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Investing


#1

Hello eminent members of this List:

My name is Nina Millington, owner of Nina-Silver Design at
http://www.nina-sd.com. I am an Australian living in Florida
and learned my trade in this Country. I have been 16 years a
silversmith, primarily doing cut and solder designing one-
of-a-kind pieces using silver and In the last couple
of years, I set up my casting workshop with a view to going
online and doing production, including wholesale. Of course,
in order to do this I had to teach myself to web write (in an
area which is a virtual writer’s desert) and so developed my
48-page-and-growing site (critiques welcome).

I exchanged links with Ganoskin a couple of months ago but only
found out about this great list through GAF last week.

It would be a great help to me if I could get some feedback from
all you experienced castors about a problem which has come up
lately in my workshop.

I started out casting with a Vic 12 Vacuum Casting Machine from
Rio Grande which, as some of you probably know, comes with a
vacuum table for debubbleising (sp?) investment. Since all my
experience in casting was with a centrifuge, I somehow could not
get that thing to work properly and turned a lot of new silver
into old and wasted a lot of wax before giving up and going back
to the centrifuge. I am about to return the Vic 12 to Rio
leaving myself with no way to deal with investing. Vacuum
Machines cost a fortune and there is no way I could get one
right now - Rio quoted me $470 for a pump, belljar and pad to
build my own which is still out of reach at the moment. So I’m
looking at a vibrating machine which is available for under $100.

Does anyone have any experience of these that they could share?
I’ve no idea how well they work - don’t want to start wasting
silver, wax and investment again.

Any help would be greatly appreciated as I need to get this
Vic12 on the truck back to Albuquerque which means I’ll be
temporarily out of business.

Thanks,
Nina

Nina - Silver Design, 9122 S. Federal Hwy, Suite 249,
Pt. St. Lucie, FL. 34952 : Toll Free:1-888-460-1800
URL: http://www.nina-sd.com : Email: @Nina


#2

Hi Nina,

I’ve never done it, but jewelers have made their own vaccuum
machines using the pump from a car’s air conditioning system or
even (I believe) a refrigerator. I think we tossed some
about on that subject recently. I recall an article
in Rock and Gem magazine on the topic, but I couldn’t tell you
how long ago it was (last five years?).

I don’t do any casting any more (I sub it out… low volume),
but I never did like those little vibrators, having gotten
questionable results from them.

I don’t know if that even counts as two cents, but there it is!
:wink:

Dave Sebaste
Sebaste Studio
Charlotte, NC
dave@sebaste.com


#3

I had the same problem when I started using a vaccum casting
machine. I found that I have to cast at about 100 degrees F to
compensate for the air being sucked through the flask and cooling
it so quickly. Casting with this method is definitely a two
person operation as you do not want to put the flast on the
vaccum caster until the metal is ready to pour.

Hope this helps.

Creole


#4

Nina: I’m surprised you can’t get vacuum casting to work for you
as it seems most professionals prefer it over centrifugal, maybe
you should be asking questions about vacuum casting and hang
onto that piece of equipment. There are many experts here who
can help you,hold off on that equipment return…Dave

www.opendoor.com/stephensdesign/crystalguy.html
Crystalguy Art Jewelry, Magical Art Jewelry for the Enlightened Mind


#5

Hi Nina,

Its a shame you could’nt get your vacuum casting machine to
work. I used to cast strictly with centrifugal force but have gone
back to vacuum casting (less turbulence, less porosity). What
kind of problems are you having with vacuum? Are you getting
incomplete castings? You may want to check with a local heating
and airconditioning firm. Sometimes they have used vacuum pumps
they will sell to you. Then its just a matter of a piece of
aluminum plate, a hole, a gauge and some rubber tubing. I’ve never
tried the vibrating table, so I can’t speak for it, but years ago,
when I first started out, I would paint my wax pattern(s) with
investment, making sure there were no bubbles- let it dry and
then fill the flask up with investment. This always worked well.
If you decide to keep your vacuum caster, you may want to try
leaving about 1/4 inch of air space at the bottom of the flask to
get a better evacuation of gasses. Also, try lining your flasks
with wax or plastic webbing. Good Luck, Ken


#6

Nina,

Here is a cheap way to build a vacuum pump. Go to a junk yard and
secure an old air conditioner compressor. It doesen’t have to be
sealed (purged) as you are going to pump air through it anyway.
Hook up a electric motor,1/4 hp. will do, with a belt and pully
attached to the motor shaft. Add a couple of hoses and a table
and you have a voracious vacuum pump. I have seen one break a
piece af 1/4 inch plate glass over the top of a 16" chamber if
left running. cheap and easy. Frank.


