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Old Jan 14, 2013, 04:29 PM
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macinr's Avatar
USA, CA, Santa Barbara
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Curing Polyurethane Glue aka Gorilla Glue - any thoughts?

So there's gotta be a better way... Not only is the weight non-evenly distributed it never helps to make the kitchen less functional for those who already have a list of reasons why they can't cook tonight

By not using enough weight I've had some spars "pop" up requiring a huge amount of work to repair...

Requirements:
  • needs to be usable indoors
  • at least 60 inches long

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Old Jan 14, 2013, 04:36 PM
Sane til the lift starts!
kpeevyhouse's Avatar
Laguna Beach, CA
Joined Jun 2008
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I guess it depends on what you're gluing the spar into. I vacuum bag my wings when I use Gorilla Glue with the wood sheeting. Works like a charm. But that's with blue or pink foam, which can handle the vacuum pressure.

EPP will undoubtedly deform too much under vacuum, so I wouldn't try it.
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Old Jan 14, 2013, 04:39 PM
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Gluing spars into EPP wings... Would prefer to do top & bottom spars at same time too.
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Old Jan 14, 2013, 04:50 PM
Sane til the lift starts!
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In the past I've done this with good success. Coat the slot with the Gorilla Glue, but leave bare spots every few inches. Push the spar down into the slot. In those bare spots, squirt some hot glue around and under the spar. The hot glue will cool quickly and hold the spar in place while the Gorilla Glue bubbles and does it's gorilla dance.

You'll have plenty of time to work before the Gorilla Glue goes off.
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Old Jan 14, 2013, 05:00 PM
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I often "sew" a number of loops (kevlar thread or Spectra fishing line) through the spar channels After misting the channels; adding glue and spars, I snug the spars into their channels; tie off the thread and trim the ends.

See drawing below...

Dawson
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Old Jan 14, 2013, 05:04 PM
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United States, CA, Cypress
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Quote:
Originally Posted by kpeevyhouse View Post
In the past I've done this with good success. Coat the slot with the Gorilla Glue, but leave bare spots every few inches. Push the spar down into the slot. In those bare spots, squirt some hot glue around and under the spar. The hot glue will cool quickly and hold the spar in place while the Gorilla Glue bubbles and does it's gorilla dance.

You'll have plenty of time to work before the Gorilla Glue goes off.
Nifty idea! Do you still use weights when you do this? I'm considering adding CF ribbon spars to a molded EPP wing (EPP Fox) which does not come with wing cores (doh! it's molded EPP) so this method might be perfect if you think it can be done without weights.

-Jonathan

EDIT: Dawson, love the diagram. Wish that would be possible if you were only inserting one spar in. The Fox wing I'm considering is too thin for a top & bottom approach.
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Old Jan 14, 2013, 05:32 PM
Flagstaff, AZ
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Twyl:

I use ribbon spars in my combat wings. In that application I like to use thin CA for the glue. Just cut the slots (a razor knife followed by a piece of hacksaw blade to widen the channel); slide in the CF ribbon spar; and then wick in thin CA... both sides. Hold the wing straight for a minute or two and you are done!

Dawson
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Old Jan 14, 2013, 05:46 PM
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Quote:
Originally Posted by dawsonh View Post
I often "sew" a number of loops (kevlar thread or Spectra fishing line) through the spar channels After misting the channels; adding glue and spars, I snug the spars into their channels; tie off the thread and trim the ends.

See drawing below...

Dawson
Ah, excellent idea for when the spars are directly opposed...
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Old Jan 14, 2013, 05:54 PM
Silent Flight
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Quote:
Originally Posted by macinr View Post
Ah, excellent idea for when the spars are directly opposed...
When spars are directly opposed, could it be said that they were... sparing?



-Jonathan
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Old Jan 14, 2013, 05:59 PM
EPP Extrordinare
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United States, CA, San Clemente
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Ive found it helps to have a hard board at least 1/4" thick (thocker is better, wood or whteer you got works fine) between the beds and weights. The board helps distribute the weight evenly across the panel. For better, faster curing, squirt some water on the glue to help kick it, since GG is activated with moisture.
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Old Jan 14, 2013, 06:14 PM
Sane til the lift starts!
kpeevyhouse's Avatar
Laguna Beach, CA
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Quote:
Originally Posted by Twyl View Post
Nifty idea! Do you still use weights when you do this? I'm considering adding CF ribbon spars to a molded EPP wing (EPP Fox) which does not come with wing cores (doh! it's molded EPP) so this method might be perfect if you think it can be done without weights.
I always use beds & weights to keep everything aligned, but obviously you can't do that with a molded EPP plane. Once the hot glue hardens up, I guess you don't need to worry too much about things shifting around. You don't even have to use hot glue, I suppose. 5-minute epoxy should give you more working time, yet still harden up before the Gorilla Glue starts going off.
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Old Jan 14, 2013, 06:21 PM
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United States, CA, San Jose
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I like the sewing idea, which could be used for a single spar. Just use any ol' hardwood dowel for the opposing (non-sparring) side until the GG sets.

I like the hot glue idea for smaller lengths...but a 60" wing with a full length spar could be problematic.

I nearly did the GG with my Assagai (EPP) spars, but decided on thick CA in the spar channel, then spar, then thin CA dribbled over the top...curing as we speak...
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Old Jan 14, 2013, 06:55 PM
Boulder Sloper
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United States, CO, Boulder
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Bolder bond

I don't use polyurethane glue often but when I do I use it I use Bolder bond. http://www.bolderbond.com/.
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Old Jan 15, 2013, 03:17 AM
I don't like your altitude
Stupot46's Avatar
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[QUOTE=Twyl;23814807]Nifty idea! Do you still use weights when you do this? I'm considering adding CF ribbon spars to a molded EPP wing (EPP Fox) which does not come with wing cores (doh! it's molded EPP) so this method might be perfect if you think it can be done without weights.

-Jonathan

I've never tried this,but thought it should be possible to bed EPP wings using a framework and expanding foam.Trial wouldnt cost much.
Stuart
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Old Jan 15, 2013, 04:11 AM
Just Toss It !!!
MATIN's Avatar
Australia, NSW, Sydney
Joined May 2004
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Download the "Raven Wing Build" manual HERE.

Read up on Section IV pages 10 thru 16. You might find the information useful.
The method described there for installing wing spars using PU glue, has been used hundreds of time (if not more) by builders of varying experience.

We have yet to hear of someone not succeeding in keeping the spar from being pushed out of the spar groove when they followed those instructions.
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