Magnetic print sheets AND glass

So my printer didnt come with a stock removable printbed. My inital solution was a glass sheet, which has worked pretty well.

Since I got my seccond printer (prusa mini) i have discovered the joy of the spring steel sheets. So im in the process of cleaning my build plate and saw a comment on this forum pointing out an issue with a glass plate over the magnetic sheet. Something to do with heat degrading the magnet.

So my question for the hive mind is this. With the spring steel sheet on, or off, would useing a glass print surface overtop be detrimental to the magnetic sticker?

My reasoning for this train of thought is i have a good glass sheet, so if im not satisfied with the steel sheet i can go back to the glass. I like how the glass works with PLA but have been hesitant to start PETG on glass.

This printer is currently only used for PLA but may be used for PETG in the near future.

I’m doing the exact same thing. I had problems with PolyCarbonate wherein the heat required was causing the magnetic material to de-laminate from the build surface material. Mind you, I ended up clipping them together and when the build surface cooled the glue holding the two materials together hardened and I had my build plate back. But that’s not the problem you’re asking about.

In response to that problem, I bought some glass and have loved it so much I haven’t gone back. Which means my magnetic material has been baking under glass for some weeks now. When this current print is finished (in 4 hours), I’ll test the magnetic surfaces and see if they still stick. I’ll fill you in this evening.

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I have no experience with glass and magnets. I do have some experience with magnets. You can buy heat resistant magnets. Regular ones might be ok but as soon as they are covered the heat will build (thermal blocking) and they will lose strength.

This might help.

Stupid, stupid, stupid. I’ve started another print but forgot to check how the magnetic material survived. Sorry. I’ve put a magnetic mat over the printer’s control panel so I won’t forget at the end of this print.

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OK. so putting a magnetic bed over my controller worked, and the answer to your question is that, after 3 weeks of being under glass, the magnetic surface is unaffected. Mind you, I’ve only been printing at PLA and PLA-F bed temperatures (70C max).


I appriciate you coming back with the 3 week input. Do you just have the magnetic sticker thing under the glass when your printing useing the glass, or do you keep the spring steel sheet under the glass too?

Thanks for the link. It seems that the flexable magnet sheet i have will likley be unhappy trying for ABS and other high print bes temp material. Though since the magnet will cover 240mmx240mm square, im not too worried about losing its magnitism. More so if the material will start to fail. Im guessing since its a popular option for many printers that it cant likley degrade that quickly to be a concern unless i do push it to higher temperatures.

I don’t have a spring steel surface, just the Creality magnetic mats. They come with a stick-on magnetic surface that goes on the aluminum plate. The glass sits on that lower magnet. I tested it with a piece of metal and with the Creality upper magnetic mat. Also, the magnetic mat that I had used with PolyCarbonate - the one where the glue holding the mat surface to the magnetic sheet melted - also still works. That is to say, even though I melted the glue holding the magnet on the magnet itself is OK.

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So how magnets (at least ferrous magnets) work is that at a certain temperature, they lose their magnetic properties temporarily. For steel this is around right around the temperature that the crystals realign and you can harden the steel, which is why black smith’s and knife makers use magnets to judge when to oil quench to harden.

I dont think our printers get hot enough to remove magnetic properties

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80ºC for the cheaper magnets. PlA not a problem but PC or certain. Most printers have high heat magnets but DIY often use cheap ones that end of failing.

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