Model Forum / General / Models / April 2008

Don't know about the plastic ones, but an old friend has sanded the
resin ones down for years to use as filler in some of the kits that he
makes. And yes, he's recycled the resin powder into some new pieces.
He did a set of 1:24 Volkswagen engines some years ago, I put one into
a scratchbuilt model of a homebuit aircraft that came out looking nice.

Stick a lot of them in a bottle of liquid cement. If you use enough,
it will melt into a thick gooey mess that can be spooned into a mold.
It will take some time to dry, but you'll have plastic parts.

That will be a future project I intend to experiment on.
I once saw a homemade plastic injection machine in a Plastics
Injection shop.  The owner was an electrician. It consisted of no more
than a metal melt cylinder for plastic beads.  He used a long rod
screw arrangement to (with a piston) pressurize the plastic melt into
an injection mold held on a vise.  The screw drive power was off a 1/2
inch highly geared low speed hand drill.  I asked about the melt tube
and all it was was a strong metal tube that was heated by a wrap
around heat pad (various sizes available from a plastics injection
mold supplies company, the supplier's name escapes me.)  Of course you
will need some temperature controller for the heat pad. I think
plastic sprue melts under 200 deg C. Subsequently I saw a glorified
version of what I just described in a Jewelry Supplies catalog.  It's
no longer in that catalog for some years now.  

To reuse sprue you will need to chop it down into "bead" size as used
in plastic beads for injection molding. A hobby project book had a
design that uses an electric portable wood planer spiral cutter as the
chopper.  This design used a cast iron drainage pipe part as the
safety housing.  This design is a bit too complex for my project. I'll
more likely use a router with a router bit housed inside a metal tube
to do the sprue reduction (to bead size).

Well, I take them and melt them down in a bottle of liquid glue. I have then made a mold out of silicon and made a part with it.
Just use the brush ion the bottle to "paint" it in the mold as thick as you want, then let it dry.
I also use it to build up areas where I put parts together as on custom cars. It's more time consuming than putty, but better in
many ways.

Mike