Centrigical vs Vacuum

Jewelry Discussion
1

Worth 1 cent . . . not two;

Started with Vacuum … as an amateur . . I continue to consider myself as
an amateur probably due to casting techniques and as one would, have tried
many, many ideas, methods, suggestions to very little added success. . .
most local "business professionals, casting for as a corporations have
suggested that,

  1. " Detail is lost with vacuum!" . . . spelled ‘Quality’

  2. " Readability, forgiveness, in method is lost with vacuum!"

… GET RID OF IT!!! …

THAT’S WHY I LOOKING FOR A CENTRIFUGAL!

C U R R E N T P R O B L E M S WITH ‘MMYY’ VACUUM PROCESS!

Instruction which came with the unit(most popular brands carry basically the
same ‘blue’ , ‘multi buck unit’)

  1. Equipment documentation suggest that the silicon pad scorches at 900

degrees. Investment break down between 1250 and 1325 . .considering the
problem presented by porosity at higher temp, in that silver melts at
16++/17++ depending on quality . . there is a ingrained problem…

( And I’ve had/have them all . . requires more control than the less
auto-equipment.

  1.  Absolute prefect surface is required relative to the bottom of the

flask being cast… drop an empty flask and you can either through
it away or file the bottom for an hour to remove the dent… a
break in the vacuum!

  1.  Slightest 'scorch/ring in the pad( $20.00 A pop!) will prevent the

vacuum from taking Place! . . . NOW WHAT ABOUT THE MOLTEN SILVER(Watch
that temp!), cylinder getting cold( greater difference in silver temp
and cylinder Temp spelled porosity!.

  1.  Vacuum allows doubt as to success with pour . . Vacuum often doesn't

come up and you feel you must pour because of the variations in temp! .
. sometimes it works … sometimes it doesn’t! . . . as Processes go
this just doesn’t make it . . according to most pros I’ve met … and
this amateurs . . unless someone out there can help!! Got to give it
up!

  1.  ETC., Etc. . . If you have the answers .... I'm listening!

HEADED FOR CENTRIFUGAL IN TAMPA!

(SOMEONE, . . . AN A MATURE, TELL ME THE PROBLEMS WITH CENTRIFUGAL…
PLEASE NOT YOUR SUCCESSES!)

THANKS,

JIM

2

Jim Chambers wrote:

Worth 1 cent . . . not two;

Started with Vacuum … as an amateur . . I continue to consider myself as
an amateur probably due to casting techniques and as one would, have tried
many, many ideas, methods, suggestions to very little added success. . .
most local "business professionals, casting for as a corporations have
suggested that,

  1. " Detail is lost with vacuum!" . . . spelled ‘Quality’
  1. " Readability, forgiveness, in method is lost with vacuum!"

… GET RID OF IT!!! …

THAT’S WHY I LOOKING FOR A CENTRIFUGAL!

C U R R E N T   P R O B L E M S WITH 'MMYY' VACUUM PROCESS!

Instruction which came with the unit(most popular brands carry basically the
same ‘blue’ , ‘multi buck unit’)

  1. Equipment documentation suggest that the silicon pad scorches at 900

degrees. Investment break down between 1250 and 1325 . .considering the
problem presented by porosity at higher temp, in that silver melts at
16++/17++ depending on quality . . there is a ingrained problem…

I don’t have any problems W/ Either. Follow instructions and every
thing will be fine. Even in casting hell (Sarasota, Florida)

3
  1. " Detail is lost with vacuum!" . . . spelled ‘Quality’

Very questionable. My experience shows me that I need to fully understand
both methods to make this kind of judgement.

  1. " Readability, forgiveness, in method is lost with vacuum!"

Again, this hasn’t been my experience.
Certain advantages are to getting good detail are an absence of trapped
gases and the weight of about 30 inches of mercury to provide steady
pressure behind the metal.

C U R R E N T P R O B L E M S WITH ‘MMYY’ VACUUM PROCESS!

