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-   -   Recovery Plan: Split Fin During Build (http://www.oldrocketforum.com/showthread.php?t=19678)

BobP_in_Nevada 07-09-2021 02:34 PM

Recovery Plan: Split Fin During Build
 
Hallo! I have a brief story and a question.

Today I cut out fins to a pattern, and was gang-sanding them down to target dimension. And as I'm finishing up the last edge and thinking to myself, "Gee, I think this is actually the first time I've ever made fins from a pattern..."

***crunch***

All three have a crack along the grain ... but it's not all the way through.

I'd really rather not start over. But I also need this model to hold up for at least six flights (Yep, it's my NARTREK Gold project. It's only a wee 18 mm min-dia streamer model, a little like the Quest Pip-Squeak, and I'm only flying it on 1/2A and A motors. The fins are symmetrical trapezoid in shape and 3/32". )

I think I can, first, rub some wood glue into the fractures and dry under weight to lock down the injury. And then, though I wasn't planning to, I think I should paper them.

What say the Voices of Experience? And thanks in advance.

ghrocketman 07-09-2021 02:55 PM

Just soak the crack with thin CA.
Repair will be stronger than original.
They will hold up longer than you are interested in the rocket. Much longer than 6 1/2A and A flights.
'Nuf said.

mojo1986 07-09-2021 09:05 PM

What GH said. I don't use glues containing water to strengthen fins because I've never been able to control warpage. If you want to make a REALLY strong fin you can use thin CA with tissue paper. Just affix an edge of the tissue paper along an edge of the fin, give it a minute to dry, then drip CA along the fin/paper interface and 'squeegee' it with an old credit card, squeezing out most of the CA. After a bit of experience you can make a fairly smooth fin that requires little sanding, is rock hard, and has the grain almost completely filled.

Gus 07-09-2021 09:50 PM

Jeepers!

Two people in a row agreeing with something GH said (yes, use thin CA).

Someone call the Weather Channel and let them know that hell has frozen over. :D

ghrocketman 07-10-2021 01:35 AM

C'mon noww, Steve !
:D

BobP_in_Nevada 07-10-2021 10:07 AM

Well, that's about the most consensus I've ever seen here. So be it.

Thank you, folks.

BEC 07-10-2021 12:51 PM

Yup. Thin CA for a split like that, either during the build or as a field repair later.....

I'll bet hell doesn't stay frozen over for long :D

BobP_in_Nevada 07-10-2021 03:04 PM

Quote:
Originally Posted by BEC
I'll bet hell doesn't stay frozen over for long :D


With the temperatures here out west lately, any frozen-over place is looking good.

ghrocketman 07-10-2021 05:23 PM

It won't stay frozen for long.
I doubt anyone would approve of my method of starting indoor fireplaces.
It involves MEK and a hand-held BP SU F-motor as the Starter.

That however is far safer than the loon Uncles on my Mother's side of the family.
Way too many incidents with them involve a gasoline can and an already LIT FIRE.
One of their idiot sons actually checked the level of gasoline in a can with a LIT MATCH at age 14.
That was around 1975. He got his face blown in and almost OFF. Darwin award candidate still to this day. He never ceases to find idiotic ideas. When they passed out brains, most of that side of the family was too busy SNIFFING GLUE.

LeeR 07-10-2021 08:29 PM

Quote:
Originally Posted by Gus
Jeepers!

Two people in a row agreeing with something GH said (yes, use thin CA).

Someone call the Weather Channel and let them know that hell has frozen over. :D


Make that THREE!!

:chuckle:


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