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Opinions of casting machines


#1

I am following the Orchid discussions for a while now, and it is
very informative. That is the reason why I would like to ask the
opinion of the members about casting machines.

I would like to get into casting, for the moment I am hand
fabricating everything. I work mainly in Sterling silver, sometime
gold.

Thank you, Monica


#2

Hi Monica

I first learned casting on a centrifugal casting machine with fairly
small (around 40mm) casting flasks, a small kiln which could hold
perhaps up to a dozen flasks and a propane torch to melt the metal in
hooded crucible in casting cradle on the machine. It worked well with
both silver and gold but was limited in the size of piece that would
fit in the flasks.

My current setup consists of a vacuum casting machine which handles
both casting and debubblising the investment. I usually use 90mm
perforated flasks which normally let me tree a number of wax
patterns. A medium size cuff bangle is about the limit of what I can
fit in these flasks. I use a small pottery kiln for burnout and a
propane fired crucible furnace to melt the metal.

I also have additional equipment for working with wax including:

A thermostatic wax pen for sprueing and fabrication
A thermostatic hot air blower for smoothing wax
A moulding box to make RTV rubber moulds
A wax injector to use with rubber moulds
Wax files
Various wax working tools (some improvised)
An assortment of scalpels and craft knives – i mostly use a #11
scalpel blade on a #3 handle.

Sprue cutter (actually a small bolt cutter from the hardware store) A
flex shaft machine and various wax burrs.

Various mandrels including a ring mandrels and a ring reamer

Various forms of wax – sprueing, injection, sheet, ring blanks,
soft moulding Digital scales – 200 grams capacity, 0.1 gram
resolution for weighing wax patterns and 3 kilogram capacity, 1 gram
resolution for weighing investment.

Ice cream tubs for mixing investment

A CD player to keep me focused and moderately sane

These are in addition to my metal working tools and equipment.

I like casting because it suits the organic approach of much of my
work which sometimes involves the incorporation of organic materials
such as leaves and seed pods in my work. Sometimes there is no
feeling quite like pouring a crucible of red hot molten metal in a
flask and after things have cooled sufficiently, plunging the hot
flask into a bucket of water and watch result of hours of work
emerge.

All the best
Jenny
Tears of the Moon Artisan Jewellery


#3

Hi Monica,

Do you mean “which brand of casting machine"or"which type of
casting machine”? (as in centrifugal or vacuum?)

For small to mid-sized one-offs, I prefer centrifugal machines. For
production casting of bigger (+4") flasks, you’re really looking at
vacuum and electro-melts.

How many cans a week do you figure to do? How big are the cans? How
many items per can?

For the centros, I’ve owned a couple of the old generic ones that
are pretty bullet proof. Used several of the Neycraft ones that live
inside their own shield drums. Not such a fan of those. The release
mechanism is prone to jamming. Then you’re juggling a half-cocked
machine, a torch, and a crucible of molten metal while you’re trying
to get the thing to fire. Really, not a fun way to spend 2 minutes.

Can cause mis-casts and all sorts of other fun if it suddenly lets
go while you’re fussing with it. Also a right pain in the ass to
slide the crucible up to the flask if you’re doing it hot. (I tend
to get the melt close to molten, then have a helper pull the flask
and load it into the machine. Which means I’m scooting the crucible
up to the flask while everything’s hot as hell. The “classic” style
machines handle that better, and have a much more dependable release
system.)

For Vac machines, I’ve used and built several. For production work,
you really want one where you drop the flask into a vacuum cylinder,
and uses perforated flasks. The ones where they just pull on the
bottom of a standard flask through a hole in the center of a plate
work, but can be a bit twitchy. You need to leave a little headspace
on the top of the flask, and remember to use slightly heavier sprues
with those, especially with bronze. Not really a fan, but they’re
easy to build. Whatever you get, make sure it’s got a metal trap on
the vac line, so that if you get a blowout, you don’t suck molten
metal into your pump. Deeply unpleasant to fix. Trust me on that.

