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Author Topic: Vacuum Bagging  (Read 1469 times))

Offline Nvreloader

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Re: Vacuum Bagging
« Reply #20 on: December 17, 2020, 08:24:29 PM »
Tom
What about a Food Saver Vacuum machine, you can make the bags as long as you want,
and there 2-3 different widths etc....... ;)

I had a friend that used to use one of these machines and dyed his thin laminates for gun stock coloring.

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Offline YEMX

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Re: Vacuum Bagging
« Reply #21 on: December 17, 2020, 10:35:33 PM »
Tom
What about a Food Saver Vacuum machine, you can make the bags as long as you want,
and there 2-3 different widths etc....... ;)

I had a friend that used to use one of these machines and dyed his thin laminates for gun stock coloring.

HTH's
Don

It's worth looking into for sure- though, I don't think they're flexible enough for my purpose.  At least not for gun stocks...

My un-scientific opinion on foam is that  the lowest grade of white EPS foam distorts at 13 HG. Pink Foamular 250 and the slightly stronger Dow blue sold in super hardware stores start to deform at 23 and 24 HG. Dow hi-load 40 takes full vacuum with a little care at the edges. Hi-load 60 and Plaza Mate easily take full vacuum, even with sharp edges.

After doing a google search, I'm not sure there's a local source for the Dupont highload foams...  I'll keep checking though.  I wouldn't ever use regular styrofoam.  The lowest grade foam I'd ever even consider using is the pink or blue XPS foams.

If I can't get a denser foam locally, I may have to buy pourable urethane expanding foam to make my own blanks...  Full vacuum is 14 psi compressive pressure?  So all I'd have to do is find something that's well above 14 psi...  Right?  Or is there more to it? 

This idea is getting more complicated by the day!  ;D
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Offline Spektr02

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Re: Vacuum Bagging
« Reply #22 on: February 14, 2021, 01:09:46 AM »
Sorry Im late to the discussion.  As a Tool Engineer at Boeing, we used silicone Vac Bags for reusability. 
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Offline YEMX

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Re: Vacuum Bagging
« Reply #23 on: February 14, 2021, 04:36:41 AM »
Sorry Im late to the discussion.  As a Tool Engineer at Boeing, we used silicone Vac Bags for reusability.

Now there's a thought!  I hadn't come across silicone vac bags in my research.  I'll have to take another gander on the web!
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Offline Madd Hatter

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Re: Vacuum Bagging
« Reply #24 on: February 14, 2021, 11:28:52 AM »
Silicone bagging wouldn't work for what you are doing IMHO. Silicone bag is for reusability for the same part and also for use in a autoclave which uses heat and pressure. At least that's what we did for the Nasa stitched wing program.
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Offline YEMX

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Re: Vacuum Bagging
« Reply #25 on: February 14, 2021, 11:38:45 AM »
Is the silicone bag molded into the general shape of the piece that's being vacuum bagged?  Or is it a thin flexible skin, similar to the disposable bagging materials?  I just figured that a thin silicone membrane would be cheaper in the long run, since I'm not throwing it out after every use... 
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Offline luge007

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Re: Vacuum Bagging
« Reply #26 on: December 19, 2021, 05:52:55 PM »
SO, where (10 months later) did this project end up??  Inquiring minds want to know. ;)



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Offline YEMX

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Re: Vacuum Bagging
« Reply #27 on: December 20, 2021, 01:44:50 AM »
SO, where (10 months later) did this project end up??  Inquiring minds want to know. ;)

I've got the vacuum pump, but I haven't figured out what foam I want to use, or if I should cast my own blocks, or really how to proceed with the foam core.  I know I want something far more dense than the pink (or blue) insulation foam.  Also, I haven't decided on what kind of fiberglass to use either.  I'm not sure I want to step up to CF, as it's really expensive.  I'm also not sure if I want to do a wet lay up then vacuum bag it, or do a resin infusion...  I have no experience in either.  I haven't given up on the idea, I just don't know how to proceed.  Also, I've got a new compressor, and I've FINALY got a tethering reg for my Great White tank, so I can FINALLY do looooong tuning strings.  Plus, silly adulting has gotten in the way too.  LOL 

Basically, I put the cart before the horse, and I don't want to waste a lot of money for an experiment!  LOL  But I WILL get back to this idea someday!
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Offline HunterWhite

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Re: Vacuum Bagging
« Reply #28 on: December 22, 2021, 02:56:12 PM »
The guys that made RC airplanes used blue foam, or pink foam from Lowes or Home depot for cheap experiments. The favorite for high-tech was Dupont Styrofoam™ Brand Highload 40 or 60  Extruded Polystyrene about 20 years ago, now they also have 100 psi foam on their website.

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Offline Firewalker

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Re: Vacuum Bagging
« Reply #29 on: December 22, 2021, 04:51:52 PM »
I'm one of those glider guys, we made pink and blue cores with either carbon fiber or glass,  depending on your specs. The Goldberg Gentle Lady style (1 meter) sail plane (powered) was our big seller.

I used 6mil roll plastic and spring clips for bags and it went in the trash after peeled it off. Flash was trimmed off and sanded smooth ready for next coat.

Volcanic rocks were used for excess epoxy take up (messy but they do work, just throw a layer of paper towel over them or they will poke through the plastic) and an inline pot was used for a safety for the pump.

Ice maker line for pull down was sacrificial and cheap!

Wing sets are easy, I bet a stock would be a bit harder.
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Offline MJP

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Re: Vacuum Bagging
« Reply #30 on: January 04, 2022, 04:58:06 AM »
For the foam, any will do. Just what you can get cheap. The foam it self wont do much, its just support for the fiber. After hardening you can melt the foam away with thinner and the part is just about as rigid as with it.

I use tubular 600mm VACtite vacuum bags for long projects and sheet for bigger. Usually you'll get three to four uses from one bag, after that there starting to be too many holes in it no matter how gently you handle it.

I wet the fibers on top of piece of bagging material then put another piece of baging on it.
Use a rubber squeezy to get all the air and excess resin from the laminate and put it in the mold. Lay everything you need and peel ply on top, the perforated releasing film on it,  then you breather material that will capture any excess resin. Seal the bad and pull vacuume. Dont go much below 300-350mBar or you'll risk collapsing the foam core. I tested around 100mBar and you'll get too dry laminate.
Hope this helps

Marko
« Last Edit: January 04, 2022, 05:02:12 AM by MJP »
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Offline MJP

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Re: Vacuum Bagging
« Reply #31 on: January 04, 2022, 04:59:50 AM »
Oh yeah, the fiber and epoxy amount must be weighed so you dont mess up the bag.
And be sure your breather material can absorb the excess.
If using the squeezy method you'll most likely be fine and dont have too much resin.

Marko
« Last Edit: January 04, 2022, 05:06:06 AM by MJP »
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