  1. Equipment documentation suggest that the silicon pad scorches at 900

degrees. Investment break down between 1250 and 1325 . .considering the
problem presented by porosity at higher temp, in that silver melts at
16++/17++ depending on quality . . there is a ingrained problem…

I regularly burnout at up to 1500 degrees and haven’t been experiencing any
investment breakdown. When I am having problems with investment breakdown,
it is usually because the stuff has been around for quite a while and too
much exposure to the atmosphere a\has also exposed it to too much H2O.
Casting itself should take place when internal flask temperatures are closer
to 1000. The temperature of molten metal drops quickly when the metal is
poured and the heat is pulled away. If these were real problems, they would
show themselves with centrifugal casting as well.

   ( And I've had/have them all . . requires more control than the less

auto-equipment.

Hey. These machines can be set up for under $1000 fro a whole rig. If you
want automation, it,s possible to start out at $100,000. What newbie wants that?

  1.  Absolute prefect surface is required relative to the bottom of the

flask being cast… drop an empty flask and you can either through
it away or file the bottom for an hour to remove the dent… a
break in the vacuum!

Actually, I do from time to time jam a flask up to a belt sander, but
usually that is because I’ve used it so many times that the iron oxides are
finally getting the better of it. I’d bet I get a couple of hundred castings
before they are this bad.

  1.  Slightest 'scorch/ring in the pad( $20.00 A pop!) will prevent the

vacuum from taking Place! . . . NOW WHAT ABOUT THE MOLTEN SILVER(Watch
that temp!), cylinder getting cold( greater difference in silver temp
and cylinder Temp spelled porosity!.

My silicon pads all have scorch marks. It’s OK. As for a perfect seal, I get
it by making the bottom of the flask a little convex by washing it under
water after it has set. If the investment is outt the way, it’ll seal right
almost every time.

  1.  Vacuum allows doubt as to success with pour . . Vacuum often doesn't

come up and you feel you must pour because of the variations in temp! .
. sometimes it works … sometimes it doesn’t! . . . as Processes go
this just doesn’t make it . . according to most pros I’ve met … and
this amateurs . . unless someone out there can help!! Got to give it
up!

Check the gauge. I think if you are drawing less than 25 inches of mercury
there is a leak somewhere and there probably is room for doubt.

  1.  ETC., Etc. . . If you have the answers .... I'm listening!

There are my two cents worth. Wish you a little better luck.
Bruce

4

First off, who was it that wrote this about vaccum casting anyway… ?? I only
have on thing to say about it… GIVE IT UP… I have been doing vaccum
casting for a long time and never have problems with my vacumm coming up or my
silcon pads scorching or loosing detail… You obviously don’t know what you
are doing. As for your investment breaking down, well maybee you should learn
how to properly mix the stuff first… Oh by the way I have had flasks in my
oven withstand temps of over 1550 degrees due to driver error (me) that is I
forgot to turn my oven down… The inevestment problem has nothing to do with
vaccum casting anyway…
MarcFrom: owner-orchid@proteus.imagiware.com on behalf of Jim Chambers
Sent: Thursday, October 03, 1996 7:40 PM
To: orchid@ganoksin.com
Subject: Centrigical vs Vacuum

Worth 1 cent . . . not two;

Started with Vacuum … as an amateur . . I continue to consider myself as
an amateur probably due to casting techniques and as one would, have tried
many, many ideas, methods, suggestions to very little added success. . .
most local "business professionals, casting for as a corporations have
suggested that,

  1. " Detail is lost with vacuum!" . . . spelled ‘Quality’

  2. " Readability, forgiveness, in method is lost with vacuum!"

… GET RID OF IT!!! …

THAT’S WHY I LOOKING FOR A CENTRIFUGAL!

C U R R E N T P R O B L E M S WITH ‘MMYY’ VACUUM PROCESS!

Instruction which came with the unit(most popular brands carry basically the
same ‘blue’ , ‘multi buck unit’)

  1. Equipment documentation suggest that the silicon pad scorches at 900

degrees. Investment break down between 1250 and 1325 . .considering the
problem presented by porosity at higher temp, in that silver melts at
16++/17++ depending on quality . . there is a ingrained problem…

( And I've had/have them all . . requires more control than the less

auto-equipment.

