substitute for $$$ vac bagging equipment?

[raptor22]

I was watching TV the other day and saw a commercial for "space bags"; simply place you clothes in and vacuum out the air to fit more in you closet. Open the ziploc seal and air comes back in again.

Do you think we could just put composites in instead and make cores with them? They seem to be large enough and in they can make a bedspread super tiny they must have enough suction from a home vacuum cleaner.

I was thinking, "thats too easy", but I remembered a similar (smaller) product I saw in the for sale forum and how well it works to use food savers. Why not?

--Alex

[Ollie]

See:
http://www.organize-everything.com/spbagpaset.html
A shop vacuum cleaner would provide enough vacuum to apply wood skins to beaded foam cores but probably not enough to hold 14 mil mylar to cores near the leading edge where the curvature is great. Another possible disadvantage is the cost at about $6 or $7 each bag, depending on how many times a bag can be reused. Thes bags could be used for wing panels up to about 42 to 45 inches. I haven't tried these bags myself but they might be handy in some cases.

I was looking at some small food saver units in WalMart a couple of weeks ago. The first thing that struck me was how the width of the bag would limit the chord of the wing panel that could be bagged with one. The boxes didn't have any specification about how much vacuum they produce.

[davidfee]

I see no reason why it can't work with some experimentation. How well can you regulate pressure with these foodsaver/space bag things? For some applications you want a lot of pressure and other times you don't. Also, how well do those things seal? Even the best vacuum bags leak slowly, which is why we have continuous/cycling pumps. Also, a shop-vac is a whole lot louder than my diaphragm vacuum pump.

[raptor22]

I know its kinda hard to regulate pressure, but I'm hoping it could work. The commercial advertise long term stirage with it, so the leaks can't be that bad.

I don't want to try huge planes; I just would like to experiment with pylon or pocket-sailplane type things for fun (without as much cost), since I have a roll of carbon fiber (3k; 42"X6') that was supposed to be used for a school project that got cancelled.

--Alex

[davidfee]

Alex,
Experiment with glass before you use the carbon, if you don't mind the suggestion. Carbon is stiffer and more difficult to work... not to mention more expensive. ;)

Good luck,
-David

[jonferran]

I covered a small balsa wing with .5oz fiberglass just between some foam and weight. It turned out okay but lots of patchy spots with not enough resin. I would like to try vac bagging next, I was thinking of a commercial product I could use for it and I saw a food saver vacuum system example in a thread. This thing seals the bag using heat and sucks the air out of the other side and seals it when it's done.

I was thinking of a 60" carbon slope racer with a kevlar LE for tough coastal landings. I have been wondering about the fuse though. Could I order a miniblade fuse and add appropriate tubes to my wings to make them removeable or do I have to reinforce it further than that?

Jon

[raptor22]

Alex,
Experiment with glass before you use the carbon, if you don't mind the suggestion. Carbon is stiffer and more difficult to work... not to mention more expensive. ;)

Good luck,
-David

Thats a good idea; I'll do that. Fortunately, I didn't pay for the CF :D .

--Alex

[raptor22]

I covered a small balsa wing with .5oz fiberglass just between some foam and weight. It turned out okay but lots of patchy spots with not enough resin. I would like to try vac bagging next, I was thinking of a commercial product I could use for it and I saw a food saver vacuum system example in a thread. This thing seals the bag using heat and sucks the air out of the other side and seals it when it's done.

I was thinking of a 60" carbon slope racer with a kevlar LE for tough coastal landings. I have been wondering about the fuse though. Could I order a miniblade fuse and add appropriate tubes to my wings to make them removeable or do I have to reinforce it further than that?

Jon

Food savers are still kinda pricey. I've been trying to get my parents to get one ("think of the money youll save on food"), but no go. Oh, well.


--Alex

[jonferran]

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=11703&item=4302769569&rd=1

$35 on ebay including a 33ft roll of bags.

Not that pricey for what you get. You dont have to hassle with a bunch of old refrigerator parts.

