Heated Beds- wiring up in series?

Hey all,

Just seeking some advice on wiring up multiple heated beds...

One day I plan to make a larger printer than the one I have, I'm basically thinking of using the stock motors and circuit boards of a RepRapPro Tricolour Mendel and putting it all on a sturdier frame.

The limiting factor I see in my plan is that the stock heated beds only come in 200x200mm size.

SO, I figured that I could use four heated beds to make a heated bed with the X & Y sizes around 400x400mm.

I would think that wiring up the heated beds in series would do for connecting them to the circuit board, but I was don't know what, if anything, needs to be beefed up on the board/s to handle the extra three heated beds.

I'd be grateful for any advice I can get in how to handle wiring up four heated beds.


Cheers

Matt

There are other, larger heaters available. There is a silicon rubber one around. I am not in the position to find the link at the moment but the retailer is on these forums and usually puts a link on when people enquire. I haven't used it so I can't say how good it is.
James

... when driving multiple heaters - connecting in series adds the needed voltages (e.g. four 12V-heaters needs then 48Volts) but use the same current, while connecting them in parallel adds the needed currents with same source voltage.

I'll wire them in parallel with individual temp. controlling, so you can adjust every heated bed to the correct (or different) temperature, what's not necessary true if they have different parameters (e.g. resistance) ...

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Viktor
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I'm thinking you're going to need extra circuitry here, although I've only really dealt with Sanguino and RAMPS. 4 heat beds isn't going to get enough voltage if you wire them in series, like Viktor said, you would need 48V to run that (Voltages in series add up), so your best bet would be to wire them in series. 12V at ~11A, make sure you check amperage draw, is 132W under Ideal conditions. You would need at least a 530W PSU to power the heat beds alone, plus the ~60W for the 12V 5A line. But these are Ideal calculations with a 100% clean power supply, so always go for a higher Wattage rating to compensate for dirty/unstable supply under full load

as for the extra circuitry, you would need a controller board that allows 5 thermistors, or if you have an extra microprocessor (such as an unused arduino) you could wire the 4 heat beds to the analog inputs and create a simple sketch/program that checks their temps and have it output analog values to the main 3D controller board the average of the 4 temperature readings.

Edited 1 time(s). Last edit at 06/14/2013 08:48AM by isonoob.

Yes you can wire them in parallel together although you will need a very large power supply AND a relay to drive them as it will overload all of the standard electronics. We have a 300x300 bed (out of stock) and a 600x600 bed (also out of stock) and can make custom sizes although there is a pretty hefty lead time at the moment. You will need an energy density of about 1.5 watts per square inch to reach the required temperatures on such a large area without it taking a very long time.

Chelsea - QU-BD

hi sir...as per wat you have mentioned. How to provide parallel connection. could you please say the electrical connection for controlling 4 heat beds?...

For heating large print beds, AC mains voltage silicone bed heaters are far more practical than low voltage bed heaters. You may be able to find the size you want here [www.aliexpress.com]. Get a heater a little smaller than your bed plate, to allow room for fixings at the edge. Aim for a power density of about 0.4W per sq cm.

You control the heater from the electronics using a DC-AC SSR. Of course there are additional safety precautions to take, in particular grounding, insulation, cable strain relief, and a RCG/GFCI for additional protection.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].