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Casting platinum


#1

Has anyone tryed to cast platinum using a large perforated
vacuum casting machine at alttitude.Iam at about 6000 ft.above
sea level.I have no problem casting golds or silver even with a
reduced vacuum but am unsure about platinum. J in
windy Colorado


#2

Hi J,

There are special vacuum casting machines from Japan mostly, but
unless you want to spend a LOT of money on them, you are better
off with a centrifugal casting unit. You can get a vertical,
centrifugal machine for about $1000.00. (Although there are
plenty of reports that a standard horizontal caster will do
platinum, it is just not the safest machine for platinum -
vertical is safer.)

If you are new to platinum casting and want to know what’s
involved, i.e. what special equipment you might need, drop me a
line. I’ve put together an equipment list with prices for a
start-up platinum casting operation. It includes this vertical
centrifugal machine and everything else you need to SAFELY and
AFFORDABLY cast platinum with a minimum of equipment and
smallest footprint possible. And most importantly the items on
the list will allow you to cast/assemble QUALITY platinum jewelry
and also lists polishing compounds and stamping requirements.

Write me here or call me at Gesswein at 1-800-544-2043 ext 287
and Ican fax or mail you the list. There is no obligation to buy
of course but it might help you to see what you will need.

Best Regards,

Elaine (Corwin)
GESSWEIN CO INC USA
Phone: 1-800-544-2043, ext 287 for me
Fax: 203-335-0300
Orders: 1-800-243-4466


#3
Has anyone tryed to cast platinum using a large perforated
vacuum casting machine at alttitude.Iam at about 6000 ft.above
sea level.I have no problem casting golds or silver even with
a reduced vacuum but am unsure about platinum. J in windy
Colorado 

For whatever it’s worth, ALL the commercial platinum casting
machines are designed around high torque centrifuges. I’ve never
even heard of anyone having success vaccuum casting platinum at
ANY altitude… The key here is the speed with which the mold
can be filled. In a spring driven centrifuge, the torch is on
the metal until a fraction of a second before the arm is
released, and then the high starting torque of the machine throws
the platinum into the mold much faster than any simple pour could
do. The speed with which platinum radiates heat, and thus
freezes up again makes this necessary. The more expensive,
motor driven centrifuges are even higher in their starting
torque, and again, their whole melting arrangement, usually an
induction coil surrounding the crucible, is designed both to
minimize the distance the molten metal must travel to get to the
mold, as well as the time between when the heat source is
removed (the coil is dropped down off the crucible) and when the
arm is moving fast enough to throw the metal. Most of these
machines will have poured all or most of the metal by the time
the arm has completed it’s first revolution. I doubt you could
manually pour the platinum that fast in a vaccuum setup, and
even then, a simple gravity pour will be moving the platinum much
more slowly than a centrifuge does. As well, the centrifuge is
much more effective at filling a mold with fine details quickly.
The G forces a centrifuge can exert far exceed the one G that a
gravity pour is limited to…

Try it if you like, but I’d suggest using a model you don’t
desperately need to have success casting… Who knows. maybe
you can get it to work. But as I said, I’d be sceptical…

Peter Rowe


#4

Dear Peter: I answered J from Windy co. and told her aslos that
vacuum casting of platinum is impossible because of the
investment itself (not porous). Try “pressure” casting. We will
be talking about this method at the Platinum Day symposium on
March 27, 1999 at Expo NY, Roger Greene, Eisinger Ent.
@Eisinger_Enterprises


#5

Hey Guys: I just finished making waxes for wedding bands- my client
wants to cast them in platinum. Here is my question- I have been
told I should not make a mold by some friends saying it will
seriously downgrade the design (my entire jewelry collection is
casted from molds so I do not understand that logic) My other option
I think is to make mulitple waxes of each ring and then cast because
platinum is really tricky to cast and the castor may need several
models to get it right (am I right on this one?) The rings that the
client approved are a tiny bit big because I was going to make a
mold but now since the seed has been planted in my brain that I
should make multiple waxes now I am torn.

Any suggestions and feedback from the orchid group would be great!

dd


#6

Dear Dede,

I vote for the mold. If nothing else a back up in case the platinum
casting doesn’t turn out. I mold everything I make also. It just
makes sense to have extras for someday or samples to show.

Besr Regards,
Todd Hawkinson
TR the Teacher
T.R.Hawkinson, Ltd.


#7

dd, I have been working in platinum for years. I can not even begin
to estimate the number of one of a kind original waxes I have sent
to different casting houses. I have seen an occasional failure. In
most cases there was still a good enough casting to get a mold from
afterwards.

I have also know people to offer casting services to the trade who
have no right to call themselves professional. Anyone can attempt
and often have success casting with a retro fitted Ney spin caster.
But the best use the latest equipment and do it daily.

My suggestion would be to size the wax down a bit and send it to a
professional platinum casting house. The guy I’m currently using is
a Orchid member and top notch. I use him due to his quality, price
and quick turn around time. He is Doug Perry at Pierret Designs. His
number is (888) 653-8994

John Sholl


#8

When I charge my customer for doing a wax model, I do not make a
mold as the design is theirs. If I do not charge for a wax model, I
make a mold as long as the customer does not think it is for them
exclusively.

If you trust your caster and you have had good luck in the past, have
a mold made after the piece is finished in platinum. You can have the
wax cast in silver, have a mold made, cast the pieces you need in
platinum.

Making molds of designs does not downgrade your design in my

opinion. It is a wise way to duplicate your effort. I make molds
sometimes just to record a piece that I like for future reference, I
can also change the design slightly, alter it so as not to duplicate
a design exactly.

Richard in dry heading toward lawnless Denver


#9

All, I would like to correct a mistake I made on my post from
yesterday. The phone number for Doug perry, who does my platinum
casting, is (888)652-8994.

John Sholl