  1.  Absolute prefect surface is required relative to the bottom of the

flask being cast… drop an empty flask and you can either through
it away or file the bottom for an hour to remove the dent… a
break in the vacuum!

  1.  Slightest 'scorch/ring in the pad( $20.00 A pop!) will prevent the

vacuum from taking Place! . . . NOW WHAT ABOUT THE MOLTEN SILVER(Watch
that temp!), cylinder getting cold( greater difference in silver temp
and cylinder Temp spelled porosity!.

  1.  Vacuum allows doubt as to success with pour . . Vacuum often doesn't

come up and you feel you must pour because of the variations in temp! .
. sometimes it works … sometimes it doesn’t! . . . as Processes go
this just doesn’t make it . . according to most pros I’ve met … and
this amateurs . . unless someone out there can help!! Got to give it
up!

  1.  ETC., Etc. . . If you have the answers .... I'm listening!

HEADED FOR CENTRIFUGAL IN TAMPA!

(SOMEONE, . . . AN A MATURE, TELL ME THE PROBLEMS WITH CENTRIFUGAL…
PLEASE NOT YOUR SUCCESSES!)

THANKS,

JIM

procedures

5

I have access both vacuum and centrifuge(the same machine I use to
vacuum investment will cast as well as do most)but just never found a
reason to use the vacuum machine.The Neycraft centrifuge works fine for
me…
One thing not mentioned by anyone else so far is that the spring
driven centrifuge is considered a hand tool and the vacuum machine a
power tool…This is important if you want to advertise your work as
handwrought.
After my flasks have been standing full of investment for an hour I
always carve the tops level with the flask walls with a sharp knife and
remove any investment stuck to the outside of the flask the same way.I
do this before removing the rubber sprue base from the flask.
I always begin burnout after letting the flasks sit only one hour and
never let them sit any longer than this.This insures the presence of
enough moisture to properly drive the melted wax out of the flask.
Gavin

6

Gavin,

Interesting, It has been suggested that I allow my flask to sit overnight
for exacally the opposite reasoning… allows the water to evaporate… that
applying heat to soon, thereby causing the water to evaporate to soon could
cause the investment to crack . . so I wait about 3/4 hours…

At 01:34 AM 10/4/96 -0500, you wrote:

7

Bruce,

What brand of investment are you using? I am aware of ‘Dental’ brand or
quality which allows temperatures of 15++ but per local wholesaler, brands
per manuf. burnout at 1325ish . . agreed … would like to pour at 1000 ,
problem is that the silicon rings(scorches) and I mean big time dents at
1000… so I’ve been doing appox. 900 which also scorches but very lightly
… trying to find ‘sheet’ silicon at a cheaper price…AM I THE ONLY VACUUM
CASTING PERSON HAVING THESE PROBLEM … IF SO THEN I MUST HAVE A METERING
PROBLEM???

I have not tried casting with the perforated flask… better???

Quality… really… most of the larger casting houses, that I’ve talked with
have suggested to ‘dump’ the process due to sensitivity of the casting
requirements using vacuum…

Think I’ll change my investment, get rid of the silicon(requires a very
perfect bottom on the flask … but works great! and have another go!

Jim

At 01:11 AM 10/4/96 -0400, you wrote:

  1. " Detail is lost with vacuum!" . . . spelled ‘Quality’

Very questionable. My experience shows me that I need to fully understand
both methods to make this kind of judgement.

  1. " Readability, forgiveness, in method is lost with vacuum!"

Again, this hasn’t been my experience.
Certain advantages are to getting good detail are an absence of trapped
gases and the weight of about 30 inches of mercury to provide steady
pressure behind the metal.

C U R R E N T P R O B L E M S WITH ‘MMYY’ VACUUM PROCESS!