Jon

[Randy G]

I currently use a cheap gast medical vacuum pump ($50 from ebay), 3ml plastic from Lowes (clear), newspapers as my breather, and caulk for the sealant. I have bagged a couple of hundred of wings and this system works as good as any!

[raptor22]

So, you just suck the air out and seal it with caulk? Or do you still have itcycling or whatever?

--Alex

[NJSoaring]

Randy: pics pics pics!?!?! Any more detail on the pump wld be nice too. I just did a search on eBay and got over 400 hits and some of those Gast pumps were monsters.

[Mighty Mik]

http://www.roarockit.com/us/rchobby_vid.php?PHPSESSID=86cbf53d4694d60bc0600ffe 328f5770

saw this in the Slope forum...AND they have a $30 hand kit.

[raptor22]

Ooooooo...VERY cool. As cheap as any option presented and looks better, too (reusable, all inclusive, etc). ONLY $30!

--Alex

[Randy G]

I would look for a nice used gast vacuum pump such as this one on ebay.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=26236&item=3816526025&rd=1

Typically they go for about $50 to $100 depending on how new. Here is how I do the bagging with great results:

I buy 3mil plastic from lowes and cut a piece of plastic big enough to give me about 6" all the way around 3 edges of the cores to be bagged. One side I leave twice as big as I fold this over. First I put down newspaper so that the cores will be sitting on top of that. I then put the core beds down on top of the newspaper, place the mylar/cores etc in the core beds, and place two layers of newspapers on top of the beds. Then I take the caulk and seal the 3 sides not inlcluding the larger piece and fold it over making a "bag". I stick in the vacuum hose and crank it on. My gast pump I have a gauge and with the dlg wings shoot for about 25 pounds of pressure. I do not cyclic it but let it run about 8 to 10 hours in the hot box on a timer. The wings turn out great! I will bag some in the next week or two and will post some pics.

[nichanderson]

Check out John Coker's rocket page for tips on how to use it..

http://www.jcrocket.com/kitchenbagging.shtml

I would say just find a cheap, used fridge compressor and modify it for bagging. There are plently of step by steps on how to do it.

Or C&H Surplus in CA has a nice Gast pump for 39.95.

Nick Anderson

[Mighty Mik]

hehehe I know these guys :) Does C&H have a web site...and which pump? and can somebody explain rotory vane vs piston performance? How do i know if an eBay pump is 'good enough'?

I think what i should do is find a small used appartment sized fridge and yank the compressor out of it. I have a tank i can use.

Check out John Coker's rocket page for tips on how to use it..

http://www.jcrocket.com/kitchenbagging.shtml

I would say just find a cheap, used fridge compressor and modify it for bagging. There are plently of step by steps on how to do it.

Or C&H Surplus in CA has a nice Gast pump for 39.95.

Nick Anderson

[nichanderson]

Yep they do.

http://www.aaaim.com/u/web/aaaimc/cgi-local/shop991/shop.pl/SID=2216669090/page=REGS.htm#PC2050

Theres one example of a pretty good pump. 1.5 cfm and 20" hg. Not full vacuum, but good enough for wing cores, etc..

You have little way of telling if a ebay is good enough, look at the specs, and then the price. Make your judgement based on those..

Nick Anderson


hehehe I know these guys :) Does C&H have a web site...and which pump? and can somebody explain rotory vane vs piston performance? How do i know if an eBay pump is 'good enough'?

I think what i should do is find a small used appartment sized fridge and yank the compressor out of it. I have a tank i can use.

