How do I repair balsa?

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Joshua F Thomas

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My 24mm WAC Corporal did an unexpected left turn a second off the pad and ended up in the trees. After retrieval, I note it has a chip in the balsa on one of the leading edge fins. How I would about repairing this? The fin is painted and I'd like to be able to return it to the same good-looking condition.
 

afadeev

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My 24mm WAC Corporal did an unexpected left turn a second off the pad and ended up in the trees. After retrieval, I note it has a chip in the balsa on one of the leading edge fins. How I would about repairing this? The fin is painted and I'd like to be able to return it to the same good-looking condition.
A picture might help us provide a better answers.
Without one, and assuming the chip is not a deep cut or a crack, I would fill it in with wood filler, sand smooth, reinforce with thin layer CA on top (sand again afterwards), repaint, and fly again!

HTH
 
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Joshua F Thomas

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A picture might help us provide a better answers.
Without one, and assuming the chip is not a deep cut or a crack, I would fill it in with wood sealer, sand smooth, reinforce with thin layer CA on top (sand again afterwards), repaint, and fly again!

HTH
wac_corporal_ship.jpg


Yeah, it's not much more than a surface chip, but still...
 

neil_w

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I would use Carpenter's Wood Filler for that. Apply it, sand to shape (protect surrounding areas so you don't scuff up anything other than the area around the repair), and then apply touch-up paint with a brush. It won't look perfect but it'll be pretty good. That is a very small bit of damage in the grand scheme of things.... most of us have learned to repair (or live with) far worse. :)
 

Spitfire222

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If touching up the paint with a brush like Neil suggested makes the repair too conspicuous for your taste, you could try very light bursts of spray paint (assuming you originally sprayed the rocket and have the same can) to blend it in. This is mainly possible because, based on the photo you provided, the area appears to all be one uniform color. Good luck, let us know how the repair goes!
 

neil_w

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If touching up the paint with a brush like Neil suggested makes the repair too conspicuous for your taste, you could try very light bursts of spray paint (assuming you originally sprayed the rocket and have the same can) to blend it in. This is mainly possible because, based on the photo you provided, the area appears to all be one uniform color. Good luck, let us know how the repair goes!
That's a good point. I'm normally averse to re-spraying because it feels risky (whether or not it actually is), but from that picture it could be a good opportunity to do it.

However, for that little chip, I'll bet the touch-up will be darn close to invisible.
 
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Funkworks

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I once repaired a balsa chip with:

1. a bit of this:
1593106615731.png

2. a little sanding once dried,
3. a few sprays from the same can as originally used.

I was pleased.
 
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David Schwantz

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I agree with filling but I like to use 2 part bondo. Use the finishing putty, not the long fiber. This will be way tougher than other stuff, especially on a LE. Sand and blend in to fin. If you are not comfortable with spraying a spot, tape off whole fin to the root and the spary. will never see the line if you hide it like that.
 

rklapp

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Authentic battle damage...

spray a bit of paint on paper and use a small paint brush to blend it in. I guarantee you’ll never get another scratch again (not really).
 

Mike Haberer

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I would use Carpenter's Wood Filler for that. Apply it, sand to shape (protect surrounding areas so you don't scuff up anything other than the area around the repair), and then apply touch-up paint with a brush. It won't look perfect but it'll be pretty good. That is a very small bit of damage in the grand scheme of things.... most of us have learned to repair (or live with) far worse. :)
I'm a "live with" flyer unless the damage compromises flight parameters. We're sticking pyrotechnics in the rear end of a tube and lighting them. What could go wrong? I prefer to use my time flying vs. making it look pretty for every flight. Once it's flown the first time, each blemish tells a story and holds the launch history in situ.
 

Joshua F Thomas

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I'm a "live with" flyer unless the damage compromises flight parameters. We're sticking pyrotechnics in the rear end of a tube and lighting them. What could go wrong? I prefer to use my time flying vs. making it look pretty for every flight. Once it's flown the first time, each blemish tells a story and holds the launch history in situ.
I'm afraid of that balsa chip getting moisture damage and causing it to swell, deforming the fin, which would definitely compromise flight performance
 

Joshua F Thomas

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I ended up just painting it over, as I was afraid of damaging the rest of the paint surface by doing a repair so small. It looks ok.

balsa_repair.jpg
 

jrap330

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I'm afraid of that balsa chip getting moisture damage and causing it to swell, deforming the fin, which would definitely compromise flight performance
Really..that is your worried...than just apply sealer and/ or paint. It is such a small chip........do anything you want...but I who make then worst looking rockets call it a battle scar.
 

