Discussion:
Making a steam dewaxer
(too old to reply)
mtnrabbit
2005-10-11 02:56:27 UTC
Permalink
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...
Peter W.. Rowe,
2005-10-11 03:09:40 UTC
Permalink
Post by mtnrabbit
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
mtnrabbit
2005-10-11 05:00:32 UTC
Permalink
Question...
After the wax has been removed , when do you put the flask in the kiln
?
Thanks ...
Peter W.. Rowe,
2005-10-11 05:03:37 UTC
Permalink
Post by mtnrabbit
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.

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
Charlie Leo
2005-10-12 02:32:18 UTC
Permalink
Post by mtnrabbit
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
mtnrabbit
2005-10-13 02:06:57 UTC
Permalink
Hello,
You say ( 300 degress is held at about 3 hours). What is the rest of
your burnout cycle ?
Thanks, Dennis Montilepre
Charlie Leo
2005-10-13 03:45:25 UTC
Permalink
Post by mtnrabbit
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.


Charlie Leo
mtnrabbit
2005-10-13 05:32:17 UTC
Permalink
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
mtnrabbit
2005-10-13 05:32:18 UTC
Permalink
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
Peter W.. Rowe,
2005-10-13 05:35:59 UTC
Permalink
Post by mtnrabbit
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
Heinrich Butschal
2005-10-13 15:13:53 UTC
Permalink
Post by mtnrabbit
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
The same cycle work also after dewaxing. You might shorten the first=20
preheating 20 minutes e.g.


Mit freundlichem Gru=DF,
Heinrich Butschal
--=20
Aktuelle News =FCber Schmuck http://www.schmuck-boerse.com/blog
Historischer Schmuck und Geschichten ber=FChmter Juwelen http://www.royal=
-magazin.de
Schmuck nach Ma=DF http://www.meister-atelier.de
Firmengeschenke http://www.schmuckfabrik.de

Continue reading on narkive:
Loading...