FWIW,
Brian


#4

Monica-

I learned jewelry casting more than 30 years ago. The jeweler I
apprenticed under was using a centrifugal machine when I started out
and later switched to a vacuum system. When I started casting for
myself I started with a vacuum caster and never considered anything
else. I even received a centrifugal machine in a tool deal and sold
it without ever using it once. I like the flexibility the vacuum
machine offers in terms of flask size. I use solid flasks from 2 1/4"
x 2"h allthe way up 4" x 5". I might be able to go wider but haven’t
had to, and I can’t go higher because 5" is the tallest that will fit
in my kiln and undermy bell jar.

I make my own flasks from stainless and/or carbon steel pipe scrap.
On the larger flasks I drill passages around the inside of the flask
=BE of the height down into the investment to increase the vacuum to
the casting. I can successfully cast two belt buckles measuring 2
1/2" x 3 1/3" each, in one of my large flasks. Although I don’t
remember any major mishaps with the centrifugal machine (just metal
spillage) it did always make me nervous. The vacuum machine just
seemed safer. The worse accident I have had with the vacuum machine
was a blowout through the bottom of the flask. When that happens the
metal just gets sucked into the casting chamber and just needs to be
cleaned up. A more common problem I had was melting too much metal
and over filling the flask. I now keep a long ingot mold next to the
casting pad to pour any excess metal into; however since I started
doing that it seems I no longer melt too much metal. The worse
casting accident I have had, had nothing to do with the vacuum
machine. I melt with an electromelt and was attempting a brass pour
(around 400 grams as I recall) and the graphite crucible slipped
through the tongs I was holding it with. That was my fault for not
recognizing the lip of the crucible was too worn out to hold safely
with those particular tongs. That spill wreaked havoc with the
linoleum flooring but, because I keep a fire extinguisher in the
studio, and I always wear leather work boots while casting the
flooring was the only thing damaged. I even finished the casting run
after cleaning up from the fire extinguisher. So, my vote is for the
vacuum machine.

Be well,
-Duke
houseofbubba.com


#5

In addition to the great advice already posted to which I can’t
really add much without being repetitious, I would highly recommend a
couple of books.

“Centrifugal or Lost Wax Jewelry Casting, for Schools, Tradesman and
Craftsmen” by Murray Bovin. This book is rather dated but contains a
wealth of info that never will go out of date, such as determining
the proportions of metals needed for alloying, melting, flask and
burnout temperatures, the science of burnout and much more. No
casting shop is complete without this classic textbook. I’ve been
doing this for more than forty years and I still refer to this book
regularly. A lot of old-school types know it simply as “the Orange
Casting Book”.

“Practical Casting, A Studio Reference” by Tim McCreight. This book
also contains a lot of info, but in addition to some of what is in
the first book, it covers techniques and procedures that might be
used by the hobbyist or artist who casts a couple times a year and
doesn’t want to put a lot of money into equipment, or that wants to
experiment with centuries-old techniques. Things like sling casting,
cuttlefish casting, sand casting, foundry techniques and much more.
This is a fun book even if you never cast a single thing.

Centrifugal versus vacuum? The age-old controversy continues and you
will probably never get a really satisfactory consensus, especially
when it comes down to specific tools. The truth is that whatever
works for you is the best way to do it.

Dave Phelps


#6

Brian,

thank you for the info, very educative. I would prefer to go with
thevacuum casting, looks much safer. When I took the casting courses
I was frightened out of my mind about the whole process. Maybe that
is one of the reasons why I was delaying it. Monica


#7

I have both a Neycraft centrifuge and a vacuum caster. Never had a
problem with the centrifuge, and have had excellent casts. However,
my experiencewith my vacuum was less than successful, as I had a
nasty blow out with it, which did a lot of damage to the vacuum as
the hot silver melted all the tubing, and created a real mess. It
also wrecked some of the parts of the vacuum, beyond anything I
could repair myself, so I had to ship the vacuum to Rio for
extensive repairs.

My vacuum does not have the wells for the flasks, but has a table
which canbe used for investing and for casting. Hence any blowouts
do serious damage, as there is nothing to capture the molten metal.
It is too shallow forme to attach a “boot,” so blow outs are a
potential problem. As a friend remarked, “Blowouts happen!, get used
to it.” Not what I wanted to hear.

I love using the centrifuge, and have had excellent results with it.
But a shoulder injury makes it extremely difficult and painful for
me to wind it. Hence I am going to have to use the vacuum system.

I see that Rio now has vacuum casters with boots that capture any
metal, keeping it from doing damage to the rest of the machine. Has
anyone had any experience with it? If you have had good results with
it, I will seriously consider getting one.

