2003-11-04 07:33:34 UTC
I was checking out the design of your powder die on Dan Williams fine
web site. It seems like a nice, simple design and I'm sure it works
very well. Of course I have some questions and I was hoping you would
be kind enough to comment on them.
The first question is about the pistons being cast with sand. Wouldn't
it be a bit safer if these were cast without the sand? I understand
you used the sand to decrease the cost of the castings, but I'm
wondering if the sand might cause a spark if the surface grains were
to somehow come loose and be crushed or come into contact with other
The second question is also about the pistons. I was looking around on
the web site www.onlinemetals.com. This company sells 6061-T6 aluminum
extruded round rod in diameters up to 8". The 3" diameter material
costs $39.46 per foot, but they will also sell it pre-cut to any
length (+- 1/8") that you desire. A 2" length would cost $8.56, and a
3" length would be $12.84. I'm not sure what the materials would cost
to cast the pistons as you did, but the cost of aluminum pistons
doesn't seem prohibitively expensive to me. I'm also not enthusiastic
about the idea of casting polyester resin, simply because I have had
no experience with it. The question then is would aluminum pistons be
a suitable replacement for the polyester/sand pistons?
The company also sells Acetal (Delrin) and Nylon round extrusions up
to 8" in diameter, but both of these materials are actually quite a
bit more expensive than the aluminum.
Any comments or suggestions will be greatly appreciated.