Re: Flat surface creation revisted

Dave,

Are you suggesting the entire table be made of concrete? Doesn't
concrete have pretty high thermal expansion properties? I'm not sure
what kind of problems this would present [other than trying to move
the beast :-) ].

What about mixing a thin mixture of concrete (really soupy) and
pouring it over the top of an I-beam or C-channel rail (with a
fixture to confine the mix to the top of the rail). Would this level
enough to provide a flat reference surface for mounting the linear
rails?

I know that float glass is very flat. They take molten glass and
pour it over sand and the top surface flattens out evenly. Maybe
Doug's epoxy method would yield similar results. Or maybe there is
another substance that would work even better.


David

--- In CAD_CAM_EDM_DRO@y..., "turbulatordude" <davemucha@j...> wrote:
> It seems that a low cost, easy homebrew table would be cement.
> good'ol concrete.
>
> one would take their linear rails, match up the mounting plates
that
> will be embeded in the table, make some sort of alignment jig, make
a
> nice flat, level pad and just pour away. what one would wind up
with
> is a massive table top and the rail supports. Then Les's final
> scraping tecnique would be easy and one would be all set.
>
> Of course, turing the table over would be pretty tricky. as would
> legs.
>
> but with some planning, the table could have a vacuum system could
> have the holes placed or uni-strut rails for table bolting runners,
> or just all thread couplings for specific point connections.
>
> A simple final epoxy flooing leveling compound would make the table
> top flat and can be leveled by the gantry itself.
>
> I'm sure there are reasons why this would and would not work, but I
> have seen kitchen counter tops made in this fashion, so for some
> parts, it is possible.
>
> Dave
>
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., "drking777" <david.king@c...> wrote:
> > Hi all,
> >
> > The method of using an epoxy goo to create a flat surface appears
> to
> > be an econimical and quick method. Can someone elaborate on this
> > method further [Doug??? :)]
> >
> > I am curious as to a supplier(s) of the epoxy, powered metal and
> > fumed silica. Also, do you have a recipe for creating the "flat
> > surface soup?" What is the best method to apply the potion? What
> > would one use as a release agent on the linear rail?
> >
> > Thanks,
> >
> > David
> >
> > Doug Harrison wrote:
> > > Any 100% solids marine epoxy filled with powdered metal and
fumed
> > silica should work.