Most of my work is fabrication, but some of my designs are best
executed by making a wax model and casting it. hence my interest in
getting a reliable vacuum caster.

Thanks for your suggestions. Alma


#8

Monica, don’t be afraid of casting. If you follow the directions,
payattention to what you are doing it is perfectly safe, with either
the centrifuge or the vacuum.

The advantage of the Neycraft centrifuge is that it is contained in
its ownshell, so that in the rare, and I do mean rare, event that
you have miscalculated the amount of metal to be cast and some of it
flies out it will be completely contained within the shell. Usually
this is a very very small amount and centrifugal force keeps it from
flying upward. Another safety feature is that you do the melting of
your metal in the crucible which is part of the centrifuge—no
pouring needed. With the vacuum, you do need to pour the molten
metal into the flask, but I use a burno crucible which has a lip,
and never have had a problem or a spill.

So, whatever you decide to get, don’t be afraid of it. If you can
geta casting buddy to work with it will make things easier. As David
Phelps advises, get some good books. I particularly like Tim
McCreight’s which David recommends.

Enjoy the process of casting. Unless you are going into heavy
production you can get by with a minimum of extra equipment. For
example no need for mold making items and injection machines. Most of
the carving tools, when you are just started, can be something as
simple as an exacto knife, which is still my favorite even though I
have accumulated a lot of other special tools—most of which I
seldom use. Alma


#9

Hi Monica,

Vacuum isn’t vastly safer than a centrifugal machine. The Neycraft
machines come in their own shields, but the standard procedure with
the ‘classic’ style is to put them in some sort of shield as well,
so all the centro machines are guarded in one way or another. Mine
is buried a foot deep in a 55 gallon steel drum, while the one I
used at school for years was in a commercial shield that worked
quite nicely. (From Otto Frei. Look for the blue octagonal shield
thing they sell right next to the ‘classic’ casting machine.)

The advantage of centrifugal machines for small, one-off castings is
that (A) you can use smaller flasks, and (B) they hit much harder,
so they can drive the metal down into very small details. My
experience with them says that you get better metal density, or
certainly better castings. As you get bigger, you get into the range
where you really don’t want that much metal spinning around the
shop. I once worked for a guy who had a home-built spin caster that
could handle a couple of pounds of bronze. that thing made you sit
up and pay attention. Never had a blowout that I know of. Because we
all paid very, very careful attention to what we were doing when it
got that big.

The big, huge, incredibly important thing is not to be afraid of
anything you’re doing. I’ve lost track of the number of times I’ve
seen someone get hurt because they let their fear get in the way,
and that caused the accident.

Sometimes the best cure for fear is understanding. Make a list of
all the things that you think can go wrong with a procedure, and
then figure out “what next?”

So you’ve got a spin caster and the metal blows out through the back
of the flask. (it happens.) What next?

It sprays off the back plate of the casting machine, and dumps into
the safety shield. Other than scaring the hell out of you, nothing
all that radical. (Most machines are rigged such that if there is
a blowout, it happens in a part of the cycle that throws the spray
away from the operator.) You get to pick a lot of very small grains
of metal out of your safety shield. Oh goody. You still want to be
wearing an apron and safety glasses though.

So you’ve got a vacuum, and you pour and miss. What happens next?
Molten metal on the top deck of the machine. Probably doesn’t stay
molten much longer than it’d take to get down to the tabletop.

Which it promptly sets on fire. Where’s your bucket of water? (I
usually keep a 5 gallon bucket of water near the casting gear to
blow out my flasks in. In a pinch, that’s the first thing I grab.
Yeah, it’ll make one hell of a mess, but much less than a fire.)

Just work through all the ‘what happens next?’ steps for every
disaster you can think of. Then do what you can to head them all off
first. And plan your responses for the rest.

The vac caster we had at school was on a stainless steel baking
tray, specifically so if it did somehow dump a bunch of molten
metal, it still wouldn’t get to the table (or over the side, onto
somebody’s toes.) We did what we could to disaster proof the gear
before anything went wrong. Because when it does all drop in the
pot, you don’t have time to think. You have to react, more-or-less
instinctively. So it’s up to you to program those instincts first.

Whatever you do, do not let your fear get in the way. That will
get you hurt. Take a deep breath, understand what’s going on, then
do your art.

