SoliForum - 3D Printing Community — Heat transfer properties

Re: Heat transfer properties

null@example.com (wardjr) — Sat, 12 Jul 2014 03:11:33 +0000

It's only money

Re: Heat transfer properties

null@example.com (michael.t.albers) — Sat, 12 Jul 2014 02:52:03 +0000

Checked it out Ward, think I am not going as thick as he did. I am looking at most at .25 (most likely) or .16 plate (may be easier to warp, but should heat up faster). Using it both as a support and a heat spreader for the glass, so I don't have to worry about warping it as much. The 18x18 inch plate is $67.00 and I can cut it to size. http://www.onlinemetals.com/merchant.cf … top_cat=60

Of course the copper would be so stylin', but at $459 per sheet, it's a wee bit expensive for my wallet.

Re: Heat transfer properties

null@example.com (wardjr) — Fri, 11 Jul 2014 15:03:23 +0000

diyengineer made a new plate using this with great results. If you search his posts there is a detailed thread about it and all the advantages.
http://www.ebay.com/itm/MIC-6-CAST-TOOL … 3cce578d0b

Re: Heat transfer properties

null@example.com (grob) — Fri, 11 Jul 2014 04:15:18 +0000

6061 is much more common, the price / availability will be better.

A few observations of my own, you might know all this but still:

* To improve both strength and heat spread, use a thicker gauge plate.

* Concentrate on getting a good thermal connection between the glass plate and the aluminium too - any air in there will counteract all your hard work heating the aluminium evenly. Best option in my mind would be to have a super-flat, smooth surface on a thick alu plate (to minimise warp), and some well-spread clamping pressure + smear of thermal grease between the glass and it. - think like you're doing a computer heatsink!

* Also, thinner glass heats up faster, and shows less temp diff between the bottom (measured) surface and top (working) surface (due to its relatively high thermal resistance and the net heat flow through the plate), but is of course more fragile. Stick to about 3mm (most plates for printers are about this size). Borosilicate is recommended as due to it's super-low thermal expansion coefficient it's far less likely to crack/distort when heated.

* Insulate the edges of the stack, I think a fair bit of heat comes out here which contributes to the cold edges.

Re: Heat transfer properties

null@example.com (michael.t.albers) — Fri, 11 Jul 2014 02:52:17 +0000

Thanks Tim!
Your input is always appreciated. Also, the 6061 is cheaper to get at the size I want.

Re: Heat transfer properties

null@example.com (elmoret) — Fri, 11 Jul 2014 02:38:24 +0000

Really all of the aluminum alloys are going to have about the same k.

6061 is about 20% better than 7075. Copper is about twice as good as 6061.

If you aren't heating centrally, it really doesn't matter.

Heat transfer properties

null@example.com (michael.t.albers) — Fri, 11 Jul 2014 01:44:31 +0000

New project in the works is a delta printer with a build area of 350mm x 350mm x 350mm. It is going to be a delta because of the footprint size. Anyway, I am looking at using a borosilicate round glass with a heater pad (probably the onyx pad from seemecnc, if they ever get in stock again) and I need to order an aluminum plate for heat transfer. I thought about copper, but waaay too expensive. So my question is, what is the best aluminum grade for heat transfer. I think a 7075 is the best mix of heat transfer to strength, but would like some other suggestions.