Anyone know if you can burn out an alumilite master when doing sand
casting? I know you can burn out foam/stryofoam, but how about
alumilite? (www.alumilite.com)

A customer has an alumilite gerbil character that he wants done in
metal, and it'll be a lot cheaper for him if I can just use (and
destroy) his original alumilite gerbil rather than carve a whole new
one.

thanks for any info...

Jud

www.judturner.com
www.customhoodornaments.com

On 23 Mar 2005 15:09:35 -0800, "Jud Turner" wrote:

Anyone know if you can burn out an alumilite master when doing sand
casting? I know you can burn out foam/stryofoam, but how about
alumilite? (www.alumilite.com)

A customer has an alumilite gerbil character that he wants done in
metal, and it'll be a lot cheaper for him if I can just use (and
destroy) his original alumilite gerbil rather than carve a whole new
one.

thanks for any info...

Jud

www.judturner.com
www.customhoodornaments.com


No.
Lost foam (aka: expendable pattern casting) only works because there
is so little plastic per unit volume, that it is able to quicky
vaporize in advance of the molten metal, And it produces so little gas
that it it is able to be vented through the sand.

A solid plastic piece will just blow metal in your face.

I could probably be burned out in an investment or ceramic shell
casting.

Other wise. Figure out a parting line and make a green sand mold.

Paul K. Dickman

(clip) it'll be a lot cheaper for him if I can just use (anddestroy) his
original alumilite gerbil rather than carve a whole new one.(clip)
^^^^^^^^^^^^^
It should not be necessary to carve a whole new one. The bronze foundry I
visit once a year follows a procedure where they coat the original with a
rubber mold material, which they then strip off. This is then used to make
a wax copy.

"Jud Turner" wrote in message
oups.com...
Anyone know if you can burn out an alumilite master when doing sand
casting? I know you can burn out foam/stryofoam, but how about
alumilite? (www.alumilite.com)

A customer has an alumilite gerbil character that he wants done in
metal, and it'll be a lot cheaper for him if I can just use (and
destroy) his original alumilite gerbil rather than carve a whole new
one.

thanks for any info...

The resin in Alumilite is thermosetting polyurethane. It will not burn out.
Most of the mass will turn black and just remain where it is.

As someone else suggested, you'll need to make a transfer molding from it.
Assuming this character has some undercuts, either a strippable latex
molding compound (cheap and easy); a silicone mold-making compound
(expensive and possibly easy, depending on configuration); or a multi-part
plaster mold (very cheap and probably difficult, as it would have to be made
in multiple, keyed-together pieces) will do the job. There are other
flexible molding compounds, including glue molds and gelatine molds, but
they're for artists and for people who want to spend their time playing with
mold-making rather than making parts.

There are more expert casters around here who may disagree with this, but my
limited experience with art casting suggests to me a dipped-latex or
silicone mold; a wax (probably a special one made for investment casting)
pattern cast in the mold; and a metal-casting-plaster mold in which you
"invest" the wax pattern, which you burn out before casting. The plaster for
metalcasting is available from art supply stores, casting supply houses, and
U.S. Gypsum.

This is not something you're likely to get right the first time you do it,
but, once you have it down pat, none of it is difficult to do.

--
Ed Huntress

Jud Turner wrote:
Anyone know if you can burn out an alumilite master when doing sand
casting? I know you can burn out foam/stryofoam, but how about
alumilite? (www.alumilite.com)

A customer has an alumilite gerbil character that he wants done in
metal, and it'll be a lot cheaper for him if I can just use (and
destroy) his original alumilite gerbil rather than carve a whole new
one.

Can't believe that in a group like this no one has asked whether the
gerbil figure is this persons original work or are they trying to rip
off someone elses work.

Robert

Thanks for the reply and info, Ed. Very helpful indeed.
The gerbil design is the creation of the customer. He's a cartoonist,
but you make a good point about ownership. I've been asked to do a
lot of things that would get me a "cease and desist" letter (i.e. the
car dealership that wanted me to make Lexus logos as hood ornaments)

- Jud

"Jud Turner" wrote in message
ups.com...
Thanks for the reply and info, Ed. Very helpful indeed.
The gerbil design is the creation of the customer. He's a cartoonist,

I thought maybe it was Karl Rove:-)

"Jud Turner" wrote in message
oups.com...
Anyone know if you can burn out an alumilite master when doing sand
casting? I know you can burn out foam/stryofoam, but how about
alumilite? (www.alumilite.com)

[No, you can't do that. Urethane resins like Alumite are highly toxic when
burned. Also, there's too much material there for the lost foam method to
work. A Styrofoam pattern contains very little actual plastic - it's mostly
air, so it retreats away from the hot metal with few combustion products.
These are vented by the loose sand the foam pattern is buried in. You can't
treat other materials this way with any hope of success.]

A customer has an alumilite gerbil character that he wants done in
metal, and it'll be a lot cheaper for him if I can just use (and
destroy) his original alumilite gerbil rather than carve a whole new
one.

thanks for any info...

Jud

[He'd destroy it okay. I have a hard time believing he carved it in
Alumilite in the first place - it's a casting resin and carves poorly. He
needs to either make a mold himself, or have one made.]

Andrew Werby
www.computersculpture.com


www.judturner.com
www.customhoodornaments.com

"Jud Turner" wrote in message
ups.com...
Thanks for the reply and info, Ed. Very helpful indeed.
The gerbil design is the creation of the customer. He's a cartoonist,
but you make a good point about ownership.

That wasn't me. It was someone else. But you're right, he makes a good
point.

I've been asked to do a
lot of things that would get me a "cease and desist" letter (i.e. the
car dealership that wanted me to make Lexus logos as hood ornaments)

Do you do other kinds of casting, Jud? If so, learning these precision
art-casting methods will add some useful experience to your bag of tricks.
There are lots of interesting things you can do with these materials. For
example, there are some plasters (some are called "gypsum cements"; the
distinction has to do with how much water they have in them, and other
tailored properties) that expand in controlled amounts. If you want to make
a dimensionally accurate reproduction of something, you can use these
materials, both in making the mold and in making intermediate patterns, that
will compensate quite accurately for the shrink factors of various metals.

--
Ed Huntress