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Need help with layer variablity / shifting  

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Ed
 Ed
(@ed-19)
Active Member
Need help with layer variablity / shifting

 

I have been running these units on and off production for last couple of years and this issue started first on one machine but now effects both equally. Both machines purchases new (direct from prusa assembled). A couple dozen kilos of filament through each. 

 

I have to fix this issue as these machine prints are unusable for my application. 

 

Any thoughts would be appreciated.

Posted : 05/04/2024 6:04 pm
Diem
 Diem
(@diem)
Illustrious Member

First thought: check belt tensions.

https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus

It MUST be printed in Prusament PETG or the spring tension will be wrong.

Cheerio,

Posted : 05/04/2024 10:52 pm
Ed
 Ed
(@ed-19)
Active Member
Topic starter answered:
RE: Need help with layer variablity / shifting

Thanks for the link to the tension gage. Unfortunately I don't have any Prusa PETG to run the test fixture. Rechecking tension (on both machines)  it appears that they are a bit too tight and I loosened the belt and am running a Benchy on each.  

Posted : 06/04/2024 12:06 am
_KaszpiR_
(@_kaszpir_)
Honorable Member
RE: Need help with layer variablity / shifting

>A couple dozen kilos of filament through each.

Afair that's the amount that the stock nozzles start to wear out.

Or belts/screws getting loose, check them and tighten them.

See my GitHub and printables.com for some 3d stuff that you may like.

Posted : 06/04/2024 7:29 pm
Ed
 Ed
(@ed-19)
Active Member
Topic starter answered:
RE: Need help with layer variablity / shifting

The relaxed tension on the x-axis belt seemed to make the benchy look better but still way too many horizonal stacking errors. 

I will change ou the nozzles and run another benchy. I am starting to see some stringing so they could use a fresh nozzle.

Posted : 06/04/2024 9:03 pm
Diem
 Diem
(@diem)
Illustrious Member

OK, have you worked though this:

Mini - https://help.prusa3d.com/en/article/regular-maintenance-mini_133222

Cheerio,

Posted : 07/04/2024 12:07 am
Ed
 Ed
(@ed-19)
Active Member
Topic starter answered:
RE: Need help with layer variablity / shifting

Thanks for the link. I have done all the things on the list except change the nozzle and update to the latest firmware. I will change out nozzles in the morning.

Posted : 07/04/2024 1:20 am
Diem
 Diem
(@diem)
Illustrious Member

Although the nozzle may be worn - which would contribute, I would tend to suspect smooth rod cleanliness and lubrication which you have just addressed, or, failing that, something  wrong with an idler pulley.

Cheerio,

 

Posted : 07/04/2024 3:36 pm
Ed
 Ed
(@ed-19)
Active Member
Topic starter answered:
RE: Need help with layer variablity / shifting

The new nozzle made no appreciable difference in the print quality. The biggest improvement came from reduction in belt tension. I think that your idea about the idler may be the last potential issue. I have replacement idler pulleys so I will try... I am not looking forward to tearing these two mini's apart to replace the idler pulley. :(.

Posted : 07/04/2024 8:50 pm
Diem
 Diem
(@diem)
Illustrious Member

You may not need to replace them - if you're lucky there will be a few wisps of filament jamming them - loosen the belts and try to move them with your fingertip - are they smooth?  They may be out of line and rubbing against the housing - if so adjust or maybe print a new housing.

While you have the tension off try turning the stepper motors by hand, you will feel the steps but otherwise they should be smooth.  Make sure the stepper pulleys are not slipping.

Cheerio,

Posted : 08/04/2024 12:34 am
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