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Intimidated by casting


#1

I have been sending my models to a casting company for a few years,
but after evaluating how much this is costing me per piece, I’ve
decided I would like to bring my casting in house and simply have the
molds made by the company (mold cutting is not one of my skills)but
I’m intimidated. I was curious about how many of you on list do the
whole production of your work yourself? If you do, do you view
casting your own work as beneficial or a time waster?

Some of my fears are as follows:

-I get an order for an expensive gold piece. After measuring and
ordering the exacting grams I need I somehow make a mistake and the
cavity in the mold isn’t completely filled. So I re-melt the metal
and try again won’t this eventually lead to porosity?

-How difficult is it to learn vacuum casting? I think the part that
causes me anxiety is the proper measuring and melting of the metal.
Would one of the cheap pocket gram scales easily purchased off of
Ebay be sufficient/accurate enough for me to use? And how do I gauge
the temperature of my metal as I’m melting it?

-Work space I’ve decided that I am just going to use my garage to
cast in because of the fumes, silica and other dangerous air born
particles involved in the process.

-A significant dent in my work time. But if it isn’t too difficult to
learn, I think I should get past this curve pretty quickly.

Any opinions?


#2

Vera:

My response to your post should be in two parts: economics and
fears. I will address the fears below but you must evaluate the
economics yourself.

Economics:

I have been sending my models to a casting company for a few years,
but after evaluating how much this is costing me per piece, 

The cost per piece depends on whether you cast one piece at a time
or many. This is true whether you do the casting yourself or send the
work out. The whole casting process has a long elapsed time because
of the investing and burnout steps. Not all of the burnout requires
your constant attention but some time is involved and the amount
depends on whether you have a simple manual burnout oven or one with
a computer controller (more expense). At any rate, if your work
schedule calls for casting each piece separately, you will find that
you will have a significant investment of your time: eg. 15 minutes
or so for investing and perhaps 3 or more hours for burnout (that
does not require your constant attention). On the other hand, if you
make molds and cast 50 or more duplicate pieces at a time, the labor
cost per piece is very low.

The same logic applies to your casting company: Are they casting one
piece at a time or many for you at one time?

Your fears:

I get an order for an expensive gold piece. After measuring and
ordering the exacting grams I need I somehow make a mistake and the
cavity in the mold isn't completely filled. 

This should never be a problem as you should always use enough metal
to fill the mold, the sprue system (passages thru which the metal
enters the mold), and a “button” of excess metal that remains in the
pouring cup. The button is important because it supplies metal to
model that shrinks while cooling. This prevents “shrinkage porosity.”

So I re-melt the metal and try again won't this eventually lead to
porosity? 

One always saves the button and sprues from a casting. An equal
amount of new metal is generally added to the used button to retain
the good properties of new casting grain.

How difficult is it to learn vacuum casting? 

There are a lot steps and details to remember when vacuum casting,
or centrifugal casting, for that matter. But none of the concepts are
difficult to understand. Most of the details are before you get
around to doing the actual casting which requires only a few minutes
to melt the metal and pour it into the mold.

I think the part that causes me anxiety is the proper measuring
and melting of the metal. Would one of the cheap pocket gram scales
easily purchased off of Ebay be sufficient/accurate enough for me
to use? 

Any scale should be adequate for calculating the amount of metal to
use. Simply weigh the wax model and the sprue system. Multiply by the
specific gravity of the alloy being used to get the weight of metal
needed to fill the model and sprues. Then add an extra amount of
metal sufficient to produce a reasonably sized button.

And how do I gauge the temperature of my metal as I'm melting it? 

This depends on whether you are melting your metal with a torch or
with a melting pot with a pyrometer on it. When using a pyrometer,
heat the casting metal to around 150 degrees above the published
melting point of the alloy and then pour.

Torch casting requires experience and judgement to determine when
the metal is sufficiently fluid. Often it is suggested that the
surface of the melted metal in the crucible will be shiny and will
swirl slightly when ready to cast. Expensive industrial casting
equipment solve these problems for you by constantly monitoring the
metal temperature with a pyrometer.

Work space I've decided that I am just going to use my garage to
cast in because of the fumes, silica and other dangerous air born
particles involved in the process. 

Just be sure to have an exhaust hood over your burnout oven and wear
a good respirator mask when working with investment in the powder
form. Steam dewaxing or other procedures will help eliminate wax
fumes.

A significant dent in my work time. But if it isn't too difficult
to learn, I think I should get past this curve pretty quickly. Any
opinions? 

