Phil

Phil

Well Known Member
Everyone has a builder moment where they slap themselves as say "Why did I do that?" This afternoon I had one.

I'm working on the HS and was in the process of removing a rivet. In the process of punching it out of the hole, I bent the (thinner) flange on the back side.

I tried to bend it back, but obviously the spring-back keeps me from getting a tight fit with the spar. This has resulted in an 1/8" gap between the rib flange & the spar.

Short of some major disassembly to replace the rib, I think I have the following options.

1) Find a way to bend it more. (That's the tip I'm hoping someone knows.)
2) Place a shim between the flange and spar and rivet through it.
3) Try and find some creative way to clamp it to the spar while setting the rivet.

Thoughts? How have some of you fixed this issue?

Phil


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Modified Bucking Bar

Glue an o-ring or thin slice of rubber tubing to your bucking bar. Shoot and buck rivet using that ring over the top of the "shop head to be." You'll get a good shop head and the ring will have snugged up the bent flange while bucking.

George
 
Seconded

George is right on. :cool: This will not be the only time you will run into a recalcitrant flange that needs some coercion to sit flat. I have a 1/8" thick rubber washer for the purpose. Bang away just long enough to clinch the pieces and then the rubber tool can be removed to finish the shop head.
 
Not being an RV builder but one who has driven a lot of rivits...I would just put the manufactrued head on the rib side and the shop head on the spar side and push the rib tab up with the rivit gun before setting the rivit.
Dave (Swift driver)
 
Thanks for the tips so far. Intrested in hearing more, I might learn a few things.

Dave62 said:
Not being an RV builder but one who has driven a lot of rivits...I would just put the manufactrued head on the rib side and the shop head on the spar side and push the rib tab up with the rivit gun before setting the rivit.
Dave (Swift driver)
Click to expand...


I thought about that too, but there's less than 5 inches of clearance for the rivet gun. So you can't get the manufactured head on that side. :(
 
Use a pulled rivet and you can hold the tab down while pulling it.

Use squeezer with longeron yoke.
 
Mel said:
Use a pulled rivet and you can hold the tab down while pulling it.

Use squeezer with longeron yoke.
Click to expand...

Speaking of that Mel, I've been looking for a chart that cross references Solid Rivets with a pulled Rivet equivelant. Do you know where I can find one?

Thanks,
Phil
 
All you need is the diameter and grip length. Unless you're talking about strength. If you're talking strength, just compare the specs. I don't know of a direct cross reference.
 
I did come up with another neat little trick.

Even after bending the flange back to shape (and if you look closely at the photos) you could still see a little wave in it.

I took my 1/8" pop rivet dimpler and reversed the dies so that the flat side of the die was against the flange. I gave it a couple of cranks and presto! A perfectly flat flange.

Now that the wave is out of it, the flange sits much flatter. I'm guessing the gap is around 1/16" or less now. It'll be much easier to get it tight now.

So don't forget about your dimple dies. They work the other way around too!
 
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Another way is to drive the rivet only slightly, just enough to expand it snug in the hole. Then put the bucking bar on the flange beside the rivet and give the manufactured head a couple light taps with the gun. That will pull the flange against with the spar and with the rivet snug in the hole, it will hold it.

Now, in your particular case, this technique probably wouldn't work, because the flange was distorted so much. But if there was just a little gap, it will work fine. Glad the pop rivet dimpler worked.
 
One other method to consider

Phil - -

I handled a near-identical situation by gooping a small layer of tank sealant between both surfaces, and closing with a higher strength (screw-type) cleco. I waited a day, removed the cleco, and the material stayed together while I set the rivet.

Good luck!
 
Factory Driven Rivets

Guys, Just wanted to throw in an interesting observation.... While working at Cessna a while back and walking on the assembly line I noticed that a lot of places where ribs are fluted in order to maintain straitness there are rivets that are located in the middle of the raised flute. In other words there is a gap between the rib and the skin where a rivet hole is located. I thought this was quite interesting.... A different situation, but I would think a similar effect would result from both.

I got curious and looked at some older Cessnas that I have access to and there are similar rivets visible through inspection holes....

Any experienced rivetters have any thoughts on the matter?
 
not very experienced but it should be fine. your not going to lose strength. it might look a little ugly but as i have learned. trying to fix minor things may come to repairing way bigger ones. in the airlines we see plenty of rivets that are damaged ,missing, blown out by lightning strikes. so one little bent flange wont be a problem. my 2 cents
 
In similar situations I've asked a friendly helper to push back the flange with the tip of a screw driver or similar while I gave the rivet a couple of hits with the gun and bucking bar to swell it and hold everything in place. You can then remove the screw driver and complete setting the rivet. It all depends on available access. I liked the earlier idea of using a some rubber or other squishy material between the bucking bar and the flange with a hole in it for the rivet tail to pass through - a bit like a spring loaded back rivet set.

Jim Sharkey
RV6 - Wiring etc
 
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