RE: Idiots guide to making a vacuum pump?
In general:
We place an item inside a sealed plastic bag. We then use a pump to remove the air from the bag. The atmospheric pressure (outside) is then greater than the pressure inside the bag, so the net result is that atmospheric pressure applies a uniform clamping force to every point on the object inside the bag. The force is applied normal (perpendicular) to the surface at every point.
This pressure can be as much as 14PSI, which equates to a 7,000 pound weight applied evenly over a 500 square inch surface. Obviously, this may be too much pressure... so we use regulators to adjust the clamping force.
We usually measure the degree of vacuum using the units of inches of mercury (in Hg) or millimeters Hg (mm Hg). We use a vacuum gauge to make these measurements.
Items which normally get "vacuum bagged" are wood or composite-skinned foam core wings, flat or contoured sandwich panels, hollow-molded wing panels, etc.
-David