Not volume, but surface area inside the gasket seal. Vacuum holding force is measured per square inch. The more square inches, the better. With no leaks, and holding a non porous material, you can probably get about 10 lbs/in^2. So a 10"x10" table can get you up to 1000 lbs of force, provided there are no leaks.The size of the vacuum chamber in the table, does size (volume) matter ? I'd like to cut the chamber(s) in a 1" thick sheet of material.