Skinning Foam Wings

OK. I have a pair of foam wing cores. I have four skins made up of some of Lonestar's best. I want to attach them using poyurethane glue (Probond etc.). What's the best approach to doing this?

Best, Hoovie

a local RC friend does the following:
tape the sheets together to cover both sides of a panel and trim the outline close. It is not necessary to glue the sheets together.
put the polyu on by spreading and scraping. The surface will appear barely damp. If you can see a glue film, it is too heavy. Might be a good idea to weigh each skin as it is glued to help keep the amount applied even.
Put the skins on the foam. Use tape to hold them from slipping. Put the core back in the block and weight it down with enough weight- at least a couple of pounds/sq.ft. spread evenly.

Pretty much the same procedure. Just did a set last night.

I had glued the sheets of 1/16 together first. Put the Polyu on the skins then scrapped as much off as possible with a stiff plastic squeegee. Then sprayed a very light mist of water on the foam from a spray bottle. Assembled the shells, skins, and foam wings on a glass surface and weighted the whole mess down with gallon cans.

The first set I did this way have stayed together without any separation.

Be sure to vacuum all the parts prior to assembly to avoid bumps and divots on the wing surfaces.

Hi David,
I just finished skinning some foam wings today. I found a double sided tape that works wonders and is about .002 to .005 thick. Man this stuff works and is not affected by the heat or sun either. I will try to find the brand name if your interested. Tape I have was given to me by a friend who uses it on his competition quickie 500 racers.

I've always used 3M-77 spray adhesive to attaché the balsa skins to the foam. Spray both the foam and skins. I’ve never had them lift. The draw back is you get one shot to lay them down. The up side is its fast and light.

David,
Once you try this stuff you'll never go back to the spray stuff. The sticky stuff gets all over everything that you don't want it on, but it works really good. I've used the 3m spray stuff also and he's right once you put the wood down thats were it's going to live, no second chance. I like the tape because I can do it indoors and not irritate the wife. But it's like the spray stuff once the wood is down that's it. Buy the tape here. I suggest the 2 in width. If you need more instruction E-mail me........Greg
(818) 998-0638
TRK
9757 eton ave
Chatsworth, Ca. 91311
Part NO. 9485PC SCOTCH BRAND TAPE 3M

>OK. I have a pair of foam wing cores. I have four skins
>made up of some of Lonestar's best. I want to attach them
>using poyurethane glue (Probond etc.). What's the best
>approach to doing this?
>
>Best, Hoovie
>
>Life is simple. Eat. Sleep. Fly.

I would only use Titebond 2. It is found at Lowes'.

Spread it. Squeegy it all off onto paper towels. When you can break the residue on the paper towels in two. You are done.

> When you
>can break the residue on the paper towels in two. You are
>done.

What exactly does this mean?

>> When you
>>can break the residue on the paper towels in two. You are
>>done.
>
>What exactly does this mean?
>
>regards,
>Rick "catdaddy" Blankenship

The excess glue goes on the paper towels.

Set them aside.

Put the cores in the cradles with the skins.

When the glue foams and hardens to the point you can snap the paper towel in two, you can take the cores out of the cradles. This takes less than a couple hours.

That's what I thought but wasn't sure.
Thanks, that's how I'm going to do mine.

>>OK. I have a pair of foam wing cores. I have four skins
>>made up of some of Lonestar's best. I want to attach them
>>using poyurethane glue (Probond etc.). What's the best
>>approach to doing this?
>>
>>Best, Hoovie
>>
>>Life is simple. Eat. Sleep. Fly.
>
>I would only use Titebond 2. It is found at Lowes'.
>
>Spread it. Squeegy it all off onto paper towels. When you
>can break the residue on the paper towels in two. You are
>done.

City Smasher,
I was in Lowe's yesterday poking around and found some Titebond II right next to the Titebond. After looking over the label, I was not able to determine if this is the polyurethane glue or not. Looks just like the Titebond, is this the right stuff? Have a couple of foam wings in my future and would rather get it right the first time.

Thanks,
John Paris

>>>OK. I have a pair of foam wing cores. I have four skins
>>>made up of some of Lonestar's best. I want to attach them
>>>using poyurethane glue (Probond etc.). What's the best
>>>approach to doing this?
>>>
>>>Best, Hoovie
>>>
>>>Life is simple. Eat. Sleep. Fly.
>>
>>I would only use Titebond 2. It is found at Lowes'.
>>
>>Spread it. Squeegy it all off onto paper towels. When you
>>can break the residue on the paper towels in two. You are
>>done.
>
>
>City Smasher,
> I was in Lowe's yesterday poking around and found some
>Titebond II right next to the Titebond. After looking over
>the label, I was not able to determine if this is the
>polyurethane glue or not. Looks just like the Titebond, is
>this the right stuff? Have a couple of foam wings in my
>future and would rather get it right the first time.
>
>Thanks,
>John Paris

Is it dark brown?

