Vacuum pump question

[Robert Engel]

Will an A/C vacuum pump pull enough pressure for veneering?

[Paul F Franklin]

It will pull enough vacuum. The question is how fast. Pumps with a high flow rating will (surprise) evacuate a vacuum bag faster.

[Bill Dufour]

I think even a venturi unit will have enough vacuum. You are not talking Torr here.
Bill D.

[Eric Arnsdorff]

The auto AC pumps I’ve used had a relatively low volumetric capacity but definitely more than adequate in terms of pressure. Atmospheric pressure is 14.7 psi and AC vacuum pumps get down to the hundredths and thousandths of a psi (meaning practically all of the 14.7 psi is acting as a clamp on the veneer). Even if it only got down to 14 psi vacuum you’d only be missing out on 0.7 psi.
It will definitely work. Just evacuate as much of the air as possible prior to closing it up.

[Bruce Wrenn]

The auto AC pumps I’ve used had a relatively low volumetric capacity but definitely more than adequate in terms of pressure. Atmospheric pressure is 14.7 psi and AC vacuum pumps get down to the hundredths and thousandths of a psi (meaning practically all of the 14.7 psi is acting as a clamp on the veneer). Even if it only got down to 14 psi vacuum you’d only be missing out on 0.7 psi.
It will definitely work. Just evacuate as much of the air as possible prior to closing it up.

Take a few minutes and read the specs on HVAC vacuum pumps. Most start at around six cubic feet per minute. Forget the HF ones. Find a HVAC place that has some old pumps that no longer pull in the micro range, and are considered scrap. Rebuilding cost about the same as a new pump, plus no time lost. I got all of mine from scrap yards for $0.15 a pound, which means 3-5 bucks each. If you want a venturi type pump, go to AirVac Engineering's web site and select a pump. If memory serves me correct, the model you want is an AH 093. It's the size of a small candy bar.

[Bill Dufour]

How long do you vacuum clamp a part? Is it just for 30 minutes until the glue sets or is overnite? I have no idea how vacuum affects glue dry times. If it is overnite better get a vacuum switch to control the pump and either use. a long hose or a small tank to store some extra vacuum so the pump does not run so often.
Bil lD

[Bill Dufour]

Buy a vacuum gauge so you know what you are doing and it will be repeatable. Too much vacuum can cause a glue starved joint.
Bill D

[Jim Becker]

How long do you vacuum clamp a part? Is it just for 30 minutes until the glue sets or is overnite? I have no idea how vacuum affects glue dry times. If it is overnite better get a vacuum switch to control the pump and either use. a long hose or a small tank to store some extra vacuum so the pump does not run so often.

Depends on the nature of the work including any bending tensions and the type of glue being used. 'Not sure I'd use the technique for a bent lamination that really required an overnight cure before "unclamping", however, for the reason you are concerned about.