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Centrifugal people [Was Centrifugal vs...]


#1

Where are all the Centrifugal people?, Centrifugal provides
denser castings every time. Less worry of “will it come this
time?” But, I realize, you don’t get the pleasure of seeing the
beautiful metal being slowly poured into the waiting mouth of
the painstakingly (is that a word?) prepared flask with straws,
nails, spaghetti, and who knows what else. Personally, I think
the straws are the best idea, I have used bobby pins to hold
them in place. I think spruing is a much more interesting and
germain topic. I know process is a lot of the joy in the work…
I like the dramatic rush of the torch, the anticipation of just
the correct instant, the choreographed movements to deliver the
flask just in time to release the pent up energy into the
waiting flask expectant of the whirling dervish dance of
Centrifugal Ectasy!! Well, I thought I’d stir things up a bit!..
How’d I do Roland? John


#2
   Where are all the Centrifugal people?, 

I seem to be one of the few. I have both, cast every day, have
used them both for many years, and like centrifugal better, it
never fails. What more could I want.

I don’t mind being different, I will also drive all night for a
particularly good pie.

Mark P.


#3
 I know process is a lot of the joy in the work... I like the
dramatic rush of the torch, the anticipation of just the
correct instant, the choreographed movements to deliver the
flask just in time to release the pent up energy into the
waiting flask expectant of the whirling dervish dance of
Centrifugal Ectasy!! Well, I thought I'd stir things up a
bit!... How'd I do Roland? 

My oh my…you’ve made me blush. On a serious note, I too prefer
a centrifugal machine…it just seems to produce more consistent
results in my experience.

Susan


#4

Hi John,

O.K. you got me! I’m the resident Dental Tech/jewelry maker and
all I do is centrifugal casting. I could never understand why
any one would do it any other way! I’ve been a tech for 30
years and made thousands of castings. The only trouble I
experience is when casting a particular palladium silver alloy
for dentistry. The problem occurs when the thin areas (less
than .2mm) are not thickened to .3mm or slightly more. I have
heard of dental labs that use vacuum casting set-ups but I’ve
never seen one. There is a new set-up out that you can
centrifugally cast in an argon atmosphere after the metal is
melted electrically but I have never seen one either.

Ever heard of steam casting or potato casting? You use a potato
to supply the steam to drive the molten metal into the mold. It
can be tricky but it works. It is an old dental trick I learned
what seems like eons ago.

Regards,

Skip

                                  Skip Meister
                                NRA Endowment and
                                   Instructor
                                @Skip_Meister
                                10/02/9712:35:56

#5

Well John - I don’t know about Roland, but that really got me
going - maybe you should add advertising to your list …

Reminds me that I have a centrifugal machine just sitting in my
basement, which my father swears by (he’s a retiring - he keeps
saying - dentist). He says that in 34 years, he only had one bad
cast. Maybe I should pull it out…

Laura


#6

Skip - Since you are the dental tech/jewelry person, I have a
question for you. I have some dental gold my dad gave me: a
button and pieces from an old casting (the latter may or may not
include solder ??). Anyway - can it be used successfully in
jewelry? Do I have to do anything different to it? Do I need to
find out what the specific alloy is from the supplier or is it
all basically the same? Thanx for the info. Laura


#7

Skip

When my brother Mark worked for Bob Stein in Boston he used a
vacuum casting that Stein developed in conjunction with a German
company. Eons ago I cast with a spring wound machine, but the
absolute best machine for a small shop that I’ve seen was the
Torit vertical arm platinum casting machine. At this point, I’d
rather send stuff out to be cast, though.

Rick
Richard D. Hamilton

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

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


#8

Hi,

I have moved away from casting mostly but that was pretty much
the focus of my University metalworking professors. We have both
set-ups and except when there was a technical reason to change I
always used the centrifuge. I was always happier with my
casting, thought it was more reliable and my profs who have been
doing this for 60+ yrs combined thought so too.

Only ones I ever lost were my own fault and I knew it. Of course,
this was an archaic lab and I’m guessing it would be different
with one of those nifty all-in-one Rio machines I have seen
advertised. I alway thought the density was better in the cast as
well, at least they seemed easier to solder on afterwards.

Besides, when working late on a Friday night you at least had the
amusement of flying molten metal to keep you on your toes.

Karen
@Karenworks


#9

Hi,

I have moved away from casting mostly but that was pretty much
the focus of my University metalworking professors. We have both
set-ups and except when there was a technical reason to change I
always used the centrifuge. I was always happier with my
casting, thought it was more reliable and my profs who have been
doing this for 60+ yrs combined thought so too.

Only ones I ever lost were my own fault and I knew it. Of course,
this was an archaic lab and I’m guessing it would be different
with one of those nifty all-in-one Rio machines I have seen
advertised. I alway thought the density was better in the cast as
well, at least they seemed easier to solder on afterwards.

Besides, when working late on a Friday night you at least had the
amusement of flying molten metal to keep you on your toes.

Karen
@Karenworks


#10

Hi,

They brought one into the lab I was doing my apprenticeship at
to give it a try. It was quickly named ‘The Golden Ferris
Wheel’. I think that they are still finding gold stuck on the
ceiling. They sent it back in 1 week.