[davidfee]

Just a word on vacuum pumps. Rotary vane types can generally provide a lower ultimate pressure than diaphragm (what we normally use) or piston pumps. However, rotary vane and piston pumps require a great deal of maintenance in terms of lubrication and upkeep. They are also quite loud compared to a diaphragm pump and you would not want to work next to one of these for any period of time. None of these pumps (or bagging materials) can get you to "full vacuum." Technically, a complete vacuum is virtually impossible to achieve. Trust me, I work in an ultra-high vacuum research lab. :)

If you need a lot of pressure for your molding procedure, a high-pressure autoclave is what you want. You vent the bag to atmosphere and apply an external pressure of up to many thousand PSI at several hundred degrees. I've not found any need for that quite yet though. ;)

happy bagging,
-David

[rorywquin]

http://www.roarockit.com/us/rchobby_vid.php?PHPSESSID=86cbf53d4694d60bc0600ffe 328f5770

saw this in the Slope forum...AND they have a $30 hand kit.

That white pump and grey plug are what they sell for re-corking wine bottles when you don't drink all the wine - I happen to have one that never gets used (guess why) - could be good for small jobs! You can probably get one from you local liquor outlet for a lot less than $30-00.

[Frounz]

Hi Guys,

I Introduce me : Fred, Belgium, Teacher... 39 on june 5th :p

I began with composites some monthes ago, and have quite poor experience.
A friend and I had bought molds of "old" f5b sailplanes from our ex-champion Stefaan de Hauwere : Zoef 5 and Zoef 6.

I made my own vac-pump on "recup" base : a fridge motor, butane container, depressiometer... It cost me peanuts and the result is really great.

here's pictures.

The switch is made with a vacuum cap (regulation of the carburator of car engine).

It switches the pomp off as the good depression is reached, and on if needed (some leakage in the bag).

This system is perfect as it allows to regulate the depression with great precision (I do it with 300mB depression)...

Hope It helps...
Sorry for my approximative English,
Regards,
Fred

[AirBornOne]

Refer compressors are designed to be cooled by the 'freon'.An open air comp will not cool as well due in part also to the limited oil flow when not used in a freon circulation system.
Used refer compressors contain "Contaminated" oil,oil which has absorbed freon and is required (by law) to be "properly disposed of ".
Used refer oil is also not healthy for breathing which will occur as the compressor heats up and the 'exposed to atmospere' oil vaporizes (with detectable levels of the freon).
My first bag job utilized a hand pump designed for bleeding brakes (UGH!).I could have arm wrestled professionally after that workout! Finally,I figured I could remove the bulk of the air with a vacuum cleaner and Then use the brake bleeder for the final vac. I think I got down to 10" (plastic sheeting and caulk bag setup).
I finally bought the ACP vacuum bag kit which used a 'Gast' vac pump and everything was much easier to accomplish.
A 'Foodsaver' would be my choice for starting bagging on the cheap.
Adjusting the vac level can be a problem,but if you directly switch the sealing element (momentary on/off) you can seal the bag when you choose (install a vac. gage) instead of when the preselected vac level is reached.
Fly on.
Jay.

[soholingo]

Jay,

I appreciate your comments about the hand air pump as that's what I was thinking of using. Once you get all the air out of the bag with the vacum pump, how much hand pumping is required?

I am also seriously considering getting the ACP vacuum setup...

j

[Mighty Mik]

Not all 'foodsavers' are created equal...

note that 'Foodsaver' is a brand, and there are immitators. I have a Deni bag sealer, and i'm wondering if it has enough vacuum. So far i'm underwhelmed, and that's just using it for food.

[AirBornOne]

Jay,
Once you get all the air out of the bag with the vacum pump, how much hand pumping is required?
LOTS!
It will cramp your carpels for sure (maybe not a problem given your moniker :p)
The leak rate of your vac bag setup (caulking,tubing,fittings,pump ...)and your desired level of vac. will determine how much pumping will be required.
Mik,
Not all 'foodsavers' are created equal... note that 'Foodsaver' is a brand, and there are immitators. I have a Deni bag sealer, and i'm wondering if it has enough vacuum. So far i'm underwhelmed, and that's just using it for food.
A gage will be worth it's weight in gold. They can be pricey for 0-30" with 1" resolution though.
These 'inexpensive' vac systems typically have a 'psi switch' which is adjusted to turn on the sealing element at a certain point.Once the bag is sealed with the pump still running,the vac level increases and then triggers the pump to shut off.
It is not uncommon for the adj. to change (typically from a good bump) and can be re-adj. if one were adventurous enough to Unplug the unit and open it up.
Have fun.
Jay.

