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Printshee doesn´t fully stick to heatbed  

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kaouch2000
(@kaouch2000)
Active Member
Printshee doesn´t fully stick to heatbed

Hi guys, I´m already prusaprinting for years without any big troubles. But now there is one problem I can´t get solved.

When I place the printsheet, no matter which one, on the heatbed it is flat on it, after heating up the heatbed the printsheets bending in the center.

First thought was maybe a magnet had fallen off in the middle. BINGO! Reglued the one which felt of in the center. But no change. Still bulging in the center :/

Any idea? 😀

Probably it´s an idiotic mistake of mine.

This topic was modified 2 months ago by kaouch2000
Posted : 01/12/2022 7:56 am
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE: Printshee doesn´t fully stick to heatbed

Or is there a need to renew all the magnets from time to time? I read stuff about, that neodym-magnets could become weak because of heat. But I assume Prusa probably (hopefully) will have special ones for the heatbed.

Posted : 01/12/2022 8:36 am
Diem
 Diem
(@diem)
Famed Member

Pictures?

Your print bed doesn't get anywhere near hot enough to derange the magnets.

Cheerio,

Posted : 01/12/2022 10:28 am
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE: Printshee doesn´t fully stick to heatbed

Hi there, thx for replying,

I´ll post a video as soon as possible (unfortunately tomorrow), you won´t see it on a picture. But maybe I can explain the problem a bit better:

When the heatbed is cold the PEI-Sheet or the structured sheet are laying flat on the bed. When the bed heats up, the printsheet starts to bend in the center. There is a little hill in the center which you could press down to the bed. That´ s why the z-calibriation is going to fail when the extruder reaches the center.

 

Sorry to be not at home till tomorrow to post you a video instantly.

Thx  Andrew

Posted : 01/12/2022 10:43 am
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE: Printshee doesn´t fully stick to heatbed

Posted : 01/12/2022 10:45 am
Diem
 Diem
(@diem)
Famed Member

Er, I should have been clearer.  I was hoping to see some indication of the degree of bending - say a straightedge laid on the sheet...

Cheerio,

Posted : 01/12/2022 12:11 pm
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE:

IMG_0397

 

I hope you can work with that 😀

This post was modified 2 months ago by kaouch2000
Posted : 01/12/2022 6:31 pm
Thomas Lynch
(@thomas-lynch)
Trusted Member
RE: Printshee doesn´t fully stick to heatbed

Does the heatbed do this without a print sheet on it when it is heated up?

Posted : 01/12/2022 10:15 pm
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE:

No, the heatbed itself stays flat. Also when I take off the hot printsheet from the heatbed it remains bended, as long as it cools down. While being hot you can easily bend/push it from one side to the other and it will make a noise like a click frog, if you know what I mean. Could it be, that the sheet gets to hot in the center. No matter what printsheet I use.

This post was modified 2 months ago by kaouch2000
Posted : 01/12/2022 11:13 pm
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE: Printshee doesn´t fully stick to heatbed

But maybe this „clickfrogging“ is a normal behaviour, I didn‘t care in the past. Usually I leave the sheet on the printer as long as it is warm.

Posted : 01/12/2022 11:32 pm
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE:

Latest: I reglued all loose magnets, no change so far. The sheet starts to warp at 80 degrees bed temperature. The bed is very hot in the middle, at the edges only warm.

I have a cut copper-strip (picture below) at the surface of the bed which is there for almost half a year and didn´t make any troubles so far. Could that suddenly cause the heatbed to only warm up in the middle? Is there a possibility to easily repair/sold the strip or to I have to order a new bed

This post was modified 2 months ago 3 times by kaouch2000
Posted : 02/12/2022 8:13 am
kaouch2000
(@kaouch2000)
Active Member
Topic starter answered:
RE: Printshee doesn´t fully stick to heatbed

Problem solved: After soldering the copper trace and finished with nail polish the bed heats up evenly and the sheet doesn´t bend anymore.

Maybe someone has the same problem, so here is the solution 😀

Thank you all for your help!

Posted : 02/12/2022 10:46 pm
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