Vacuum bagging tips?
 

I am going to be doing some vacuum bagging, but am running on a very tight budget. So, I was wondering if anyone has any suggestions on materials to use for bleeders, breathers, bags, etc. Also, where can I get an inexpensive vacuum pump? Also, do you have any vacuum bagging tips? Thanks

RE: Vacuum bagging tips?
 

Also, how much vacuum should I pull if I will be using a soft foam core?

RE: Vacuum bagging tips?
 

check this out:

www.acp-composites.com/acp-vbs.htm

This is the system I have and it works great for the white foam.

Jack

RE: Vacuum bagging tips?
 

Check out the link that follows for a video from Jim Young. http://www.rcgroups.com/links/index.php?id=4901 Jim uses a foodsaver system and gets awesome results. I know Jim and his work, and can attest to the craftsmanship and strength achieved through his methods.

RE: Vacuum bagging tips?
 

If you are really on a tight budget and not sure if bagging is for you spend 30.00 and buy the large space saver bags. You can bag your wings and even bag small layups using these and your vacuum cleaner I have all the bagging equipment and if I am in a pinch and don't want to set it up I have used these.

RE: Vacuum bagging tips?
 

A little investment in [link=http://www.paonline.com/hayman/video.htm]THIS[/link] can save you A LOT of money down the road.

Bill

RE: Vacuum bagging tips?
 

I thought about the food saver, but the things we want to vacuum bag are too big for it.

RE: Vacuum bagging tips?
 

Hi Hatty,
I do the composite wing by use normal a plastic bag,for the breather I 've use a polyester cloth and the peel ply I 've use the nylon cloth which is using to make a wind breakeror umbeller, the hold system is just only 15 USD for 40" X60 " inch.

RE: Vacuum bagging tips?
 

hayman

I sent you a PM

RE: Vacuum bagging tips?
 

Dear Sir,
I didn't mean degrade to someone. I'm willing to help them how I do the vaccum bag which using the instead of material. However the material that I bought is not expensive in my country. Please apologize for making you misunderstood.
Best regards,
Tommy

RE: Vacuum bagging tips?
 

Thanks Tommy. I will keep your suggestions in mind. They were what I was looking for.

RE: Vacuum bagging tips?
 

:) Ive got a question for you guys........ i was looking at a air brush compresor that i used to have, and noticed that can control how much air gets in the tank, the question is if i can insted of getting the air from the usual place conect a hose to get the presur to vacumme the wing bags..... that migth get thing going????

thanks for the tip!!!

RE: Vacuum bagging tips?
 

Dear Hatty,
Re the vaccum pump,I made it by used aircompressure from the car ,power with 1/3 Hp elect motor, and the reserve tank. it's running about 1000 rpm. It's work super ! Even as big vaccum bag 80X100 inch.
best regards,
Tommy

RE: Vacuum bagging tips?
 

Hatty,

I think i'm using the cheaper solution: I took the engine (the freon compressor) from an old fridge; you can became it free in any dumping or in a scarpmetal dealer. You cut the three copper tubes, unjoin it from the fridge and you bring your vacuum pump at home.

At this point you must join the air intake tube to a plastic Y connection; in one Y side you join the vacuum bag, in the second Y side you join the vacuum regulation (for the regulation i use an old SuperTigre carburator)

Total COST= 0 US$$$

If you want any instrument to read the pressure, you can buy it for less than 20 US$, and join it with another Y connection to the intake line.

For the bag i use normal nylon with mastic.

Best regards

depo

RE: Vacuum bagging tips?
 

Well, I have tried emailing ACP a couple times and have not gotten a response from them. Their pump is exactly what I want, but since they seem to be *******s and not care about their customers, I guess I cannot get it. Is there any other company that sells an identical pump? Thank you.

RE: Vacuum bagging tips?
 

How about calling them? It's something many of us used to do before we bacame enslaved to computers. Their number from their website is (800)811-2009. I found them to be extremely helpful via email or phone, but to me nothing beats the personal touch that is completely lost with email.

RE: Vacuum bagging tips?
 

