I'm lost. After 6+ years of printing... MK2.5S is randomly shifting x and y...
 
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I'm lost. After 6+ years of printing... MK2.5S is randomly shifting x and y...  

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JasonJason
(@jasonjason)
Active Member
I'm lost. After 6+ years of printing... MK2.5S is randomly shifting x and y...

After printing non stop for 5.5 years straight, I noticed oily metal dust accumulating on the rod and bearings. I started to have a bit of layer shift (like slightly skewed prints). Then I started to notice bigger shifts (like picture). So I invested some time and money and rebuilt the entire printer's x, y, and Z's linear motion.

I don't know to do. I've done:

  • Replaced all bearings with new Misumi
  • Replaced all linear rods with new Misumi
  • New gates new belts. Updated the Y bolt holder to the newest MK3s+ setup so you can tension. 
  • Updated the right side X axis to a bear version to allows for tensioning of the x axis belt
  • New idler pullies from printed solid .
  • Re torqued the splined gears at the motors (snugging up super tight on flats first then round)
  • Redone the entire printer calibration for xyz, first layer cal. 
  • None of the harnesses (x axis, or y axis snag anywhere)
  • The motion of the x axis moves smoothly across it's full travel (tilting the bed like 25 deg, the x axis slides across), same for Y axis
  • I used superLube in the brand new misumi bearings upon assembly. Made sure they were all clocked per assembly instructions
  • the y belt and x belt when plucked sound like a bass guitar string.

I can do 1 part print 75% of the time successfully. But if I do a big bed print of the same part it starts to randomly shift. Can be Y, can be X. Even other small parts I see this problem. Anything over 5 hours.

I noticed that the layer shift normally happens at the same layer height. 12.80mm layer. 

I'm printing petg, max 50mm/s, 800 mm/s/s accelerations. 245Deg hotend, 90bed. I only ever print petG.

Can it be my Einsy Mini Rambo board going bad? 

 

 

Napsal : 05/08/2022 5:33 pm
JasonJason
(@jasonjason)
Active Member
Topic starter answered:
RE: I'm lost. After 6+ years of printing... MK2.5S is randomly shifting x and y...

Could belts too tight cause this?

Napsal : 05/08/2022 9:49 pm
kengineer
(@kengineer)
Active Member
RE: I'm lost. After 6+ years of printing... MK2.5S is randomly shifting x and y...

Well it looks like you covered everything that may cause a problem by replacing it. 

I would cross off slicer problems, it is shifting the same direction regardless of the orientation. 

When it just can't be anything, I tend to look at things it can't be. How about the idea that the filament is snagging on the roll or the table is hitting an object on the table next to it? is is happening with one spool? Is it happening when you set your drink in one place? 

 

I would drive the table to the suspected Z height and start  X - Ying around to see if i could detect a catch anywhere. 

Napsal : 06/09/2022 9:00 pm
JasonJason
(@jasonjason)
Active Member
Topic starter answered:
RE: I'm lost. After 6+ years of printing... MK2.5S is randomly shifting x and y...

So to follow up. I finally reached out to Prusa chat support. After so many years of experience 3D printing I thought I knew everything. Turns out I have my belts too tight. Since this is an older machine the motors can't detect the belt tension value. It's the old fashion pluck and make it sound like a bass cord for bass guitars. 

I was chasing it the wrong way, I kept tightening and tightening which caused the axis to bind and the gears to slip on the belt. When Prusa support watched the video of me plucking the belts they told me they are too tight, and I loosened them a lot. 

That fixed the problem. 

Napsal : 06/09/2022 10:17 pm
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