On Oct 13, 2:41*pm, RS at work wrote:
I am going to build a chamber type vacuum sealer.

Unlike the Food-saver Seal-a-Meal machines that pull a weak vacuum, do
not seal really well and use expensive special bags, a chamber style
has an impulse sealer inside the chamber and the product is bagged,
set inside the chamber, and sealed after you have drawn a vacuum.

I presume you are aiming for rough vacuum (air pressure is about
30 inches-of-Hg, and you'd be satisfied with 0.5 inches-of-Hg). The
force on the sidewalls, about 15 psi, means that flat-sided
boxes aren't suitable. Usually, one sees a glass bell jar atop
a castiron plate, gravity and a greased rubbery gasket hold the
vacuum,
or aluminum or SS pipe-spools with flanges on the ends for
bolted-compression gasketing or O-rings.

Cylinders and hemispheres (like the bell jar dome) can be made
of light construction, and still be safe. The lid, though, will
require
machined plate or flanges, so a machine shop is called for. One
with welding equipment, preferably.