Using ptc heaters for a 400x300 bed ?

Is using ptc heaters for a 400x300 bed the best option ?

Thanks Nikki

What is a PTC heater? I duck'd it and got what appear to be self-regulating heaters.

A 400x300 bed would probably work with an ordinary silicone heater.

this is a ptc heater Thanks for the tip about silicone heaters ill have a look for one the correct size.

thanks Nikki

ive just found this do you think it will be ok ? am not sure why there a 4 wires ???

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Nikki81
ive just found this do you think it will be ok ? am not sure why there a 4 wires ???

That would be absolutely fine as long as you have a 220-240V ac supply the 4 wires are AC Feed and 2 for the inbuilt Thermitor (If it indeed has one it does say picture is for info if not you can ask for one to be installed or you can add your own) also be aware that you will need something like a DC - AC SSR to switch it but they are quite cheap anyway many of these chinese companies will actually make one to your specification and needs and I would think something around 400-500 watts would be enough.

HTH

Doug

The PTC heater you linked was 12V DC, the silicone heater is 220V AC, I don't think 12V would ever be practical for a 400x300 mm bed (it would require 37.5 Amps for a 450W heater), but a mains voltage heated bed may be much more complex to implement safely, particularly if the heated bed moves (if you are not confident you understand all the risks then don't use mains AC).

As a rough guide, the MKII PCB heatbeds that everyone uses are about 120W for a 200x200 bed, and can only just get the bed to about 105C for ABS, that equates to 30W per 100mm^2, so to scale that up you need a minimum of 360W for 400x300. However because the MKII bed is underpowered you should probably aim to add 25% minimum to that figure, that gives you a starting point of 450W. This seller will make a silicon heater to your requirements (just specify dimensions, power, and voltage).

The next decision you have to make is what voltage to use, and how you will switch it (it's unlikely that the MOSFET on your controller board will be able to switch the current required for 450W). If you want to stick to DC then a 36V DC supply may be your best choice, and either use a 36V controller (and other electronics) or use a separate supply for everything else, however that will need an expensive DC/DC SSR to switch it. AC is easier to switch because a reasonable AC/DC SSR's isn't as expensive, another choice is to go with 24V and use one of these power expanders (they can handle up to 30V max), I've heard good reports of them and they are far cheaper than a SSR (the downside of that is that your heated bed wires will need to take about 18A).

As a point of reference, I have a 450W heater on the 305mm x 317mm x 6.35mm cast tooling plate bed in my printer and it gets up to 105C for printing ABS in about 5 minutes.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks plankton for the link ! I will send them a message. I think ill go 220v and use a ssr.

thanks nikki