So I’ve been fuzzing over this vacuum bagging idea. I might want to do a foam sandwich or a veneer over EPS. I don’t want to have to set up a whole compressor deal to pull vacuum. I have a friend who owns a company that makes these:
Its a home-shop brake bleeder. It can be converted to pull vacuum, to drain differentials, etc. The reservoir isn’t all that big.
My questions:
How much vacuum pressure do you need to pull?
Does anyone make their own close-tolerance bags out of thin film and one of those heat welders they sell to package home-made freeze-dried food?
I assume, the more air you can get out before closing up, the less you have to pull, but what’s realistic to expect in terms of residual air volume? Any ideas?
How do you spread the resin on both sides before putting the board & glass in the bag? Or is it one side at a time, like a normal lam?
I am getting ready to set up a bag too, this would be a very cheap alternative for sure.I have a compressor and have been checking bagging/composite sites on the net to get the odds and ends that I need. I believe(someone correct me if wrong…) that all you need is around 7-8" hg pull to bag a board nicely. I have a question to add to yours -what if you brushed a THIN layer of resin over the EPS to seal it and then bagged the laminate? Strong and light for sure,but not as strong as putting a veneer and then glass to form a composite…correct??? My other question was the same as yours…both sides at once …or in steps? Thanks in advance…
depending on the quality of your bag … anywhere between 2 and 20 cubic meters an hour , depending on your resin anywhere between 10 and 24 hours …2 hours at the least , with a full vacbake setup …
for the 10 hours your standing there pumping that thing … you could make enough money to buy a cheap vacumn pump …
can you pull vacumn by hand , yes …
can you pull enough to stick a veneer down ??? you do the maths …
So its practically impossible to pull the vacuum, seal it, and let it sit to do its thing? Its not only a continuous vacuum state, but a continuously increasing process as well?
No, it is because it is actually impossible to get a perfect seal…there is ALWAYS a small leak(even a “perfect” bag has holes…microscopic…)…and to keep the correct vacuum you need a gauge and a pump which has a vacuum check and cycles on when needed…
depending on the quality of your bag … anywhere between 2 and 20 cubic meters an hour , depending on your resin anywhere between 10 and 24 hours …2 hours at the least , with a full vacbake setup …
for the 10 hours your standing there pumping that thing … you could make enough money to buy a cheap vacumn pump …
can you pull vacumn by hand , yes …
can you pull enough to stick a veneer down ??? you do the maths …
regards
BERT
Haha I had a vidid image of someone standing there pumping away for 10 hours good points Burt. -Carl
There’s a small paragraph on this site about using water to create vacuum. Seems like a simple alternative for the DIY’er, although I’m not sure how you’d measure vacuum pressure.
Get an old fridge compresser from the dump,free then get a negitive psi gauge from any hydrolics shop nz$15 then get a small valve and hardware shop etc nz$6 Add some tube NZ$15
There you now have a vacuume system that will run all night, pull down to at least -95psi (between -80 and -100 is considared a good vacuume) and only make as much noise as a normal fridge also it will only use the same power as the standard fridge .Total cost nz$36
I’m gunna say no. For bagging of an EPS board and composite skin I’d recommend a oil-less Gast or something similar, most of these pump obtain about 24-27"Hg. You can do a search on eBay and probably get one real cheap. You don’t need an oil rotary vane pump that pulls deep vacuum for what we’d be doing. One of those things that pulls vacuum off your compressor would work too. You can initially pull the air out of the bag with your vacuum cleaner then apply the constant vacuum from the pump. You’ll need a relief valve inline before the bag so that you don’t pull too much vacuum. Once you have the vacuum you need your cfm of the pump does not matter, because any vacuum pump can keep the vacuum once it is obtained considering you don’t spring a leak. You will need a vacuum gauge on a Vacuum connection at the bag to determine the vacuum in the bag. Best deal on vacuum connection is $15 from bondlineproducts.com. but there are other ways to seal a vacuum connection at the bag. You’ll need a sealant tape, bleeder material, and a barbed t fitting for cheaper.
I too have searched for a ‘cheap’ way to vacuum bag a board. I found and article in the archives about a guy that used a automotive hand vacuum pump, I got one and tested it on small carbon fiber bike water bottle cages. It worked pretty good so next step was to try it on a 9’ board.
I pumped and pumped and pumped! Then franticly modified the shop vac hose to fit the bag… IT WORKED! I left the shop vac on for 1 1/2 hours (over 2 hours from start of lam).
I did one side at a time. This was my third board, but first bagging. I have another that I’m shaping now (first with EPS) and will bag it also. I like the way bagging positivly adheres the lam and leaves a fairly smooth surface preped and ready to hot coat.
In the past (10-15 years ago) I made a compressor to spray paint my house with an auto air conditioner unit. It had two openings, one pressure and the other vacuum. If I still had it I’d try changing the hose to the vacuum…?!
Les
Attached is a pic of board number 3 hooked up to the vacuum. I too have searched for a ‘cheap’ way to vacuum bag a board. I found and article in the archives about a guy that used a automotive hand vacuum pump, I got one and tested it on small carbon fiber bike water bottle cages. It worked pretty good so next step was to try it on a 9’ board.
