.

Posted : 04/11/2022 4:59 pm
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