500mm x 500mm heated bed

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JoelDriver
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Joined: Mon Sep 25, 2017 2:54 am

500mm x 500mm heated bed

Post by JoelDriver » Mon Sep 25, 2017 3:27 am

Hello-

Has anyone seen a large heated bed at a reasonable price? I have been thinking of building a large printer...

Something like this one:
https://www.amazon.com/SainSmart-Creali ... words=cr10

Thanks!
Joel

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PartTimeRonin
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Joined: Mon May 22, 2017 2:33 pm

Re: 500mm x 500mm heated bed

Post by PartTimeRonin » Mon Sep 25, 2017 5:22 am

Get some aluminium plate(preferably cast plate but it can be expensive), machine it flat and stick silicone heater under it.
For that size 110/220VAC heater with SSR is better choice but you need to make sure to wire it properly and use protective earth.

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JoelDriver
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Re: 500mm x 500mm heated bed

Post by JoelDriver » Mon Sep 25, 2017 5:34 am

Thanks!

I had assumed 120/220 based on the size. I am guessing cast to reduce warping when heated?

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PartTimeRonin
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Re: 500mm x 500mm heated bed

Post by PartTimeRonin » Mon Sep 25, 2017 6:05 am

JoelDriver wrote:
Mon Sep 25, 2017 5:34 am
Thanks!

I had assumed 120/220 based on the size. I am guessing cast to reduce warping when heated?
110V or 220V depend on what country you are in.
If you don't know about electric much I suggest find someone who know before go with main power heater(main voltage can kill you if not done properly)
Otherwise just use 24V DC instead.(You will need quite big PSU and wire thichness for bed that size though, or wait quite a long time for bed to heat up)
Cast plate seem to be less affect by heat but many people use regular plate just fine, make sure it isn't too thin. 4-5mm should be good.

Tomasz Stawarz
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Joined: Sat May 27, 2017 3:27 pm

Re: 500mm x 500mm heated bed

Post by Tomasz Stawarz » Thu Sep 28, 2017 8:18 pm

As far as i remember Tom said once https://youtu.be/eure74A9HNc?t=5m15s (an it is consistent with my own calculations) you need about somewhere between 0,6-1W per 1 square centimetre. If You would like to have 50x50cm heatbed it will be whooping 1,5-2,5kW! And I'm using because it is somewhere between one third and a half of combined power of all heaters I have in my flat... But back to main topic - 1,5 kW/24V is 62,5 A, and 2,5kW/24V is over 100A. You would have to use some insanely thick cables to connect that, and monstrous power supply, not mentioning that there (as far as i knew) is no controller board that would be able to deliver more than 30 something amps - so maybe half of what you need considering lower number. Basically if you are trained in connecting mains voltage pay someone to do that, and probably even then you will be better of in money departament taking into account prices of DC-DC SSR and that power supply. Also I would recommend 5-6mm aluminium plate, and really, really good thermal insulation under heater. You can try 5-10mm aerogel mat - in Poland there is company called POROGEL but you will probably be able to buy this kind of stuff through internet anywhere you live. It will allow you reach higher temperatures in shorter time, and spend less power on it. Yea, thats all i think.

antineutrino2
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Joined: Sat Oct 07, 2017 8:45 am

Re: 500mm x 500mm heated bed

Post by antineutrino2 » Sat Oct 07, 2017 8:54 am

JoelDriver wrote:
Mon Sep 25, 2017 3:27 am
Hello-

Has anyone seen a large heated bed at a reasonable price? I have been thinking of building a large printer...

Something like this one:
https://www.amazon.com/SainSmart-Creali ... words=cr10

Thanks!
Joel
500x500 bed http://www.ebay.com.au/itm/322098431336 😉

Tomasz Stawarz
Posts: 39
Joined: Sat May 27, 2017 3:27 pm

Re: 500mm x 500mm heated bed

Post by Tomasz Stawarz » Mon Oct 09, 2017 5:18 pm

Yea, but still this thing is between 320-570W depending on voltage you will be pushing through it. With 24V it is also almost 14Amps of current, and with 32V it will be even higher like 18Amps (but higher power also). Taking higher power into consideration 570W and dividing it into 50cm^2 it is: 570W/50cm^2=570W/2500cm^2=0.228W/cm^2 . So it's not even half of what should be pushed into this thing.
I also have to add that only reasonable solution i can see is to either:
- switchable heatbed - one bigger 50x50cm powered with main voltage and operated with SSR, and smaller one - like 20x20cm (having SSR and so on i would also go with main voltage.
- double or triple concentric heating zones 50x50cm heatbed runing on main voltage with SSR also. So for the smallest print you have somewhere around 15x15-20x20cm first zone, and one or two bigger ones.
Saying that I have chosen second solution with my planned 40x40cm build platform. Also insulate, insulate, and again insulate. I don't knew maybe in other countries electricity is so freaking cheap that people does not give a crap about that but if not for economical matter than for a matter of good design heatbed should be really very well insulated on bottom side (yeah i knew that convection is moving heat upwards but still I can assure you that not insulating bottom of your heatbed is eating considerable amount of its effectiveness).

Vertigo
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Joined: Mon Jul 31, 2017 9:00 am

Re: 500mm x 500mm heated bed

Post by Vertigo » Mon Oct 09, 2017 11:19 pm

You're exaggerating. 0.5-1W per cm² is overkill. It would mean 500W for my prusa MK2 bed. In reality, it doesnt even draw 1/3 of that and yet it still heats up to >100C in a few minutes. And Im guessing the OP doesnt plan on printing ABS with such a mega bed, 50-60C would be enough for him..

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LugNut
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Re: 500mm x 500mm heated bed

Post by LugNut » Sun Oct 29, 2017 9:45 am

I have a strange Idea... and everyone can laugh all you want...

Example hot plate URL:
https://www.bestbuy.com/site/elite-cuis ... GbVP9g_cEg

The hot bed doesn't have to be like the others moving tables; it doesn't have to move...RIght?
A machine that size can lift the XandY the same way we lift the hot bed table.
It is not impossible...in fact someone raised XandY to 3d print a house
https://www.youtube.com/watch?v=GUdnrtnjT5Q

If your ok with not moving the hot bed... Now you can just throw a bunch of heat in a BOX
and call it a heated bed... I suggest this because moving a lot of power back and forth really does
cost a LOT of money to do it right with the right electrical cables... and I doubt that anyone could
sell a machine that wasn't wired by code.

I would start with a box metal with adjustable feet and
fill it with sand, to insulate the bottom; then heating coils and something to detect the temps...
and top it off with a thick copper sheet and on top of that a large granite slab like they use in a pizza oven.

Ok, it a silly idea, but not as silly as my first idea with hot air guns.... ;-)

All joking aside; look at electrical ovens or stove tops and get inspired....because that is actually what your trying to do... isn't it?

I got this idea while ordering some Chinese food and watching the cook flip all that good food on
a large hot flat piece of metal..... and I thought... umm I am hungry... LOL have a great day folks
I want the PRUSA MK3 CONTROLS FEATURES and its 200mm x 300mm hot bed
and the MARK 2 enclosure, Bowden duel j-heads attached to bondtech extruders
or something geared 7:1 so 3mm filament is still an option. PM Please

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