I want to buy a vacuum caster and need help deciding what kind to
get, and will appreciate your assistance. I have ruled out trying
to make one on my own with used pump and second hand table, and will
have to buy one all assembled and ready to go. However i am
puzzled as to what kind to get. I see there are several kinds,
a vacuum that has one table and can be used for investing and
casting, 2) a vacuum that has two tables, one for investing and a
separate one for casting. 3) bell jars which are side draw----
have the hose attached at the side (these are are the Rio Grande
catalogs). And those that have just plain bell jars. I would
prefer a caster which uses solid flasks rather than perforated
ones. My budget is very limited so I need to get the most economical
vacuum caster that will do the job efficiently. . I have been
advised that it is essential that neither the melt nor the flask
be allowed to cool down, but that both must be at proper temps for
the cast to be successful, therefore as I will be working alone with
no one to help, I will need to get an electro-melt, so will need to
budget for that item also. Hence my desire to make a wise purchase
at the outset so that i will not have a lot of problems down the
road.
Another related question about the Neycraft casters. Is it true
that there is often a problem of the crucible fusing to the flask
if there is an excess of metal in the button. Some time ago
someone wrote in that there were problems of this sort and that the
crucibles had to be forced from the flask as they had fused
together during the cast resulting in broken crucibles. Is this a
recurrent or an occasional , or even just a rare occurence.
Thanks for all your help. Alma–who is in a quandry as to
what to buy.
Hi Alma, I used to use the typical swing arm caster. I shared it
with a relative who didn’t understand the balancing procedure and
consequently had bent the center pole which caused the flask to
literally fly out of it’s cradle. SCARY and luckily no one got hit
in the head. So, got rid of that (not the relative, LOL) and bought
a Neycraft which I love. Never have had a problem (with the
Neycraft, the relative is another story!) at all after 8 years of
use.
Hi Alma, We use a Memco Electro-Vac Casting System which just does
the casting, although it does it very well. It also cost us a several
thousand dollars, as I recall. What I like about it is that it uses a
nitrogen/hydrogen cover gas that nearly eliminates all firescale.
Also the crucible temperature is digitally controlled. I am really
pleased with it. Of course, we do commercial casting for other
jewelers, so it pays for itself.
As far as the flasks, ours requires the perforated flasks with the
lip/flange around it. The perforations allow for a greater vaccuum
pull during the casting process, which I believe makes for better
casting.
We also use a Memco Oven Controller for our kiln, which allows us to
program all of the burnout stages. I can invest in the afternoon, put
the flasks in the kiln in the evening and cast the next morning.
Sweet!
We are still working on streamlining the investing process. We use a
small vacuum table for vacuuming the investment and it’s difficult to
do more than one flask at a time. But we’re working on it.
JoAnna Kelleher
Pearl Exotics Trading Company
Progressive Jewelry - Commercial Casting - Tahitian Pearls www.pearlexotics.com
Hi Alma, We may be able to help with both issues. First I’ll answer
your questions then tell you what we have. We repair the equipment
jewelers use and we know from experience which equipment is good and
which is not.
The side draw bell jar is preferable in the event of accidental
overflow/spilling of investment. The straight bell jars have the
vacuum drawn down through the table and if investment gets spilled
or boils over the top of the flasks it can get sucked into the lines
and pump. When this happens the unit has to be taken apart and can
take several hours to clean and get running again. This won’t happen
with the side draw units.
The two table units are preferable because the casting chamber is
made to handle blowouts if they should occur. In other words they
capture the bulk of the investment and metal before it can get to
the vacuum lines.
As for the Ney spin caster I would have to say they probably over
fluxed their melt and had too much metal. They may have overheated
the metal as well. With an electro-melt you don’t ever flux the
metal so you don’t have this problem and you pour the metal so if
you did have too much in the melter you don’t have to pour all of it
in the flask. You will also be able to melt enough metal for several
small flasks at the same time in the electro-melt. This can speed
casting because you don’t have to wait for the metal to melt for
each flask.
Now, we have a used Rio vic 12 unit that is selling for $650. It has
the ‘Assistant’ which can be removed easily and we warranty the unit
for 6 months. It uses a 5 cfm vacuum pump so you will get better
casting results and better fills. It’s in very good condition and
will save you a few hundred dollars.
Also we have a new 30 ozt manual electro-melt we used for display
at a show and we are selling it for $499. It has a full one year
warranty on it and comes complete with stirring rod and crucible.
This will also save you a couple hundred dollars.
If you are interested in these or have other questions let me know
by email or calling toll free 1-877-262-2185.
The Vacuum pump itself should be the 1st deciding factor
(capacity & reliability)
The size of the flasks (depending on what you are going to cast).
If you need a perforated flask for what you want to do.
What is the size of space that you will have for this equipment?
My recommendations will be based on your answers.
If you want a good reliable pump, an average flask size, possible
for perforated flask and have more than 36" of counter space, go for
the procraft combination investment and vacuum table. $840.00 plus
shipping. Comes complete with bell jar, flask tongs & the nine yards
If you are limited for space and don’t need to use perforated flask
go for the procraft vacuum pump and investment/cast table split unit
pump & table are separate but is not bulky as these is no vacuum
chamber. Price is $595.00 plus shipping is cheaper as it weighs
less. It also comes with bell jar & all you need to start a job.
There are other cheaper machines if you are going to sacrifice the
cfm (pump capacities), reliability and size of flask etc.
My experience is based on a very little casting more on customer
feed back from sales & service of these units. You should hear the
actual users too.
I want to buy a vacuum caster and need help deciding what kind
to get
Hi Alma, In response to your question about buying an all in one
casting machine, those are not a bad deal but you can get the same
results without spending that much money. Don’t rule out that
second hand pump and second hand table. If you have a used vacuum
pump that pulls 27-29 inches, you will get good castings.
Having one table just means that you will have to change the rubber
investing pad and the silicone casting pad depending on whether you
are investing or casting. Not hard. One of the drawbacks of the
all in one casting machine is changing the oil. I use an oil-less
vacuum pump. The side draw bell jars help prevent investment from
clogging up the hoses. If you’re careful, a regular bell jar should
be fine.
If you’re going to use an Electromelt, I would spend a little extra
and get an automatic, rather than a manual. This will save you lots
of aggravation. Pinch your pennies on the casting machine, spend
them on the Electromelt.
The Neycraft fusing problem is caused by not weighing the metal
accurately. When there is too much metal it sticks the crucible to
the flask and you get sculpture. If you’re using the Electromelt to
do spincasting, make sure you preheat your crucible. The graphite
crucible in the electromelt deteriorates when exposed to air, so if
you’re doing small batches, you’ll be going through lots of
crucibles. It’s better for vacuum casting where you pour one right
after another.