Need bigger heatbed for bigger Prusa

I'm building my second Prusa, making this one larger and 24 volt. I could handle a heatbed up to about 350 x 350. Does anyone have any idea if such a heatbed can be found? I will probably settle for anything larger than the 200 x 200 heatbed on my current prusa. Biggest I've seen so far is 200x300. It that's the best I can do I guess it will be ok.

I plan to use the Rambo board again and stick with Marlin. Anything I need to be cautious of with 24 volt would be great to know. Thanks in advance.

Charlie

QUBD has a 12" x 12" (300 x 300) silicone rubber heated bed which would be much better than the standard 8" x 8" that most people have.

QUBD Silicone heat bed

This is another exampe of "be careful what you ask for". Size on the QUBD 12 X 12 is exactly what I was hopping to find. What I didn't expect is 20 amps. I'm going to need to figure out how to handle this. Right now, my existing reprap is on a 12 x 20 (240w) power supply. Now they are recommending a dedicated power supply that can handle 20 amps for this QUBD bed.. At this point, I am plugged into a 15amp circuit from my fusebox and having no issues, so I am sure the 240w is not a problem, but I was plainning to go to a 24v 20 amp p/s. I think another 12/20 on top of that would be tough.

Is there anyone else out there that has run into this kind of draw on a regular house 15amp circuit? First thought is Don't Do It I guess I can talk to an electrician about going to a 40 amp circuit, but I don't even know if that's possible.

.

you are fine, 15ax120v= 1800 watts, so assuming 70% efficiency you could have up to a 100 amp 12v supply, although that would cost you a pretty penny. I made a 12x12 pcb using some legal paper and my laser printer to do a toner transfer onto a double sided 12" pcb, I dont know how many amps it draws but its above 20. you can get a 12v regulated 30a power supply on amazon for 30 bucks, and it allows you to adjust the voltage too.

You are confusing your amps at 12/24 volts vs 120

12 volts x 20 amps = 240 Watts / 120Vac = 2 Amps

24 volts x 20 Amps = 480 Watts / 120 vac = 4 Amps

Total 6 Amps, so 15 Amp circuit breaker is fine.


For example, there are about 10 hair dryers on Amazon that are over 1500 Watts, which is well over 10 Amps. Additionally, hair dryers usually will plug into GFCI which are notorious for tripping easily.

Quote
aduy
I made a 12x12 pcb using some legal paper and my laser printer to do a toner transfer onto a double sided 12" pcb, I dont know how many amps it draws but its above 20

You can use a laser printer to make a heated bed? Instructions? Link?

Easiest thing to do for a large heated bed is get an AC powered heater pad like this, and control it with a solid state relay like this. Stick the heater pad to an aluminum spreader plate (3mm thick or so). Wire the heated bed output from your electronics to the relay, and wire one side of the heated bed through the relay and the other directly to mains.

Be careful if you do it this way though, 120VAC can hurt. Make sure all electrical connections are covered and isolated.

I run my RepRap this way, with a similar 12in x 12in heater pad from McMaster.

Edited 2 time(s). Last edit at 10/23/2013 10:30PM by NewPerfection.

---

Help improve the RepRap wiki! Just click "Edit" in the top-right corner of the page and start typing. Anyone can edit the wiki!

I dont have a tutorial, but basically i just used this site to figure out the trace size i needed, which was 5mm, then just made a pattern using inventor for the traces, and converted it to an stl then into an svg. then I printed it out on legal paper in two parts. then I used an iron to transfer the toner onto the pcb. it was kind of a pain in the ass because i didnt have the correct transfer paper. then I soaked the paper and scrubbed it off as best i could leaving the toner attached. then for the etching solution it was pool acid and hydrogen peroxide.

suprisingly it came out mostly ok, I just soldered over the bad parts. so pretty easy to make and considering ive only etched a small pcb before it came out pretty nicely.

also since there are two pair of traces it can be configured for either 24 or 12 volts

Cool, thanks for the followup.

I found a howto: Etched Heated Bed Howto

then i used a ground granite tile instead glass, the glass i got wasnt well cut.

NewPerfection: I went ahead and ordered the parts you indicated. This made more sense to me than buying another power supply to go with the 24v p/s for the Rambo, Jhead and motors. I stumble through with the help of my efriends, but I always get there.


I still want to try making a pcb bed, but I can do that for the next one.

Thanks all.