Hey guys(and gals), I was hoping someone might be able to tell me where I can find/get a heat source for a hot bed. Some friends and I are designing our own printer, build volume ~406mm x 889mmx 584mm(16"x35"x23"), and are struggling with this last part, “How to heat the bed.”
We’re trying to keep our options opened so our bed isn’t constructed yet(frame and everything else is). We were hoping to figure out how to heat the bed, then “design” it.
The first thought that occurred to me was, we could use a 12"x12" hotbed and mount that in an aluminum sleeve welded to the bottom of our print bed… But I suspect that between the power consumption and time to heat the entire surface, it would be impractical.
So, how about it gang? Any thoughts?
Also, I should not, we are trying to keep this cost effective, so far everything minus the hotbed, we are at just under $300, with a budget <$400.
check out this link. I’ve purchased large heatbed from them on ebay, but you can call them (phone# is in the posting. They are in Arizona.). They do custom PCB and high power heat beds.
You could use multiple Kapton heaters, which you can stick onto an aluminium plate (for heat dispersion). I’d suggest to use 24V instead of 12V, otherwise you’ll have to switch really large currents (>40A or so). I believe there’s also 110/230V heaters.
Also, I’d advice to make the build volume enclosed. First of all because you’ll need less power for the heated bed. Second, with a printer that large you’ll propably get lots of warping, a heated chamber will prevent that.
Can I recommend if you are going to make a heat bed that you do it in zones. You can then heat the area that you are printing on. i.e. small print zone 1, medium print zone 2 large print zone 3. alternatively you could have integrated zones so that they better distributed heat. good luck with your monster printer, it sounds like it will be awesome. any pictures?
Please forget the PCB type ones they are slow and need a strong DC powesupply.
As suggested already, go with silicone heaters here is a 400 x 500 witch works from AC POWER!!! so no need for a big power supply and even a thermistor is installed in it. :
How the hell you can connect it to your electronics? With a Solid state relay (SSR) DC to AC type (DC part connected to you electronics witch simply switching on and of the bed at connected to the relays AC part.)
I would also advise to section the bed for a 400x500 and a 400x300 area (based on the silicone heater I linked, but its up to you how to slice it up).
The only problem will be the ALU plate in a such a size(you need this plate to stick the silicone heaters to its bottom) you have to use at least 6MM thick one as the middle part maybe be lifting due to the heat.
I would also suggest to drill small holes pattern into to table, like the Zortrax’s table, this way the heat will not bend the alu plate that much, and with printing a raft witch put/push the plastic into to holes it will stick to the bed really well during the print time. (if you have a printer already just look for a faulty microwave, its door will usually have a similar mesh in it, just cut the mesh out, put it into your printbed, level the Z axis and test it)
I’d be concerned about even heat distribution, if you place a sleeve/plate on top of an off-the-shelf hotplate that’s smaller than your total print area. I had issues with this in the past. Perhaps consider four smaller ones that all evenly heat their respective quadrants properly with a thin plate on top (haven’t tried this, myself). Glass could work, since it’s level and easy to cut into the exact print surface area dimensions. Not sure if you’re planning to commercialize this, so my suggestions may not work out in that regard… Anyway, just some quick thoughts for you.
I heard back from the silicone heater manufacturer concerning how close the resistive element can be from the edge of the silicone rubber heater. Typically they design the traces to set back from the edge .125”. Occasionally for 120V heaters, they have reduced the set back from the edge to .094” to enable a longer circuit length. That would result in a much smaller distance between outer-edge traces at the seam of two heaters. With a glass bed I imagine the temperature would be fairly even. If I can get ahold of two heaters with a small edge set back I’ll do a test.
