Re: Vacuum Table

--- In CAD_CAM_EDM_DRO@yahoogroups.com, H & J Johnson <hjjohnson@...>
wrote:

>
> No extra bracing will be required for a vacuum table [over a

non-vacuum] as there is no 'atmoshereic pressure difference' between
the two. As was mentioned the pressure is applied both to the top and
bottom of the surface so no 'net change' occurs. The beauty of a
vacuum is the immense pressure which can be obtained WITHOUT have to
build the table extra heavy.

>
> FWIW
> Jarrett

yes and no.

With a shop vac, about the best you can get is about 10 inches of
WATER, or about 1/3 of a PSI. 1 psi = 27.72 inches of water.
1 atmosphere = 14.7 psi or 29.92 inches of mercury.

with a tight seal, and a vac pump, theoretically you can get the
pressure about 40 times stronger, or 14.7 PSI.

If you are putting a sheet of plywood over your aluminum table, the
ply will bend like a reed in the wind.

however, if you are putting a 3/4" thick sheet of aluminum over your
plywood table, your table will bend like a reed in the wind.

considder the material, and the pressure and the supports. to hold
paper or whatever the film is made of in a graphics shop, they only
put in one tiny hole. the film would bend if the hole were too big.

Just common sense.

Dave