Titebond II is a regular wood glue. I have used it thinned down to attach wing skins but the polyurethane (on the left)is better. I also spritz the core with a fine mist of water before attaching the skins. Makes the glue foam slightly. I think this forces the glue into the foam surface and the balsa skin just a little better.

>Titebond II is a regular wood glue.

Oops, I had it backwards. My bad.

Spritzing the foam is a good idea. Wouldn't hurt. Usually the stuff foams like mad, but water makes it foam even more, which is good for bonding to the foam.

I have been doing Impact cores at .1 oz per skin or .2 oz per core. That is about half the weight of epoxy. I have also never had a delam, which is awesome for me.

For my money there is nothing more simple, easy to use, lightweight, or bulletproof as skinning with PU glue.

JimW,
Thanks for the picture. Makes things a lot more clear. Did not see that particular bottle in the area, so will have to look around some more.
John

John,
I don't know if Lowes carries it (they probably do) but I get mine at Home Depot. Should find it near the other polyurethanes; Elmers, Gorilla Glue, etc.

>John,
>I don't know if Lowes carries it (they probably do) but I
>get mine at Home Depot. Should find it near the other
>polyurethanes; Elmers, Gorilla Glue, etc.
>
>Jim Womack

I never found it at Home Depot. I had to make a special trip to Lowes' (I never go there).

I could not find the Titebond Polyurethane glue locally. I had to mail order it from Woodcraft in Parkersburg, WV. 1-800-225-1153.
It is not in their current catalog but they do carry it.

I've used both Elmer's and TiteBond PU glues - both for balsa skins for foam wings and some general balsa/balsa joints.

I like it - initially. What I've found over time (perhaps a year or so) is the polyU glue seam tends to get very dark and shows through. The foam cores are brown almost all the way through.

Is this typical?

David,
Where do you live? I'm in Southern California and own a vacum bag system specifically designed to laminate the skins to the foam cores. If were close I would be more than happy to let you borrow it. If you want, give me a call at my office 858-569-0755 x110.
Regards,
Dave Sabon

I, like Larry Foster, have used 3M-77 for years with no complaints. However, about a year or so ago 3M changed the formula for #77. It now contains acetone and is not recommended anymore for Styrafoam. It will say right on the ingredients list, acetone....that is how you can tell if it is the old or new formula.

Will some one tell me exactly, step by step, how to use the PU foaming glue. I have used thinned Titebond but not the PU.

Thanks, Dee Rice

>I, like Larry Foster, have used 3M-77 for years with no
>complaints. However, about a year or so ago 3M changed the
>formula for #77. It now contains acetone and is not
>recommended anymore for Styrafoam. It will say right on the
>ingredients list, acetone....that is how you can tell if it
>is the old or new formula.
>
>Will some one tell me exactly, step by step, how to use the
>PU foaming glue. I have used thinned Titebond but not the
>PU.
>
>Thanks, Dee Rice

Sure.

(this is from an old thread I posted, it was also ripped from SSW and put in the Stunt News)

>Whats the best method to put
>the skins (1/16"sheet) on?

I fully sheet using Titebond 2 Poly urethane glue (available at Lowe's), I do not recommend any others for sheeting foam, as they are all substantially thicker and foam much less (I have tried Gorilla and Elmer's).

There are several advantages to the Titebond over epoxy. First of all it is a one part glue and so no mixing is required. Second, it is fully cured in about an hour and the wing is completely done. Third the glue foams which allows the user to remove ALL EXCESS glue as no extra is required. Fourth, since the glue expands and foams, the joints in the sheeting are actually filled by the foamed glue, making the joints in the sheets less critical. Lastly, it is really a snap to use! First, I put the sheeting over a big strip of paper towel (face down) then I just make big "Z" stripes on the sheeting with the PU glue, and then spread the whole mess around with an old credit card until every inch has been in contact with the glue. Then squeegee all of the glue off onto the paper towel. Try to get it all off, there is no need to leave any extra. You will, in fact, not get all of the glue off, no matter how hard you try. Put the cores back into the cradles, straighten everything up and weigh down with a board and something very heavy. Make sure you use a flat surface to support your cradles while they dry. Keep the paper towels that were covered in glue, and when the glue has foamed and turned rock hard, you can remove the cores from the cradles. This usually takes about an hour.

(You can also wet the glue lightly with a spritz of water, this can increase the foaming action).

One trick for joining sheeting. Buy a piece of Teflon! Teflon! It looks like clear plastic and is about 1/32" thick. Join all your sheets over the Teflon. Press the sheets together and down against the Teflon with your fingers (I do not even true the edges anymore since I hacked off the end of my thumb) and tack every 3" or so with thin CA. Then when the entire edge is done, Fill in with thin CA between the tacks. The side face down to the Teflon will show no seam at all (that is to be the side that shows on your 'rplane, mark the glue side "inside" in big letters with a felt tip pen)! It's a snap, and super fast, but you must get the Teflon sheeting for it to work.