  1. Equipment documentation suggest that the silicon pad scorches at 900

degrees. Investment break down between 1250 and 1325 . .considering the
problem presented by porosity at higher temp, in that silver melts at
16++/17++ depending on quality . . there is a ingrained problem…

I regularly burnout at up to 1500 degrees and haven’t been experiencing any
investment breakdown. When I am having problems with investment breakdown,
it is usually because the stuff has been around for quite a while and too
much exposure to the atmosphere a\has also exposed it to too much H2O.
Casting itself should take place when internal flask temperatures are closer
to 1000. The temperature of molten metal drops quickly when the metal is
poured and the heat is pulled away. If these were real problems, they would
show themselves with centrifugal casting as well.

   ( And I've had/have them all . . requires more control than the less

auto-equipment.

Hey. These machines can be set up for under $1000 fro a whole rig. If you
want automation, it,s possible to start out at $100,000. What newbie wants
that?

8

Jim Chambers wrote:

Gavin,

Interesting, It has been suggested that I allow my flask to sit overnight
for exacally the opposite reasoning… allows the water to evaporate… that
applying heat to soon, thereby causing the water to evaporate to soon could
cause the investment to crack . . so I wait about 3/4 hours…

At 01:34 AM 10/4/96 -0500, you wrote:

I have access both vacuum and centrifuge(the same machine I use to
vacuum investment will cast as well as do most)but just never found a
reason to use the vacuum machine.The Neycraft centrifuge works fine for
me…
One thing not mentioned by anyone else so far is that the spring
driven centrifuge is considered a hand tool and the vacuum machine a
power tool…This is important if you want to advertise your work as
handwrought.
After my flasks have been standing full of investment for an hour I
always carve the tops level with the flask walls with a sharp knife and
remove any investment stuck to the outside of the flask the same way.I
do this before removing the rubber sprue base from the flask.
I always begin burnout after letting the flasks sit only one hour and
never let them sit any longer than this.This insures the presence of
enough moisture to properly drive the melted wax out of the flask.
Gavin

orchid@ganoksin.com

orchid@ganoksin.com

Jim,
The instructions I find to be best on casting are in the
book"Jewelry Making for Schools,Tradesmen,Craftsmen" by Murray
Bovin.While there are a series of three books available I find the
single one with the gold colored cover to be nearly all inclusive.This
is a must have book for anyone interested in jewelry making.
Murray Bovin recommends a 2 hour wait time after pouring the
investment for a larger flask.I use several small flasks as opposed to
one large one and find 1 hour to be enough.I am careful not to allow the
kiln temperature during the first hour of the burnout to rise above 350
degrees F…also I mix my investment thick enough so that a heavy
coating sticks to my hand 1/8 inch thick or more and it’s too thin if it
runs from your fingers in a steady stream.Lots of people go based on
alot of complicated weighing of the investment and water and I just know
from experience so I never weigh the water or investment. I mix in a
rubber bowl with my hand working out the lumps out by squeezing it
between my fingers.This is the only way I have found to be certain there
are no lumps of dry investment left unmixed…Check my website at
http://www.connecti.com/~gchando for more on casting…Gavin

9

Bruce,

What brand of investment are you using? I am aware of ‘Dental’ brand or
quality which allows temperatures of 15++ but per local wholesaler, brands
per manuf. burnout at 1325ish . . agreed … would like to pour at 1000 ,
problem is that the silicon rings(scorches) and I mean big time dents at
1000… so I’ve been doing appox. 900 which also scorches but very lightly
… trying to find ‘sheet’ silicon at a cheaper price…AM I THE ONLY VACUUM
CASTING PERSON HAVING THESE PROBLEM … IF SO THEN I MUST HAVE A METERING
PROBLEM???

I have not tried casting with the perforated flask… better???

Quality… really… most of the larger casting houses, that I’ve talked with
have suggested to ‘dump’ the process due to sensitivity of the casting
requirements using vacuum…

Think I’ll change my investment, get rid of the silicon(requires a very
perfect bottom on the flask … but works great! and have another go!

