Official Luthiers Forum!

I am researching a vacuum press system. Which is preferable oil or oil free or does it matter?
Also what is the optimum size ( what should I be looking for)?

thanks
Richard

Check out this link for great info on vac systems http://www.joewoodworker.com/. I'm not sure if you're asking about stand alone vac pumps or for info on choosing a compressor to run a venturi pump. (In other words I didn't know there was an oil or oilless vac pump - but maybe I can bump the topic to someone who does.) I went with the 1.1cfm stand alone pump because at the time I didn't have a compressor. I also thought that the noise of a venturi pump would make the boss unhappy. My press is shaped like a circle and a little larger than my radius dish. It takes the pump about 15 seconds to draw down all of the air in the press. I've thought about adding a reserve canister, but even a small pump works pretty well without one. Extra cfm's from a larger pump will make up for leaky jigs or air getting pulled through the pores of thin woods (if you decide to use a vac clamp to hold bodies as well), so that's also something to think about too. One last thought, if you're only using it to glue braces or bridges you only have to run the pump for 30 minutes or so at a time, so a venturi pump might be a good option if you already have a capable compressor.

There are a lot of easy options to silence a Venturi, BTW. I listened to mine for about a year before I came across them.

Easiest is to put a piece of vinyl tube (as long as you can) on the exhaust, plug the very end of the tube, and drill a whole bunch of holes in the side of the tube. That, alone, will be much quieter.

Vaccon makes them with two-stage silencers now (silencer is like $14 on top of the pump) and those are really quiet!

_________________
Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

The only experience I have with vacuum is working on automotive AC systems, but I would think a vacuum pump is basically a vacuum pump. They're may be different vacuum requirments, but it's still vacuum. A stand alone, electric vacuum pump is alot quiter and I would think alot more energy efficient. Even if you have a HUGE air compressor it's still going to have to run quite a bit to operate a vacuum pump. Unless the CFM requirments are alot less for vacuum clamping than they are for HVAC work I wouldn't even consider one that runs off air.

Again, my only experience is with vacuum pumps in HVAC work. Vacuum clamping may be entirely different.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

I am talking about oil/oil free vacuums there seems to be a lot on ebay like this http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 3415wt_817

these seem to be a lot less than their oil free counterparts if you look at HP or CFM's

Anyone know why?

Thanks
R

The only oil free vacuum pumps I've seen(in HVAC work) are venturi type that run off an air compressor. I would suspect that an oil free piston type vacuum pump would have the same drawback as an oil free compressor. A piston or vane type vacuum pump is basically an air compressor, but it works in reverse. Oil free would probably make more noise, and have a lower duty cycle. It might also be a little less efficient. Again, these thoughts are just guesses.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

A rotary vane type pump will work just fine. There is no advantage for a clamping operation when using an oil type of pump. Rotary vanes are pretty much maintenance free unlike oil pumps.
3CFM or so should be plenty.

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Jim Watts
http://jameswattsguitars.com