On Jan 16, 12:25*am, "Ed Huntress" wrote:
...I'd
get involved now just for the hobbyist satisfaction of it IF there were at
least a dozen other people who were serious about it and who would
contribute. ...Civil engineers usually know general reinforcement and
prestressing. Now I need to find a few of those who also are amateur
machinists. d8-)
Ed Huntress

Are you thinking of this as a manufacturing process or one that
hobbyists could use to bootstrap a machine shop, like Gingery's cast
aluminum tools?

I'll build things with whatever works, castings or welded steel or
logs chainsawed flat or anchors drilled into a big flat rock. Assuming
a hobbyist without FEA or the knowledge to apply it, I think metal
bearings and support plates jigged in place and connected by the cast
material might make sense. I would join the pieces with threaded rods
so it could be disassembled for repair or improvement, and the casting
wouldn't have to take much tension. Otherwise no matter how strong it
is, it has to bond to the metal and they have very different thermal
expansions. If the casting came out badly the metal could be reused. I
have a vacuum oven to remove trapped bubbles but I don't suppose too
many others do. I bought it cheap at an auction and spent most of a
day chipping the old spilled resin out of the chamber and fixing
leaks.

Nonmetallic castings seem to be used hesitantly in industry. My
Powermate generator has one alternator bearing cast into the plastic
end housing. DeWalt chose magnesium for the gear case on their high-
end cordless drills, reportedly because they couldn't make a plastic
one strong enough. I think that was in Design News. The Drill Doctor
chuck is an example of a casting that isn't quite as satisfactory as a
metal one. Polymer pistols have metal inserts cast in, I don't have
one to decribe how, and the Segway which I've dis and reassembled
many times has a very solid metal structure under the plastic.

Jim Wilkins