ricfly52

Well now I hope I didn't screw up!
I have been a carpenter, wood worker for 30 years. I have also done quite a lot of work with laminates. So when I was sheeting some foam wings the other day this is what I did.
1. I glued the 4 inch by 36 inch by 1/16 balsa strips together with thin CA. It took 4 strips and a half of another. Times 4 for the two sides of two wings.
2. Then when I acually sheeted the foam cores I used water based contact glue. Just like you might use for gluing formica or thin wood sheeting.
It was so simple that I got to thinking that maybe I screwed up! All you have to do is paint one side of each surface to be glued (one foam wing side, one side of the wood panel). Let it dry then re-coat it one more time and let dry. Then line 'em up and stick them together. No weights and no overnight curing time.
Has anyone else done it this way?

fastcat

Thats the way most everyone does it. You can also coat the sheeting and foam with titebond wood glue. Let the titebond get fairly dry and then iron it on using the wife's iron. The heat activates the glue.

sideshow

My Feedback: (11)

I think a lot of people are wary of contact cement. You got one shot to get it right. I used polyurethane glue to sheet the wings on my Edge. There is time to get the position exactly right and the glue foams as it cures filling any voids and actually sending fingers down into the foam.

I have heard, anecdotally, that some people have had problems with contact cement coming apart after a while. I didn't give much weight to these stories because it was mostly people who had "heard" of this happening.

I like to use wood glue to glue up the sheets of balsa. I tape the pieces together and then turn it over, I let the peices hang over the edge of my table and put wood glue in the joint. As you pull the pieces flat on the table glue fills the joint and you just wipe off the excess and put a piece of waxpaper over the glue joint to dry. The taped side will be perfect, not hard like a CA joint.

Man, that was some rambling........

Bob

flyindoc

My Feedback: (8)

Here is my method of sheeting foam wings.

1. I true up all the edges if the balsa wood first. Due this with a long straight edge or fabricate an edge sander with a piece of angle aluminum mounted to a flat piece of board and glue some sandpaper to it.

2. Tape all the sheets together with masking tape on one side only.

3. Spread titebond, gorilla or probond polyurethane glue all over the side opposite the tape and spread it very, very thin. Use an old playing card or bondo spreader.

4. Do both skins, top and bottom.

5. Lay one skin tape side down in the bottom cull and spray water on the wing core. Now lay it on top of the skin. Now spray the other side of the core with water and lay the other skin on top of it followed by the top cull.

6. Add as much weight on top of the whole assy as possible. Let it dry for atleast 8 hours.

7. The polyurethane glue will foam up and dig into the foam creating a great bond.

Try this and you will surely be happy with the results. The best part of it is you don't have to glue the sheets together with thin ca, because the polyurethane glue will fill the cracks in the sheets where they are taped together. This saves time, allot of time.

Andy

Blackie

I have to ask a stupid question.

Where can I find this polyurethane glue? Can it be purchased at homedepot and other stores of the like? or will have to get it from the Local hobby shop? :stupid:

Thanks
Blackie

T Koffler

My Feedback: (13)

Local hobby store probably wont sell it..... It can be found at Lowes or Home Depot ... It's called PROBOND.. Good luck

ricfly52

It is very possible that in some instances that contact glue would release. A person has to know how to use contact properly for it to work right. The key factors being to coat it once. LET IT DRY. Coat it for a second time. LET IT DRY until when you touch it it doesn't stick on your finger. Then it is ready to stick. Also temperature and humidity have influencing factors.

I guess that being said, a person is better off with poly glue and weighing the whole thing down until it dries. (24 hours) Unless you have had experience with contact glue. I will let you all know if I have any problems with what I have done with my wings.

Rick

sideshow

My Feedback: (11)

I found the Probond (Elmers) polyurethane glue at Orchard Supply Hardware. Our Home Depot didn't carry the poly........just every other Probond formula. There are a lot of brands of the polyurethane glue, I went with the Probond because that is the one I read about. The others would probably work the same. Check out the article on using this here. Click on the articles on the left margin. First article on the top.

http://www.aerobatix.com/aerobatix/index.html

Vince

My Feedback: (1)

I can attest to contact glue releasing after awhile. Happened to me twice, both times on a Kaos foam wing. First time it was sheeted with 3M #77, awfull stuff for sheeting wings IMO. Second time was Southern R/C Sorgum. After a few years in the Southeast Texas sun it started to debond in areas. I then switched to slow cure epoxy for all my foam wings. I have yet to try the poly U glue for this, but I suspect it would be better than epoxy.

Vince

gizmo8012

My Feedback: (15)

I just sheeted foam wings on a Lanier G-202 and used Probond poly glue after looking at pics and a review on Carden aircraft's website.. It worked great and is easily sandible and veryyyyy strong, especially where I cut some foam out of the wings for lighting the wing, I cant tell there is no foam there under the sheeting... I found my container of probond on the yahoo search and bought it from a Tru-value store online $15.00 for a 16oz container. good deal I thought being that Wal-mart has it 2 oz for around 5.00, later all!

