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Hey guys,

So I’ve started work on a large format (500mm x 500mm x 350mm) printer recently, and I’ve got a lot of details ironed out. One thing I’m missing, however, is a heated bed. I intend to use a 450mm square silicone heater as my heating element - most likely driven by mains voltage and switched by an SSR. My issue is that, with a heated bed of this size, I’m concerned about my bed warping in the center due to weight or as heat is applied. I was planning on using two aluminum plates to form my bed. One would be a stiffer plate that would directly mount to my Z-axis bearings and lead screws, and the other would sit above it, anchored by leveling screws at each corner, with the heating element stuck to the bottom. What I’ve got in mind is pretty much a scaled-up ultimaker heated bed. Does anyone know where I can get aluminum at this size, and whether or not what I have planned is a good idea or not? I’d like to make sure that my bed is as flat as possible.

PS - I hate glass build plates. I know they’re supposed to be super flat, but I’m not a fan. If it comes down to it, I’ll use one. Ideally, however, I’d like to avoid a glass plate.

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Go out to the Folgertech site and look at the FT-5 to see how that bed is and also to the 713 maker site to see his upgrades for it.

https://folgertech.com/

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I would recommend you to get some milled flat cast aluminium tooling plate about 10 mm thick. Then you would have a plate that is about as flat as it will get and if you mount it properly (i.e. Three mounting points instead of four and allow these to move as the plate expands and contracts with the heat) you should not need more than one plate. This is at least how I’ve done it on my printer (90*90 cm) and it works wonderfully.

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Do you have any issues with heat loss or too much power being used? I was concerned that having a plate that thick would be difficult to heat

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That’s pretty much what I had in mind. I like the pocket milled in the back for the heater. It’s a nice touch.

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I’m running a 2,2kw heater for the plate which heats it up in about five minutes depending on what temperature I want. If you want reasonable heating times you should aim for a power density of at least 0,3w/square cm. the heater will take quite a bit of power but you will have an unbeatable build plate.

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