Brass Melting and Machining

[Jaden]

Hi all just wondering if any of you have either poured your own brass or aluminum moulds and machined it successfully?

[Lee Bell]

I've done aluminum quite a number of times but my small furnace doesn't get hot enough to melt brass. I have found that when using aluminum scrap (meaning who knows what alloys are actually in the pot) that adding a small amount of copper to the mix makes it much easier to machine and less gummy acting. Most of what I cast is simple forms to use on my Smithy 3n1 machine.

[Jerrdan john]

Hi all just wondering if any of you have either poured your own brass or aluminum moulds and machined it successfully?

I made many parts sand casting aluminum. I have used cast iron parts for molds by using bondo to smooth out the part and radiuses. I poured some brass, but the difference in temp is a lot when melting I am not saying melting points 1200 and 1900, I am talking the actual feel to be around it and how hard it is to get to that temp from the 1200 aluminum point. I have also used wood molds and they work better. All my parts were eventually machined so that's never been a problem. As Lee said everything is alloy, not much pure aluminum. I used pistons only and the castings were very strong I just added salt that I had previously melted and poured into cubes. Jonathan

[Workshopshed]

I've cast and machined aluminium from old hard drive cases. Good sand (I bought some Petrobond) and a closed mold seems to produce better results. I know what you mean by "gummy" I'm wondering if it's because the pure aluminium is quite soft in reality?

[jkahn]

Hi Jaden,
Having made jewelry and sculpture for the past 45 years, I have cast thousands of nonferrous castings in gold, silver, brass, bronze and aluminum. These have been nearly all investment and ceramic shell castings from a couple grams to around 80 pounds.

One of the most important things I have learned is, if you want scrap castings, use scrap metal.

Be aware of the alloy you are using and use fresh, Ingot for 50% of the metal if you can. For aluminum, I use Almag and an alloy called 357, they cast well, finish and machine easily and even anodize cleanly, although that is a completely different problem. Al. casting alloys are designated differently from wrought alloys, if you can get some 1100 al. that casts well also. I have heard pistons used to be made from a good casting alloy.

Brass is another matter, I try to talk my customers into bronze instead of brass because there are many fewer problems. Brass is a little tricky to melt without overheating and burning off some of the alloy, it is also not too healthy to breathe the fumes. After a piece is cast in brass, while it machines easily, it is hard to fill porosity as it does not take too kindly to welding.
Bronze offers none of these problems and is much easier to work.

All these metals can be melted with an oxy\acetylene torch in a small hand crucible, available from Rio Grande jewelry making supplies, jewelry tools and jewellery supply , of course larger quantities over 1/2 lb. will need a considerably larger furnace.

If you want a few ounces of a few metals to try, I'm sure I have then hanging around, I'll let you pay the postage.
Hope this long winded story helps.