Finshed

HI..

I have been looking at buying a heated bed (http://www.reprapsource.com/en/show/6403) and have been offered a better price if we buy 5 units.
Prices.
If we can get 5 units cost will be $55.00AU + $5.00 postage
If I we get 10 units cost will be $50.00AU + $5.00 postage
Payment via paypal, money order.

So if you would like one please PM me here or e-mail auzzemit@gmail.com

Auzze.

PS: offer only valid for Australia reprappers

Edited 2 time(s). Last edit at 09/30/2011 06:34AM by Auzze.

pm sent

email sent

Same here, email sent.

how are we going for numbers?

Hi..

We are very close to having 5 but as this has taken so long to get 4 I have been working on building a heated bed using 2mm Alum with 4mm Glass top, using 8 1.2ohm 10watt power transistors running from a PC PS. Total price $18.00.
As I have 2 printers I have been able to build 2 HB for the price of one PCB.

So I feel the price is way to high and have decided to withdraw this offer.

Auzze

fair enough i'm going to have to agree with you about the price, i have everything here to make one just have to bite the bullet and do it.

No probs, thanks anyway Auzze. Where did you get your cheap aluminium and glass?

HI..

I was luck too get them local here in Ballarat, but i think the Alum was an off cut.

Auzze

myndale the 4mm glass you could find in an old scanner or photocopier if you can find one, might not be wide enough for a mendel though.

mlagana: brilliant idea. I actually have an old scanner here that I replaced a couple of weeks ago and was about to throw out, looks like the glass is 23cm exactly.

i am also going to try 4mm glass from a scanner, on dibond heated with nichrome like adrians style. resistors are a bit chunky, but probably easier to control.

For those still wanting a heat bed I've just made one for <$50 using parts sourced locally and based on a design that Auzze showed me. Jaycar sell 295x295mm aluminium sheets for $15, at 1.024mm thick they're thin enough to cut with a dremel or hacksaw but stiff enough to hold a heavy sheet of glass flat on top, at least from what I found. To the bottom of that you glue 8 12-ohm wire-wound resistors (10W), also available from Jaycar. I glued them in the following arrangement:

[tinyurl.com]

I hooked them up in parallel using some plumbing solder I picked up from Bunnings, although I suspect at the relatively low temperatures that a heat bed operates at you could probably use regular solder as well. You will need something to glue the resistors such as JB Weld (available from Jaycar for $15) or Black Patch Stove Putty (available from BBQs Galore for around $5 I think).

Finally there's the glass. I went into a store in Southland shopping center called "Funk" and found $13 picture frames with a 4mm thick piece of glass that was exactly 20x20cm, so they didn't even need cutting. My next plan is to glue a single-sided copper/fiberglass PCB to the open side, that should bump the temp up high enough to need regulation.

If you do it exactly as I have then your heat bed will draw 8 amps at 12V i.e. 96 watts. As you can see from the photo above I can maintain 75 degrees C in a cold (i.e. 10 degrees C) garage. According to some people that's hot enough to print ABS on Kapton tape.

One last thing, Jaycar sell a cheap fiberglass sleeving called "Vidaflex". It's an extremely good thermal insulator, as shown rather graphically in the follow photo (notice I'm holding the piece with my bare fingers):

[tinyurl.com]

(Edited to add the resistor power rating).

Edited 1 time(s). Last edit at 07/26/2011 08:45AM by Myndale.