Hi Guys
I’m out of my leauge on this one!
I’m just getting into vaccum bagging and want to try it on a few boards and to make some veneer panels for a project at home. Now I can get my hands on a nice old becker SV 5.90/5 pump
specs are
capacity 45m2/h
inlet pressure -90 mbar
discharge pressure + 110mbar
It does pull a vaccum but is it going to be big enough for the job or should I build one from scratch?
I’ve attached a charts which gives some indication to the performance.
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cheers Joe
hey joe
not sure exactly what milibar is
but if you use online conversions and convert from Hg
what you want is about 7hg to max maybe 10hg
thats it
not much even a small $20 diaphragm pump will do it
the smaller pumps are slow to remove the air though
so i used to just empty the bag with a vacuum cleaner first then hook the tube up to the pump
hope this helps
you will need a guage and vacuum controller for effective controlled vaccing
to much pressure is a NO NO imo
Thanks silly so if I’m right, this pump could be pulling 67.51 torr (hg) http://www.convert-me.com/en/convert/pressure.
So it could be worth getting.
cheers Joe
um i thought hg
was inches of mercury
yup definately HG is inches of mercury
so 7 hg converts to 237millibar
so no
that s the wrong pump
methinks
Cheers silly, I’ll think I’ll go down the road of scratch building on from the archives. At least it saves me trying to smuggle it out from work 
cheers Joe
If you want to go cheap get the compressor from an old fridge and poke around the joe woodworker site.
Built mine for under AU$50 (US$25-US$30).
cheers doug, i had a look at that last week,looks like the way to go.
cheers joe
i dunno about that
personally i find a rotary vane pump to be the way to go
ive been finding medical surplus and old ones from the food industry
also the bigger pumps used by fridge mechanics
one sold on trademe for 25$ the other week
it empties the bag in about 20 seconds and runs every 10 minutes for about 5 seconds
noice and quiet as well
it hooked up to a tank with a guage and vacuum controller
i used proper bagging material and mastic these days (no leaking fittings)
you can see the guage attached to the tank and the green thing is a vacuum controller
there is filters on this pump as it is oilless
you can see i just used mastic to seal the pipe into the bag
board is setup on a foam rocker table
yello stuff is a permenent mastic that cost 7$ per roll
ive used this bag for 4 boards alraeady and still going strong
cost about 40$
i try and keep everything clean with no left over bits of fibreglass to put holes in the bag
etc etc
this is a roll of not so permenent mastic for the bag entrance
it peels of easily and can be used to seal the pipe entrance
the pipe has some shade cloth over the top so it doesnt block
artwork on board is influenced by Mondrian
not really its just tape
hey doug
i got all my info off the joe woodworker site
its an excellent resource for vac bagging stuff
i just question the reliablitly of a old fridge pump
it would be a bummer if it died halfway through a pproject
i would recomend a backup if your going down that route
cuz it may overheat and cut out if you run it continously
Hi Silly,
You are the man 
I still appreciate the tips you’ve given me 
Yeah, that would be a bummer. Mine doesn’t run anywhere near continuously. About one second per minute.
And the beauty of free old fridge compressors is that I run two of them on the same line.
Love redundancy!
hey doug
i know Sabs still uses old fridge compressors sucessfully
i noticed he had a wee stash of them though when i visited
do you have that vacuum switch made from the auto vac advance off a dizzy
i thought that was clever
it looked really super sensitive as well
i will get around to making one
mines got a 3 hg pressure swing
its hasnt seemed to be a problem though
i have a small diaphragm pump and valve as a backup
i just need my setup to be quick and easy
sometimes ill bag before work or something
like things to go smooth
if it works
go for it!!!
I got a medical evacuation pump off Ebay for $40. It is a Gomco oiless with an adjustable gauge and will pump 21hg’s for days. The medical evac pumps are nice because they are designed to run for long periods of time and are pretty reliable.
Hey Paul!
I’ve never had a problem with the older compressors. I’ve run some in tests non-stop of 8-12 hours without a hiccup - as long as they have oil… The ones from newer fridges all seem to have problems. Needless to say I carry tools for ripping fridge compressors out in my boot. If I see an old fridge out by the road I knock on the door and ask - noone has turned me down yet.
Yeah, I made a vac advance vac switch. It’s accurate to around +/-1"hg. It was pretty fiddly to construct, but fun tho.
I would have been making boards a whole lot quicker if I had simply bought everything - like 12+ months sooner. But that’s life on a shoestring budget. Oh to be independently wealthy!
My setup actually empties a 12’x3’ bag surprisingly quickly. Less than five minutes.
Cheers mate!
I’m using fridge pump with a vac switch made from a car dizzy vacuum advance, and I get the same kind of accuracy Doug does, +/- 1" Hg.
I searched everywhere for a proper switch, and never found anything for under $200!
So I made my own and it works flawlessly.
The only problem with it is my adjustment range is only from 7" to 11". I’d have to adjust the micro switch or the spring to get different pressures outside that range.
I have a constant-run switch that I flick on, bypassing the vac switch, and pulling a really high vacuum in my reservoir, so I can suck the bag down quickly,
Then the vac switch comes in to play again.
Simply smoothing down the vac bag around the board before you seal it gets rid of a huge amount of air.
I’m not a big fan of constant-running systems, even if your pump is designed to handle it.
Why risk your bleed valve blocking?
Why waste power having the pump running all night?
It can mask other problems, such as excessive holes in your bag. The frequency of your pump flick on and off tells you clearly how well you old tatty bag is sealing!
Oh, when removing a pump from an old fridge, bend and crimp the tubes on either side of the compressor before you cut them. Then the only ozone-eating gas that is released is the stuff left in the pump, not the whole system.
Slightly more concious of the enviromment, but you really should get it degassed properly to be guilt free
Kit
Hi Kit!
Yeah, I agree. I reckon if you are running more than a few seconds a minute you have a bad seal and/or a puncture. Who wants to run a vac pump continuously? Not me! Besides the efficiency, money, risk of damaging the equipment, fire risk, etc there’s the carbon emissions. The more juice you use the more harm you are doing to the environment.
Sounds like we pull pumps the same way BTW. Since I knock on the door I ask them about the fridge and what’s wrong with it. In most cases they give the answer I am after “it’s been sitting around for ages and makes a humming noise but never gets cold”. That tells me the gas is already long gone and I don’t have to be so careful. I still run a long crimp on both sides cut the centre and fold it back twice up away from the compressor to be safe.