Regards,

Skip

                                  Skip Meister
                                NRA Endowment and
                                   Instructor
                                @Skip_Meister
                                10/04/9702:08:08

#11
 I know process is a lot of the joy in the work... I like the
dramatic rush of the torch, the anticipation of just the
correct instant, the choreographed movements to deliver the
flask just in time to release the pent up energy into the
waiting flask expectant of the whirling dervish dance of
Centrifugal Ectasy!! Well, I thought I'd stir things up a
bit!... How'd I do Roland? 

hi john,

whew, your inspiration has just made me perspire. why did you
stop?

ok, here’s an answer and more questions: i’ve always preferred
centrifigal to vacuum. lot’s more success. though reading
several threads here and observing the advent of mondo tedchno
vacuum casting machines there, i’ve wondereed if perhaps i was
missing something about vacuum casting. i’ve actually heard
claims that a 5cfm vacuum caster produces denser castings than
centrifigal. hard for me to believe. especially when one
considers that there isn’t a vacuum caster that is able to cast
platinum. or is there, and i haven’t heard of it? anyway, i’ve
tried the old vacuum ‘assist’ for a few items recently, and it
worked well for large items (just like the ancient casting books
tell us) but not so good on small items. i was casting sterling,
not wanting to wxperiment with anything expensive.

in my spare time (ha ha ho ho hee hee) i would like to build a
true vacuum caster that utilizes perferated flasks. got all the
parts, just have to put it together. it was also read on this
forum that if one puts an air tank in line on the vacuum, a 3cfm
can act like a much bigger (and more expensive) 5 or more cfm
unit. your thoughts would greatly be appreciated.

best regards,

geo fox


#12

Hey George, Been there, done it…I used a 5 gal propane tank to
achieve a “battery” of vacuum, and yes, it does work. But it’s
still vac casting. I use vac for big items. I have a 4KW Memco
Inducto-Vac machine w/ the use of forming gas, induction melting,
graphite crucible, you know…all the bells and whistles. I still
get the best results with torch melt and an Romanoff electic
centrifuge. I’m casting sometimes thousands of pieces a week. I
keep the flasks to a size where I can keep a handle on the
quality. We call the Memco the “LOCM”, for "large object casting
machine. There are tool catalogue companies out there that have
glossy color photograph catalogues that will sell you a tool for
anything you don’t know how to do! Beware… Vac casting is
great for folks doing limited quantity and with careful attention
it produces great results.


#13
 Anyway - can it be used successfully in jewelry?  Do I have to
do anything different to it?  D 

Some friends of mine took Dental gold and hammered it till it
was flat, then cut it up into pieces to make shot, we don’t cast,
but we can use gold shot as embelishment to our silver pieces .
…just a thought . …


#14

They say dentists are always down in the mouth. It’s probably
because they really wanted to be jewelers. I have cast with
dental gold on several occations. Finding the exact karat is the
toughest part. Once you know that you can alloy it up or down to
suit your needs. It works best if you don’t do this in the
crucible as a one step process. The very imminate possibility is
over heating your mix. The casting will suffer and you’ll blame
the metal. Get a large stainless steel canning pot, about 12"
deep and fill it with ice water. Alloy your metal in a long arm
pouring crucible and pour it in a circular motion into the ice
water with a reduced flame shared over the crucible and the slow
pour. You can dry it in a toaster oven @ 375F for 1/2 hr before
casting. If you add metal to bring the karat down, you can
lighten or darken the alloy by the amount of copper or silver
respectively(your guess is as good as mine on how much of each).
J.A.Henkel


#15

John Henckel:

Interested in your assessment that vac casting produces good
results for limited quantities of work. Please explain. I
thought the centrifugal machines you’re talking about took about
the same largest flask as a perf vac maching (5x7?). If the vac
is better at large pieces (always heard that) why would it be
better kept to small quantities?


#16

hi john,

thankyou for verifying what i’ve suspected all along. sometimes
i don’t like to trust my own singular experience because i might
miss learning something new or something i’ve forgotten.

great suggestion about requesting msds sheet on alloys!

is ‘forming gas’ like an inert gas to replace our atmospere
while your memco induction melts?

yes, i am wary about gizmos and widgets. though i love gadgets
that work.

thanks again.

best regards,

geo fox


#17
Interested in your assessment that vac casting produces good
results for limited quantities of work.  Please explain.  I
thought the centrifugal machines you're talking about took about
the same largest flask as a perf vac maching (5x7?).  If the vac
is better at large pieces (always heard that) why would it be
better kept to small quantities?

Jess, Drop the “c” and we can talk! No really… I torch melt and
find if I keep it to about 1,lb I can catch that illusive moment
more consistantly. Pesonal preference I suppose, not that anyone
else can’t do more or larger. The people who polish the stuff are
the real arbiters of quality, wouldn’t you say? Vac casting is
swell but it’s just not as dense. Like I said, I have a Memco,
it’s nice, but I still get better results centrifugaly. Thats not
to say you wouldn’t, just not as dense. J.A.Henkel


#18
    The people who polish the stuff are  the real arbiters of
quality, wouldn't you say? Vac casting is swell but it's just
not as dense. Like I said, I have a Memco.  it's nice, but I
still get better results centrifugaly. Thats not   to say you
wouldn't, just not as dense. 

I have heard several people say that centrifugal casting
produces denser castings. What exactly is meant by that. Do you
mean that by whirling molten metal around in a circle it changes
its specific gravity or that there is less porosity?

Kenneth Gastineau
@Kenneth_Gastineau1
http://www.ud.net/gastineau


#19

Kenneth, Denser, to me, means tighter recrystalization as the
metal is cooling with the help of the extra “G’s” J.A.


#20

This thread is very interesting … we discussed this about XX
months ago and the Vac was the machine to have and produced
better detail which is what I believe is ment by ‘dense casting’

Jim