On Wed, 09 Nov 2005 07:49:54 GMT, mark
wrote:

Could a person melt brass or bronze

Go with bronze ("copper" loose change is good, but sort it with a magnet
first) Brass has the problem of zinc boil-off, which is significant for
small loadings.

with a oxy welding torch

Oxy-propane maybe, oxy-acetylene is too much temperature and not enough
heat. Best of all is a well-insulated box kiln around the crucible and
something like a Ron Reil propane-air injector burner.

in a cruxible

Crucibles are good, but you can get away with steel pipe and a welded
end cap for your first attempts. Don't melt too little at a time,
because you need to maintain temperature from the kiln to the pour.

and pour it in a shallow, crude mold of plaster paris or some
other material?

Don't think crude, you don't have to. Lost foam in sand works
(builder's insulation foam, builder's sand) So does cuttlefish bone.
Plaster is mainly used as an investment around lost wax, and you might
want to buy specific investment plasters for that, then follow the
bake-out rules properly.

Greensand moulding around a woodern pattern is worth trying, but it's
easier to mould a large piece than a small piece, and easier to pour a
small piece than a large piece. For one-offs, I'd use lost foam.


Jarkman and I have been doing some of this lately. We're still pretty
rubbish at it, but it's fun.
http://www.jarkman.co.uk/catalog/fripperies/index.htm

"Andy Dingley" wrote in message
...
On Wed, 09 Nov 2005 07:49:54 GMT, mark
wrote:

Could a person melt brass or bronze

Go with bronze ("copper" loose change is good, but sort it with a magnet
first) Brass has the problem of zinc boil-off, which is significant for
small loadings.

Not with US coinage. Early pennies are copper/zinc alloy, and newer
pennies are copper plated zinc. The balance of our coins are either
nickel/copper alloy, or nickel copper sandwiched. There are no bronze coins
made in the US.

Harold

"Harold and Susan Vordos" wrote in message
...

"Andy Dingley" wrote in message
...
On Wed, 09 Nov 2005 07:49:54 GMT, mark
wrote:

Could a person melt brass or bronze

Go with bronze ("copper" loose change is good, but sort it with a magnet
first) Brass has the problem of zinc boil-off, which is significant for
small loadings.

Not with US coinage. Early pennies are copper/zinc alloy, and newer
pennies are copper plated zinc. The balance of our coins are either
nickel/copper alloy, or nickel copper sandwiched. There are no bronze
coins
made in the US.

Harold

[I believe the new Sacajawea dollars are manganese bronze, but it would be
rather uneconomical to melt them down. Send them to me, and I'll give you an
equal weight in new silicon bronze ingot, the American foundryman's
overwhelming choice...

As for the Original Poster's question, yes - you can pour brass in a mold.
No, straight plaster of Paris isn't a good idea. Yes, you need to heat any
plaster-based investment to drive off the chemically-entrained water; 1250F
is a good temperature for that. No, you don't have to buy jeweler's
investment; you can add 2 parts sand by volume to 1 part plaster of Paris to
give it sufficient strength to withstand burnout. Yes, you can melt bronze
in a crucible with an oxy-acetylene torch, but no, that won't give you
enough to pour with straight gravity. For small amounts of metal, you need
some way to overcome surface tension, like vacuum from the bottom of the
flask, or centrifugal force, or even steam pressure. If you want to melt
enough to pour by gravity, then you need a furnace to melt in. Yes, you can
improvise a crucible with a steel pipe or whatever, but no, this isn't a
good idea - the temperature of molten bronze is too high, and the
consequences of a crucible failure are too dire. Get a real clay-graphite or
silicon carbide crucible; they aren't that expensive compared to
hospitalization. (Of course this doesn't apply to the British, who get
hospitalized for free...)]

Andrew Werby
www.unitedartworks.com

Keywords:
In article , Andy Dingley wrote:
On Wed, 09 Nov 2005 07:49:54 GMT, mark
wrote:

Could a person melt brass or bronze

Go with bronze ("copper" loose change is good, but sort it with a magnet
first) Brass has the problem of zinc boil-off, which is significant for
small loadings.

I've been hearing this for years from knowledgeable folk, so it's
probably correct. I'm just glad I didn't know it in 9th grade when I
made a cast brass fireplace tool bracket. I just got some scrap brass,
melted it in the Jr. High foundry & poured it into a sand mold. It
polished up nicely, and is still bolted to the side of my Mom's fireplace
40 years later. I have no idea how I got away with it, but it worked
great. The brass was mixed chunks from the Los Alamos surplus yard, and
could have been all sorts of alloys.

Doug White

"Doug White" wrote in message
...
Keywords:
In article , Andy Dingley
wrote:
On Wed, 09 Nov 2005 07:49:54 GMT, mark
wrote:

Could a person melt brass or bronze

Go with bronze ("copper" loose change is good, but sort it with a magnet
first) Brass has the problem of zinc boil-off, which is significant for
small loadings.

I've been hearing this for years from knowledgeable folk, so it's
probably correct. I'm just glad I didn't know it in 9th grade when I
made a cast brass fireplace tool bracket. I just got some scrap brass,
melted it in the Jr. High foundry & poured it into a sand mold. It
polished up nicely, and is still bolted to the side of my Mom's fireplace
40 years later. I have no idea how I got away with it, but it worked
great. The brass was mixed chunks from the Los Alamos surplus yard, and
could have been all sorts of alloys.

Doug White

As long as you melted with a crucible in a furnace, that would work fine,
and is commonly done. I mean, that's *how* it's done (unless the metal is
melted by cupola or induction furnace). This guy is asking about torch
melting by applying the torch directly to the metal. That is a recipe for
failure with brass.

Congrats on the nice fireplace tool bracket. Such projects are a pleasure to
have in our later years. I lost all my high school machine shop projects
when I was burglarized many years ago. Must have been one damned desperate
thief.

Harold

Doug White wrote:

The brass was mixed chunks from the Los Alamos surplus yard, and
could have been all sorts of alloys.

If that's not an invitation to wild speculation, I don't know what is!