Let's forget about bronze for now, and just focus on lower temperature alloys that you can melt on a stove top!

Field's metal melts at 144C (the temperature of a hot cup of coffee) and is nontoxic. It's a bit expensive though, because of its high Indium content. There's some Bismuth/Tin alloys that melt at a little above the boiling point of water and are much cheaper. Great for casting buttons, medals, figurines, and other trinkets. Or for mechanical components that won't be exposed to high heat.

There's a bunch of other low-temperature casting metals available that have different useful properties in terms of strength and ductibility etc. See:

https://en.wikipedia.org/wiki/Fusible_alloy#Low_melting_alloys_and_metallic_elements
http://www.rotometals.com/Low-Melting-Fusible-Alloys-s/21.htm

Field's: http://www.rotometals.com/product-p/lowmeltingpoint144.htm $69 for 1/4lb
"used for die casting and easy prototyping."

Bi/Sn: http://www.rotometals.com/product-p/lowmeltingpoint281alloy.htm $15.29/lb
"This alloy can be used to anchor shafts in permanent Magnesiumnet rotors, locator members in aircraft assembly fixtures, metal parts in glass, Magnesiumnets in fixtures, make nests for parts in jigs and dial feed stations, Cores for electroforming, Embossing dies, form blocks, Joggle jaws, Lost wax pattern dies, Duplicate foundry patterns, Tracer models in profiling, Molds for plastics, sheet plastics, plastic teeth, prosthetic development, Potting electronic components, Laps for rifle barrels."

Patrik


On Wed, Jul 30, 2014 at 9:38 AM, Anca Mosoiu <anca@techliminal.com> wrote:
I too would love to participate in a wax carving workshop, and a mold-making one as well. And I would love to learn more about bronze casting.  

tl;dr below:

I know someone who's a sculptor, and she talks about the expense of working with bronze - both in terms of the cost of materials, and the cost of operating a forge.  She also talks about how incredible it is to work with FIRE and melt metal, which makes it sound really amazing.

There's a fair bit of time involved in preparing the mold for complicated object so that it can be cast properly.  The lost wax casting method involves making the wax object, putting the mold material around it, drilling holes in the mold where the metal gets poured in, and then melting the wax out.  If you plan to make a one-off piece, you break the mold after pouring the metal.  Otherwise, you have to know how to cut it so that it can be removed from the cast object (e.g.if you have parts that fold in on themselves).

I was curious, so I went online to see where one might buy the raw metal for casting.  Bronze is apparently about $15/lb (http://www.mcmaster.com/#red-metal-ingots/=t29up6) from an industrial supplier, but I found it cheaper through eBay (12lb ingots for $90 + $20 shipping from the east coast).  It contains copper, which at the moment has a pretty high market value (and is a reason why people steal copper wire, statues, and things).  People buy leftover bronze from machine shops, but there are issues with mixing different kinds of bronze alloys together.

Woo!

Anca.



On Wed, Jul 30, 2014 at 12:06 AM, Jake <jake@spaz.org> wrote:
I will have to ask about pricing, but perhaps we can make something so awesome that they will decide to make it "on the side" so that they can sell copies of it for their own profit.  Think something immensely useful.


On Wed, 30 Jul 2014, Marc Juul wrote:


On Tue, Jul 29, 2014 at 9:32 PM, Jake <jake@spaz.org> wrote:
      yes the place I got the robot from is a foundry that makes seriously the most beautiful bronze sculptures / statues (no size
      too big) that i have ever seen ever.

      and one of their people visited sudoroom and liked the place.  If we made someting out of wax that was beautiful, we could
      talk with them about turning it into bronze.. or a negative that could make many copies.


My experience with professional bronze casting is that it's super expensive! Are they willing to give us a hefty discount or what? I'd be
interested if I knew it could be made into bronze for sure without breaking my/our budget.

--
marc/juul
 
      On Tue, 29 Jul 2014, Vicky Knox wrote:

            Wax into bronze?!?!?!!?!?!?! :D I love chose your own adventure email threads. I just clicked on the "..." on the
            sentence: "Also the people who sold us the robot can turn wax
            into bronze..."


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