Aluminum Print Bed?

[old man emu]

Yeah. I'm looking at 48" x 48". I think I;ll have to talk to someone who works in fibreglassing to see how to make a fibreglass sheet that big. I could embed an aluminium sheet into the fibreglass, or just lay the resistor wire between two layers of fibreglass. I was going to use nichrome wire as the heater resistor because its resistance per metre is known, and I can work out the power consumption.

Old Man Emu

[Davo]

Wow. Printing an easy chair?

[WildZBill]

Heating the bed can take a lot of power. That's one of the problems when scaling up. For an 8x8 I have used 2 ohms of resistance at 12 volts, about 6 amps. At that level you have to worry about the resistance of your wiring and connections. I suggest that if at all possible you heat the bead with more voltage and less current.

[ronnytedeski]

Yeah. I'm looking at 48" x 48". I think I;ll have to talk to someone who works in fibreglassing to see how to make a fibreglass sheet that big. I could embed an aluminium sheet into the fibreglass, or just lay the resistor wire between two layers of fibreglass. I was going to use nichrome wire as the heater resistor because its resistance per metre is known, and I can work out the power consumption.

Old Man Emu

Wow, that's pretty huge. What are you planning on printing?

[old man emu]

Wow, that's pretty huge. What are you planning on printing?

Think about what sort of things are long and flat, or long wide and flat.

OME

[bstott]

@old man emu ---- Do you realize that the beds are generally heated between 60°C to 110°C? You will have one million four hundred forty thousand square millimeters heating? For we running on the old system that is ~15.5 square feet at 140°F to 230°F degrees. That is one BIG HEATER drawing A LOT OF POWER and putting our A LOT OF HEAT. A Suggestion ---- Print with PLA and no heat. Or Nylon. Otherwise you are going to need to call you electric company for more connections and a contractor for more insulation around the machine and the HVAC guys for more A/C for anyone in the area..... ;-D

More math --- on one of my machines heating up draws 190W for a small hot end and a 4" X 4" (102mm X 102mm) heated bed. For our calcs and the inefficiencies for a massive head bed we will assume my tiny hot end consumption is negligible. So, 190W to heat 16 square inches (10,486 sq mm) of heated bed. Ignoring rounding errors for discussions Your bed is ~2,232 square inches (1,440,000 sq mm). 190W/16sq in = 11.9W/sqin. times this by your 2,232sqin = 26,505W or 27kW... I don't even want to know what the Btu would be..... Whew its hot over there......

(disclaimer: It is 2am here, I'm tired... I may have really screwed up the math somewhere.... But, it is to be one BIG HEATER!)

Brian.