Vacuum Press/Compressor

[mahking51]

Hi Guys,

I have just bought a heavy duty continously rated vacuum pump to use on AC systems. It runs for up to an hour at a time to pull moisture out of the system.
I assume it will also be fine for veneering work.
Can the bags and other and pieces be bought separately?
Regards,
Martin
PS: Pump was American and about £180 and seems very well made indeed.

 

[jasonB]

Bagpress sell all the bits separately

http://www.instant-shop.com/bagpress

PS I would avoid sighning up for their forum as I get quite a bit of spam originating from there :x

Jason

 

[Scrit]

Martin

A lot of the pipework stuff is available through compressed air firms. The two names to look for are IMI Norgren (Enotts) and Festool although Camozzi also has a subsidiary doing vacuum stuff. I tend to use compressed ait push fittings in 8 and 10mm OD simply because they're readily available. A useful specialist supplier is FlowTech in Skelmersdale - they're trade only but will send you a catalogue and tell you their local suippliers name. Not always the cheapest (a bit like RS) but a huge range of stuff.

One trick about vacuum veneering - empty the majority of the air out of the bag with your shop vacuum before attaching the vacuum pump. You'll achieve max. vacuum quicker

Scrit

 

[Inspector]

Woodythepecker

"While looking around for a decent Vacuum Press i have been told that you can in fact use a compressor. Has anyone used one in this way?"

I haven't tried this myself so can't give you first hand experience but you might want to look into it further.

I have read on various forums (perhaps even this one) that an air compressor can be used directly as a vacuum pump. The line to the air tank is removed, or the tank opened to keep the pressure from building, and a fitting put in the inlet of the pump in place of the filter.

I don't know what the long term effects would be on compressor life, whether there are any oil consumption issues, or if a vacuum pressure switch is needed to cycle it, just that it does work. The compressor doesn't know if it sucks or blows. :?

 

[Scrit]

I have read on various forums (perhaps even this one) that an air compressor can be used directly as a vacuum pump. The line to the air tank is removed, or the tank opened to keep the pressure from building, and a fitting put in the inlet of the pump in place of the filter.

I don't know what the long term effects would be on compressor life, whether there are any oil consumption issues, or if a vacuum pressure switch is needed to cycle it, just that it does work.

I can see a couple of problems with it, Inspector, at least if you use a larger oil-filled compressor. If you have negative pressure inside the cylinders won't that tend to draw oil past the rings in piston compressors? And if the oil is drawn through and the receiver is still attached won't that then contaminate the receiver with compressor oil? Providing the compressor is only ever used for air tools (not for spraying) and all of those tools have exhausts which direct the exhausted air away from the workspace then you're OK (unfortunately, few do). Oil contaminated exhaust air can give you surface contamination problems which affect your finishing. Trying to spray finish using a compressor with an oil contaminated tank will probably be even more problematic - coalescing oil filters won't last nearly so long between clean-out or replacement. You'd still require a vacuum filter (to protect the pump from particulate contamination) and it would be necessary to rig up a vacuum cut-out switch and solenoid cut-off valve, as leaving the pump under negative pressure would exarcebate the oil draw issue.

Industry has found that the best vacuum pumps to use in a dusty environment such as a woodworking shop are the oil-less variety with carbon vanes - they don't contaminate anything because there's no oil in them, although like any vacuum pump they still need a solenoid cut-off valve and sensor and they should be protected with a filter. It's notable that companies like Becker and Gast offer vane vacuum pumps which can also provide compressed air as well as vacuum whilst they don't offer many piston pumps, and none at all in larger sizes.

I suppose if you were keen it might be possible to use a small oil-less piston or diaphragm compressor to provide vacuum (Bambi-style diaphragm compressors are sometimes used to do this), in which case it might well be sensible to re-plumb the tank to act as a vacuum receiver, rather like the vacuum pump set-ups used on some CNC routers

Scrit

 

[Inspector]

Scrit

I agree with every thing that you've said. I mentioned it because that was the meaning I got from Woodythepecker's question and thought perhaps that was what the people that told him about the compressor were referring to.

In my aircraft maintenance days I had lots of chances to get vane pumps from the air tankers (were part of the fight instrument systems) we worked on that were not one of our companies standard models. They would have been perfect for a press but couldn't think of a use for them at the time. #-o Missed another opportunity when offered a pump from the milking parlor of a small dairy.

Although I have not done much with veneer my interest in vacuum bagging is more along the avenues of bent laminating solid wood and for work holding. When I get to that kind of project I'll be using an air driven venturi setup that was originally used for skin repairs of composite wings. It is muffled and will maintain less than 20" hg as long as there are no big bag leaks and since the compressor I have has an 80 gallon tank it doesn't cycle very often. Should be fine for a hobby woodworker like myself.

 

[Emerald Pete]

The printing industry used vacuum pumps until the last few years. Maybe there are still some about?!