Jim

I am using Kerr Satin Cast 20 for my investment. I did a little

casting today that I allowed to reach about 1500 for a half hour or so. My
casting mchine is a Vigor MasterVac that I purchased about 15 years ago. My
first casting were in certrifugal that I did when I was in high school. Big
problems. I used to own a little springloaded centrifugal machine and it
worked ok, but used up a little too much valuable space. I think that my
results are competitive with everything that I ever got wiht a centrifige.
Occaisionally I use perforated flasks, but most of the time I am doing 3-6
rings that will fit into a 2" flask. This allows me to burn out a flask in
an hour or two.
I am beginning to suspect that maybe you are having a metering
problem. It has taken me a long time to learn where I can shortcut for my
needs. No doubt it’ll take you a while to learn what you need to do and what
you can get away with. Keep reading the newsgroups and stay on htis
listserver. I’ve gotten a lot of good tips recently.
Here is a tip. Not too long ago, there was a thread in the
rec.crafts.jewelry newsgroup. I just caught a couple of replies in it, but
it got me very interested. The thread was about casting with diamonds in the
waxes. I started doing burnouts at about 800 degrees and casting the metal
directly on the stones. I’ve only done it a couple of times. Last night, I
set up some diamonds girdle to girdle in the wax. I could intuit that this
might be problem, but I wouldn’t know for sure unless I tried it. It was a
big mistake. Cost me a couple/few hundred dollars. Now, someone else might
be able to learn from my mistake. I usually have to learn by experience.
Twenty six years and still learning. The tip is this. Whatever you are
building, never ever ever try to allow the stones to touch each other. I’ve
seen setters get this stuff out the door only to have the customer bump one
of the stones slightly causing a stone to bust.

Bruce D. Holmgrain
E-mail: Manmountaindense@Knight-Hub.com
WWW: http://www.knight-hub.com/manmtndense/bhh3.htm
Snail Mail: POB 7972, McLean, VA 22106

10

Jim: on your burnout kiln have you calibrated your temperature gauge? Leave
the door open check the room temperature and adjust your kiln gauge to
match…Dave

Art Jewelry for Conscious People
http://www.opendoor.com/stephensdesign/crystalguy.html

11

A very good idea… meter provides about 1/8(?)" for 25 degrees but its
worth a try … thinking about haveing someone look it over completely anyway
Thanks,
Jim

At 04:02 PM 10/4/96 -0800, you wrote:

12

Jim Chambers wrote:

A very good idea… meter provides about 1/8(?)" for 25 degrees but its
worth a try … thinking about haveing someone look it over completely anyway
Thanks,
Jim

At 04:02 PM 10/4/96 -0800, you wrote:

Jim: on your burnout kiln have you calibrated your temperature gauge? Leave
the door open check the room temperature and adjust your kiln gauge to
match…Dave

Art Jewelry for Conscious People
http://www.opendoor.com/stephensdesign/crystalguy.html

orchid@ganoksin.com

orchid@ganoksin.com

Jim,
If you are in doubt about it set the meter(should be a screw driver
slot in the gauge either front or back centered below the needle)for 3/4
of the first 100 degrees.This is about 75 degrees…Remember some gauges
are marked in degrees Celsius or Centigrade only so you have to convert
to Fahrenheit…Gavin

13

Bruce Holmgrain wrote:

Bruce,

What brand of investment are you using? I am aware of ‘Dental’ brand or
quality which allows temperatures of 15++ but per local wholesaler, brands
per manuf. burnout at 1325ish . . agreed … would like to pour at 1000 ,
problem is that the silicon rings(scorches) and I mean big time dents at
1000… so I’ve been doing appox. 900 which also scorches but very lightly
… trying to find ‘sheet’ silicon at a cheaper price…AM I THE ONLY VACUUM
CASTING PERSON HAVING THESE PROBLEM … IF SO THEN I MUST HAVE A METERING
PROBLEM???

I have not tried casting with the perforated flask… better???

Quality… really… most of the larger casting houses, that I’ve talked with
have suggested to ‘dump’ the process due to sensitivity of the casting
requirements using vacuum…

Think I’ll change my investment, get rid of the silicon(requires a very
perfect bottom on the flask … but works great! and have another go!

