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Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2  

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Kamil
(@kamil-3)
Eminent Member
Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

Hi,

After update to MK3S and MMU2S, I getting a layer shift for a bigger model printed. As presented, in the attached image. I am using firmware 3.7.2 and the latest for MMU2 I think 1.05. I am using as well the octoprint. I know that there was once a problem regarding the octoprint. However, it was solved as far as I know. Any clues what it can be?

Attachment removed
Posted : 05/07/2019 7:55 am
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(@)
Illustrious Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

Tight or dry bearings on the X-Axis.  Put a few drops of lithium grease (or oil) on the X-Axis rods and move the extruder back and forth a few times to distribute it. Same for the Y-Axis. 

Also, the MK3S has a known issue where the extruder housing screws can clamp the bearings too tightly and cause excessive friction (similar to the Y-Axis U-bolts).

And last - make sure belt tension isn't too tight. If you adjusted to get 240 on the LCD, those numbers are measuring friction, not belt tension, and 240 is a LOT of friction (my printer is at 296 and 298).

This post was modified 5 years ago by --
Posted : 05/07/2019 5:45 pm
Josh
 Josh
(@josh-8)
New Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

Hello,

please help.

I just loaded 3.7.2 on my MK3 with MMU2 and started getting layer shifts in the Y (bed) direction. Worked flawlessly with the last few firmware.  It says "heating..." and then the Y is layer shifted. If Im lucky it shifts multiple times and ends up aligned again.  forcing layershift detection doesn't always help.  (side note: X layer shift detection doesnt seem to work at all)  When I force it to detect a layer shift, its not aligned with the original home when the print started.  however I can force layer shifts and it will be the same every time. 

I was having a lot of trouble with the MMU2 and previous firmware not retracting filament.  I did a full reset on the MMU2 before and after loading 1.0.5 firmware because it seemed to have a mind of its own.  The MMU2 is now responding how I would think it should and filament isnt getting stuck anymore.

The bed feels like it moves about as easy as the X axis and the belt status is X 272, Y 282.

The parts im printing are 210 x 220 x 180.  this worked before with older firmware but it is at the exact limit of PrusaSlicer.

Posted : 16/07/2019 1:04 am
Kamil
(@kamil-3)
Eminent Member
Topic starter answered:
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

Sorry for late replay. It is not a belt. I did not have a problem with prevoius firmware. I found that some people have a layer shift. I will wait for new firmware but meantime I will off steal mode and layer detection. I will let you know if it helps

Posted : 16/07/2019 6:18 am
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(@)
Illustrious Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

A second look, layers that have infill that steps to solid infill can have small patches that tend to curl. The curled edge grabs the nozzle as it passes by and will cause a crash - or if crash detection is off - a layer shift: the extruder or bed is moving, the nozzle catches on a curl of plastic, and the motor stalls a few steps or more.  Crash detection will count the error and I though stop the print; but if disabled the print will continue as if everything is okay,; but the extruder is no longer referenced properly to home; so the print continues with an offset, or shift.

Posted : 16/07/2019 6:24 am
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(@)
Illustrious Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2
Posted by: josh.m3

Hello,

please help.

I just loaded 3.7.2 on my MK3 with MMU2 and started getting layer shifts in the Y (bed) direction. Worked flawlessly with the last few firmware.  It says "heating..." and then the Y is layer shifted. If Im lucky it shifts multiple times and ends up aligned again.  forcing layershift detection doesn't always help.  (side note: X layer shift detection doesnt seem to work at all)  When I force it to detect a layer shift, its not aligned with the original home when the print started.  however I can force layer shifts and it will be the same every time. 

I was having a lot of trouble with the MMU2 and previous firmware not retracting filament.  I did a full reset on the MMU2 before and after loading 1.0.5 firmware because it seemed to have a mind of its own.  The MMU2 is now responding how I would think it should and filament isnt getting stuck anymore.

The bed feels like it moves about as easy as the X axis and the belt status is X 272, Y 282.

The parts im printing are 210 x 220 x 180.  this worked before with older firmware but it is at the exact limit of PrusaSlicer.

This sounds like a belt or drive gear slipping.   Make sure the set screws are tight, and that one is on the motor shaft flat.  If not, then tighten the set screws.

Flat First: Drive gears must be tightened flat-first.

1)   Start with both set screws fully loosened so the pulley is free to spin on the motor shaft.

2)   Align one set screw dead center with the flat on the motor shaft, slowly tighten the screw until it fully contacts the flat surface.

3)   Torque the flat set screw to spec.

4)   Now tighten the jam set screw, and torque it to spec.

Once tightened, never touch the flat set screw unless the jam screw is first fully loosened.

Why Flat First? Set screws have flat ends. If you tighten the jam screw first the set screw on the shaft flat doesn't fully contact the shaft, only one small edge of the screw surface is biting. Reversing torques can easily shift the shaft to a position the flat screw no longer contacts the shaft. This lets the jam screw wriggle loose. And after a while, vibration loosens the screws until the gear is free to rotate.

Posted : 16/07/2019 6:28 am
Josh
 Josh
(@josh-8)
New Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

Hello tim-m30,

Thanks for responding.

The belt and Y axis motor pulley was the first thing I checked.  There were no problems with anything in the Y axis that I could find.

Posted : 17/07/2019 2:45 am
Dave Avery
(@dave-avery)
Honorable Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

i doubt it's firmware related, 1000s of people are running 3.7.2 without problems

 

 

Posted : 17/07/2019 2:24 pm
Kamil
(@kamil-3)
Eminent Member
Topic starter answered:
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

Check it...

https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-general-discussion-announcements-and-releases/printer-is-trash/

It is not only my problem.

Posted : 23/07/2019 7:59 am
Casey liked
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(@)
Illustrious Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

And it is clear from that thread the problem was NOT the firmware.

Posted : 23/07/2019 8:25 pm
Casey
(@casey-2)
Estimable Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

While this may be true.... have you seen the new MMU2S firmware? Contemplating that, seriously....Look at what it solves in the sticky.
Nearly exactly what I was experiencing.... before a few  forum trolls decided to successfully trick Jakub into thinking I'm just some jerk on the Prusa forums making it my battleground.... At least devs got on it finally, and fixed it, despite telling me and a few others that nothing is wrong at all... 😛

If it wasn't broken, why would there be a need to fix it? 😉 

Finally got the parts to fix the printer I got back from repair at Prusa Research (yep I just said that). Will be glad when it's working. The handling of the situation, by their own admission, was pretty bad... but I forgive easily... Just don't keep doing the crazy stuff... 😛

This post was modified 5 years ago by Casey
Posted : 30/07/2019 1:18 am
CybrSage
(@cybrsage)
Honorable Member
RE: Layer shift, Firmware 3.7.2, MK3s, Prusa i3 MMU2S & MMU2

I am running 1.6 rc2 and it makes the mmu2 run smoother.  It was not broken before, but something does not need to he broken to be improved and this definately improves it.

Posted : 30/07/2019 11:21 pm
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