#7

Hi Nina,

Welcome to the Forum, I know you’ll enjoy it & get lots of good
info!

I am about to return the Vic 12 to Rio leaving myself with no way
to deal with investing. Vacuum Machines cost a fortune and there
is no way I could get one right now - Rio quoted me $470 for a
pump, belljar and pad to build my own which is still out of reach
at the moment.

One additional source for vacumn pumps is the refrigeration
trade. Some folks have used old refrigerator compressors as
vacumn pumps. Refrig service techs regularly use vacumn pumps in
their work. These are available new (and used) in several sizes
at just about all refrig service suppliers. The price will
probably be less than Rio. You might also watch the want ads in
the local paper, just last week I saw 2 used pumps for sale in
ours.

Try your local resteraunt supplier for a large glass/heavy
plastic bowl for a bell jar, lots cheaper than Rio. My
neighborhood hardware store has square sheets of 1/8" rubber. You
might also try a medical or scientific supplier.

Good luck,

Dave


#8

Hi List,

Just want to thank everybody for being so helpful about my
problem with vacuuming investment.

Going to try to make one and may write one or two of you
privately looking for more details, if you don’t mind.

Nobody can convince me to keep the Vic12 - that thing has been
the cause of so much heartache - I hate the sight of it. Have
spent literally hours on the phone with Rio’s technical man who
keeps saying it’s me and suggesting more things to try - but
each new thing costs me more in time, silver and wax. I think we
finished up with eight casts of about 5 flasks each time - and
I’ve had it - nothing but huge lumpy sprues.

Anyway, thanks again - and I’ll try to return the favor if (just
by a long shot) I happen to know something someone can use.

Nina


#9

hi nina,

don’t return it, please! if you could get a nice fellow
professional caster to physically show you how to use your vacuum
you might like it… a lot. try bribing them. someone should be
delighted to be a consultant.

best regards,

geo fox


#10

It has been a while since I cast, and I mostly used a
centrifuge, but… it does sound possibly like your sprues are
too small in diameter, or the flask is too cold, or the metal
temperature is dropping too fast. You could buy some waxes and
practice with those. Vacuum casting requires that the vacuum draw
the air out of the cavity, so the invested waxes should be
relatively near the surface.

Rick
Richard D. Hamilton

Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com
@rick_hamilton


#11

In regards to Nina: hey, here’s a chance for all you guys who
think casting isn’t “rocket science” to create some good karma
for yourselves. No, Nina, don’t return that vacuum caster. Maybe
someone would be kind enough to explain in a sequential detailed
way how to cast using vacuum assist so Nina can get back to
production…Dave

www.opendoor.com/stephensdesign/crystalguy.html
Crystalguy Art Jewelry, Magical Art Jewelry for the Enlightened Mind


#12

Who says there aren’t any nice guys out there? You just have to
know what they look like. Thanks, Dave. Sounds like the boys
were rough-housing indoors again.

Besides, I live near JPL (Jet Propulsion Laboratory–as in Cal
Tech and rocket science) I’m a doctor.

I will tell you, Nina; brain sugery isn’t brain surgery. Any
farmer with a Black & Decker drill can save your life from a farm
head injury. Same technique–same tool.

In addition, after the Hubbell telescope disaster and the Mars
Observer mess, rocket science isn’t rocket science any more.
Even at JPL.

Remember, these guys weren’t born knowing what they know. They
learned it from scratch, too, and they made their mistakes,
too–probably some real doozies. At least they didn’t have to
bury their mistakes like doctors do.

The ones who invented different techniques didn’t learn from
someone else. They usually stumbled on it when they made a
mistake trying to do something else. I know, I was a pioneer in
my specialty.