Jim

    I am using Kerr Satin Cast 20 for my investment. I did a little

casting today that I allowed to reach about 1500 for a half hour or so. My
casting mchine is a Vigor MasterVac that I purchased about 15 years ago. My
first casting were in certrifugal that I did when I was in high school. Big
problems. I used to own a little springloaded centrifugal machine and it
worked ok, but used up a little too much valuable space. I think that my
results are competitive with everything that I ever got wiht a centrifige.
Occaisionally I use perforated flasks, but most of the time I am doing 3-6
rings that will fit into a 2" flask. This allows me to burn out a flask in
an hour or two.
I am beginning to suspect that maybe you are having a metering
problem. It has taken me a long time to learn where I can shortcut for my
needs. No doubt it’ll take you a while to learn what you need to do and what
you can get away with. Keep reading the newsgroups and stay on htis
listserver. I’ve gotten a lot of good tips recently.
Here is a tip. Not too long ago, there was a thread in the
rec.crafts.jewelry newsgroup. I just caught a couple of replies in it, but
it got me very interested. The thread was about casting with diamonds in the
waxes. I started doing burnouts at about 800 degrees and casting the metal
directly on the stones. I’ve only done it a couple of times. Last night, I
set up some diamonds girdle to girdle in the wax. I could intuit that this
might be problem, but I wouldn’t know for sure unless I tried it. It was a
big mistake. Cost me a couple/few hundred dollars. Now, someone else might
be able to learn from my mistake. I usually have to learn by experience.
Twenty six years and still learning. The tip is this. Whatever you are
building, never ever ever try to allow the stones to touch each other. I’ve
seen setters get this stuff out the door only to have the customer bump one
of the stones slightly causing a stone to bust.

Bruce D. Holmgrain
E-mail: Manmountaindense@Knight-Hub.com
WWW: http://www.knight-hub.com/manmtndense/bhh3.htm
Snail Mail: POB 7972, McLean, VA 22106

orchid@ganoksin.com

Just wanted to add that I have seen things with garnet and ruby and
other stones cast into them as well as diamonds…The garnets were a
surprise because I would have thought there was no way it would work.I
thought they would craze with alot of fractures from the heat but it
worked one out of about a dozen of the garnets cracked in the
casting…G

14

Know your equiptment! Screw is at about 75 degrees… however, this is Fla.
and intend to have the unit looked over top to bottom also have a very small
x4x
Kelenko (think for dental caps… great little oven) will have it look at as well
Thanks again,
Jim

At 11:30 PM 10/4/96 -0500, you wrote:

Jim Chambers wrote:

A very good idea… meter provides about 1/8(?)" for 25 degrees but its
worth a try … thinking about haveing someone look it over completely anyway
Thanks,
Jim

At 04:02 PM 10/4/96 -0800, you wrote:

Jim: on your burnout kiln have you calibrated your temperature gauge? Leave
the door open check the room temperature and adjust your kiln gauge to
match…Dave

Art Jewelry for Conscious People
http://www.opendoor.com/stephensdesign/crystalguy.html

orchid@ganoksin.com

procedures

orchid@ganoksin.com

procedures

15

Jim: a good time Gavin gave me a long time ago, set your meter to room temp
then crank it up to 350 or lower and then put a candy thermometer in the
oven and see if it reads the same temp. it worked for me…Dave

Art Jewelry for Conscious People
http://www.opendoor.com/stephensdesign/crystalguy.html

16

Dave Stephens wrote:

Jim: a good time Gavin gave me a long time ago, set your meter to room temp
then crank it up to 350 or lower and then put a candy thermometer in the
oven and see if it reads the same temp. it worked for me…Dave

