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CNC milling stock


Looking for a little help in finding a plastic or other material
that is easy to mill, like a hard wax, that will take the heat
of vulcanizing rubber molds. What I would like is to find is a
material that is low cost and easy to obtain. Any info would be


Steve I don’t know of any materials that you describe, however
as a solution let me suggest you look in to room temperature
vulcanazing rubbers to make your molds. My favorite ( I have been
using it for 20 something years for everything from wax to
animals ) is Dow Corning Silastic RTV. Check your local phone
book under silicones. Look for the one pound can. Try the E or
The L one is stiffer for less delicate molds the other is very
flexible. Look for the Dow Corning 800 number and
they will help you find a distributor. Not what you asked for but
a solution never the less. If you need more info email me at
@Frank_Goss Frank.


Steve: There is a material called “Nylamid” who is used to lathe
gears, Im not sure if it would stand the 350 f of the



Hi Steve,

Try any industrial supplier. They have machinable wax in blocks
& cylinders of various sizes. Typically, industry uses wax for
test runs of new programs for CNC work. Wax is a lot more
forgiving if the program doesn’t do what you want it to. MSC
(800-645-7270) lists several shapes & sizes in ther catalog.
(Not connected with MSC, just a satisfied customer.)




What about Castaldo’s “Quick Sil” room temp. mold compound? It
needs no vacum chamber, it’s much neater and quicker and makes an
excellent NO SHRINK mold in as little as 15 minuites! Now,
underatand that I am in no way connected with The Castaldo Co.
nor do I sell this product. I’m just a very satisfied user.

Steve Klepinger



Cadillac Plastic has a warehouse in Naperville, IL and other
cities in the U.S. You can call there and they can give you
more than you would ever want on the different
properties of plastic.

If you are near one of their distribution centers, they usually
have scrap that they will sell you, or you can order what you
want in small amounts. Not all plastic manufactures tend to be
as helpful.

These guys tend to be user friendly when you tell them you are
an “artist”, student or just looking for small amounts of

The number in Naperville, IL is (630) 428-4350. I’m sure they
will give you the phone numbers of other distribution sites that
may be closer to you.

Sally Richards


Steve, You need a material called butter block from Goldenwest. It
is a machineable plastic code name R1/M15. Extremely strong and
durable. Can be machined, painted, stained screwed etc. etc.

PO Box 1148,
Cedar Ridge,
CA 95924.
Contact Cliff Stewart.


Hello Steve- Have you tried delrin or teflon, or maybe phenolic?
I never did like all those hot metal shavings anyway ) The delrin
machines very well for patterns and molds, and like teflon, will
stand up to 400*f no problem. I have a local source, but you
should have luck with the Thomas register. Ricky Low


I like the Castaldo product and have used it once. The drawbacks
I found are its sensative to humidity, which we have an abundance
of here in Houston, Tx. The other thing is after you open the
containers the shelf life is about a week. Not good. Also there
is a warning not to store them with vulcanized molds so now I
have to find a second storage for molds with this product. These
are my experiences for what they are worth. Frank


Steve My memory of this material is twenty years old but I once
used Delrin(Dupont Product) for stoppers for sterling perfume
bottles. As I recall, turning it on a metal lathe was quite
easy although it is definitely less forgiving than wax. Delrin
machines and finishes beautifully(surface feels great after
using 600 silicone carbide and then fine pumice powder) and might
withstand the temperature of the vulcanization process. Sorry I
don’t have any additional but you might be able to
contact Dupont for product specifications. As to price and
availability, I bought my Delrin at the overrun/cutoff sales
room of a plastics (Plexiglass) supplier but don’t remember how
much it cost.
Linda M



Personally, the advantages to the “Quick Sil” preduct are so
great that you might consider installing a dehumidifier in your
shop. You might find the lack of excessive humidity an advantage
in other ways as well. However, I have had my inital sample of
this product around for about 2 months and not noticed a problem.
What happened to your mold compounds to cause you to think they
had “gone bad?” Perhaps there was a contamination problem. Were
your hands and the counter top clean?

Steve Klepinger