So I'm building a custom heated bed, loosely following the instructions for Robert's heated bed. I have some questions.
I cautiously connected everything up for the first time, there were no big explosions/balls of fire. Bit smelly, I'm not entirely sure which part is causing the smell, but it wasn't burning.
I have a 3mm aluminium plate, this is painted with black stove paint. I figured it would provide a tough insulated base. The wire is haphazardly strung around the bed, there's 7 metres in total which has a resistance of 0.8ohms.
It gets warm fast, using a cheap heat measuring gun the middle part reached 160degrees. I had it on for about 3 minutes, it seemed to peak after about 30 seconds I'd guess, then just incrementally warmed.
So my multimeter gave me the 0.8ohms figure, which I think is too high. It is 7m of 24swg (.56mm) wire, which should be 0.47ohms according to this calculator. The wire is enamelled, so I burnt off the enamel AND sanded the ends before measuring. So which is more likely to be accurate?
At 0.8ohms it would draw 15 amps. 0.47 would be 307watts which would work as that power supply is 360watts.
I've figured out the electronics side of it now, I just need to built the actual bed. This one, the wire is stuck on with Kapton tape which is already peeling off, so I need to rethink that. Part of that is the way I made the loops of wire. They were springing all over the place.
[attachment 42821 HeatedBed.jpg]
I cautiously connected everything up for the first time, there were no big explosions/balls of fire. Bit smelly, I'm not entirely sure which part is causing the smell, but it wasn't burning.
I have a 3mm aluminium plate, this is painted with black stove paint. I figured it would provide a tough insulated base. The wire is haphazardly strung around the bed, there's 7 metres in total which has a resistance of 0.8ohms.
It gets warm fast, using a cheap heat measuring gun the middle part reached 160degrees. I had it on for about 3 minutes, it seemed to peak after about 30 seconds I'd guess, then just incrementally warmed.
So my multimeter gave me the 0.8ohms figure, which I think is too high. It is 7m of 24swg (.56mm) wire, which should be 0.47ohms according to this calculator. The wire is enamelled, so I burnt off the enamel AND sanded the ends before measuring. So which is more likely to be accurate?
At 0.8ohms it would draw 15 amps. 0.47 would be 307watts which would work as that power supply is 360watts.
I've figured out the electronics side of it now, I just need to built the actual bed. This one, the wire is stuck on with Kapton tape which is already peeling off, so I need to rethink that. Part of that is the way I made the loops of wire. They were springing all over the place.
[attachment 42821 HeatedBed.jpg]