Art Jewelry for Conscious People
http://www.opendoor.com/stephensdesign/crystalguy.html

orchid@ganoksin.com

Dave,
Darn I forgot all about that one…At one time I had a metal thing
that the woodstove people from Earth Stoves sold for a stovetop oven
that went to about 850 degrees and was really sort of like a watch
spring and that was useful for the same purpose…Another way is to get
the ceramic temperature cones from a good ceramics shop and check and
set the pyrometer temperature based on their listed temperature
indication properties.You can place several in the furnace that will
droop or melt at different temperatures and check across a spectrum of
several temperatures that way also.These temperature indicating cones
are inexpensive compared to what most service shops would charge to do
the same thing anyway…They are about $1.25 each if I remember
correctly.
Also “Action Mining” in Las Vegas Nevada sells a portable temperature
probe/pyrometer with a digital readout for about $125 which is perhaps a
good option if you have a furnace without a gauge.To get one that
installs directly onto a single furnace with all the stuff you need
costs about $90 also from Action Mining…Gavin

17

Going to do that TOOOO!

This group will make (or certainly give it a great try) a descent jewelry
out of me . . yet!

My continual thanks,

Jim

At 04:17 PM 10/5/96 -0800, you wrote:

18

HI all

I’m somewhat amazed that in this extensive thread, the fundamental
differences between vacuum and centrifugal casting have not come up.

I would first like to say, THEY BOTH WORK VERY WELL!!! And I might add
that most of the professional casting shops I have worked in use vacuum
assisted casting!

What I recommend is anyone interested in really learning casting do
reasearch, get every book you can find and read them. If you really
understand the theory and complications (which are MANY), you’ll usually
get good results.

I need to say this, NO DETAIL IS LOST IN VACUUM CASTING, depending on
the metal being cast. For instance, I wouldn’t cast 10k white gold on a
vacuum unit.

The problems that exist with centrifugal casting also exist with vacuum
casting. They basically boil down to knowing the correct temperatures
for the metal being cast, and spruing the piece properly.

As a casting professional, I must say that you have to know what you’re
doing to get good results, and long experience is a great teacher. It
took me YEARS of problem solving to REALLY understand what goes on when
the metal is poured or injected.

Jeffrey Everett
Jim Chambers wrote:

Worth 1 cent . . . not two;

Started with Vacuum … as an amateur . . I continue to consider myself as
an amateur probably due to casting techniques and as one would, have tried
many, many ideas, methods, suggestions to very little added success. . .
most local "business professionals, casting for as a corporations have
suggested that,

  1. " Detail is lost with vacuum!" . . . spelled ‘Quality’
  1. " Readability, forgiveness, in method is lost with vacuum!"

… GET RID OF IT!!! …

THAT’S WHY I LOOKING FOR A CENTRIFUGAL!

C U R R E N T   P R O B L E M S WITH 'MMYY' VACUUM PROCESS!

Instruction which came with the unit(most popular brands carry basically the
same ‘blue’ , ‘multi buck unit’)

  1. Equipment documentation suggest that the silicon pad scorches at 900

degrees. Investment break down between 1250 and 1325 . .considering the
problem presented by porosity at higher temp, in that silver melts at
16++/17++ depending on quality . . there is a ingrained problem…

    ( And I've had/have them all . . requires more control than the less

auto-equipment.

  1.  Absolute prefect surface is required relative to the bottom of the

flask being cast… drop an empty flask and you can either through
it away or file the bottom for an hour to remove the dent… a
break in the vacuum!

  1.  Slightest 'scorch/ring in the pad( $20.00 A pop!) will prevent the

vacuum from taking Place! . . . NOW WHAT ABOUT THE MOLTEN SILVER(Watch
that temp!), cylinder getting cold( greater difference in silver temp
and cylinder Temp spelled porosity!.

  1.  Vacuum allows doubt as to success with pour . . Vacuum often doesn't

come up and you feel you must pour because of the variations in temp! .
. sometimes it works … sometimes it doesn’t! . . . as Processes go
this just doesn’t make it . . according to most pros I’ve met … and
this amateurs . . unless someone out there can help!! Got to give it
up!

  1.  ETC., Etc. . . If you have the answers .... I'm listening!

HEADED FOR CENTRIFUGAL IN TAMPA!

(SOMEONE, . . . AN A MATURE, TELL ME THE PROBLEMS WITH CENTRIFUGAL…
PLEASE NOT YOUR SUCCESSES!)