Joshua F Thomas

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Is that a thing?
Fins deforming due to moisture? Yes, yes it is. I just tossed out some fins from a kit because I used too much water when I mixed my sealer. Fins deformed. I tried to put them in a c-clamp for a few days with some padding, but it didn't work out. Lucky I had some balsa on hand to cut new fins.
 

jrap330

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Again small chip...not a whole fin area...So,use sealer. And do we not know that painting seals wood. Heck you could put glue on it or CA..used to seal fins by Rocketeers. But, what you stated happens sometimes, which is downside of papering fins...don;'t thin out white glue.

Good luck with whatever choice you perform.
 

rklapp

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Fins deforming due to moisture? Yes, yes it is. I just tossed out some fins from a kit because I used too much water when I mixed my sealer. Fins deformed. I tried to put them in a c-clamp for a few days with some padding, but it didn't work out. Lucky I had some balsa on hand to cut new fins.
Sure the whole fin but what about a small gouge? Once the fin is painted, it’s pretty well sealed even if dunked in water.
 

BABAR

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Sure the whole fin but what about a small gouge? Once the fin is painted, it’s pretty well sealed even if dunked in water.
I’m with you, unless it’s a really big chip (kind of an oxymoron) wood filler isn’t likely to flex a previously painted fin.

Of course, I am a fan of the 30 meter finish. I would have gone over it with a black sharpie and called it done!
 

beeblebrox

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Sure the whole fin but what about a small gouge? Once the fin is painted, it’s pretty well sealed even if dunked in water.
Use lightweight spackle. Comes on an 8oz container at HomeDepot, Lowes, Ace, Tru Value etc... If fins are small, use a single edge razor blade as a putty knife. It sands easily.
 

Joshua F Thomas

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Again small chip...not a whole fin area...So,use sealer. And do we not know that painting seals wood. Heck you could put glue on it or CA..used to seal fins by Rocketeers. But, what you stated happens sometimes, which is downside of papering fins...don;'t thin out white glue.

Good luck with whatever choice you perform.
I used just a slight spray of paint because the chip was so small, as you can see in the photos above.

Funny you mention papering. I tried to paper some balsa but I didn't like the process, as it was hard to get it to contour exactly to the shaped fins, and sanding down the edges of the paper to make them even meant I had to reshape the edges again. Maybe I need more practice.
 

jrap330

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I used just a slight spray of paint because the chip was so small, as you can see in the photos above.

Funny you mention papering. I tried to paper some balsa but I didn't like the process, as it was hard to get it to contour exactly to the shaped fins, and sanding down the edges of the paper to make them even meant I had to reshape the edges again. Maybe I need more practice.
No one ever states do you paper to the edge of the fin or wrap around the edge (too hard) so the two times I did it , I made the paper slightly smaller, so what if you see the edge of the paper. One time, not bad but the other time...the paper bubble up. Not sure I will tried again. I assumed when you stated, I water down the white glue...you papered the fin.
 

rklapp

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I've been papering for the past month, a lot less messy than thin wood sealer. I mistakenly bought frosted clear labels which surprisingly worked well. I use the Airfoil Assistant from NCR which also works surprisingly well on the edges. I just received paper labels that I'll start using.
 

neil_w

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No one ever states do you paper to the edge of the fin or wrap around the edge (too hard) so the two times I did it , I made the paper slightly smaller, so what if you see the edge of the paper. One time, not bad but the other time...the paper bubble up. Not sure I will tried again.
Pretty much any possible approach you can name, someone around here does it.

Personally, I never wrap around the edge, because I have so many fins that have complex leading edges that simply don't lend themselves to it.

I start with oversized pieces, sand off the excess, seal the edges (usually with TBII, but considering a switch to CA), then sand the edges smooth. I really enjoy the process. I usually use adhesive label paper, but have also glued copy paper when the situation called for it. I have *never* had any bubbling, edge lifting, or anything. Was it by the edge, or in the middle? Are you spreading the glue *really thin*?

One good thing about papering is that it's very cheap and easy to practice on wood scraps to master the technique.
 

rklapp

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Maus Werx on YT glues Kevlar strips to the fin edges. Not sure if I’m that dedicated to protecting fins.
 

BABAR

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Pretty much any possible approach you can name, someone around here does it.

Personally, I never wrap around the edge, because I have so many fins that have complex leading edges that simply don't lend themselves to it.

I start with oversized pieces, sand off the excess, seal the edges (usually with TBII, but considering a switch to CA), then sand the edges smooth. I really enjoy the process. I usually use adhesive label paper, but have also glued copy paper when the situation called for it. I have *never* had any bubbling, edge lifting, or anything. Was it by the edge, or in the middle? Are you spreading the glue *really thin*?

One good thing about papering is that it's very cheap and easy to practice on wood scraps to master the technique.
I go the opposite route. Balsa edges are either square or round. I wrap paper all the way around the free edges (sparing the root, obviously.) It does leave a small seam, which can be covered in various ways, or even incorporated into the design, like @neil_w ‘s vent holes;)
 
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