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Vulcanized vs. RTV

#1

First, is that the responsibility of making the mold from a wax
pattern or other non metallic part is the responsibility of the
manufacturer… So … what happens if the pattern is broken in the
process? Oh well… another patern may need to be made… and at
what expense !!!

Hi, Dan–sorry I was unable to present much depth in my effort to
quickly pass on useful relating to the use of RTV
Silicones. You are correct, and many manufacturers still follow the
route you outline. However, the original wax or SLA is at risk if
you need to invest it in the model making process. Many original
waxes are lost at this point. Many folks think that the original wax
is at lower risk for loss if it breaks in the mold cutting process.
Why? because you still have the mold from which to shoot copies. The
shrink of platinum cure RTV is under 1/10 of 1% if cured at room
temperature, so the dimensional change in the mold does not affect
these applications. An 1/8" section will shrink less than .000125".
Of course there are other shrink considerations down line, but I did
not intend to address these as they do not relate directly to my
original point.

Cheers!

Bill Mull

Zero-D Products, Inc.
38285 North Lane. #103
Willoughby, OH 44094 USA
800-382-3271
440-942-1150
fax 440 942 2130
WWW.ZERODPRODUCTS.COM

#2 
However, the original wax or SLA is at risk if you need to invest
it in the model making process. Many original waxes are lost at
this point. Many folks think that the original wax is at lower risk
for loss if it breaks in the mold cutting process. Why? because you
still have the mold from which to shoot copies.

Hi Bill, We do tend to agree with each other … I just like to make
sure that All people on orchid understand exactly what is invoved
when manufacturing. Many are not aware of various processes. Many
have dealt with casters and casting companies that don’t give enough
accurate …Some of theses casters are not model makers
and don’t do finished products… many don’t do Hand polished high
quality finished products which we do .

In my previous post, I did make mention to use RTV molds to make the
production models… In otherwords… make an RTV of the wax or SLA
pattern… cast a wax from the mold into metal and perfect that
pattern. This perfected casting now becomes the production model
that can be copied in any rubber and as many molds as you wish can
be made from it without any problems. This also guarantees a better
model since the cast model can be perfected beyond what is capable
in wax or SLA. To do this, It is important to know the shrinkages of
the molds, waxes and castings. I deal with these problems on a daily
basis… we get some 20 models a day sometimes and these come as
carved waxes, SLA’s ,metal models tree bark and what have you…often
over 200 molds /week are made . 95 % of the models we get in wax are
definitely not ready for production mold making and require extra
work in the metal model to truly make a great casting. These are
just some of the reasons why our customers like the casting and
finishing work that we do for them… we try and cover every detail
as best we can so that their finished product comes out the way they
would like. That is also why , as a Manufacturer we would not
recommend RTV 'ing a wax and using that mold for production … only
to create the production models in metal

I believe we both agree that making an RTV of the wax and producing
a metal model is the best way to go…for production.

I would certainly like to try your platinum rubber as I’m sure we
will have good uses for it.

Best Wishes,
Daniel Grandi
Racecar Jewelry Co. Inc.
52 Glen Rd. Cranston, RI 02920
contact: sales@racecarjewelry.com
Tel: 401-461-7803