THANKS,

JIM

orchid@ganoksin.com

Handmade 18K and platinum gemstone jewelry. Fine die
and mold engraving. Diamond setting. Class rings/pins.
25 years experience in the jewelry trade. 515-472-9830

19

Jeffrey Everett wrote:

20

Thanks Jeff,

Going to hang in there and try some of the things suggested… still talking
to Gavin in understanding how to cast using the perforated flask… however,
Everyone suggest you, ‘CAST AT THE RIGHT TEMP’ . . well, when using a torch
and crucible other that just looking at the melt; movement, shine, way it
rolls, ???

… which does’t tell the temp . . who do you know other than experience??

Jim
At 01:11 AM 10/11/96 -0500, you wrote:

HI all

I’m somewhat amazed that in this extensive thread, the fundamental
differences between vacuum and centrifugal casting have not come up.

I would first like to say, THEY BOTH WORK VERY WELL!!! And I might add
that most of the professional casting shops I have worked in use vacuum
assisted casting!

What I recommend is anyone interested in really learning casting do
reasearch, get every book you can find and read them. If you really
understand the theory and complications (which are MANY), you’ll usually
get good results.

I need to say this, NO DETAIL IS LOST IN VACUUM CASTING, depending on
the metal being cast. For instance, I wouldn’t cast 10k white gold on a
vacuum unit.

The problems that exist with centrifugal casting also exist with vacuum
casting. They basically boil down to knowing the correct temperatures
for the metal being cast, and spruing the piece properly.

As a casting professional, I must say that you have to know what you’re
doing to get good results, and long experience is a great teacher. It
took me YEARS of problem solving to REALLY understand what goes on when
the metal is poured or injected.

Jeffrey Everett
Jim Chambers wrote:

Worth 1 cent . . . not two;

Started with Vacuum … as an amateur . . I continue to consider myself as
an amateur probably due to casting techniques and as one would, have tried
many, many ideas, methods, suggestions to very little added success. . .
most local "business professionals, casting for as a corporations have
suggested that,

  1. " Detail is lost with vacuum!" . . . spelled ‘Quality’
  1. " Readability, forgiveness, in method is lost with vacuum!"

… GET RID OF IT!!! …

THAT’S WHY I LOOKING FOR A CENTRIFUGAL!

C U R R E N T   P R O B L E M S WITH 'MMYY' VACUUM PROCESS!

Instruction which came with the unit(most popular brands carry basically the
same ‘blue’ , ‘multi buck unit’)

  1. Equipment documentation suggest that the silicon pad scorches at 900

degrees. Investment break down between 1250 and 1325 . .considering the
problem presented by porosity at higher temp, in that silver melts at
16++/17++ depending on quality . . there is a ingrained problem…

    ( And I've had/have them all . . requires more control than the less

auto-equipment.

  1.  Absolute prefect surface is required relative to the bottom of the

flask being cast… drop an empty flask and you can either through
it away or file the bottom for an hour to remove the dent… a
break in the vacuum!

  1.  Slightest 'scorch/ring in the pad( $20.00 A pop!) will prevent the

vacuum from taking Place! . . . NOW WHAT ABOUT THE MOLTEN SILVER(Watch
that temp!), cylinder getting cold( greater difference in silver temp
and cylinder Temp spelled porosity!.

  1.  Vacuum allows doubt as to success with pour . . Vacuum often doesn't

come up and you feel you must pour because of the variations in temp! .
. sometimes it works … sometimes it doesn’t! . . . as Processes go
this just doesn’t make it . . according to most pros I’ve met … and
this amateurs . . unless someone out there can help!! Got to give it
up!

  1.  ETC., Etc. . . If you have the answers .... I'm listening!

HEADED FOR CENTRIFUGAL IN TAMPA!

(SOMEONE, . . . AN A MATURE, TELL ME THE PROBLEMS WITH CENTRIFUGAL…
PLEASE NOT YOUR SUCCESSES!)

THANKS,

JIM

orchid@ganoksin.com

procedures