submikester

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boink!

JettPilot

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That is not horribly bad, it should fly fine. Cover it with covering so it does not look bad, take it to the filed and see how you like flying it.

30 minute epoxy is much stronger than the 5 minutes stuff, you did good using that. BTW: Tape is not always a good option to hold wings in place, it can slip over time before the glue dries [:@]

JettPilot

da Rock

As you've learned, there is a technique to using epoxy. Just as you need to hurry with 5-minute, you have to do something special with 30 minute. You have to check a couple of minutes after it's clamped to make sure the clamps (or tape) haven't slipped.

The value of using longer cure epoxies is mostly weight and strength. 5 minute epoxy has no time to penetrate very deeply. It does grab the surface but that's about it. And it sets up so fast that most of the epoxy you've smeared on the joint simply fills gaps. Sometimes it creates the gaps, so it's nice that it does gap filling. But what you've gotten is a lot of epoxy going aloft that's doing very little for you. I try to wipe the excess that squeezes out from a compressed joint, and quit using 5 minute because so little showed up and what did was so easy to peel off the wood.

But you didn't ask your question to get a lecture on the benefits of slow curing epoxy.

If I were you, I'd fly go ahead and fly it. Truth is, that joint isn't much weaker than it would have been with 5 minute, if in fact it is weaker. The only consideration to flying it would be how it "fits" now. Are the retract linkages out of range now? Has the dihedral changed much? That could make the airplane look strange as well as make the landing gear struts angle out.

da Rock

It actually might not be too much effort to fix it.

A friend of mine recently changed the dihedral of one of his wings. He hacksawed down the centerline. Turns out that the inside ribs were plywood and the hacksaw blade left most of the ply on each side. He then sanded the new angle in, half to a side, and re-epoxied the two halves.

In your case, after you saw the two halves apart, you'll need to remove the excess epoxy. You'll need to get that out of the way so the two halves will mate at the correct angle. Good thing is that the longer cure epoxies will bond to cured epoxy strongly. So any residual cured epoxy won't weaken the joint. Resist the temptation to reglue with 5 minute. It doesn't stick to cured glues as well as slow cure does.

submikester

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boink!

Robby

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Here is a little hint for you..
Do as Darock suggested.. Cut <carefully> apart...
Sand flat..
THEN....
Use your 'woodpecker' ,, yes, the one for covering...
Run it thourghly over both pieces making damn sure
it is completely covered with tiny 'holes'...
Always use 30 min set epoxy to join wings... Mix
glue,, use covering heat gun to warm both pieces..
Watch you do not over heat covering on ends..
The heat will cause the epoxy to get thin and flow
into the holes easier... And yes, it will cause epoxy
to set faster.. This will make for a stronger attachment
and reduce much of the minute bubbles in the glue..
Put glue on one piece,, work it well so it goes into
the holes,, do other piece the same.. Then stick together
making sure you have proper alignment..
Let set for few minutes then wipe off excess with
alky<99%> .. Keep wiping,, it will remove all
of the excess...

da Rock

Actually, cutting out the joiner isn't necessary at all.

Drill a couple of oversized holes into the existing joiners. The idea is to use a couple of short pieces of almost anything strong as "sub joiners". The new joiners are merely to strongly link the existing one. The existing one will do exactly the job it was designed to do after it's strongly joined at the saw cut.

I've used short carbon fiber tubes as short joiners. They'd work here like gangbusters. Make the holes they fit into oversized enough that those carbon fiber tubes don't have to be forced in. Matter of fact, they ought to sorta rattle around. You don't want them to affect the dihedral with their fit. They're going to wind up fitting perfectly and strongly with the generous use of epoxy.

When you've got the two wing halves mating perfectly, and the two new short joiner holes ready, fill those holes generously. Then press the new short joiners into the holes. Any epoxy that squeezes out can be wiped on the wing ribs. The epoxy will fill the loose fit and when cured, the CF tubes will be SOLIDLY and perfectly "aligned".

The idea is to use epoxy's gap filling to advantage. Once the CF tubes support the center of the cut apart joiner, that joiner will provide whatever strength it was originally going to provide.

If you're worried about the CF tubes getting excess weight inside them, simply plug the ends with balsa plugs or tape the ends with masking tape.

submikester

My Feedback: (6)

Boink!

da Rock

Glad that idea seems workable to you.

I've got that same ARF in it's box, sitting under the workbench, so am more than mildly interested in your effort. Of course, it's been pushed back once by the Kyosho P40 Warhawk I just finished. And pushed back again by the Clipped Wing Cub I just got after being bitten by the 4cycle bug. But the Cub can't take too long to assemble.

cochinito77

another possible soulution that ive been told is that a heat gun applied to the epoxy will make it gooey and melt it, im sure its not good for covering but can't have everything...

da Rock

I would bet that the guy who told you that didn't think to mention how much heat it takes to soften the epoxy. It takes a lot. Some epoxies don't go soft until they start to char (burn). A number of them can't be defeated by a covering heat gun.

And for the most part, the heat doesn't melt the epoxy as most of us define "melt". Most things that melt will "freeze" back.

cochinito77

ok, i never tried that solution but thats what he said, i was gonna try it my mustang tail (horizontal stab) shifted when i was gluing it about a half of an inch-ish longer to the right, so when its on slow approach it dives at me, how do i fix that? thrust the engine the other way?

da Rock

Ask him if he knows what brand/kind of epoxy he did the heatgun trick to. If he's actually done it then no doubt it'll work for you if you've got the same gun and used the same epoxy BUT..... I wouldn't come close to trying it on just any epoxy with any heatgun, especially since the depth of the joint would work against the heat getting deep enough into the epoxy to "melt" any past the surface stuff.

About the only solution to a badly aligned wing joint, no matter what glue was used, is THE SAW !!!

But truth is, once you get your mind to accept the job, it ain't too bad a job, if you're careful.

submikester

My Feedback: (6)

Spent a few minutes down in the garage this morning...

I took some pictures but they were washed out by the flash so I'll redo them tonight.

I separate the wing from the center section and there is no way that joint would have held. It came apart way too easy. It was like the only thing holding it together was the dihedral brace so once I had the saw through that it came apart nearly clean. So now I just have to sand a little to get to some wood on the end of each section, make the new braces and drill the holes for them. It came apart without damaging the exterior at all too so I'm pretty pleased. Once I get it back together I don't think anyone will be able to tell there ever was a problem.

submikester

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boink!

BankYank

My Feedback: (63)

Hmmm. I have used the heat gun trick twice and it did work. I found the trick is once you start heating it up you must keep at it and not let it cool back down until its apart. Had to do it on a TF Cessna 182 rudder and did it on a something or other needing repair. After reading about it on here.
Pat

da Rock

The problem with it working on a wing joint is the depth of the wing joint. The heat from a heatgun will only go so deep. And as stated, you need to keep the melted area soft with heat, so you can't stop heating one side and go over to the other cool side. The heated side cools as you heat up the other side. And you can't pry the joint apart as one side of it melts because the cool epoxy holds that wide joint closed from the other side.

Heat does soften epoxy. But it won't work on every epoxy joint. It depends on the joint size and the heating tool.

And it depends on the epoxy. I once had to use a torch because a plumber's soldering iron (them puppies are HUGE and HOT) couldn't melt it.