Hatty,

I have dealt with Aerospace Composite Products (ACP) for years and haven't had a bad experience with them, but that's another topic. George Spar, owner of ACP is very knowledgeable when it comes to vacuum bagging and composite materials.
Building a vacuum bagger requires several components.
There are many different levels of vacuum bagging, such as a food storage unit, which I have never seen the results of so I cannot accurately comment on it and the results from one. However, the food storage units that I have seen operate on food, do not posses the same characteristics as a self-regulating vacuum bagging machine. The food storage unit pulls some degree of vacuum, which you don't have, a pressure gauge to measure the amount of vacuum that is being pulled, and it stops and seals the bag. So you don't know if the vacuum is maintained or if it has depleted.
And what is the purpose of vacuum bagging? To apply a regulated uniform amount of pressure over a surface.
If you want to vacuum bag large wings, then you will need something more than ACPs pump that runs continuously.
You will need a pump. A pump from a refrigerator will work and it will pull up to nearly 30 inches of mercury. Keep in mind that simply cutting the lines to a refrigerator or freezer without capturing the refrigerant could result in a $25,000.00 fine. And the person that reports you gets $5,000.00 of that. So, look for a refrigerator repair place. I got one for 20 dollars from a place like that.
You will also need a gauge. If you pull too much vacuum, you will crush the foam. White foam can only handle something like 6 inches of mercury or about 3lbs per sq inch. Blue foam varies in density and Dow can help you with that. Denser foams also weigh more.
A vacuum switch to shut the pump off when the desired pressure is reached and back on when it drops too low is also required. Something the food storage unit won't do. With regards to vacuum switches, they have what is called dead band. The dead band is the amount of pressure that is lost before the pump comes back on. I don't know what ACPs dead band is but it's in many systems and all of those people are getting good results. Mine has a one-inch dead band, which means it drops one inch before coming back on. Sorry, just bragging there. It also cost someone 140 dollars. They also come with variable dead bands.
You will and should have some sort of reservoir. The reservoir is between the pump and bag. It holds a vacuum and the larger the reservoir, the less frequently your pump will cycle. I used 3 or 4 inch PVC thick wall drain pipe with end caps that I tapped first for nipples and the pressure gauge before gluing them in place.
You will also need a check valve to prevent air from entering the reservoir after the pump has shut off.
Some hose. A connector for the bag. A few nipples.

Good luck,
Mike

RE: Vacuum bagging tips?
 

Norwegian modeller Ola Fremming has a description on how to use a refrigerator compressor here:
http://home.online.no/~ofremmi/HowTo.../VacuumBag.htm

I have a similar system, and it works very well.

Magne

RE: Vacuum bagging tips?
 

funky...

Check out the link that follows for a video from Jim Young. http://www.rcgroups.com/links/index.php?id=4901 Jim uses a foodsaver system and gets awesome results. I know Jim and his work, and can attest to the craftsmanship and strength achieved through his methods.

I have the ACP EZ-Vac system (the smaller one that is offered) and it has worked very well for me with my wing sections (3) each about 3' long and a chord of about 18".

RE: Vacuum bagging tips?
 

Newc,

Thanks for the link. I have seen the video before. Although, like I said, I have never seen one in operation on a wing nor the results from using a food saver type machine for vacuum bagging wings in person. So I cannot attest to end result of a food saver wing. It is the principal that I am questioning.
I was wondering though, how much vacuum does one of those machines pull, can you regulate it, and what do you do if a leak develops overnight or when the wing is unattended?
I do not doubt that someone can get, as you put it "awesome results". However, it seems to me that it is a one shot deal using the food saver method. If something goes wrong when pulling the vacuum, like the foam shifting and becoming miss-aligned with the skin as sometimes does happen, then you need to make a new bag and start over.
With the system that I have, if things shift around, I can clamp the vacuum line and reset them before the unit has stabilized at the pre-set amount of vacuum. If it still isn't right when the level of vacuum has been achieved, I can open the bag, reset everything and draw another vacuum. With the vacuum switch in the system, if a leak develops, the pump will turn back on and maintain the vacuum.
It is my opinion that the food saver does not have as many applications compared to the vacuum system I described above. I am not trying to bash the food saver method, I only trying to convey my experience with regards to the subject.

