1 Topic by Sooks569

  • Sooks569
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Topic: PCB Heatbed on SD3

I am the process of starting the PCB upgrade and would like a little guidance.  I'm using a 1/4" piece of 8 1/2" square pine board that I mounted to the original bed mount using the 3 countersunk screws for leveling the bed (with the springs underneath the board, and the screw holes countersunk).  I leveled it already so it's good so far.  I made the two forward corner mount holes for the heatbed in the pine and wondering if I should just use the single center mount hole for the AFT end (wiring side) or use both corner holes since the bed is technically level now.  I'm mounting the board using M3 hex bolts with washers on top and a rubber grommet between the heatbed and the pine.  I will then use another washer and a locknut on the bottom of the pine.  Would there be an issue with this setup?  Also do I REALLY need to use a piece of glass or could I just use Kapton tape on it?  Finally, I keep hearing about needing a second power supply for the PCB heatbed because of the current draw.  Do I really need a second P/S or could I just use s 20 amp directly with the Sanguinololu?  Will it handle the current?

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2 Reply by adrian

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Re: PCB Heatbed on SD3

No, the stock sang wont handle the current... for long anyway. The PCB tracks are way underspec'ed. You will need to add the direct wire jumpers between the MOSFET and the power input.  If you fix this, then sure, you can run it directly via the Sang. I'd be putting a heatsink and some sort of cooling on that MOSFET though still... You don't need a second PSU as much as the Sang is not geared to handle high-currents.

As for Kapton vs Glass... choice is yours, but SilkScreen isn't industructible, and neither is FR4... the glass will provide an important mechanical layer of protection to the board.

If you are careful or not concerned, then sure, whack Kapton straight on the backside and be done with it... But keep in mind that will put the circuit side in contact with your Pine... and in my thermal images you'll see the MkII PCB can easily sit over 100°C in patches.. so you basically with have exposed heated elements right next to wood...

I'd also want to make sure its not *treated* pine, as when you heat that, very nasty stuff is released (at least they stopped using arsenic these days....)

3 Reply by Sooks569

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Re: PCB Heatbed on SD3

Can you provide a link to a good P/S that will handle the current demand and info on where to the jumpers?

4 Reply by adrian (edited by adrian 2013-06-13 09:44:32)

  • adrian
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Re: PCB Heatbed on SD3

Pics of the jumper upgrades needed: http://create3d.com.au/images/sanguino- … 0_2260.png
Thread where its already discussed: http://www.soliforum.com/topic/1819/hea … isonsstls/

PSU.. there is far too many options to list. Many have purchased Dell Server PSU's that can do past 500W's...
You want anything that can do AT LEAST 300W's and supply 12V...  You will also want to upgrade the wiring between the PSU and the Solidoodle - the standard wiring is not suitable for high-current use.  You want wire rated to handle 15, if not 25, amps. (never operate near to limits, you want to usually only operate at up to 50% of the rating of a wire to prevent it overheating/melting etc etc).

An expensive but highly reliable brand new PSU is for example http://www.meanwell.com/search/gs220/default.htm

The Dell versions work just fine, about a 1/5th of the price: http://www.soliforum.com/topic/1185/pow … 0w-for-12/

5 Reply by Sooks569

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Re: PCB Heatbed on SD3

I see a couple discrepancies between the photos as far as where to soldier the jumpers.  Even the photos that show the "labelled" and "complete" setup show slightly different soldier points.  Are there any clearer shots or schematics of the solider points?