Making a steam dewaxer

Does anybody know how to make a steam Dewaxer ? or have a link to the
instructions.
I have heard that you can make one by using a pressure cooker ?
Thanks...

On Mon, 10 Oct 2005 19:56:27 -0700, in h=07=F5 "mtnrabbit" =

wrote:

Does anybody know how to make a steam Dewaxer ? or have a link to the
instructions.
I have heard that you can make one by using a pressure cooker ?
Thanks...


You can use a pressure cooker if you wish, but it's overkill. Steam =
dewaxers
are not pressurized, or at least, don't need to be for normal injection =
waxes.
When my commercially made dewaxer died, I switched to the simple home =
brew stove
top version. It's a large kitchen type stainless steel stock pot of a =
size that
will hold my casting flasks. The only modification is a wire rack that =
sits in
the bottom a few inches above the bottom. To use it, you put water in =
the pot
to just under the wire rack. Put your flasks in the pot, vent hole down,=
put on
the cover, and place on the stove or a hotplate, etc.. Bring to a boil =
for a
while. A half hour is often enough, but the time needed, same as with a
commercial unit, depends on how many waxes you've got in the flask, size =
of
flask, etc. The main thing to watch is not to let it boil dry or you =
burn
wax, making a smelly mess. Also, don't use one of your kitchen pots with=
the
expectation of ever using it again for food. I suppose it's possible to =
clean
out the gunky wax residue that will be all over the inside of the pot =
when
you're done, but frankly, I never quite figured out an easy way to do =
it.
Most of the wax is removed just by letting the water cool, and the wax =
freezes
to a film floating on top, easily picked out. But there will still be a =
good
deal of wax residue on the portions of the pot that are above the water =
line.
And it was a cheap import quality pot from the hardware store anyway. =
But
that's all there is to it. The commercial dewaxers are nothing more than=
a
water reservoir area under a wire rack of some sort, with a heating coil =
in the
water. They're only closed, not pressure sealed. And the stove top =
version has
one advantage too. My commercial one died when I forgot about it, and it=
boiled
dry, letting the heating coil be exposed, whereupon it burned itself out =
from
over heating. The stock pot version isn't prone to that, as most hot =
plates and
stoves don't mind running nice and hot with nothing sitting on them... =
If it
boils dry, the removed wax in the bottom of the pot can burn, but even =
that
causes no real harm other than smoking up your work area. The flasks =
could
still go right in the burn out kiln no matter what. And the now darkened=
pot is
still usable as a dewaxer...

Peter

Question...
After the wax has been removed , when do you put the flask in the kiln
?
Thanks ...

On Mon, 10 Oct 2005 22:00:31 -0700, in T=07=F5 "mtnrabbit" =

wrote:

Question...
After the wax has been removed , when do you put the flask in the kiln
?
Thanks ...


Well, you don't put it in the steam dewaxer all that much earlier than =
you'd
put it in the kiln if you weren't dewaxing the flask, so after dewaxing, =
put it
in the kiln at any time between right away, to whenever you want, so long=
as the
flask has not totally dried out, just as you'd do if you weren't =
dewaxing.=20

If it's dried out, then it's best, according to some folks, to soak it =
briefly
in water. The water content, which is there in freshly invested flasks, =
or
after steam dewaxing, helps heat transfer evenly to the interior of the =
flask
during the first couple hundred degrees, which happens to be when the =
investment
seems most at risk of cracking from uneven heating, in part due to a =
change in
the structure of the investment between 300 and 350 that causes an =
unusually
rapid rate of thermal expansion as it goes through that temp range. . By=
that
time, of course, the water is vaporized, but at least getting the =
interior to
212 degrees F. at about the same time as the outer portion of the flask, =
helps a
good deal.

But all of this is a "your mileage may vary" situation, depending on
the speed of your burnout, the size of your flask, and the type and mix =
ratio of
your investment, and your own experience with what works best for you.

Peter =20

On Tue, 11 Oct 2005 02:56:27 GMT, "mtnrabbit"
wrote:

Does anybody know how to make a steam Dewaxer ? or have a link to the
instructions.
I have heard that you can make one by using a pressure cooker ?
Thanks...

I use an old frying pan with a high-domed lid. (Before we got smart
and bought a stainless steel skillet, wife & I would wear out a
non-stick pan in about 18 months - so I get to recycle it). I take a
regular cooling rack and turn down the corners so that the rack is
raised about 1.5 inches off the bottom of the pan, then pour about 1
inch of water in it. The high dome will accomodate a 4 inch high
flask. Turn the thermostat up to barely boiling - wax is gone in about
20 to 30 minutes. Flasks go directly into a cold kiln and the
controller is set at 300 degrees for the first part of the cycle (300
degress is held at about 3 hours).

Charlie Leo

Hello,
You say ( 300 degress is held at about 3 hours). What is the rest of
your burnout cycle ?
Thanks, Dennis Montilepre

On Thu, 13 Oct 2005 02:06:57 GMT, "mtnrabbit"
wrote:

Hello,
You say ( 300 degress is held at about 3 hours). What is the rest of
your burnout cycle ?
Thanks, Dennis Montilepre


I have a manual controller - I do most of my burnouts overnight so I
am ready to cast in the morning. Here is the cycle that I shoot for:
300 degrees F. for 3 hours, 800 degrees for 6 to 7 hours, 1250-1300
degress for 2 hours. Then I turn the controller down to 900 degrees
and hold until I finish casting. It takes the kiln about 2 hours to
come back down to casting temperature (the 900 degrees). I have held
that temperature for 6 or 7 hours and still have gotten good castings
(This is for demo purposes at our show - www.hgms.org).

Generally, I will cast 3 to 5 flasks - about 60 to 90 grams of
sterling each. Each flask will have several pieces in it - rings and
pendants. I have cast more metal (a friend & I did a 170 gm bronze
casting a couple of weeks ago), but I really don't like working with
an overly full crucible.

Back to the burnout cycle: The programable controller that I have
access to has a 5 hour, an eight hour, and a 12 hour cycle. I have
heard of dental students casting a tooth with a one hour burn out. The
Incans cast gold with no temperature control using charcoal as a heat
source. In other words, find the best cycle that works for you and
your particular situation, then stick with it.=20


Charlie Leo

Hi,
I have never dewaxed before and I am going to give it a try. My main
question is by dewaxing does the burnout cycle change from a standard
cycle ?
Dennis Montilepre

Hi,
I have never dewaxed before and I am going to give it a try. My main
question is by dewaxing does the burnout cycle change from a standard
cycle ?
Dennis Montilepre

On Wed, 12 Oct 2005 22:32:15 -0700, in |=07=F5 "mtnrabbit" =

wrote:

Hi,
I have never dewaxed before and I am going to give it a try. My main
question is by dewaxing does the burnout cycle change from a standard
cycle ?
Dennis Montilepre


Dewaxing removes the bulk of the wax, but not every last bit. So you =
still may
wish to use mostly the same burnout. But you can shorten it some, as =
there's
less wax, and resulting carbon on the investment, to burn away. If you =
need to
reduce the temp of the actual burnout step (as is done in =
"stone-in-place"
casting, for example, you can get away with doing so more easily. And =
the big
benefit for some is simply a workshop with a LOT less smoke and smell =
during
burnout.

Peter