To get back to the topic of this thread, Hatty emailed me and asked a follow up question regarding the pump that runs continuously. I looked at ACP's website and noticed that the new model is set at 10 inches of mercury. It has been my understanding that pulling more than 6 inches would result in crushing the foam. As I have not tested beyond this setting to identify a measurable crushing point on "known" white foam, I can only go by what I have read and experienced. As I said, I thought 6 inches of mercury was the limit for white foam. I have built many white foam wing cores and pulled up to 6 inches without any crushing effects. I know I have read some threads that claim higher settings for white foam, however I can't recall what those values were. With regards to known and unknown white foam, last summer I went to repair a white foam wing. I believe it was a Great Planes Viper ARF. I do not know what type of foam they use on that thing, it was white, and it did get crushed at 6 inches of mercury. So, apparently not all foam is the same.
So, will the pump that pulls 10 inches of mercury be too much for white foam wings? It seems like it would. However, I would certainly contact the people at ACP and get some feedback from them.
Is it worth the money to assemble the parts to make your own vacuum bagging system? Ultimately it depends on the application and your needs.
In my opinion, a vacuum bagging system has the widest range of applications (i.e. fiberglass fuse, glassed wings, giant scale wings, composite spars, complex shapes). I also think it is worth the money and effort if you plan on or want to try some composite construction or making your own fuselages or whatever. Why stop at wings?

RE: Vacuum bagging tips?
 

Couple of comments that hopefully will clarify some misstatements made above - I'm sure inadvertently.

Perhaps you feel the need to touch and feel everything that you might consider using, and if so, nothing anyone says or any videos such as Jim's will change that. However, I have seen the results of Jim's system; he's a frequent expert contributor to RC Groups where they support him writing a column, etc. I trust his method, and would have used it if the bags available were large enough to handle my wing sections. Also, the price from ACP was less than $50 more, so I went with theirs while others could take the opposite approach and even make up large enough bags if they already have a foodsaver bagging unit.

This is inconsistent with the first sentence that is quoted from you above, (I have seen the video before.) because if you had watched the video you would have seen Jim stop the foodsaver while it was drawing a vacuum, make sure that all was well lined-up and then start it again.

Where on the ACP website were you looking? Here's what they state about the EZ-VAC that I and many others have used quite successfully: "The EZ-VAC is a quiet, industrial, double bellows design, electric pump preset to deliver 7-8" Hg. It is rated for continuous operation, providing a steady vacuum throughout the duration of the cure cycle. Two year manufacturers' warranty."

RE: Vacuum bagging tips?
 

Newc,

thanks for pointing that out. the EZ-Vac does pull 7-8" Hg.

Saw the video a while ago and didn't recall that detail. Sorry.

thanks again,

Mike

RE: Vacuum bagging tips?
 

How funky??

RE: Vacuum bagging tips?
 

It's all about the funk.

RE: Vacuum bagging tips?
 

Look at CST Sales, ACP, Fibre Glast and Aircraft Spruce. ACP has large nylon baggie stock that works very well as vacuum sock to surround the work and also have really simple to use seals for the baggie. CST Sales vacuum set up comes with a nice compact pump that can draw up to 25" Hg. They supply a 0-30" Hg vac gauge and most importantly, a bleeder valve that allows simple setting of the amount of vacuum you want. It isn't a vac regulator or anything that fancy...just a simple needle valve that bleeds in air controlling applied vacuum.

Breather stock I use is also very difficult to get...NOT!! It's simple paper towels. When skinning wings, I cover the outside of the sheeting completely with paper towels. They breathe exceedingly well and allow the proper contact to happen with no dead spots on the wood. For the tiny pesky areas that need to be sealed, I use plumber's putty. Easy to mold to shape, it doesn't stick to the bag and its reusable.

I have used the Food Saver machine for smaller work such as propeller or landing gear lamination with excellent results. The super thing about Food Saver apparatus is that it seals the bag. The bag then can be placed in warm water to accelerate the cure; works great.

If you need more details contact me

MattK