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

--- In CAD_CAM_EDM_DRO@y..., "Doug Harrison" <prototype@c...> wrote:

> Tom;
> Do a search on polymer concrete and you will find a wealth of

information on

> the subject. PC has good damping properties and is fairly easy to

work

> with.

Thanks for your reply, Doug.
I have done the searching and have a wealth of links to info and
supliers. However, using resin seems to be such a great solution,
that a little red flag goes up in my mind. Too easy, you know what I
mean? I really want to be certain that my idea will work.

> I would stay away from polyester resins because it shrinks as it

cures

> (about 4%) and gives off styrene as it cures. Epoxy is toxic and

nasty to

> handle until it cures. After that, however, you can eat off it.

Epoxy has

> practically no shrinkage if it is solvent free and the cure time is

often

> easier to control...

I will go with epoxy, no doubt. What about additives, like powdered
metal or granite? Overkill?

Another concern:
I know of a company that manufactured replicas of museum statues in a
cast resin and powdered stone mixture. Allegedly the statues would
begin to crumble after a few years. I am wondering now if it had to
do with exposure to the ultraviolet light in sunlight. I'd hate to
have a crumbling cnc mill in a few years if I forget to draw the
shades...

Tom Murray