vjaqua wrote:

Something to consider for this application is "lost styrofoam" casting. You sculpt your
part
from easily removed blue foam, and ship it off to a casting house. The foam is vaporized
by the incoming melted aluminum. Good detail, and no fancy cores - the downside - you
have to make a new sculpture for each pour. - Vance

I think I might try that Vance. That sounds like it might work.
How would you make a hollow runner? Just carve it out from two
pieces and glue it together? Perhaps John Lynch can 3D machine
the styrofoam runner halves from a program. Can the foundry
stuff sand down in the runner with out breaking the foam?

Yes the foudry can stuff sand into holes, and some the core techniques
can probably be used such as resin etc for more structral integrity.
You could probably carve most of the passages with a ball burr, and
fairly long shaft, and the foam pices can be assembled, if required. Vance

Is blue foam the best to use or perhaps some other finer grain
foam? I think in production they use a mold and steam expanded styrofoam
beads that give a smoother surface finish.

The "blown" foams have the advantage of a lower density and are easier for the aluminm
to vaporize, as well as being more suited to series production and smoother
surface than carved.

The lost wax is a great process - tho more costly. You coat the wax with a refractory
plaster, which is fired, vaporizing the wax before the metal is poured. The lost foam
just uses sans.-Vance

 
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