Gluing in spars

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gsjames
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Gluing in spars

Post by gsjames »

I'm making up a batch of wings so that I can get flying again. They use the normal 1/8" fiberglass rod kitesticks. I used the standard technique where I put a little bit of Urethane glue ( I used Gorilla Glue) in the spar slots, roughened and then moistened the fiberglass rods with water before putting them in the slots. I covered over the slots with 1" wide masking tape, put them back in the shucks, put weights on the top to keep everything straight and waited for it to cure.

WHAT A MESS!

The glue not only foamed up to fill the voids as needed but creeped under the masking tape and oozed out the edges. It left big lumps on the foam where it oozed out and even where it stayed under the tape, there are big bumps. It's going to be hell to sand all that crap down. Hours of extra work just to get the wing halfway smooth for the armor tape.

There has GOT to be a better way! I didn't use all that much glue.

Does anyone have a better way of gluing in spars? I see that Chris Gunter has used adhesive caulk on his Tomahawks. How's that working out?
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Dane McGee
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Re: Gluing in spars

Post by Dane McGee »

.............Epoxy.


My latest wing spars have all been glued with epoxy.,,,its quick, strong and no foaming mess. I use gorilla glue for repairs and thats about it now.
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Re: Gluing in spars

Post by EK »

I don't use any water and woodpecker the masking tape along the rod (both sides for relief) so the expansion can get out. Check it after about 4 hours (using gorilla glue) and if it doesn't stick to your finger, pull the tape. Most of the expansion is finished and you could put on the bi-di but I let it finish drying without moving the wing. Some will put the rod in and put on the bi-di instead of masking tape. Woodpecker it and scrap off the expansion when it's cured.
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Re: Gluing in spars

Post by mad »

I usually drill 1/8 inch holes from spar grove to spar grove about 1 inch apart. this gives the glue a place to expand to as well as makes it much much more difficult for the spar to break loose from the foam.
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Re: Gluing in spars

Post by boiler »

I use very little pu glue in the spar slots and run a craft stick down and back at least 3 times to spread it evenly. I then hold the spar in place with t-pins at an angle. I place the wing bottom on the shucks and the spar with glue on the top without the shucks. I put weights to hold it in place. When dry I remove the pins and if the pu glue expanded above the spar a narrow utility knife takes off the excess easily. I then flip the wing over onto the top shucks to repeat the process. It is an extra step but works well for me.
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Re: Gluing in spars

Post by Quickdraw »

I have a Master Airscrew wood plane that I use to remove excess PU. I set the blade so that it barely cuts. Works good for me.
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Re: Gluing in spars

Post by Dr. Kamakaze »

I glue the wing halves together using epoxy first and let it cure in the shucks so it's straight. I then use my dremel router to cut the slot (a little deeper than 1/8th inch) in the foam top and bottom of the wing. Then I mark on each wing panel in about 4 spots and punch through from the top to bottom of the wing using a scratch-all and pass the smallest zip tie they make through the wing and just leave it in place loose along the spar groove. Then I run a bead of gorilla glue (not too much) down the bottom side of the wing groove, wet down the spar with water, slide the spar in under the preplaced zip tie, and lay a strip of Bi-Di tape over it. I then repeat the same process on the top side of the wing, tighten down the zip-ties to cinch up the top and bottom spars and push the end of the zip tie down into the foam after trimming the tail off the zip tie. Lay the Bi-Di tape over the top and place in the shucks overnight to cure with weights on top. I just got my pool table set up again so will be able to glue up 5 wings at a time on the ping pong table top I have for it...that is when I have time :roll:
Hope that makes sense and helps,
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Re: Gluing in spars

Post by Blue Note »

I am still using the CLEAR PolySeamSeal ( PSS ) with outstanding results. ( DO NOT USE THE WHITE VERSION...IT IS DIFFERENT ) The PSS tested to have better retention strength than the PU for both peeling and direct pull-out pressure. If you apply enough pressure to peal the 1/8" FG out of the slot, you are usually ripping foam out with it and a direct pull-out basically destroys the foam. It is not at all brittle, and you have no worry about it swelling during the drying phase leaving you a mess to grind off. I have had several severe hits and have yet to have a single spar come loose. I did have a spar actually break, but it stayed in place perfectly, and was in fact difficult to find until I removed the tape. ( I performed a quick "field repair" splicing in a couple 6" pieces of scrap FG rod with the fast drying white Gorilla glue since I was going to use the plane later that day and the PolySeamSeal needs time to fully cure. ) The "bend, don't break" philosophy of the spar combined with my EPP leading edges has really paid off when it comes to durability.

