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Heatbed shifting during print  

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denoise
(@denoise)
Active Member
Heatbed shifting during print

Hi,

I was just printing the final files for the Mini-modified Ikea Lack Enclosure V2 and I found this mess on the morning:

It seems that the nozzle touched the part moving the whole printer bed and shifting the following layers.

I'm printing the parts using PETG and I found the original slicer files where adding supports that are too difficult to remove, so I changed some settings for the supports:

I don't think that this changes could be the cause of the problem but I post them here anyway.

Another think to note, Because I was using cheap PETG form Amazon I had to remove the nozzle and clean it with a heat gun and a needle, reinstall it and recalibrate the first layer before printing this part. When I installed the nozzle again, I realised that the heating block sits just a little bit loose on the hot end but I couldn't find a way to tighten it and I though this was normal on the mini.

Can anyone guide me to solve this issue?

Thanks!

Posted : 07/10/2021 3:49 am
fuchsr
(@fuchsr)
Noble Member

Could be all the usual suspects for layer shifts, i.e., wrong belt tension, grub screws not tight or not secured against the flat side of the motor shaft, etc etc. Or could be the nozzle hitting infill. Has happened to me a few times on the LACK enclosure parts that are by default sliced with grid infill (which crosses within a layer and can create little pileups that can hit the nozzle). Never had a problem since switching to gyroid or adaptive cubic infill. Or it could be something leaking from the hot end if you didn't assemble the hotend correctly when you replaced the nozzle. You said it's a bit loose, so I'd start there and disassemble/reassemble it and recalibrate Live Z.

Posted : 07/10/2021 11:16 am
denoise
(@denoise)
Active Member
Topic starter answered:
... and so it is evolving the problem

The shifting occurred clearly because the magnetic steel sheet moved, so belt tension is probably not the issue.

I managed to print a small part with red PLA and I tried to print the Ikea Lack part with black PETG again. On the first layers the nozzle released occasionally some small red clots of the previous filament and some layers where really stringy.

Some minutes later, the heaterblock released some old red PLA and some of the loaded black PETG from the top, so everything leads me to think there is something wrong with the installation of the nozzle.

Posted : 07/10/2021 7:27 pm
fuchsr
(@fuchsr)
Noble Member

That picture looks pretty clear cut. Almost certainly the nozzle not tightened properly against the heat break.  Just follow the directions in the Prusa knowledge base when you reassemble them hotend and make sure you hot tighten at 285 degrees. 

Posted : 07/10/2021 7:35 pm
BogdanH
(@bogdanh)
Honorable Member

 

Posted by: @denoise

The shifting occurred clearly because the magnetic steel sheet moved, so belt tension is probably not the issue.

I think it's impossible that print sheet would move on heatbed during printing -magnets are just too strong. I tried to move sheet by hand and needed quite some force for that.

[Mini+] [MK3S+BEAR]...
Posted : 07/10/2021 10:04 pm
Diem
 Diem
(@diem)
Noble Member

I think it's impossible that print sheet would move on heatbed during printing -magnets are just too strong.

With large objects that are firmly stuck to the print-bed warping sometimes bends the bed thus reducing the magnetic attraction...

The solution is to follow the usual steps to reduce warping.

Cheerio,

 

Posted : 08/10/2021 2:46 am
denoise
(@denoise)
Active Member
Topic starter answered:

actually that is exactly what happened. If you look a the first picture you can notice the shifted print sheet. I was printing with PETG and no warping occurred.

Posted by: @diem

I think it's impossible that print sheet would move on heatbed during printing -magnets are just too strong.

With large objects that are firmly stuck to the print-bed warping sometimes bends the bed thus reducing the magnetic attraction...

The solution is to follow the usual steps to reduce warping.

Cheerio,

 

 

Posted : 08/10/2021 7:01 am
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