Has anyone use polymer clay, after it is "fired", for parts? Perhaps a
replacement knob or whatever? Any comments on machining the stuff?
Is it abrasive? Does it powder or chip or distort with age?

Thanks,
P.Isaac

No, it's not. It will burn above 270 degrees. Toxic, nasty fumes, too.

I have quite a bit of experience with polymer clay. It's really a PVC
plastisol with additives to make it a modeling clay. Make sure you
thoroughly cure the part in an oven. Once cured it is easily machined with
standard tools. I'd use angles like you'd use for aluminum and wood. It
lasts a long time, although it sometimes chalks in sunlight. It would be
good for a knob or decorative part. You can also use it for models to pull
a RTV silicone mold from. Dan

How heat resistant is it once cured? Would it work as a high temperature
insulator for an electric furnace? Probably not, huh?

Chuck Fellows
Cave Creek, AZ

Usually organics carbonize at high temperatures and turn into conductors.
Maybe machinable ceramic would do what you want.

I had a customer create a sculptured case prototype that he wanted
duplicated using this kind of material, it was good enough when sanded and
painted to get an idea of the functionality before committing $20K+ to
making an injection mold.

Um, it is not very heat resistant. Must consider time at temperature.
Either very long time but low temperature, or very short time at high
temperature. Glad I could be of assistance.

P.Isaac

I turned a cylinder made from my daughter's Sculpy III clay.
It turned fine, although it tended to crack if I wasn't gentle
with the chuck.

Best,

Jude Miller

A newer polymer clay, Premo, is said to be stronger than
Sculpey III. You can get a lot more info on this from
rec.crafts.polymer-clay. There's a lot of reference
material online, also mail-order places that sell at good
prices in small quantities.

The formulas for the polymer clays vary slightly. Premo and Fimo have some
acrylic co-polymer mixed in with the vinyl. This results in a harder and
higher tensile strength part. I've not tried machining these clays. All of
my experience is with the SuperSculpey III. We buy the 24# bulk box of the
neutral/beige color. The instructions say cure at 275 degrees 15 minutes
for each 1/4" of thickness. A great place to buy this online is Prairie
Craft:

http://www.prairiecraft.com/

Actually, it burns at 320 degrees, but I'm just in a nit-picky mood.
It's a good fine grained clay for maquettes and is often used that way.

Katherine Dewey

Thanks Katherine. I always want the best info I can get. I had said
270 because I'd had white clay toast at that temp. I stand corrected.

Kim