I have revised the spar installation a little since the Tomahawk build thread, but very little. PSS needs air to dry, so I am not using any tape in the process. Squeeze a bead in the spar slot along the length and insert the spar from one end while twisting it. My slots are a little undercut, which helps hold the spar below the surface, but I make sure by placing a few large T-pins at angles that force the spar deep into the slot. Top off the top of the spar slot with more PSS , then use something like an old credit card to squeegee the top of the slot clean and flush. After about 2 hours, you can remove the pins and you will notice that the PSS has settled into the slot a little. Reapply and re-level flush to the wing surface and let dry. The process makes it difficult to do both spars at the same time if you have the wing pressed in the husks, but I feel it is worth the time. The process is very easy, clean, and you can have no worries about having to grind away expanded PU when you are done...not to mention the final result has thus proven superior to PU, at least for me. ( Note : Results might be a little different depending on the type of foam your wing is cut from. A little "roughening" of the spar slot may help adhesion, but I am very hesitant to cut deeper into the wing to provide a place for glue to travel. The fully dried PSS still feels quite sticky and further improves the adhesion of a layer of Bi-Di ( or possible Hurricane Tape ) over the spar. My wings are plenty stiff for flight loads, but give enough to flex a little upon impact and thus dissipate some of the kinetic energy. When it is time to finally retire the wing, you can rip the spars out and quickly peel the PSS off of them for reuse. Reclaiming spars has been about impossible with PU and it is very time consuming to scrape all of the glue residue off of them. Once removed from the wing, the PSS installed spars clean up in just a few seconds as it basically peels off and leaves no residue. Try it, I think you'll like it.
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Re: Gluing in spars

Post by midair02 »

I also use epoxy. Never had any problems with it. I only do one spar at a time though in batches of usually 10 or so wings at a time. I use the laminated shelving from Menards to put the wings on and stack them in rack while curing. Epoxy easily scrapes off of the shelving material using a razor blade.


Chris,

Where do you get this PolySeamSeal and is that the brand name?

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Re: Gluing in spars

Post by Blue Note »

midair02 wrote:

Chris,

Where do you get this PolySeamSeal and is that the brand name?
Loctite is the brand name and you can get it at Home Depot, Lowes, etc. I've even seen it at Wal-Mart. It's also pretty cheap. I usually get the dispenser for the caulk gun instead of the squeeze tube pictured above.

Last edited by Blue Note on Tue Nov 13, 2012 9:00 pm, edited 1 time in total.
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Re: Gluing in spars

Post by gsjames »

Thanks for all the great ideas!

I found a tube of "Foam Safe Construction Adhesive" in the caulking aisle of Home Depot the other day. I'm going to give it a try on a test wing and see how it works. I've pretty much had it with PU glues. :x
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Re: Gluing in spars

Post by sgilkey »

i did a google search for "clear polyseamseal" and came up with two different types.

there is "loctite" which does not look like the same stuff Chris posted, even though it has a similar "polyseamseal" logo on it, it also clearly says "loctite" which Chris' photo does not show.

The stuff on the Home Depot website also shows the Loctite brand name on it.


I also found "Henkel Polyseamseal" at various online places, this has the "polyseamseal" logo but does not say "loctite"

Chris, which one of these (or neither, or both) is the stuff you use, looks like great stuff!

Thanks
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Re: Gluing in spars

Post by Blue Note »

sgilkey wrote:i did a google search for "clear polyseamseal" and came up with two different types.

there is "loctite" which does not look like the same stuff Chris posted, even though it has a similar "polyseamseal" logo on it, it also clearly says "loctite" which Chris' photo does not show.

The stuff on the Home Depot website also shows the Loctite brand name on it.


I also found "Henkel Polyseamseal" at various online places, this has the "polyseamseal" logo but does not say "loctite"

Chris, which one of these (or neither, or both) is the stuff you use, looks like great stuff!

Thanks

The tubes have been changed a little and now clearly read the brand name of Loctite. Just be sure to use the CLEAR version. The white doesn't work near as well.


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Re: Gluing in spars

Post by sgilkey »

ok, thanks!
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Re: Gluing in spars

Post by PFawcett »

Chris, I tried the polyseamseal. I think i will like it. one note for anyone going to try this method: make sure you allow them 24hrs to dry before adding tape. or it will not cure all the way.

I am interested to see how well int holds up to midairs and dirtnaps. it does stay a bit flexable. very little. Thanks for sharing Chris.
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