Bed Heater

I have a Tantillus with a 5" square aluminum print platform 1/4" thick. I would like to add a heating system to bring the temperature up to about 60 degrees centigrade for printing PLA. I have a 415 watt coil of nichrome wire that has a total resistance of about 18 ohms. When I apply 13 volts DC across it, it brings the temperature up to something over 150 degrees very quickly. I'm thinking I can embed this in grooved, 1/2" thick calcium silicate under the aluminum bed with a thermistor to measure temperature. I'm also thinking I should also be able to connect this directly to the bed heater on my Sanguinololu board. Anybody see a problem with this plan?

Thx...
Chuck

At 18 Ohms resistance and 12V DC, that's only 8W of power. That may be enough to bring the nichrome by its self to 150*C, but you'll have trouble getting your build platform even to 60*C. I would recommend a shorter length of nichrome, maybe totaling 5 Ohms or so, which would give you almost 30W of heating power.

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Controller should be able to provide the current to power it. However the energy required to heat the aluminum plate and the surrounding air to the plate because it is a thermal conductor would be really high. I think if you surrounded the bed with insulation, and properly insulated the sides it may heat up over a period of 30 minutes or so...


Reducing length of nichrome would seem to be the correct solution; however you will need to have it powered by a relay, or modify the controller used with a wire going along the traces to the power terminals on the board. There are issues with the trace burning up with high current.
traces to the power terminals on the board. there are issues with the trace burning up with high current.

I use 2 peltier pads, bed heats up very quickly, pwm controlled, gets to 100c in under 3 mins