Question for Ray D. about his article in ER

Hi Ray,
I read with interest your article in the latest ER but I had a question--
You use kevlar cord to reinforce the fin roots and seal the cord to the MMT
with CA. I thought CA shouldn't be used with kevlar as it weakens it?
Am I missing something?
Thanks
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NaCl wrote:

I've heard that claim too, but in my experience I've never seen any evidence of significant weakening. I've been using kevlar and CA this way for many years, and also anchoring kevlar shock cords with thick CA. Never had a failure at the glued point yet.

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There's a reason. Kevlar cord can be ordered from the factory in a form that will not become embrittled with cyanoacrylate glues. You must be getting your Kevlar cord from someone in the rocket biz who has gotten the right stuff. I wouldn't put Super Glue on Kevlar fishing line. I actually prefer to soak my Kevlar cords in epoxy resin, which has a little flex to it, but a good grade of CyA glue will work just fine. By the way, you can actually sand hardened CyA if you wet-sand it with debonder on the sanding paper. It's hard to conceal a CyA-balsa joint line because the balsa is so much softer than the glue, but wet sanding with debonder will feather the edge out nicely.
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