Heat bed with Gen 6 electronics. Pre-deluxe

Hello!

Does anybody know if there is any way to add support for a heated bed on Gen 6 electronics? If not, is there an easy way to control heated bed without using the printers electronics. I'm using MK1 Heat bed for Prusa and would like it between 50-70c for PLA.

Thanks!!!!!!

I use this.

[www.flickr.com]

It is based on Arcol's blog post [blog.arcol.hu]. I will be writing up a description of the mods I have made to it as soon as possible. I have to finish a bit of code to get the fan controller/timers working but as a controller it has worked fine for 6 months.

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www.Robosprout.com RepRap Mendel parts and accessories.
Message if there is anything you need...I have more than what is listed on my site.
Located in the Spokane, WA / Coeur d'Alene, ID area.
Contact: Robosprout@gmail.com Flickr: [www.flickr.com]

I built one last month.

[myhomelessmind.blogspot.com]

M.

These would certainly do the trick but I'm looking for a cheaper easier solution as I'll be setting up 6 machines on a budget.
After some tests with the heat beds I have, MK1 from lulzbot.com, they all seem to max out between 70 and 85 on 12V. I'm no sure if 85 is to hot for PLA but I know 70 will work, so I may just hook them straight to 12V and go. If 85 is to hot I was thinking of adding a resistor or rheostat, but a 100 watt 1/4 ohm resistor doesn't seem to exist.

Any other ideas?

A variable voltage PSU will do the trick, give it higher voltage to heat up and then lower it to maintain temperature (this is how Camiel did it). I also ran my first nichrome bed like that, though the laptop brick I used could only heat the bed to 45C, which was barely enough for PLA on a clean glass plate.

Remember you might want a use fan to better print overhangs, and that will also cool the bed down. I rarely go above 60C when printing, and I'd say 85C is too high for PLA.

People have also been building heated beds with cheap clothes irons connected directly to the mains.

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-Nudel
Blog with RepRap Comic

Such resistors do exist, but you run into a whole new set of issues, namely some mathematics on calculating the desired resistance to achieve a target temperature. Shouldn't be that bad, but it's been a while since I last took a Physics class. Also, you'll need to sink the heat generated by such a resistor. Would it be cheap? Absolutely. But what if your calculation is wrong? What if you want to adjust the temperature? Buy more resistors and solder them in? Seems like a lot of effort to save a very small amount of money. And the resistors aren't that cheap. If you're spot-on in your measurement/calculation then it can be done, but the problem becomes one of error cost. If you're wrong and have to get new resistors for the desired value then shipping costs will swallow your budget pretty fast. The best/cheapest way to control the high current loads you're describing is with a mosfet (as far as I know). You could control all 6 with a single arduino, 6 mosfets and 6 thermistors. You'd have to manually control the setpoint for each machine in software but that's relatively easy. Omit the LCD screen and and just use serial monitor if you want to see what's happening. Just be sure to ground all the power supplies together - arduino and the ones you use for the heated beds. You would need a heatsink for the mosfets, and a small fan too, but any old large PC heatsink will work for that. An xbox360 GPU heatsink would work well too - $5 on ebay.

(1) Arduino: $25
(6) Mosfets (FQP30N06L): $6
(6) 10K Thermistors(07J8183): $6
(6) 10K Resistors, 1/4W: $1
(1) heatsink: $5

newark.com or mouser.com or digikey.com

For less than $45 you can be up and running on all 6, excluding the power supplies, heated beds and shipping of course...

Edited 1 time(s). Last edit at 04/01/2012 05:19PM by akhlut.

Hey Matt (@akhlut)
I looked over you blog about the heated bed upgrade and I really liked it.
Im having the same problem as @miro87043 and also Im just too lazy to follow your directions and make one
so i was wondering if you are interested in making one for me (perhaps exactly like yours)
if interested, can you please calculate the price and contact me.
I will pay with Paypal
My email is billmacs@yahoo.com

I'm a bit late to the party, but I had this saved for the stuff other people linked. I ended up making my own setup for it, which works wonders, and is fairly straight forward. It may turn out to be a bit more pricey then other solutions, but like I said, it works.
Here's a link to it

Check the link in my signature if you want a daughter board solution and the ability to set temps in pronterface etc...

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A wise man once told me "Never trust a man who doesn't own a shed!"
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Gen 6 daughter board
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Mendel PCB heatbed
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