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

I looked into this once. The company I researched that does it uses an
mixture of silca and castable poy. the minimum "grit" size for the "silica"
is 1/2" diameter. After reading the info at the site, you find out the
"silica" is actually rocks!

The machine beds they make are cast in steel molds which have to have
inserts built into them for any bolt holes, keyways any any other cavities
or desired projections.

The molds are custom made for each project and are EXPEN$IVE!

Another disadvantages to using resin (I've tried it) is that it isn't
anywhere near as strong as aluminum or steel, consequently web cross
sections need to be much thicker.

IMO you'd be better off just using weldments. You won't need to make a
pattern or a mold. The weldment can be stress relieved at a local (in a big
city) shop. If you can cast your own parts, all you need is an easy to make
wax pattern (for one off castings) and don't need a mold.

Smoke

>In the recent past there was a thread covering the topic of using
>epoxy and polyester resins in the construction of mill frames. A few
>weeks before that thread started, I was surprise to learn that at
>least one commercial manufacturer (Light Machines) builds the frame
>of their mills out of resin. I began to wonder if this would be a
>good way to build a home-built system, for there are some obvious
>advantages. First of all, casting resin is a lot easier than casting
>substantial pieces of iron or aluminum. Second, although the
>underlying structure should be solidly joined together, I don't think
>there is any need for welding it. Third, from what I have read, it
>seems that cast resin cuts resonance by a substantial amount.
>
>