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 Post subject: Sealing the vacuum bag
PostPosted: Mon Nov 28, 2011 9:20 pm 
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Joined: Thu Aug 04, 2011 4:21 pm
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Location: Ottawa, Canada
Just getting to the vacuum bagging process. I have a pump but not a good connector for the bag.

Any suggestions?

How do you determine if you have a good seal?

How do you decide what vacuum pressure to use?

Are there any videos around on the process?


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 Post subject: Re: Sealing the vacuum bag
PostPosted: Thu Dec 01, 2011 12:11 am 
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Joined: Tue Jan 02, 2007 11:50 pm
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Location: Ottawa, Canada
Are you bagging onto a rocker table with a "half bag" or putting the whole thing into a bag? You don't need a lot of vacuum to pull the board onto the table, but you need more if your goal is to move a lot of resin and squeeze it really hard, which is not always necessary. On a softer core surfboard you could crush the board if you're not careful, but on a twin tip with hard foam a wide range of pressures are OK.

You'll know if you have a good seal just by the way it squeezes, and also if you have a gauge (not necessary though). I use thick sealant tape, similar to what is used to seal around windows. I also don't have a special connector, I just put the tube through where the plastic seals to the table, with lots of sealant wrapped around it and squeezed to fit. Make sure the bag does not seal off the end of the tube though, you have to put it in with something porous that will breath.

If you have leaks, you can hear them if your vacuum is quiet enough. Otherwise, just keep squeezing and working the seal and watchfor the gauge to rdop lower or for the wrinkles to get tighter.

Peter


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 Post subject: Re: Sealing the vacuum bag
PostPosted: Thu Dec 01, 2011 2:19 am 
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Joined: Thu Aug 04, 2011 4:21 pm
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Location: Ottawa, Canada
Hi Pete,

Thanks for the reply.
I am bagging over a jig with the board on top. It's probably 2.5 +-" thick.

The core for this one is cedar.

This tape you refer to, where do you get it?

Is it 2 sided such as this:
http://www.canadiantire.ca/AST/browse/3 ... ?locale=en

Or is it removable ?

Cheers
Al


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 Post subject: Re: Sealing the vacuum bag
PostPosted: Thu Dec 01, 2011 7:07 pm 
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ONE of the benefits for hooking up your vacuum pump
inline with an old 22gal air compressor tank or equivalent, is
that even a Small pump can now supply the appropriate amount
of CF/M to get the bag sealed !
After-which the pump will now only run for 5min each hour with a
properly sealed bag.

Finding Leaks :
Take a (1 M ) section of hose, (any diameter) even a garden hose will work ;
place on your ear and run the other end around the sealant -tape.
You'll hear a leak right away.

Bille


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 Post subject: Re: Sealing the vacuum bag
PostPosted: Thu Dec 01, 2011 7:14 pm 
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Joined: Thu Aug 04, 2011 4:21 pm
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Location: Ottawa, Canada
Bille wrote:
ONE of the benefits for hooking up your vacuum pump
inline with an old 22gal air compressor tank or equivalent, is
that even a Small pump can now supply the appropriate amount
of CF/M to get the bag sealed !
After-which the pump will now only run for 5min each hour with a
properly sealed bag.

Finding Leaks :
Take a (1 M ) section of hose, (any diameter) even a garden hose will work ;
place on your ear and run the other end around the sealant -tape.
You'll hear a leak right away.

Bille

Excellent idea. I can do one better now that you mention it. I have one of those things that Doctors put up to their ears and them listen to your chest when you breath deeply to listen for unusual sounds. (Stethoscope)

You can buy them in Automotive parts places for listening to a device for weird noises. I forgot I had it.


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 Post subject: Re: Sealing the vacuum bag
PostPosted: Thu Dec 01, 2011 11:53 pm 
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Joined: Tue Jan 02, 2007 11:50 pm
Posts: 262
Location: Ottawa, Canada
Oh.... hi Al, fancy meeting you here! The tape I use is a bit like putty, about 2 mm thick on a roll, separated by paper. Whan you use it coul stratch it out longer and thinner. Mime came from one of the fibreglass shops in Toronto, sold as a vacuum bagging supply, but I think they do exist in hardware stores for other purposes, but have not looked for them locally.

Peter


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 Post subject: Re: Sealing the vacuum bag
PostPosted: Fri Dec 02, 2011 2:29 am 
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Joined: Thu Aug 04, 2011 4:21 pm
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Location: Ottawa, Canada
Hi Pete,
I was in Toronto when I got my supplies but neglected to get the tape.

I may try another solution. The putty-like tubes (heavy grey coloured strings) that used to be common for sealing windows. If no joy I will contact Composites C.

Thanks Pete
Al


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