springcreek

My Feedback: (3)

I'm sure this has been addressed many times before, but this is my first time doing it. So...what adhesives and procedures do you use for the best results? I am going to start building Lanier's 1/3 scale Laser 200 kit. Any helpful hints and tips would be greatly appreciated.

AQ500

Everyone has their own method. I use a 30 minute epoxy thinned with rubbing alcohol. I apply the epoxy to both the core and the sheeting with a squeegee (sp?). I then sandwich the wing with the sheeting in the block of foam that the wing was cut out of. I then place 100 pounds or so depending on size on the foam blocks. I let it cure overnight. I'm sure it's not the best way, but it works for me.

Edwin

My Feedback: (2)

Same method, different glue. I use Probond polyurathan glue. I also sandwich the foam between 2 2'x4' self boards with formica on it to ensure its straight.
Edwin

tonyc

My Feedback: (4)

Edwin
Who makes the Probond?
tony

TRP

My Feedback: (1)

Really? that's it? I have two kits that require sheeting over the foam cores and I just assumed that I had to vacuum bag the wings.

If I can just use some weight on the cores (in their beds) then I can get started sooner than I thought!

Whaoo!
Ted

Vince

My Feedback: (1)

Vacuum bagging insures an even application of pressure vs just putting weights on it when the core is in it's shucks. Having said that, just weighing it down has worked for many people for many years.

I also use Probond, it's vastly superior to epoxy for sheeting foam wings. Probond is marketed by Elmers and is availible at lumber and hardware supply stores. There are also several other brands of polurethane glue that are excellent, like Gorilla Glue, and PL. I suggest you experiment on a scrap piece of foam to get a feel for how much the glue foams as it cures, so you will know how much to use, it really doesn't take a whole lot.

Vince

WarpedWing

My Feedback: (3)

I think everybody does have their own method. I've built the Lanier CAP. I used thinned epoxy on the wings, ProBond on the tail feathers. I liked the thinned epoxy better---but that seems to be a minority opinion among the guys I know. Anyway, whatever you use, keep in mind that it doesn't take much adhesive-----use an old business card or credit card to "squeegee" off the excess adhesive. I found that you only need enough adhesive to make the sheeting look slightly "wet". Never, never apply the adhesive to the foam core (it'll simply absorb into the core and add excess weight). I apply sheeting to both sides at the same time, and place the sheeted core back into the foam "molds" that they originally came in. You might have to slide the sheeting around slightly to make sure it keeps aligned correctly. To weight the molds down, I used sandwich bags filled with sand----probably used 25-30 or so bags per wing half. Make sure the cores/mold are placed on an absolutely flat surface first. I let 'em cure overnight (use 30 minute epoxy!!). After taking the wing halves out of the "mold", if there were any places on the leading or trailing edge that didn't glue well, I simply used Probond or Epoxy on that one spot. Worked great for me----lot easier than a built-up wing.

RC Pilot56

My Feedback: (4)

I have used "3M Super 77 Spray Adhesive" for some time now and never had the sheeting come loose. It is quick, easy and the cleanest method I know of. Simply follow directions on the can for dry time. I use a table in the backyard because of the overspray. I spray an even coat of 3M on the foam core and on the wood sheeting and let it tack up. I then come back and spray another light coat of 3M in the opposite direction on both the foam and sheeting making sure I cover the leading and trailing edges thoroughly, again letting it tack up.
The next step is the most important step!
Be sure that when you put your sheeting on the foam core that it is right where you want it because when the sheeting touches the foam there's no moving it. I perfer to start at the trailing edge and working my way to the leading edge by rubbing the sheeting down smoothly. No need to put back in the (foam beds) and weigh them down but I guess it wouldn't hurt. BE SURE TO PLACE THE SHEETING RIGHT THE FIRST TIME cause if you try to remove it, you will take up foam too. Another great thing with this method is it won't add excessive weight to your model. I have friends that use this method on their 100"+w/s Warbirds. Give it a try on some scrap material first if your sceptical, and I'll bet you will never go back to e-poxy.

AirplaneDan98

How do you thin Probond glue? If it's polyurethane, can you still use water? Thanks, Dan

Vince

My Feedback: (1)

You do not need to thin the Pro Bond, just spread it out thin with a playing card or some other device, all it takes is a very thin layer. Lightly mist the back of the sheeting with water, spread the Pro Bond out onto the sheeting. Place the sheeting onto the foam core and weight it down sufficiently.

If you first try this method on a piece of scrap foam you will see how the Pro Bond foams and penetrates about 1/4" into the foam beads. This allows much greater surface area contac with the foam than epoxy or spray contact adhesives do.

Vince

Sense963

My Feedback: (10)

My 2 cents here. I've found 2 things when dealing with foam. I'll NEVER EVER use the spray contact cement again, as I think it stinks as a reliable adhesive method. (And yes, I can read and follow directions on the can!) My sheeting just pulled up with the slightest temperature difference, and I had to pull it off to use the real deal, which was "Gorilla Glue" polyurethane adhesive. Gorilla was just what I used, I'm sure any other poly will do ok too, especially the Pro bond, I think it was? Anyway, the Gorilla penetrates nicely and holds like nobody's business. I used it to glue in blocks for my aileron servo, and they'll never come out. The stuff is like cement. Good luck.