Radman

I thought the idea when sheeting foam wings was to gain strength. My thoughts were that epoxy on the balsa skins acted like a monoque design. The strength came from the epoxy hardning the balsa, and the foam was just there to give it form. I've seen a lot of wings cored length wise after using this technique and saving a lot of weight in the process.

does probond harden like epoxy? Is it heavier than epoxy? Has anybody tried both ways and can say which is better?

You all got me wondering which is better now.

Vince

My Feedback: (1)

Contrary to some popular belief, the foam core does impart some strength to the wing. Epoxy is a good method to sheet wings, but Polutethane glue is much better IMO. The glue foams as it cures and migrates down into the foam. Is is lighter than epoxy? Yes I think so. Is it stronger than epoxy? Tes I think it is.

Vince

sideshow

My Feedback: (11)

The poly glue foams as it cures and will send "fingers" down into the foam. I made a test piece and the fingers were about 1/8 to 3/16 deep. It is ridiculously strong and MUCH lighter than epoxy. Give it a try....you will love it.

Bob

bash-ace-RCU

My Feedback: (16)

Gotta love that Pro-Bond, I won't use anything else (except maybe Gorilla Glue).

NCC-1701

One additional thought. I highly recommend vacuum bagging instead of stacking weights. Drawing a 6 psi vacuum on a 200 square inch core is equal to stacking 1200 lbs of weight on top. And the pressure is evenly applied.

Aerospace Composite Products sells a starter kit for about $100.

bash-ace-RCU

My Feedback: (16)

NCC-1701

I don't think I've seen your Enterprise out at the field, do you fly out at EAM?

NCC-1701

Basher Ace,

I sure do fly at the EAM field. You haven't seen the Enterprise because of AMA red tape and limitations on 21st century aeromodeling technology. You think it's tough getting a turbine waiver, you oughta try and get a waiver for warp drive!

Also, Jack, Jim, and Ron don't stock anti-matter fuel, not even 5% and Futaba and Hitec crystals aren't suitable substitutes for dilithium!

So, I'm having to settle for a Stinger and a Finess, at least for right now!

bash-ace-RCU

My Feedback: (16)

Do you have the yellow and white stinger? Haven't seen your finesse yet (unless I'm losing it).

TOMMYSTA

My Feedback: (15)

IF YOU MUST USE A CONTACT TYPE CEMENT FOR SHEETING TRY 3M 78. I'VE USED A COUPLE TIMES AND IS MUCH STRONGER THAN THE 77 AND SO FAR IT HAS NOT LET GO. IT'S A LITTLE THICKER THAN THE 77 ALSO...MAKING IT EASIER TO SEE AN EVEN SPRAY COAT APPLIED.

nchrome

One of the things that you guys are doing that I found out don't work to well is the thin CA to glue the sheeting together. When you go to sand if it is a little uneven these areas are a little harder than the rest of the sheeting and will leave waves at your seams. Titebond to blend to gether the sheeting works very well for me then I'll use garrila glue on it when sheeting. Both are very sandable and I come out with a smother wing . :spinnyeye

Scorpionjack

Not single one of you mentioned Sorgum! Yes I use Probond as well, neat stuff! snazzy! will fills pours Superb. But Racers of Old use to use Dave Brown's Sorgum. It was a water based rubber cement just as rickfly described. We covered the foam and the sheeting with a thin coat let it dry then rolled the wing on the sheeting.
No it's not like 3M77 or 78. 3M77 took a technique that few could get perfect all the time. Doing it wrong would definately cause sheet separation from the foam. But Sorgum would rip the plane apart before it let loose. Just as someone pointed out you get one chance no more. So rick the answer to your question is you did not mess up. Sorgum is still used today, I think I still have a container of it. But as I said I use Probond now, cause it is the cats meow for sheeting.

bash-ace-RCU

My Feedback: (16)

I used to use sourgum, it was the best thing to use back in the day. Problem is, if it froze at any time (storage, transit to hobby shop, in your shed), it would be unstable for wing sheeting, you would certainly get sheeting separation at some point earlier than you would want.

Scorpionjack

hmmm Never had it freeze, but being in North Dakota temps only get to -41F Ambient in the winter Windchills at -108 F : ).

All kidding aside, we had winter flys but never saw a separation, not saying that it can't just never saw it.

DF_Flyer

I'm not sure if they make it anymore, but I have had great success sheeting wings with Sig Corebond. I've sheeted a couple of dozen wings over the last 15 years and have yet to have one delaminate.

BTW, I've even used it to bond 1/64 ply to a foam core. Much easier than gluing 1/16 balsa sheets together and virtually no sanding required.

I'll have to give the PU glue a try though. It sounds interesting. Thanks for starting a good thread guys.