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[Closed] magnetic bed - how stable?  

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cypis.r
(@cypis-r)
New Member
magnetic bed - how stable?

Is there any specific maximum temperature to use on MK3's heatbed?

I worry about magnets loosing their strength over time - temps in range of 100C are quite harmful for those...

Posted : 23/12/2017 4:32 am
dryja123
(@dryja123)
Honorable Member
Re: magnetic bed - how stable?

The heatbed max temp setting is 125c.

Posted : 23/12/2017 5:14 am
kelchm
(@kelchm)
Eminent Member
Re: magnetic bed - how stable?


Is there any specific maximum temperature to use on MK3's heatbed?

I worry about magnets loosing their strength over time - temps in range of 100C are quite harmful for those...

I believe the magnets being used are samarium cobalt, which have a higher tolerance to heat than neodymium magnets.

Posted : 23/12/2017 5:54 am
Chris
(@chris-16)
Reputable Member
Re: magnetic bed - how stable?


I believe the magnets being used are samarium cobalt, which have a higher tolerance to heat than neodymium magnets.

I was wondering by what witchcraft they were doing that. I was dropping neodidlies into a print and at just 90c they were dead within seconds. so i had no idea how they were making that work.

Posted : 24/12/2017 12:48 am
cypis.r
(@cypis-r)
New Member
Topic starter answered:
Re: magnetic bed - how stable?

Turns out, standard neodymiums are rated up to 60 or 80C.

But...there are grades with operating temperature as high as 230C
(vide https://www.duramag.com/neodymium-magnets-ndfeb/available-neodymium-magnet-grades/ )

Posted : 24/12/2017 8:28 am
dean.c2
(@dean-c2)
New Member
Re: magnetic bed - how stable?

reviving an old thread but a little research on this subject reveals technicalities about magnet type compatible with 3d printing. I explored this in the past but stopped research after finding "all magnets permanently reduce magnetic strength after 100C for extended periods". Well, it's more complex. For example, N42 magnets designed for high heat use will work fine up to 180C. Additionally, a little bit of math will reveal the "permeance coefficient" for a specific magnet. Essentiall, the rule of thumb to follow for normal neo magnets is keep it as high as it is wide - the magnet won't lose strength until ~150C. Now, Prusa's magnets aren't as high as they are wide. So they're (hopefully) using N42 high heat magnets.

Posted : 17/02/2018 3:57 am
Neolker
(@neolker)
Re: magnetic bed - how stable?

I just look at the specs of Prusas magnets:
Maximum working temperature is 150 °C 45SH Neodym Block Magnet - NiCuNi

Posted : 17/02/2018 1:05 pm
julissa
(@julissa)
New Member
RE: magnetic bed - how stable?

I agree with dean-c2, it is true that the N42 neodymium magnet performs better in this respect, and this type of magnet can maintain normal operation at high temperatures.

Posted : 29/05/2020 5:39 am
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