Goofed up, forgot to put CWF on fin before attaching

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Bill S

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I had decided to give CWF another try, after deciding that the Bondo glaze I had been using was adding too much weight (plus the stench is a bit much). I had planned on applying CWF on both sides, then putting between some books to dry for a day, then sand, and glue them to the body tube. Well I got into my usual routine and forgot to put the CWF on the fins before attaching, and glued one on the body tube. Can I still use the CWF and not get warping on that fin, or should I use the Bondo on that fin and CWF the other 2 that aren't attached yet?
 

neil_w

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I'm not certain but I would be reluctant to try CWF on an attached fin. I think the Bondo is a better idea.
 

Bill S

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I'm not certain but I would be reluctant to try CWF on an attached fin. I think the Bondo is a better idea.
That was my gut reaction as well, but I wasn't sure.
 

Nathan

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If you are talking about balsa fins then yes, CWF might make them warp. If you are talking about birch plywood fins then there should be no problem.
 

CalebJ

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Why can't you clamp an attached fin as needed?
 

rklapp

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Shouldn't be too hard to pop the fin off (assuming you haven't crazy filleted and painted yet)...
 

Bill S

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The fin is firmly attached, but it might be possible to remove it to put the CWF on it. I'll look at that.
 

Kreitz

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Could you CWF then clamp the fin between 2 pcs of medium thick Ply? Something like 3/16" plywood chunks with binder clips in several spots around fin.
 

CalebJ

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That's what I was curious about - seems like clamping with them mounted wouldn't be a problem.
 

CalebJ

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Even a couple of books and c clamps could work.
 

neil_w

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Could you CWF then clamp the fin between 2 pcs of medium thick Ply? Something like 3/16" plywood chunks with binder clips in several spots around fin.
That sounds pretty good to me. I wouldn't remove the fin for this purpose.
 

Bill S

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I decided to put CWF on the attached fin, and put parchment paper on both sides, on the edge of a table, inside a large book I don't care about, weighed down with about 6 other books. If that doesn't keep the fin flat while it dries, nothing will. :)
 

BABAR

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For things you can’t stick into a book, Hotel key cards and clothes pins or other clamps can be helpful in keeping surfaces flat while drying, I use this when I need to repair broken fins as well, when part is attached to the rocket and the other part is partially or completely broken off.
 

Bill S

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After a day of drying, I took the books off of the fin that was attached to the body tube, and all looks well. No warping, etc, so I can continue on. I've also CWF'd the other 2 fins off of the body, and after sanding, they'll be attached to the body.
 

Ez2cDave

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Pardon a dumb question . . . "CWF" ?

Dave F.
 

rklapp

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Thanks, Chuck !

Too many "acronyms" . . . LOL !

Dave F.
I use it for filling tube spirals and is easy to sand outside on the lanai. I find its really messy when sanding balsa and easily warps so I stick with sanding sealer that I use as a dip.
 

Lee

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I’m a rookie here – first post. Since my launch field is 3 soccer fields surrounded by large trees, I build disposable “wind tester rockets” and launch one before risking my regular rockets. My wind testers are simply rolled up copy paper, rolled nose cone from card stock, and scrap balsa left over from kits. Since the balsa grain from the scrap usually runs the wrong direction, I strengthen the balsa by coating with tightbond. which actually makes the fins stronger than CWF would.

I am currently building an Este Door Knob kit which, disappointingly, has balsa fins. Why not use tightbond to strengthen them?
 

neil_w

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I am currently building an Este Door Knob kit which, disappointingly, has balsa fins. Why not use tightbond to strengthen them?
Welcome!

You're not the first to use Titebond for this purpose. I am not a fan. It's wet, messy, runs, and is terrible to sand. For adding strength, I consider papering to be a greatly superior approach (either with label paper, my personal preference, or by gluing copy paper which adds more strength).

Ultimately, everyone uses the technique that works best for them. It's good to try a few different ones.
 

Blast it Tom!

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I used watered down Titebond III on my brother-in-law's Estes V2, and yes, it was a bit of a pain to sand, but it did end up very nice, and stronger, I believe. TBH if I had to do it over again I'd be strongly tempted to replace with plywood.
 

Sooner Boomer

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I guess I'm just getting old*. I never had any problems with fins warping. We glued everything together *then* worried about the finish. The first thing we usually did, was to lay down a coat of butrate dope (lacquer - used on model planes). This seals the grain, won't cause wood to warp, and lets you slather just about any sort of sanding sealer or finish smoother on that you want. Dope by itself is very thin - it won't make the surface smooth. To make it smooth, we would make our own by mixing a small amount of baby powder with clear dope. I've also done this with water-based polyurathane (put the poly on first, and you risk warping!). After several coats, sanding between each coat, you get a mirror finish. Just remember, you can put enamel over dope, but never dope over enamel!

*now get off my lawn!
 

splangie

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Welcome!

You're not the first to use Titebond for this purpose. I am not a fan. It's wet, messy, runs, and is terrible to sand. For adding strength, I consider papering to be a greatly superior approach (either with label paper, my personal preference, or by gluing copy paper which adds more strength).

Ultimately, everyone uses the technique that works best for them. It's good to try a few different ones.
Agreed. I paper all the balsa fins. I think it is well worth the effort. Especially since it doesn't really take much effort.
 

Lee

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I don't experience warping as long as I fill both sides of the fin at the same time. I fill with CWF or watered down tighbond - apply just enough to do the job without getting drippy. The fins dry while elevated by safety pins stuck in the root edge. Has worked every time for me.
 

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