Printrboard w/Silicone Heated Bed

Hey Guys,

Has anyone had any experience using a silicone heated bed with printrboard? I'm currently using the PCB MkI heated bed, but like the idea of being able to heat a larger print surface with a silicone pad.

Has anyone done this (with printrboard)? Did you have to do anything special (ie. hook up a 12v relay, etc.)?

Thanks.

No, not with reprap, but I've used them for other purposes in my professional life. The MK boards are simply rigid FR-4 based heating circuits. Flexible, silicon heating pads are really no different in principle, just that they use a flexible substrate instead of a rigid one.

Your concerns are quite simple.

1) adhesion to the device to be heated (glue or use compression...consult the mfg data and tech literature for specifics)
2) power. (use an appropriately sourced power supply for the load characteristics of the heated pad, per mfg spec.)

As long as the heater doesn't draw more than 10 or so amps at 12 V, then it will work just fine with the printrboard. For anything requiring more power you will need to use a relay.

Excuse my ignorance here, but that is exactly my question. Does the printrboard have the power to SAFELY drive a silicone bed that draws 15A? I've searched, but cannot find that info.

The printrboard has a 4-pin connector that it uses to power the mkI. The MkI draws about 7 - 10A. My understanding is that the silicone heated bed draws up to 15A. I can't find any information on the printrboard wiki that mentions what the max amps are for the heated-bed header.

Any help would be appreciated.

NewPerfection Wrote:
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> As long as the heater doesn't draw more than 10 or
> so amps at 12 V, then it will work just fine with
> the printrboard. For anything requiring more
> power you will need to use a relay.


Ah ha! You posted while I was typing my reply. This is the info I needed. I supposed 15A is too much.

So, my obvious noob follow-up question is, where can I find information about implementing a relay with printrboard?

Thanks again.

Even 10 A is pretty marginal with the 4-pin connector, so I definitely recommend a relay. Wiring up the relay is quite simple. Two of the pins get hooked up to the output of the printrboard (the pins there are doubled up ++--, you only need one + and one - since the current draw of the relay is low). The other two pins interrupt one of the wires going to the heated bed, just like a switch.

If you need further clarification either I or someone else could make or find a picture to describe it.

You could always bypass the printrboard's onboard FET and use an offboard FET. I believe Traumflaug sells a commercial offboard FET circuit which is almost identical to one (in content) I've been using since the early 1990s that will do the job..And if it's too low powered, then you can specify a FET that will fit the bill or choose a FET relay for the purpose. There are plenty of options available at a myriad of electronics distributors.

What about the sevenswitch?
Its what I'm going to be using... I have the 8x8 silicon heater as well.
Still yet to wire it in though...

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Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

Yes, that's the circuit I was talking about.

I have a Prusa Air divertive called the Genie and it uses Printrboard electronics.
I have two versions of heat bed, one is 12 volt DC using a heat pad directly controlled by the Printrboard (heat pad needs to be low amperage like no more than 85 watts) and the other is mains powered using a solidstate relay that is controlled by the Printrboard and the relay switched the mains power. Both work fine, but I prefer the mains powered because it heats up faster and draws very much less current from my power supply.

If you want to see how the assembly has been done then go to my website that is still under construction, but shows the solidstate relay.
[regpye.com.au]

Cheers,