Is there a simple way or some device on the market that can be driven by air pressure to operate a vacuum system to do small panels and one off board projects?
I have some new ideas in the works for fins that would require vacuum bagging I’m also considering a balsa railed 1lb EPS board that would be skinned with either balsa or bamboo veneer and wondering how a .015" bamboo skin would behave compared to balsa. I’m thinking that using my air compressor to drive the system would be an efficient and facilitate a nice clean process.
Call the guys up at the dump and they will tell you when the freon recycle guys come and they will probably save you a fridge pump that has been eco friendly salvaged. I think they come every two weeks. Then get the switch. then you are laughing.
switch and relay, inline filter, and gauge from Joe woodworker
relay is unneccesary for this setup, but if I wanted to i could use this controller to drive up to 1 horsepower…Balsa Yacht, anyone? some pumps do draw heavy current on turn on, the relay protects the switch…plus, it looks and sounds cool…klik, klackbrrrrrrrrr, klik, with the little spark…
fittings (mostly 1/4" male pipe thread to 1/4 ID hose barb),
hose (1/4 ID braidedmesh)
pipe and caps for reservoir (SCH 80 PVC is recommended, mine are black ABS)
all from local building supply…
I still need to get a check valve, although this pump seems to hold its breath fine…notice in the upper pic, hard to read the numbers, but it’s pulling just over 28"hg.
gimme another sec and Ill see if I cant sketch up some schematics…
basically, you’ve got two circuits here, one with your vac switch and relay coil in series, and the other with the relay switch and outlet in series.
Vac switch is wired normally closed, so it will be on until proper vacuum is pulled, then will turn off.
Relay switch is wired normally open, so that when the vac switch turns off and releases the coil, it disconnects the pump. (normal being when the coil is not energized)
Switch is continuously dialable from 5"hg to 28"hg, with a 4" hysteresis. You could also plug other stuff into the switched outlet, like a lightbulb or fan or something, so that you could tell it’s cycling, or to cool/vent the pump.
Joe woodworker sends the little jumper connectors with the switch and relay.
with a decent size reservoir, one of these will cycle on for about 15 sec. about once every five or ten minutes on small jobs like fins, more if you seal your system well…That’s well below the duty cycle that pump would see in a fridge…
I just pull off the inlet tube and squirt a little oil in the pipe while it’s on once and a while, it doesn’t seem to use much…it does emit a bit of oily exhaust, I rigged some crude filtering over my oil catch, the room fan does the rest. (do make sure and filter/vent it, as I’m sure oily mist is no good for contaminating epoxy layups. many vac pumps do this…)
If you are serious you should really check out Joe Woodworker or spend some time in the archives.
I did mine for under AU$30 (under US$20). To lazy to pull out the link again. Search for “vac pump” or something against my handle for more info… Or just check out Joe Woodworker.
I was trying to figure out a way to vac bagging without spending money- I started a thread about the auto brake bleeders, I bought a venturi vacuum to use with a compressor (didn’t hold vac). I ending up spending about $150 for a Gast pump. Mine is super quiet, it is rated 24/7 so you can just keep it running instead of having to set up reservoirs and what not. It has an inlet and outlet, each with a bleeder valve and pressure guages, so you can just turn it on, dial in the pressure you want and leave it. I think it was a great investment. I searched on EBAY for a long while. I kept getting outbid. Who’d have ever thought there was such a market for vacuum pumps? But after a while I knew what the going price for certain pumps was and I got what I wanted for less than half of what a new pump would cost and as far as I can tell the pump was new.
I’d recommend checking EBAY and getting a good pump.
