concrete/molded structural elements

Mike Romine
wrote:

>My CNC is fairly stiff for what I am doing, but I have a huge problem with
>vibration. I am using aluminum and steel extrusions and box channel for
>the frame. These hollow members are very underdamped in nature. 2 ways
>to decrease the amplitude of vibrations is to either increase the
>damping coefficient of the material, or increase the mass of the
>system.

<snip>

>I was lucky to spend a day with Dan Huggins, programmer of
>Dancad, and he gave me the idea of making a precast concrete frame
>components.

<snip>

>I think I am going to try to fill my hollow structural parts with a
>reinforced polymerized concrete.

Not being an engineer, I ask your indulgence if this suggestion is
stupid, but how about foam-cored structural members, molded from a
Corian-type material? Advantages would be lightness and easy machining
with common tools, but would they be strong enough? Would the foam
cores help to "increase the damping coefficient" of the
material/structure?

On a related question, how would reinforced concrete work for the bed
of a largish (5' x 6') CNC wood router?

Geoff
Tennessee