Re: [CAD_CAM_EDM_DRO] Re: Cast resin for a cnc mill design - good idea?

Hi Tom,

there was a good article in one of the trade mags awhile back on
cast granite for machine tools with some construction details
the short list went like this;
every maker has there own formula for it but they all seem to be
about 95% crushed stone from dust size to coarse gravel with just
enough epoxy to make it solid
the cross sections used are about 3X thicker than cast iron to make
up for strength and add damping mass
they use cast in place inserts for threads and bearing surfaces and
can cast in conduits using PVC pipe
they use a slow cure epoxy (~24 hrs) and a vibrating table to shake down
the filler stone for a nearly solid stone surface on the finished casting
molds can be built from plywood but need to be strong enough to
stand up to the shakedown step and any surface patterns will show up
on the finished part
the raw materials cost was not much lower than cast iron but the tooling
is much less and all the work could be done in the home shop

one of the machines featured in the article was this one
http://www.newcenturyinc.com/century_turn1.html
and some other examples are at
http://www.polymerconcrete.com/machine_tools.htm

I think most of the epoxies are UV stable ,some even UV cure
if not then a coat of paint should take care of it
or make a sheet metal form in the mold and leave it on the finished part

it may take some diffrent tricks to make it work but it looks like a good
way to go for a home built machine

Brian