Plywood delamination--amelioration

I have a plywood fin that has delamination damage from a crash. The delamination affects about a square inch of 1/8", 7-layer plywood. The layers themselves seem largely intact.

Soaking the plywood in CA would penetrate deep into inter-layer seams, but I worry about CA being brittle. Other glues are thicker and getting them deep enough between layers is a challenge.

I wonder about techniques people have used to re-bond layers in similar situations.

Ari.

Ari- Had the same with a bonus delay that drove the fibreglas nose cone deep into a fin. Nose cone shoulder shattered, but the fin only dented and delaminated. I warmed some West Systems to thin, mixed and used a syringe with a big needle to 'inject' it as deep as I could between layers-only takes a little. I wrapped industrial Teflon tape (sticky side out) to kinda conform to the airfoil and clamped it for several hours. Sanded and re-shot it-perfect. Then I killed it the next flight *sigh*

Yep, epoxy has good gap-filling properties (unlike CyA).

Thank you guys. Gap-filling is less of a concern in this case--the veneers are all there, they simply bend together like the pages of a magazine :=)

Ari.

I'd slightly thin some yellow glue and try to force it into the delaminated area with a stiff bristled artist's brush. Let it sit for a little while to allow the wood to soak up the glue, then clamp the area using plastic cauls (so the glue won't stick). You shouldn't need too much pressure, just enough to get everything back into shape. Excess pressure might actually force the glue out of the wood.

fyrwrxz said:

Ari- Had the same with a bonus delay that drove the fibreglas nose cone deep into a fin. Nose cone shoulder shattered, but the fin only dented and delaminated. I warmed some West Systems to thin, mixed and used a syringe with a big needle to 'inject' it as deep as I could between layers-only takes a little. I wrapped industrial Teflon tape (sticky side out) to kinda conform to the airfoil and clamped it for several hours. Sanded and re-shot it-perfect. Then I killed it the next flight *sigh*

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Timely thread, my 3.9 LOC V2 has a delaminated fin from a motor defect generated playa interference event. Fin needs fixing before a long awaited J350 flight. Is there anything special about West Systems, or can the same be done with aero proxy?

WoShuGui said:

Timely thread, my 3.9 LOC V2 has a delaminated fin from a motor defect generated playa interference event. Fin needs fixing before a long awaited J350 flight. Is there anything special about West Systems, or can the same be done with aero proxy?

Click to expand...

LOL! "Playa Interference" indeed! Same thing happened to my Thumper Jr. (catalogue model for What's Up Hobbies). Forgot to take a pic of the crater-dammit! I've never tried warming AeroPoxy, but be warned-anything past ambient tends to accelerate epoxies so I adjust working times accordingly. I also use *slightly* less hardener-be careful there. Some exothermics tend to catalyze quickly, so you have to experiment a bit. Keep in mind you are using really small batches so any concentration of warmed two parters kick off rather fast when confined to a smaller volume container (like a syringe). I like doing this more than using whatever solvent or thinner unless I have a ton of experience with it. I think Xylene may work with Proline, but I have to go out-of-state to get some to try. I use Hysol for most alchohol based thinning. I'd avoid anything else (like rubbing or wood alkies) that contains water. I have found internal applications of 86 proof to make the repairs more enjoyable and time passes faster. (That goes in the rocketeer)

Wood glue, injected with a syringe, then clamped for a few hours.

The plywood wasn't made with epoxy; it doesn't need to be fixed with it, either....

-Kevin