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

Yes. I am looking at making a pattern for just the bottom 90 degrees.
If I could only figure out how to get the cores in the mold.

I now understand core boxes, core prints, drags and copes.
I still don't fully understand curved parting lines.
I need to take a trip up to the foundry and have a look around.

Paul Lamar

Paul,
I worked in a foundry many years ago as a youth.
We used two types of mediums

1. Gassed sand (gas was carbon dioxide I believe which
was a catalyst for a compound mixed with the sand)
2. Black Earth ( it doesn't start black but is coloured with use)

I believe the best medium is the sand in this instance as
it is more rigid.

a. The way I would tackle it would be to first mould the inside runners
individually and cover them with the blue foam ie the thickness of
the wall required.

b. Place them inside  your mould box with foam for top and bottom flanges
    gently pour in sand -pack and gas. Use spacers and remove them as you
    pack in the sand if you need to keep the runners parallel

c. place pour hole at top of mould and pour.

I given it considerable thought and can't think of an easier way.
The tube shape and even wall thickness was the hardest part
to work out.

The only mould you would need is the inside runner shape. Then
tube foam over this.
Hope it helps
George (down under)

I got the traditional sand casting  pattern figured out George. 

Here is a sketch with the core boxes, cores and core prints 
indicated. Its a little tricky. Chinese puzzle actually. The problem
with foam is its a one off unless you make molds. I have
a friend with a 3D router and Pro Engineer that can make all
the patterns and core boxes if I can talk him into it.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/            http://www.linux.org