RC Pilot56

My Feedback: (4)

Sense 963,
I'm glad to hear that you can read. Maybe it's the understanding part you have trouble with. So you did something wrong, why blame it on the glue. You said you had to pull it off and use the real deal. If that were so then you would have pulled off foam along with the sheeting (if you applied if properly). I use it here in South Louisiana where one day it's hot and humid and the next day it's cool and dry and I have yet to have the glue fail due to climate conditions. Call it luck, but it works.

I used to love silkspan & dope for a finish... if only I could remember why...

Could be that the dope gets you high!

Vince

My Feedback: (1)

The only contact adhesive that I have had good results with was Southern RC's sorgum. I have also had problems with 3M #77 and do not even consider it any longer. I like the polyurethane glue, or epoxy because it allows you a little time to position the sheeting correctly.

Vince

djlyon

I use 3m77 and never had a problem, but do put it back in the sadle and weigh it down. I still use silk and dope and primer and laquer when I want a nice maintenance free job. When I want to work on finishing an airplane 10 or 15 minutes at a time I use moneycoat.

AQ500

Live and learn.......

I'm definitely using Probond from now on.

TRP

My Feedback: (1)

Where can I purchase ProBond and How much weight does it add?

Would you use ProBond over thinned 30 min epoxy?

Ted

Edwin

My Feedback: (2)

Pro bond can be bought at Home Depot, Lowes, Walmart, places like that, maybe in the paint section. Make sure you wipe off the excess as it squeezes out. It does sand ok, but not as easy as some had told me earlier. Just different opinions on whats easy and whats not. Still not a problem sanding. My main technique was to use the to shelf boards with 100lbs of weigt on it. That ensured a straight wing panel. The first one I did was a little shy on glue, squeegy'd a little too much off. All later ones had just a little bit more and worked fine. I'm sure it adds weight, just no idea how much. Do you mean using it on a previously epoxied surface, no idea. Do I prefer pro bond instead of epoxy (for sheeting), yes. Just because I dont have to mix it.
Edwin

snsmith

My Feedback: (5)

Elmer's ProBond is the way to go...also produced by various companies such Titebond and Gorilla Glue which are just fine. When buying Elmer's ProBond, be sure you get the polyurethane glue. White bottle, big gold letters...the glue looks like honey in color and consistency. For some unknown reason, Elmer's also markets professional-grade wood glue with the ProBond name. It would probably fine, but you wouldn't get the foaming and penetration characteristics of the polyurethane glue.

I squeegee it thinly on the balsa sheet and wipe the foam core with a damp cloth before joining to be sure there is enough moisture to get a good cure. Although I haven't tried it, some people don't bother to pre-glue the balsa sheets into skins and simply tape them tightly together...the polyurethane glue to pentrate the edge joint and do the job at the same time. Great stuff!

TOYMAKER

My Feedback: (6)

The urethane glue is as good as anything out there. My main reason for using it is three-fold.

1. NO MIXING... just squeegy on to the skins enough for a shiny sheen.

2. Is about $6-7.00 for 8oz bottle(cheaper then epoxy)

3. It expands/cures with the application of moisture. Helps to fill the openings between cells providing more surface retention.

Things not to do with Pro-Bond:

1. DO NOT use on edging or end caps. The expanding glue will push your part away from the gluing surface. As it is hard to get enough even pressure on these smaller edges. Use alphetic glues.

2. DO NOT THIN it... use it straight out of the bottle like fine whiskey.

Things to do:

1. I mist a very fine spray of water over the foam cores before application, then wipe it in with a soft cloth.

2. Seal the skins with nitrate dope and sand smooth. This will keep the balsa from absorbing to much urethane glue. I have done it both ways and you do have to use a little more glue if its not sealed. Some guys claim using cheap hair spray will aslo work to seal the wood.

3. Use at least 150-200lbs of evenly distributed weight, some people say more or less, this amount of wieght has worked fine for me. Even pressure here is a must. I use MDF board between the cores and one on top. Nice smooth even table and let set at least 20-24hrs.


I have taken strips out of my wing that are about a 1/2 wideand 20 in long like the cut outs for the ailerons and I can twist them 360 degrees with out any separation.

crosswind

There is one other method of attaching the skins to foam cores that hasn't been mentioned. You can use 3M adhesive transfer tape (no. 924) ... assuming they still make it. Lay down strips spanwise keeping any gaps between strips to no more than a sixteenth of an inch. Peel off the tape backing and apply the skins normally. It's not as messy as some other methods, such as spraying contact cement. My Dodgeson Saber sailplane was done this way at the reccomendation of Bob Dodgeson some ten years ago, and the obechi skins are still firmly in place. By the way, if you're using obechi and are using Pro-bond, whatever you do DON'T get water on the obechi. It will crinkle up like mad. Epoxy and other adhesives don't seem to affect obechi, but keep it away from water!