Read a good book that will reveal the details and/or take a several
day course at a workshop. Workshops at professional jewelry schools
are expensive but one can often learn the basics at relatively
inexpensive workshops sponsored by gem and mineral societies. (See
www.amfed.org/sfms/lapidary-workshops.html) I think the hands-on
experience at a workshop is the best way to decide whether you want
to invest in a casting shop.

Hope this helps,
Fred
Fred Sias – Woodsmere Press
Books for the crafts and jewelry trade


#3

Casting is easy. It’s also an art more than science. Your two
questions: You should never run out of metal because you should never
cut it that close. You put the wax on the scale (any scale will do,
but better is always better, plus there’s and investment factor),
weigh it, calculate by specific gravity, which give you the estimated
weight. Then you add 1/2 oz to 2 ounces to that, depending on the
size of the casting. This is your margin of error, but it is more
your button, which is the ram behind the metal the packs it in the
flask, and leaves a reservoir of metal as it cools. The rule of heat
is “when the surface is swimming”. That means that there will be
kind’ve a flux-ey glaze on the surface, which will follow the heat of
the torch, and it will appear fluid like water. It’s hard to
describe, but when you see it, you will know.

We use centrifugal casting - I’ve been around vacuum, but have never
done it myself - we use the vacuum for investing. It’s true that we
are a commercial shop, but I would say that the casting equipment has
paid for itself at least 50 times over. I still use the same vacuum,
that cost me about $500 gently used, and the same centrifuge. I’ve
bought about 5 kilns over the years. Plus the convenience - we just
pop a flask in the kiln anytime, and the next morning we have a
casting in hand.

AS far as safety - putting casting into the basement of your house is
probably stretching the limits of what should be done at home.
Investment is relatively harmless - what they call nuisance dust,
which you still shouldn’t breath. But it’s the fire, and some amount
of fumes. If you cast brass or bronze there’s a LOT of fumes. I’ve
said it befoRe: If you buy a torch, buy a fire extinguisher, too.
Finally - as I said, casting is easy. Once you get over the initial
nerves and get a little practice, you’ll be wondering what your
nerves were about…

http://www.donivanandmaggiora.com


#4

Vera -

I understand your intimidation with casting. I have taken numerous
classes on casting and have used both Centrifuge and Vacuum methods
and am still not ready to have casting equipment at my home. I am
located near Dallas and we have a wonderful studio The Art Guild
that has casting classes and on-hand experts to guide us when we
have questions or problems. You may check in your area to see if you
have a similar organization or someone that has done casting on
their own and will help you through the process in the beginning.
Good Luck!

Judy Koslow
Corporate Meetings & Incentives, Inc.


#5

Also consider taking a course at a state school. I am shocked by the
difference between the price of courses at the Fashion Institute of
Technology, which is a well respected SUNY school and the cost of
jewelry workshops. The instructors are almost always world class, and
you could wind up saving thousands.


#6

My Dear Vera,

I have read some where that,

Theory with out practice is fruitless.

Practice with out Theory is Rootless.

So buy the book “Centrifugal Lost Wax Casting” by Murray Bovin.

Read it and start practicing it.

-The seed will become a beautiful tree one day.

-Jump in to the water with out being afraid,you will become an
expert swimmer one day.

-Nothing in this world is difficult you have the courage inside you,
awake it and march ahead and be succesful.

  • Before remelting,always clean the casted sprues and button and
    rejected castings throughly,so that no residue of old investment
    powder and oxide film remains when you cast it again, it will
    prevent inclusion porosity.

-I prefer tourch melting for centrifucgal or vaccum casting, since
the flame prevents the metal from being oxidised by forming a
protective cover on the molten metal.

You already know that expereince is a great teacher the more
castings you do the more better you will become day by day, and the
satisfaction will be the greatest reward you will get by doing it
yourself.

Follow the above Book throughly read it several times while you
start doing castings your self, and here at Orchid all of us are
there to encorage and guide you in your new venture of casting.

Best of luck.

May god bless all with Total Health,Mental-Physical-Spiritual and
Social.

Strive to be Be Happy.

Umesh

Note :visit the site of one of our Orchidian friend at
www.racecarjewelry.com/page03.html


#7

Vera…goodness there is no reason to be intimidated by casting.
There are certain protocols to be followed of course, but by and
large everything is pretty much above board. Both vacuum and
centrifuge casting are quite safe if the protocols are followed. At
the school, we once had a cracked investment and when we cast all the
metal shot straight through the flask…nearly 5 oz of it. Guess
what? The entire load was captured in the flask holder…not one
drop went outside the holder or the tub. Casting with a torch is no
different than soldering in terms of danger.

