vacuum veneering ,bag seal


I have just got a new large vacuum veneering bag. I am using an old frig compressor as a pump . this compressor will pull 25" of vacuum easily .
the problem is sealing the bag . I have tried the two boards with sealing tape , the pvc pipe method a la taunton veering book and the two boards with a 1/2"dowel glued insert .....all top no avail .the pump will not pull any vacuum at all because I cammot get a decent seal .
Any suggestions appreciated.......mjh
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I have just got a new large vacuum veneering bag. I am using an old frig compressor as a pump . this compressor will pull 25" of vacuum easily .
the problem is sealing the bag . I have tried the two boards with sealing tape , the pvc pipe method a la taunton veering book and the two boards with a 1/2"dowel glued insert .....all top no avail .the pump will not pull any vacuum at all because I cammot get a decent seal .
Any suggestions appreciated.......mjh
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mike hide (in laKdnQEZYca4f97enZ2dnUVZ snipped-for-privacy@comcast.com) said:
| I have just got a new large vacuum veneering bag. I am using an old | frig compressor as a pump . this compressor will pull 25" of vacuum | easily . | | the problem is sealing the bag . I have tried the two boards with | sealing tape , the pvc pipe method a la taunton veering book and | the two boards with a 1/2"dowel glued insert .....all top no avail | .the pump will not pull any vacuum at all because I cammot get a | decent seal .
Mike...
I've worked with vacuum clamping and not with veneer pressing; but would like to suggest laying out a strip of _closed_-cell weatherstripping (1" wide, any thickness) and folding it lengthwise over the end of the bag you want to seal (no wrinkles allowed!). Leave a quarter-inch or so between the end of the bag and the fold and trim the foam so it protrudess about a half-inch beyond the already sealed sides of the bag.
Then clamp a pair of 1" small boards over the entire length of the foam to maintain the closure.
The weatherstripping should seal well to the plastic, and _really_ well to itself. It's inexpensive and readily available. Make sure that what you use is closed-cell.
The weatherstripping should do the job. It's what I use to provide the seal on my vacuum pucks with good result. When you're done, remove the boards and the weatherstripping is easily removed.
HTH
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/solar.html
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Go to veneersupplies.com/joewoodworker.com for some good advice on vacuum bags and veneering. For my vac bag, I use a piece of scrap about 1 x 3. Rip in half. Into one edge of each piece, cut a V notch down the length. Glue a dowel into one side's v-notch. Index the 2 pieces back together with a dowel that goes vertically through one end into the other piece. The rounded dowel places pretty consistent pressure across the bag opening. I fold the opening over once or twice, then clamp the 2 pieces of wood around the folds. Seals perfectly every time.
My 2 cents
Gary in KC

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As my setup was as Gary suggested with the exception of doubling the bag over , I tried that and doubling the bag over seems to do the trick ......thamks again.....mjh
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The problem is likely that your pump, while capable of plenty of pressure, does not move enough volume. It's like trying to seat a tire bead with a hand pump.
Anyway, I would try taping the bag opening with a strip of plastic packaging tape, then using your other clamping method. -- ******** Bill Pounds http://www.billpounds.com
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day or so . At this point I will be happy to try anything after a week or so of frustration.
I have been working with Joe woodworker,who has been very helpful, and Yes it may be the pump has the pressure capability but not enough volume capacity to overcom,e the initial leakage .I think once the pump starts pulling a vacuum it automatically pulls the plastic sheets together and essentially forms it's own seal..
I will report on progress later .In the meantime thanks for the suggestions .....mjh
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