cracked dimple

[hydroguy2]

Last night I thought I could whip out riveting the aileron brace to the top skin on my -7QB. Did the left wing on the table a few days ago and was easy. I work alone, so the right wing is still in the stand. First few rivets were not perfect, but ok. I tried to adjust my technique to make them better, but noluck. Here's a next couple....Yikes! I'll be perfecting my drillout skills.


But what do I do about the one that cracked the dimple?


B

[robertahegy]

That crack will do nothing but grow. If it is confined to the bracket, I would replace it. Also, I hope you are not just dimpling the punched holes without drilling and deburring before you dimple. That could explain the cracking.

Roberta

[asav8tor]

Agree. Hard to tell from the photo but it looks like your debur process needs improvement. That said, don't over do it. I have seen holes countersunk, that's not good either.

[LettersFromFlyoverCountry]

Maybe it's the resolution -- or maybe it' s just my old eyes -- but that edge on the left one looks a little ragged too.

[TerryWighs]

Replace bracket IMHO....Also, is the bracket thickness more amendable for countersink drilling rather than squeeze dimpling???

[alpinelakespilot2000]

You could drill it up to 1/8 or 5/16, debur, and re-dimple for a larger flush rivet. That should help having to avoid replacing the hole brace, especially since it appears that many or all of the other rivets have already been set. Good luck.

[jsharkey]

When did the crack appear? After dimpling or after riveting?
It shouldn't happen after either. Knowing when might help identify the problem. How are you setting the rivets? Bucking? Hand Squeezing? Pneumatic squeezing?
Jim Sharkey

[cytoxin]

the rivet next to it looks sheared. note the figure 8 shop head. how are you driving these? what kind of dimple dies?

[hydroguy2]

Let's see where do I start.

Match drilled, light deburr, then dimpled using Avery dimple die. Hand squeezed with Tatco squeezer. I use very tiny amount of deburring, because it seems to enlarge the hole when dimpled. Last night I seemed to have a few rivets which leaned a bit, but covered the hole and were acceptable.
These two happened while I was trying to improve, they started to cleat over, so I tried to salvage the lean. This is the result. I stopped when things got worse. These are the only bad ones, the other side of the brace is already riveted to the rear spar, so was trying to avoid drillng out 30+ rivets. I can probably get a TechAdvisor to stop by and have a look and possible repair options

[MTBehnke]

It could be my eyes - but the angle of the dimple looks pretty steep. Is it possible you dimpled with a larger die? That would likely lead to cracking, and the loose fit could result in the bent rivets.