Regards,
Brian


#10

The responses to this topic have made me realize just how old I am.
When I left the refractory world to go into teaching, we at Kerr
were testing our products (SatinCast, etc.) primarily with
centrifugal machines. We were just evaluating vacuum machines. The
only real comparison I can come up with is that we seemed to hit a
limit of 5 class rings per flask using the admittedly primitive
vacuum apparatus, while 20 rings per flask was the standard using
the centrifugal machine. I presume that production casting using
vacuum has increased its capacity"or am I just an old-timer thinking
wistfully. Jim Hrkins Blessed be…


#11

To prevent investment and blow out stuff from reaching your vacuumed
pump. go to the auto parts store and buy a large inline fuel filter.
cut the vacuumhose and splice in the filter. saves your pump from
investment dust as wellas metal when you have a blow out…

Install it between the vacuum gauge and the casting table. That way
you calsee on the vacuum gauge if it is getting clogged with dust
and is time to change it. A good $10.00 investment…


#12

Hi Monica, I have 2 different types of casting machines. I have a
centrifugal machine and a vacuum casting machine. I prefer the
centrifugal machine hands down over the vacuum caster. It seems to
be a lot less finicky, andI rarely have issues with incomplete
casts. I have used both and find it easier and more consistent. I
have both a Neycraft Spincaster and a Rio centrifugal caster, reason
being is the largest crucible I can use on my Neycraft is a 4 inch
long crucible. I can use all the way up to a 6 inch with the Rio.
The Neycraft is very handy, and I just hold it down with C-clampson
my bench when I am ready to cast, and hang it on the wall when not
using it.

The nice thing about the vacuum machine, is you can use it for
investing, and you can cast any size crucible. Some people swear by
the vacuum caster, my dad has used one for 30 years and loves it.
Like I said before, I like the centrifugal machine better.

Hope this helps, Tom


#13

I recall way back when I went to Kerr to learn how to mix investment
and work on the casting machines. Times have changed we still have
people using the old spin caster which is a great machine, there are
different types of vacuum units. the old Swest Vacuum units. and now
people are looking at induction units… Is Time moving quick. I
loved the Classes at Kerr.

Andy “The Tool Guy” Kroungold
Director Tool Sales & Stuller Bench
Stuller Inc.


#14

Vernon, What a great idea about installing an auto filter to catch
blow-out material. Thanks. Alma


#15

My experience with vacuum versus centrifugal casting is similar to
Jim’s in that for the small shop, vacuum works well for limited
numbers and larger volume style pieces and pieces with not a lot of
intricate areas to fill, e. g. signet rings, belt buckles, etc.
Centrifugal comes into its own with big trees of smaller pieces and
for pieces with lots of little nooks and crannies to fill. Like Brian
said, it just seems to hit harder. That said, many manufacturers cast
trees of literally hundreds of rings using vacuum. But they are also
using inert gas induction machines, so they don’t have to deal with
many of the issues we have in the small shop. Load it up and press
the button. Grab a cup of coffee, wait about ten minutes, go back and
unload it.

Another consideration about casting method is metal temperature.
When using centrifugal, it can be more difficult to judge when the
metal is at exactly the right temperature as you can’t easily move
the crucible around to see when it stops sticking, which makes it
easier to overheat the metal. I throw about three seconds after it
stops sticking, regardless of method. Any longer and I’m likely to
get porosity from over-heating. It is also not possible to use an
Electromelt or other temperature controlled crucible with
centrifugal, unless you have an induction casting machine, in which
case you wouldn’t need to ask about casting, you’d probably be
answering. :wink:

Vacuum is also easier to load for casting, as Brian pointed out.
Even though it’s about a wash as to which method is actually safer,
vacuum is often less intimidating for many rookies so it really is,
for many people, the right choice for initial learning. You’re going
to need a vacuum machine for investing anyway, so it’s almost a
no-brainer to start with a combination vacuum investing/casting unit
and expand into centrifugal if and when the need arises.

Just 'cause someone might want to know, I started out using both;
vacuum for heavy, simple stuff, centrifugal for trees and light,
frilly stuff that is less prone to high-temp induced porosity issues,
but now I cast using centrifugal almost exclusively. Can’t remember
the last time I used vacuum, except that it blew out and cost me
several hours of clean-up and re-carving time. That’s never happened
to me with centrifugal, not yet anyway. Knock on wood.

