homebuilt vacuum press pumps?

[Bruce Wrenn]

I have always been a little confused on vacuum pumps and such.

Is there not a valve or the like that one could just hook up to a standard shop air compressor. Not buy a vacuum pump with motor and all ?

YES, if the inlet filter has standard pipe threads. Put a tee between the filter, and pump. Add a ball valve and reinstall filter on one side of the tee. Cap the other side when not in use. To use as a vacuum pump, open drain valve on tank to relieve pressure. Close off ball valve, and remove cap from other side of the tee. Connect vacuum line here. Now you have a vac pump.

[Tara Covell]

I suggest to use ARKSEN 5CFM HVAC Vacuum Pump. It's cost is under $300. You get the best experience. It's a good inexpensive pump and Gauge works well.

[Chris Fournier]

Price out your build if you are hoping to include a regulator and gauges, then you can compare to the readily available pumps with the same features.

Yes Dave you can buy a pump that is based on a venturi design and uses shop air, a lot of shop air. And it is noisy. But effective.

[Bill Adamsen]

As you've discovered the "Joe Woodworker" web-site has good information on the various pumps and venturi systems you could source.

He also provides plans to build a system and provides the parts as a kit. I built their EVS system using a Thomas 3-4 cfm wobble piston vacuum pump I sourced from ebay. Total system cost which included the EVS kit and vacuum was just south of $300. I can sustain 21 inches of hg with a 4' x 8' bag.

[James W Glenn]

Quick question. I am looking at getting a Rolair JC10 compressor and was wondering if it would be suitable for for vacuum bagging smaller projects? There looked to be a Joe Woodworker venturi kit that was compatible with the Rolair, which has an output of "2.35 CFM at 90 PSI 2.5 Gallon" I was thinking of adding an 11 gallon air reservoir to the system. I'm getting a small compressor first because it will pay for itself quickly out of the shop.

The Joe Woodworker Venturi specs are:

Vac Pro Model Vacuum Flow Vacuum Port Size Air Demand at 80 PSI Air Demand at 90 PSI Maximum Bag Size Mini™ .5 CFM 1/4" NPT .8 CFM 1.2 CFM 2' x 4' Basic™ 1.2 CFM 1/4" NPT 1.8 CFM 2.2 CFM 4' x 4' Plus™ 3.2 CFM 1/4" NPT 4.8 CFM 5.5 CFM 4' x 9'

[Gerry Grzadzinski]

If you have any leaks at all in your bag, that thing will run non stop.
I would not attempt to use a venturi pump with a small compressor like that.

[James W Glenn]

Will an extra 11 gallons of air reservoir make a difference in the constant running? I'm thinking of doing small volume projects like bow limbs and small boat composite parts.

[Andy Booth]

Storage does not do much for vacuum
- 10 cubic feet of air at 120 psi is is equal to 8 x 10 = 80 CF of air at 15 psi. Using 10 CF of air will reduce the pressure to 7/8 the starting pressure (~105 psi)
Vacuum - at best it is at -15 psi (perfect vacuum). This is 1 x the volume. 10 CF of leak results in atmospheric pressure.

[James W Glenn]

I might need to see that on a chalk board....