Re: re:Levelling large table

--- In CAD_CAM_EDM_DRO@egroups.com, "Joe Fahy" <72510.1173@c...>
wrote:

> Hi Doug,
>
> About 2 months ago, I received a Nasa TechBriefs. In it was a

short, ~200

> words, write-up on composite laminators switching from aluminum

tool plate

> to plate glass. Cost and inherent flatness were given as the

reasons. I

> received a quote from a local glass company of $288 for

72"x144"x1/4" sheet

> delivered, $4/sqft.

Be careful what you pick for glass. Cast glass is normally used for
1/8" window panes, and is not held to very tight tolerances.
However, so called "float glass" is made by pouring the molten glass
onto a very slowly flowing and recirculated bed of molten metal (tin,
I believe). The glass has a slightly lower melting point than the
tin, so it slowly cools to the gravity-flat surface of the metal and
comes off in a continuous strip. Float glass is most common in
heavier thickness and larger dimensions (store windows, etc.),
because the length of a sheet is not limited by the process. Using
float glass and fine wet-and-dry sandpaper as a honing plate for
chisels and plane irons is an old woodworker's trick that beats any
arkansas stone.

- Ken