[Mighty Mik]

This unit is pretty primitive. Press the right side to vacuum, left to seal. It doesn't seem to go down far enough to conform to the food very well. I will examine it at some point, and maybe it can be hacked to work better.




Mik,

A gage will be worth it's weight in gold. They can be pricey for 0-30" with 1" resolution though.
These 'inexpensive' vac systems typically have a 'psi switch' which is adjusted to turn on the sealing element at a certain point.Once the bag is sealed with the pump still running,the vac level increases and then triggers the pump to shut off.
It is not uncommon for the adj. to change (typically from a good bump) and can be re-adj. if one were adventurous enough to Unplug the unit and open it up.
Have fun.
Jay.

[Ragged]

I do have a vacuum bag system at our site at www.roarockit.com. Look in the RC/Hobbyist area. We have two systems. The etap is great for small projects as it comes with everything you need to get started. Electric Pump, check valve, Butyl tape and vinyl hose. This industrial pump can be run continuous and pulls between 25 to 27 hg.
Our hand pump system works great. I have taught kids deckmaking for 3 years now using both the hand pump and a large industrial pump. The hand pump pulls as much hg as the large one. Check out the video in the RC area to see what can be done.

Ted

[Mighty Mik]

That video still doesn't work, not even in Realplayer.:eek: Re-encoding into quicktime would be nice.

[soholingo]

yep that video is broken...

j

[Ragged]

Thanks for letting me know about the problem. I will figure out and let you know when it is up
Ted

[Ragged]

Video is up and running. It was fire wall issue...You will have to clear your cash probably to view it.
The video is of me building a cool sculpture using our hand vacuum pump. It worked great on all of the 8 components of the piece. That pump will pull 25 hg and as long as you have a good bag seal the air will not leak back in. The vacuum is so strong the veneer once bent holds it shape until the glue dries.

Ted
www.roarockit.com

[davidfee]

I just want to say that I've never been a skater... but I checked out your website and that is just about the coolest thing I've ever seen. I think it is brilliant what you have done with ordinary materials and made it possible for a newbie to make their own molded skate deck. That's really great. :)

-David

[soholingo]

firewall must be messing up again... I can't see the video... can you put on an ftp site?

[Mighty Mik]

Ya... now, about laying up a wing... just what size object can go into that bag anyway? :D

[Mighty Mik]

It plays on both PC and Mac here, but you may need a little faster box for it...maybe 500MHz+. Clear your cache and try it again. It's not bad.

firewall must be messing up again... I can't see the video... can you put on an ftp site?

[davidfee]

The videos all seem to work fine for me. Maybe I'm lucky?

[Ragged]

David
Thanks for the compliment. My wife Norah and I have worked hard on this and even though the kids end up with a real deck we see all this as a teaching project to get kids to use their hands building things. I teach at an art college in Toronto for 4 months a year and have found a notable decrease in new students being able to interpret 3D thoughts into something real. I think RC building is great for this as it has all of the things needed to get kids excited about building things and learning this process.
We are just beginning to see schools, community centers and camps buying kits to teach deckmaking. This is exciting for us.
I will work on a way to send our video by FTP.

Ted
www.roarockit.com

[davidfee]

I know what you mean about "kids these days." I'm very greatful my Dad got me started building planes when I was about 5 years old. It's hard to believe but, that was almost 25 years ago!

Keep up the good work!!

-David

[soholingo]

Ted,

How long does it take to pump all the air out of the bag? Thanks...

Jay

[Ragged]

Jay

The vacuum bag we us is about 14 x 48. With the Etap unit it takes about 1 minute. The hand pump is about 1.5. Both are less if you have spent time pushing most of the air from the bag before sealing the end.

Ted