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Old Feb 08, 2013, 09:26 AM
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United States, MA, Fitchburg
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kevlar thread wrap spars info

i wrapped the spars/joiner box on my oly ii with kevlar
what do i coat with?
epoxy or CA or polycrylic?
jon
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Old Feb 08, 2013, 09:31 AM
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Joensuu, Finland
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Any of those will do. The purpose of the adhesive is only to prevent the thread sliding along the spar. Epoxy will be heaviest, ca quickest.
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Old Feb 08, 2013, 10:07 AM
Kurt Zimmerman ≡LSF 4461≡
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Montrose, NY
Joined May 2003
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I would thin down epoxy with alcohol, coat the kevlar then blot it with paper towels... As jkettu stated, the idea is to lock it into place. The coating does little to nothing in adding strength. I just don't like using ca on a spar with the chance it wicks into the wood. I learned my lesson long ago that ca and spars don't mix. The wood becomes too brittle and looses it's flexibility which could result in failure.

Kurt
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Old Feb 08, 2013, 11:39 AM
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Use thick CA. Apply liberally, wipe excess off with a tissue or paper towel, then hit it with accelerator. Minimal wicking (per KZ) and will effectively lock the thread in place.

JT
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Old Feb 08, 2013, 12:23 PM
Chuck 'Em and Chase 'Em
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why not just use laminating epoxy?
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Old Feb 08, 2013, 02:13 PM
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Quote:
Originally Posted by Fly2High View Post
why not just use laminating epoxy?
Lots of extra hassle for no structural value. All one needs to do is keep the thread whipping in place, and epoxy won't do that any more efficiently than CA, though it will likely add more weight.

JT
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Old Feb 08, 2013, 06:50 PM
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United States, VA, Alexandria
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Just use Weldwood or polyurethane, light + cheap!
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Old Feb 10, 2013, 01:30 AM
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.... ;-(
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Last edited by ozmo01; Feb 14, 2013 at 10:42 PM. Reason: Bad Info OOPs
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Old Feb 11, 2013, 11:20 AM
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St. Louis, MO
Joined Oct 2002
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I agree with JT....I see no need to add anything except at the ends of the wrap. Look at an Ava spar. The wrapping is not bonded down except where the wrap starts and ends and where the D-tube is attached to the spar. Whatever you use will not add anything to the strength of the wrap since the wrap is being stressed in tension only. Also, remember to round the corners of the spar cap so that the wrap is not running over a sharp corner.
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Old Feb 14, 2013, 10:41 PM
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Hi Mark,
I thought the instructions for the BD called for wetting the Kevlar?
It wouldn't be the first time I was wrong.
I went back and reviewed the Allegro light files and they talk about wetting the tow out AFTER wrapping the spar then blotting down well. I should not post when I have just come off a long work shift! I think I confused the method of wetting cloth to bag a wing here, MY BAD.
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Old Feb 16, 2013, 12:03 AM
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I would totally wet it out with thin ca
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