better heated bed for SD4? (Page 2 of 4)

I"m actually having some difficulty finding that 3-hole PCB i mentioned. I know I saw it *somewhere*. I'll keep looking.

The thermistor glass bead gets Kapton taped to the bottom of the PCB so, yes, the hole in the cork accommodates that bead if you are sandwiching the Glass bed, the PCB, the cork and the original Aluminum bed together.

The cork also insulates and directs the heat upward toward the glass so it won't be lost out the bottom...

Actually, quite tricky to find. This was what I came up with:

http://reprap.org/wiki/PCB_Heatbed - this heatbed is very common, claimed resistance >=1 ohm (so <=12A @ 12V)
http://www.soliforum.com/topic/3530/pcb-heatbed-mk2/ - does seems to draw around 12A by a fairly reliable account
http://www.printrbottalk.com/forum/view … amp;t=8299 - recommended to keep under about 7A from the heat bed connector on the printrboard

I would highly recommend using an external solid state relay for any other heatbed (most are more powerful than the stock). Research why and how to do this, to make sure you select the right kind and install it correctly.

I tried mine on the bench with a SD3 power supply and the numbers are:

11.75Volts
119Watts
10Amps`

Not exact numbers but almost

I will be powering my PCDB heater with a external SSR and PSU

Yes, you can...you hook up the current heater bed output wires to the coil on the relay, and then the power supply, PCB and switching side of the relay in series...

The downsides: 
- You MUST disable PID (enabling Bang-Bang) in the configuration.h or else you will be using PWM which will cycle that mechanical relay like crazy, eventually burn it out and most likely in the closed or ON position.  Not safe!!

- Bang-Bang control results in a slower heat control cycle which will likely cause a vertical squishing (banding) effect. 

At the end of the day, a lot less toil and trouble and way more safe to just use a SSR!

The diode can't hurt...I did not use one when I had a mechanical relay set up while waiting for my SSR; but then again, I was using a RAMPS board.  Someone else who has done this on a Sang can weigh in...

No diode needed on the Sang but I can't speak for the PrinterBoard.

Got it. So how to connect all this to the motherboard?

Go here:
http://www.ebay.com/itm/261629781877?_t … EBIDX%3AIT

Good delivery time, they send the directions on how to wire it up. Use the relay, according to solidoodle, the board is not set up to handle that much current for long, don't forget it's going to draw 10-14 amps, I forget the exact amount just know it's enough to fry your board.

Ok, I will then.

grob, thank you very much!

This should be in the wiki or something.

Is that a 30A SSR in the photo?

Again, thanks.
if it was something else, I'd just try it and see if it works. But having burnt one printrboard I'm just paranoid with anything to do with the mobo...

You were debating whether or not grob is a nice guy? or whether or not to do this mod? Or whether or not to post a diagram how to do this mod?