Just some thoughts and observations from my experience. I hope it’s
helpful.

Dave Phelps


#16

Well, if it were not for the fact that a shoulder injury makes it
difficult for me to wind my centrifuge, I would far prefer using it
instead of the vacuum. I have always had excellent results with it,
never had an problems at all. Great detail in my castings, and safe
and easy to use.

I especially like the fact that one can do the melting right in the
crucible which is attached to the centrifuge. No pouring. Just watch
the melt carefully so that you know when it is ready for you to
release the shell and the Neycraft centrifuge takes over and does
what a centrifuge is supposed to do.

I won’t go into detail about the major blowout I had with the
vacuum. Entirely my fault as I had not mixed the investment
properly. Really created such damage that I had to have the vacuum
professionally repaired.

This is not to imply that the vacuum is not as good as the
centrifuge, but in my case, the blowout left me feeling apprehensive
about vacuum casting. However, I am going to have to get over that
feeling as I really don’t havea choice. It is either the vacuum or
no casting. But, believe me, I will be careful about how I mix my
investment. Don’t want to deal with another blowout.

As far as vacuum casting, many had excellent results, and the vacuum
sure takes up a lot less room in your studio than a centrifuge.

Alma


#17

Hi gang,

As David mentioned, it is harder to evaluate the melt when torch
melting on a centrifugal machine. My trick has always been to use a
carbon stirring rod (in a holder) to both stir the melt, and feel
around in there for un-melted bits. (like when the kids give you
scrap, and there turns out to be fine silver in there. Makes it easy
to find it, and make sure it’s melted.)

The advantage to the carbon rods is that they burn away as CO2, and
take the oxygen away with them. Which makes your melt cleaner, by
scavenging the O2. Not a panacea, but it does help. It’s a variation
of the old ‘throw a green twig into the melt’ trick from ages past.

Once I can feel that the whole load is molten, we’re off to the
races.

Regards,
Brian


#18

Hello Monica & and to all in the Orchid group I couldn’t help notice
this thread regarding Casting Machines. My Company LUCAS DENTAL CO.
has been manufacturing centrifugal casting machines for the last 60
years plus and are always featured in the Featured Products Section
of each Orchid Digest. We have two machines that we feel are the best
Centrifugal Casting Machines in the Industry and they are Made in the
USA at our factory in New York. Our #750 “Giant” long arm casting
machine at $282.00 and ourLatest Model #8500 “Jewel” long arm casting
machine at $459.00. Either one of these machines should fit your
needs and can be ordered directly from us. You can contact us at
Toll-Free 1-(800)-332-5573 Mon - Friday 9:00am - 3:00pm eastern time
or by Email: Lucadent@verizon. net When you call, you can ask to
speak with Richard Lucas. the owner. PS: we are also the Manufacturer
of the #9 LowBoy Rheostat and our New #9XR Rheostat that can be used
on the Foredom DC TX motors… Thank you for your time, Sincerely,
Richard Lucas


#19

For what it’s worth I’m absolutely loving centrifugal casting that I
have just started a few short months ago. It’s a very forgiving
process if you already know how to use a torch relatively well. I
will still expand to vacuum casting in the future but centrifugal
meets my present needs just fine. I love how simple it is and yet
pretty effective. It’s all down to a main spring and a balanced arm.
I think you mentioned you have a bad shoulder and are worried about
turning the machine. I think if you were to mount the machine at
waist level, you could mostly turn the machine while keeping your
arm against your own body and use more of your body/legs/hips to do
the 3 or so spins before you lock it. (picture not extending your arm
very high or out) and maybe that is not so much wear on your
shoulder)? Especially if you were to mount the machine in the center
of a room or leave enough room to walk around the whole machine so
you can turn the machine while keeping your arm down and mostly
against your body.

Just an idea,
Rick


#20

while on the subject, a friend of the family used a technique on
small scale castings with some success…

the investment had a throat, sufficient to hold all the melted
silver required for the casting.

He then took a stick with many sheets of newspaper nailed to the
end, and soaked that in water. He pressed that down firmly on the
molten pool of silver, generating steam with sufficient pressure to
force it into the mould…

it works surprisingly well…