Archived from groups: rec.games.vectrex (
More info?)
"Richard Hutchinson" <richard.hutchinson@dsl.pipex.com> wrote in message
news:40b36135$0$20515$cc9e4d1f@news-text.dial.pipex.com...
> Anyone had custom casings made for electronic circuits ?
>
> Kev, Clay ?
Yep... I've done quite a bit of plastic injection molding stuff for "work"
and other side projects. Generally it's pretty cost prohibitive unless
you're planning on moving a lot of pieces, but there's a couple new things
available that are actually pretty cost effective now. You can get a model
made-- (usually a finished SLA or similar) and have castings made with
bismuth-tin which can then be used in a mold base for plastic injection.
You can't run *every* material (the bismuth tin is softer and has a lower
melting point than steel) and the run lenth is limited due to wear (but
probably still at least in the hundreds depending on size/complexity), but
it's a lot cheaper than tooling aluminum or steel.
You want to try to try to have a "straight pull" cavity-- (ie, no hidden
surfaces looking at it face-on) otherwise the tool needs 'slides' and
multiple molding steps. That's trickier (and more expensive) to pull off in
the softer bismuth tin material...
The main thing you save on is the tooling and the cost of the mold base, the
downside is that you're limited to the quality of the original model for the
quality of the final plastic. (GIGO ;-) Real tooling in aluminum or steel
with texturing is pretty spendy. Figure at least $4K on up. I did a little
socket for a lithium-ion battery pack that was about 2"x3" and had a couple
slides and the cost was over $10K. You could probably get that done for
less in Korea/China/Russia, but it probably wouldn't be a good "first
project" to try overseas... ;-)
-Clay
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