Don’t let it intimidate you. I have cast at the school and in my
home for years with no problems. Take a class, study up a bit and
just do it! You’ll love it.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2


#8

Dear Vera,

I would recommend getting either Fred Sias book Lost-Wax Casting or
the old classic by Murray Bovin Jewelry Casting. Arm yourself with
knowledge!

Vacuum casting is not difficult and will (IMHO) provide a better
percentage of successful castings.

I would not recommend a garage unless you have removed all old gas
cans and oil spills. Fire hazards. Jewelry manufacturers have been
casting indoors and in small studios for decades using dust masks for
protection from particulates. The danger involved, if materials are
used correctly, are not that great.

Nanz Aalund
Associate Editor / Art Jewelry magazine
21027 Crossroads Circle / Waukesha WI 53187-1612
262.796.8776 ext.228


#9

There is no need to be intimidated by casting.

The best way to learn casting is to take a course. Junior colleges
and the city parks and Recreations sometimes have casting classes.
The casting process is somewhat of a mechanical process with a lot of
magic added.

If you are interested, I would be happy to send you a 32 page copy
of an illustrated paper I wrote on vacuum casting.

Casting your own work will take time from you ability to create.
Especially if you do not have an controlled oven and a controlled
melt furnace. A non controlled burnout oven requires you to monitor
and adjust the rheostat frequently in order to maintain the correct
warm up cycle and flask casting temperature.

Doing your own casting has an advantage in that you will have a
faster turn around time from creation of wax to the finish the item.

The purchase of casting equipment will take a hunk out of your bank
account especially if you buy a controlled burnout oven and furnace.

One advantage of vacuum casting is that the weight of metal is not
as critical as when you centrifugal cast you just need to insure you
melt enough metal. Melting too much is not a problem. Most scales
will work for vacuum casting as long as they can weight enough metal.

It is recommended that at least 50 % new metal be used in each
casting mix. It is very important to completely clean you scrap
metal before melting it. Any investment left on the scrap can cause
porosity.

The garage will be a good place to set up your casting equipment.
Make sure all flammable materials are removed. Heating and cooling
the garage might be a problem depending upon the weather conditions
where you live.

I vacuum cast all my waxes. I also create my own rubber molds
although I admit if I had more intricate designs I am not sure if I
would do that. I do not cast until I have an oven full of flasks.

If I take a special order the delivery time will depend on when I
have enough to fill the burnout oven.

I have a controlled burnout oven and a controlled Electro-melt
furnace. Even with the automatic equipment I find that I will not do
any creating work for a about three days when I cast. There is
plenty of free time between all the casting steps when using
automatic equipment but I find it is difficult to get creative when
my mind is on casting.

It takes a good bit of a day to sprue all the waxes required to fill
my oven.

The second day I invest the flasks. I start that around 11:00 AM.
Investing that many flasks takes up to two hours. I place the flasks
in the burnout oven around 3:00 PM. I never feel like creating while
this is going on.

My oven gets up to the burnout temperature around midnight. I soak
the flasks at that temperature for about 8 hours because of the
amount of wax I have in the burnout oven… The burnout oven is set to
the casting temperature around 8:00 AM the second day. I start
pouring metal around 11:00 and may continue until late in the
afternoon,

Casting one or two items at a time can be done in a day. If you push
it the casting can be done in hours.


#10

Thanks to all of you for the wisdom, generous tips and heart-felt
encouragement. I have ordered all of my needed materials and plan to
practice casting with brass next weekend. After reading your
responses I now wonder what I was so afraid of - failure I guess :slight_smile:

Life is about learning, so let me get on with it :wink:

Thanks once again to all of you for the gentle shove.

-Vera

P.S. I just wanted to add a side note for those who were concerned
about me casting in the garage. I’d rather cast here so that no
contaminants make into the lungs of my cats or dog, who always find a
way into my basement studio no matter how hard I try to keep them out.

I have 2 fire extinguishers - 1 in the garage and 1 in the basement
and I have long since moved typical garage stuffs out of there - so
no gas cans, oil cans cars or any other combustibles.


#11
weigh it, calculate by specific gravity, which give you the
estimated weight. Then you add 1/2 oz to 2 ounces to that,
depending on the size of the casting. 

If you are doing one-offs or small lots, just multiply the
calculated metal weight, including sprues, times 1.3 to allow for the
button.

