"Tim Williams" wrote in message
...
"Ed Huntress" wrote in message
...
If you want metal, spincasters have cast aluminum diecasting alloys in
silicone rubber. The rubber is a very hard, high-temperature version. It
doesn't last for many shots but it does work. It doesn't much resemble
the
common RTV type that's used for low-temperature casting.
I would suggest ZA-27 (27% aluminum, balance zinc, you can whip it up with
a
dollar or two of 1983-or-newer pennies and some scrap aluminum). Strong
as
mild steel, hard as heck, melting point less than aluminum (circa 1000
degrees).
The Zamak family of alloys (look into ZA-8) have
tensile and compression strengths on the order of 40 kpsi and good
bearing
properties.
Oh...there you have it
I don't like the looks of ZA-8, at least the stuff I've made; makes big
huge
crystals, visible when you break a face.
Tim
What kind of mold are you casting it in? If you're using plaster, it chills
too slowly for ZA-8.
Ed Huntress