I pumped and pumped and pumped! Then franticly modified the shop vac hose to fit the bag… IT WORKED! I left the shop vac on for 1 1/2 hours (over 2 hours from start of lam).
I did one side at a time. This was my third board, but first bagging. I have another that I’m shaping now (first with EPS) and will bag it also. I like the way bagging positivly adheres the lam and leaves a fairly smooth surface preped and ready to hot coat.
In the past (10-15 years ago) I made a compressor to spray paint my house with an auto air conditioner unit. It had two openings, one pressure and the other vacuum. If I still had it I’d try changing the hose to the vacuum…?!
I made a compressor to spray paint my house with an auto air conditioner unit. It had two openings, one pressure and the other vacuum. If I still had it I’d try changing the hose to the vacuum…?!
Les
Lots of guys making home-made kiteboards are using refrigerator or air conditioner compressors as vacuum pumps. Sounds like it works good most of the time, some guys spray a little wd40 into the intake to keep the pump lubercated since the freon (or substitute) is missing. Also sounds like the older the compressor is, the better the chances that it will last a long time when subjected to this kind of abuse.
I haven’t tried it myself, I picked up a nice Gast diaphram pump off of e-bay for about $40. I use an automotive vacuum guage to measure pressure and a 40 cent brass aquarium valve to regulate.
This past summer, I thought about using a kite pump, some mastic tape, 5min. epoxy and a grabage bag to field repair a guy’s delaminated kiteboard at the beach. The standard kite pumps let you switch to suction so you can get all the air out of the kite to pack it up nicely. I chickened out - it was a little warm out and I didn’t think get everything in to the bag and sealed in time, so I ended up just using one of the fins as a clamp and holding the rest back together with a bunch of masking tape. Maybe if I would have had some “1 hour” epoxy?
Get a fridge compressor and some plastic tubing, I have been using the same fridge compressor for the last 6 years I just top it up with car oil every 5 or 6 boards. It’s cheap quiet and it works I let it run for 8 to 10 hours at a time.
If you guys are saying that it takes minimal suction pressure to do the bagging thing, and if you over pressure it could crush the foam. It sounds like a modified aquarium pump would work pretty well? I’m guessing it would pull at about 3 lbs? wouldn’t that be enough to laminate all the stuff together? Now I’m not talking about a production shop set up, but for the guy that wants to do a board or two per year.
I tried a large aquarium pump and it did not work well at all. It was also very noisy. The valves in there are designed for pressure and dont work right when subjected to vacuum at the air intake. The air pump from the pet store I think cost more than the used vacuum pump I bought on e-bay.
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If you guys are saying that it takes minimal suction pressure to do the bagging thing, and if you over pressure it could crush the foam. It sounds like a modified aquarium pump would work pretty well? I’m guessing it would pull at about 3 lbs? wouldn’t that be enough to laminate all the stuff together? Now I’m not talking about a production shop set up, but for the guy that wants to do a board or two per year.
I save everything. I took apart an old washing machine last year and still have the motor connected to the purge pump. It’s designed to run the pump the whole time the machine was in spin mode - the same motor also has the pulley that drove the belt to the tub - so I’m assuming that running dry won’t cavitate the pump. It’s got easy plastic inlet/outlet ports - a 1" rubber hose with a hoseclamp sealed well enough for water.
I was thinking that at the far end (away from the vacuum hose) a bicycle inner-tube valve would be a good pressure check valve. I would hot-glue it through a hole in my bag and it could allow air to seep in if I got into an over- vacuum situation. I have plenty of ‘donor’ tubes, every time I split one open I keep it for clamping & tying things.
I normally use a system very much similar to many of the previous persons who have responded:
Three old cast iron, rotary refrigerator compressors driven by an electric motor as the vacuum pump, a valve built into each compressor (that was probably used to charge the system with freon) as a bleed valve to set the vacuum (although it occasionally requires a minor readjustment on something like hourly intervals), and an automotive vacuum guage to measure the degree of vacuum. Shop vac to remove most of the air; refrig vac pump for final bagging.
However, I just used what I think is the cheapest set-up possible for the largest vacuum bagging project that I have done: a pair of 18’ Unicorn catamaran hulls (single handed version of a Tornado catamaran) over an uncompleted wooden hull used as the plug. The formed hull had a layer of 6 oz glass on each side, with a core of Clark 3/8" thick sheet foam. A shop vac was used to pull the vacuum and PE sheet for the bag. No vac guage, and the vacuum hose end just taped to the bag (lots of volume flux for any minor leaks). The shop vac worked great at conforming the foam over the plug (and survived the four baggings, each lasting many hours). Only major drawback: the screaming noise, which lasted for just as many hours. The most critical/challenging element was applying the resin, positioning and securing the foam in place, inserting the whole thing into the bag (thanks for the help mom!), and getting it all sealed up and the vacuum stabilized before the resin started to go off (MEK catalyzed polyester).