Jein Kodiak


#12

As I am a hands-on-do-it-all-yourself kind of person I do all my own
casting It is really exciting to cast a piece and appreciate the
results of your efforts. It is nothing to be feared. I took several
classes, and read a number of books. I always use caution, and
careful measurements. I recently took a workshop in wax carving, and
have added that to working with the build-up technique.

I havet a Neycraft centrifuge caster, which I understand is one of
the safest one can get. I also have a vacuum, but only use it for
investing, as vacuum casting is a two person job unless one has an
electromelt. Some people can do the vacuum casting alone, but I found
it difficult, therefore I stick to my centrifuge until I get myself
an electromelt.

Most of my work is fabrication, so I always have a lot of clean
scrap to use for casting. To supplement these, I get grain. The
savings in doing my own work is really good. And I enjoy working with
waxes.

There are a number of excellent books available, so do some reading,
takea class if possible, and if you can, get a casting buddy to work
with you. More fun that way.

Alma


#13

Vera,

I think that it’s great that you are going to try casting. However,
casting brass can be difficult and over heating it can result in
zinc fumes. In my experience it is a fickle casting metal that is
tough to “read” and is definitely not an ideal metal to learn the
process on.

I’d recommend sterling or silicon bronze. The sterling will cost
more, but your learning curve will that much more successful.

Andy Cooperman


#14

Dear Alma,

What is an Electromelt? it sounds like the electrical Induction loop
that I have been looking for to melt silver in a crucible without the
use of a torch.

Any info would be gratefully received.
Sa.


#15

Hi Sam. The one I am referring to is the Kerr Electromelt.
–although there are other brands on the market. You can get a full
description of it in the Rio Grande, and other catalogs, and also you
can log onto the Kerr website. The premeasured metal is melted in the
crucible and when the correct temperature is achieved, is poured in
one smooth operation into the flask which one has already set onto
the vacuum table. No torch is needed.

The Kerr electromelt has a handle (think of a big coffee cup), and
the crucible is not removed for the pour. Other brands are made so
that the crucible is removed with tongs for the pour. Each has its
advantages and disadvantages, and I am sure other Orchidians can off
good advice about each kind.

Hope this helps. Alma


#16

SA,

Look at the website for RDO Enterprises they have all sorts of
Induction Machines, I was able to find a Ti casting machine through
them.

Just Google RDO Enterprises the guy to speak to is Robert Okner

Regards,
James McMurray


#17

an electromelt is an electronic melter which is basically a steel and
ceramic chamber on a base which holds an elongated crucible in it.
You can get programmable or manual melters. I bought one of the
programmable rio ones and really love it! I hated using a blow torch
when I did casting earlier. With this one, I set the program to go
to a certain temperature and hold…put the silver in it w/ a little
flux, and wait until the temp gets up to melting temp, open and stir
to get out the crud, let it continue up etc. When I’m ready to cast,
I simply take out my flask from t he kiln and put it on the vacuum
platform and start it, when the vacuum is at full, I simply remove
the crucible and pour it into the flask…no scary blow
torches…much more relaxed. Also, with doing filigree, I needed to
superheat the silver so it would stay molten long enough to fill the
flasks, and with an electromelt, you know when it’s reached the
right temperature. I’d guess it’s more suitable to vacuum casting
than to centrifugal, though I believe there are some centrifugal ones
with built in electromelts.

Jeanne
jeannius designs
jeannius.com
http://www.jeannius.com


#18
I'd recommend sterling or silicon bronze. The sterling will cost
more, but your learning curve will that much more successful. 

I would suggest that you get some of the casting alloy that gold
casters use to add 24K to in order to make 14 K, etc. We cast it in
school to make practice rings for learning diamond setting, and it
casts and works very well. Sterling is not really all that expensive
either, if you are casting small items. Some types of brass are
awful, I agree with a previous poster. You could also cast some
chunkier designs in pewter, if you like, to just learn the process of
investing, etc. Good luck, and have a fun time!

M’lou Brubaker
Minnesota, USA


#19

An advantage of learning to cast with silver, or gold, is that any
casting that you don’t want to keep can be reused by adding
sufficient new metal. Or, you can trade it in for fresh metal. You
will at least get the price scrap is going for. Also, I agree with the
others. Bass is a real pain.

Alma


#20

Jeanne mentioned in her post that she put a bit of flux in her
electromelt along with her silver. By flux, I assume she means a
pinch of borax. However, I was told that one should not add borax
when using an electromelt. As I am planning to get one, I would
appreciate knowing whether or not to use borax.

Thanks Alma