Casting in metal vs. plastics (was: Re: [DSII] Genre)

> Nyrath the nearly wise <nyrath@clark.net> wrote:

OK, you asked for it!! <grin>
We spin-cast in black rubber moulds (vulcanised nitrile rubber, same
sort of stuff (and strength) as a car tyre. You CAN use RTV silicones instead,
but these tend to be kept either for initial prototyping or else used by
hobby casters who don't have a vulcanising press - RTV moulds are more
expensive and don't last anywhere near as long as vulcanised ones. The casting
machinery (caster, melting pot and vulcaniser) will cost you something in the
region of £6000 or so for "professional" kit, less for more basic ones. The
blank mould discs (from which you press the moulds) are a few pounds a pair,
and their life is anything from a couple of
hundred spins upwards, depending on how hard you run them - if they're
not left to cool down between spins they'll burn out faster. In contrast, a
single mould for an injection plastic sprue is in the order of tens of
thousands of pounds, and the machinery to do it even more. Metal casting can,
in theory, be done by almost anyone with a little bit of money
and a garden shed; injection plastics require a major factory set-up.
It's worth doing a metal miniature if you think you're going to sell a hundred
of them or so; for plastics, you need to KNOW you'll sell many thousand sets
of a given item before you can even THINK about doing it. That's why even GW
restrict their plastics releases to the things they know will shift in
bucketloads to the snotlings, and still do their more "specialised" stuff in
metal.

Jon (GZG)

Jon (GZG)

> Miniatures being usually low volume items, metal moulding is the