Hi Ed,
I know nothing about casting (and probably won't be doing any in the
forseeable future), but I've followed this thread and been intrigued by
your last comment "If you're using plaster, it chills too slowly for ZA-8."
Why did you suppose he might be using plaster? And what does "chills too
slowly for ZA-8" mean/imply?
Just curious.
Roger
Ed Huntress wrote:
"Tim Williams" wrote in message
...
"Ed Huntress" wrote in message
et...
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