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Uneven temperatures across heatbed  

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Alabuk
(@alabuk)
Member
Uneven temperatures across heatbed

First off, I bought my printer used, so I don't know all of it's history.

I downloaded one of the Z-offset calibration patterns from Printables.  I am printing with PETG on a satin sheet.  I had a lot of trouble with the PETG not sticking in front third of the heatbed.  I used a laser thermometer to measure the temperature at various points on the heatbed, and the front third of the hotbed is 10-15C cooler than the rest of the bed.  Any idea why this might be happening?  Or is it just time to replace the heatbed?  

     

This topic was modified 4 months ago by Alabuk
Posted : 30/08/2024 10:07 pm
_KaszpiR_
(@_kaszpir_)
Prominent Member
RE: Uneven temperatures across heatbed

can you provide temperatures with the bed sheet on it?
Either way maybe bed quality wasn't the best so maybe it's worth to replace.

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

Posted : 31/08/2024 7:29 am
Diem
 Diem
(@diem)
Illustrious Member

Variation like that can be caused by as litle as a light draft...

but we can't really judge the first layer until you get the print sheet properly clean - look up threads here about cleaning.

Then protect from drafts, allow time for the print sheet temperature to stabilise and try again.

Come back if problems persist.

Cheerio,

Posted : 31/08/2024 10:45 am
Alabuk
(@alabuk)
Member
Topic starter answered:
RE: Uneven temperatures across heatbed

Here’s more of the steps I’ve taken debugging this issue:

I have cleaned my sheet with dish soap and water, followed by 99% IPA with no improvement  
I’ve dedicated one side of this sheet to PETG and the other to PLA.   I get similar results with PLA on the PLA side of the sheet.  
I print in an acrylic enclosure, and I get the same issue with the door open and closed. 

Posted : 03/09/2024 12:38 am
_KaszpiR_
(@_kaszpir_)
Prominent Member
RE: Uneven temperatures across heatbed

Replace the bed or learn to limit used area when printing.

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

Posted : 03/09/2024 6:11 am
Diem
 Diem
(@diem)
Illustrious Member

Your pictures clearly show poor adhesion even where the first layer looks OK  - if regular cleaning isn't working then maybe it's time for a drastic clean...

Work neat dishwashing detergent (Dawn/Fairy) into the surface of the sheet - wait for ten minutes then rinse it away with very *HOT* water.  Dry by dabbing with a fresh paper towel, handle by the edges only and finish drying by placing it on the heatbed and raising the temperature.

Adjust your first layer Z offset so the centre of the pattern is best and show us the result.

Cheerio,

Posted : 03/09/2024 6:45 am
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