Mk2 PCB Heated Print Bed

Hello All,

I've treated my Mendel to one of those Mk2 PCB heated print beds but i cant get it to heat up. As i run gen 6 electronics i'm running it off an external power pack, initally i used a laptop style power pack at 12v but i realised that it was only running 70w so i wired the bed into a spare pc i've got knocking around, 12v again but this time 200w.

I've measured the voltage across the terminals on the print bed and there is 12v across them, but it doesnt heat up. I'm not using resistors or leds so there is nothing in these holes. Should there be something there to "compete the circuit"? Are the positive and negative terminals on the bed directional?

I'm clearly missing something silly and obvious, does anyone have any ideas?

Thanks in advance,

Andrew

The outer two pads with holes are the connections. No you don't need any components fitted. No it is not directional, just four zigzag tracks wired in parallel.

I can't think why it wouldn't work if there is 12V across the two connections. It would mean all four tracks must be broken, which would be unlikely. Perhaps you made the connection on the wrong side and the holes aren't plated through.

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[www.hydraraptor.blogspot.com]

Send a pic of your wiring at the heated bed (I recommend starting a Flickr or similar account...pictures tell everything in this project). It could be a bad solder joint...or it might be attached wrong somehow. If that is not the problem I suggest looking over the PCB very closely with magnification and see if there is an issue in one of the traces (although, for something this big you probably can see it with the naked eye, and as Nophead said it is doubtful it is the traces).

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Hi guys, thanks for your replies. I've had a look at the tracks and i cant see any brakes, here's some pics:









Thanks, Andrew

What is the measured resistance between those two solder points?

Hi Andy

I think Nophead has alredy guessed the answer here and your photos seem to confirm it, the pads on the solid copper side are not connected to anything electrical and are just there for extra anchorage of the wire, your last photo clearly shows a lack of solder on the pads on the tracked side of the board where your wires enter the board.

all you need do is desolder and resolder it with the wires poking in from the other side, so the soldered ends of the wires connect to the pads on the tracked side of the board.

that should do it.

Graham

I am about to wire mine up hence me stumbling over your post.

Ah brilliant, thanks everyone. I'll take a look in a few days and let you know if it works.

Thanks muchly

Andrew

Those are plated through holes. Soldering on one side will make a connection to the other side so I'm not convinced that will be the problem.

The board is supposed to be made without plating because plating is not an accurate enough process to get the correct track resistance. I.e. when a board is plated it is not just the vias. The whole copper area gets about twice as thick.

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[www.hydraraptor.blogspot.com]

It worked!! Thanks everyone.

Can you print directly onto it? I know it wont be perfectly flat like glass but at this stage that wont be a problem, obviously i'll put some kapton tape on the board.

You probably can but it will dome upwards in the middle if you don't have glass on top because the solid copper side expands more than then zigzag copper. Normally this is a benefit as it means you can fasten it to the glass in the corners and the middle will be pressed tight.

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[www.hydraraptor.blogspot.com]

Hi Andy,
Glad you got to the bottom of the problem. I'm thinking of ordering the heated bed myself also and am in the same boat with the Gen6 board that has not heated bed control (the order Gen6).

If you have any ideas on how you plan controlling the temperature of the heated bed I'd be interested in hearing from you.
Thanks,
NumberSix.

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[numbersixreprap.blogspot.com]

I just completed the temp control on mine. I ordered a couple different controllers. The one I am using now is like this one.
[www.ebay.com]

Be aware though that it comes as the higher voltage model. I had to run it on 110 VAC. Then I needed a DC/DC SSR. The control voltage on this is like 3 to 32 VDC. My heat bed power supply is 15 amp. I had to get an SSR that would handle that current and voltage. They sell lot of the on Ebay. Then with this temp control, you also need thermocouples. I bought two on Amazon.
[www.amazon.com]

Now this is a fairly costly and kinda heavy duty setup. I invested in it because I will be building a larger machine eventually.

For a lower cost solution, you might consider this type thing.
[cgi.ebay.com]

I have ordered one from this seller. You can find cheaper versions of this same one on Ebay. He ships the low voltage model to the US, but just mention that at time of order. I haven't yet received this one, but it's in the mail.

I fried two MK137 kits after just a few hours heating by each one. Just don't trust those any longer.

Tks. Some useful suggestions there.

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[numbersixreprap.blogspot.com]

I made a heatbed controller a while ago as I'm running Gen6 and had no way to control the temp.

Check my blog, March 16th and 25th posts have the details.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

I know this is an older post... But did this work ? It looks like an easy setup , and not a ton of money ... Im still running my Gen6 with my heat bed.. And its a pain to turn it on and off to keep temp ...

Leeway Wrote:
-------------------------------------------------------
> I just completed the temp control on mine. I
> ordered a couple different controllers. The one I
> am using now is like this one.
> [www.ebay.com]
> rature-Control-Controller-SSR-2-Alarms-K-J-E-S-T-B
> -R?item=130632901642&cmd=ViewItem&_trksid=p5197.m7
> &_trkparms=algo%3DLVI%26itu%3DUCI%26otn%3D5%26po%3
> DLVI%26ps%3D63%26clkid%3D7850919737153873703#ht_29
> 38wt_1398
>
> Be aware though that it comes as the higher
> voltage model. I had to run it on 110 VAC. Then I
> needed a DC/DC SSR. The control voltage on this is
> like 3 to 32 VDC. My heat bed power supply is 15
> amp. I had to get an SSR that would handle that
> current and voltage. They sell lot of the on Ebay.
> Then with this temp control, you also need
> thermocouples. I bought two on Amazon.
> [www.amazon.com]
> 21431760_C1_cs_sce_dp_2
>
> Now this is a fairly costly and kinda heavy duty
> setup. I invested in it because I will be building
> a larger machine eventually.
>
> For a lower cost solution, you might consider this
> type thing.
> [cgi.ebay.com]
> =330615687890#ht_6515wt_1398
>
> I have ordered one from this seller. You can find
> cheaper versions of this same one on Ebay. He
> ships the low voltage model to the US, but just
> mention that at time of order. I haven't yet
> received this one, but it's in the mail.
>
> I fried two MK137 kits after just a few hours
> heating by each one. Just don't trust those any
> longer.

im a power concious "freak" user, my take on heated beds is that, to improve the efficiency to some extent, the top bed should be the only surface that emits the heat and there should be some kind of heat insulation on the bottom. not sure if that makes sense or if someone has tried it?

redreprap Wrote:
-------------------------------------------------------
> im a power concious "freak" user, my take on
> heated beds is that, to improve the efficiency to
> some extent, the top bed should be the only
> surface that emits the heat and there should be
> some kind of heat insulation on the bottom. not
> sure if that makes sense or if someone has tried
> it?

Since you generally want your top surface to be glass, that usually isn't possible. Most people have the PCB heater directly under glass. Adding insulation under that is a good idea, something that I do but not everyone does.