Rudder Stiffener Rivets

[tim.randles]

I was back riveting my rudder stiffeners when I realized the rivets were ending up a bit flat, over-set. Is this something to worry about? None of the dimples or rivets are cracked. Are there critical structural loads on the stiffeners such that I should be worried about how much I've set the rivets? If these rivets were holding skins to ribs/spars I would probably drill them out and reset them. Maybe that answers my question... Ideas?

 

[HEGASIS]

do you have pics?

 

[Paul Thomas]

While not as critical as a spar to the integrity of the airplane, if they fail you'll be in trouble. I'd hate to have to think about it in flight. Are you going to do acro? Any rivet that not set right is being replaced on my airplane; I know many believe the second rivet will be worse, but to me, it only means I'll have to replace it again... I also put the first dent in a skin doing that.

I understand the rationale of rivets not having to be set perfectly on a shelf, but I don't understand it when it comes to any control surfaces or places I won't be able to get to. IMO, if you have several of them in a row that are bad, it get exponentially worse.

I guess I'm just scared of the gloom and doom scenarios, but I'm also glad to be as it forces me to do things as best I can.

 

[mannanj]

Rivets

If it's only the stiffeners and they're not split or totally squashed even with the dimple, you're probably ok. If you're not experienced in drilling out faulty rivets, you will probably do more harm than good.

Check the upset head. (flatened side on the inside.) the ideal size should be 1.5 times the rivet shank diameter. I'm sure you know that already. A little over or under is not going to bring you down in flames.

I don't have the info in front of me now; but others on this and other websites have done extensive tests and even grossly over or under driven rivets met or exceeded the strength requirements for a riveted joint.

If you can get an EAA Tech Counselor or an A&P or an experienced builder to look at your work, I would do that before I proceeded further.

 

[tim.randles]

This is one of the worst ones. It's pretty square, not sure why it looks like it was set on a slant in the picture.

 

[az_gila]

Numbers

For an exact evaluation of tolerances allowable, actual numbers are here...

http://home.earthlink.net/~gilalex/rivet_spec/rivet_a.htm

gil A

 

[ditch]

[QUOTE
I don't have the info in front of me now; but others on this and other websites have done extensive tests and even grossly over or under driven rivets met or exceeded the strength requirements for a riveted joint.

QUOTE]

This is the kind of statement that I've been waiting to hear. I've asked this a few times but not much luck with a solid answer. I too have rivets that look exactly like the ones in the picture and consider them just fine. One thing that I have noticed is that when you are riveting and you insert the rivet into the hole and see how much is sticking out, you buck it and it looks proportional to how much was showing, but when you come back and look at them again, you forget how they looked before bucking and think you over did the rivets. I guess, I would be satisfied with your bucking, but then again, mine look simular. We're either both going to crash or live to a ripe old age, hopefully the latter

 

[Brantel]

http://www.kilohotel.com/rv8/rvlinks/marvelrivets.html

http://www.vansairforce.com/community/showthread.php?t=10959&highlight=rivet+strength

 

[tim.randles]

http://www.kilohotel.com/rv8/rvlinks/marvelrivets.html

http://www.vansairforce.com/community/showthread.php?t=10959&highlight=rivet+strength

Thanks for the link. I'd heard of this write-up but never actually read it. Good information.

I think I'll go back and take a close inventory of all of the rivets to see exactly how many are over set and what their relationship is to any other over set rivets. I'm a little worried about drilling out rivets in the thin .016 rudder skin. If I have two or more over set in a row I'll drill out a few to break up a continuous section of them. If there is only one in a stiffener I'll probably just leave it.

 

[jsharkey]

This is one of the worst ones. It's pretty square, not sure why it looks like it was set on a slant in the picture.

They look great - build on!

Odds on that drilling out and resetting will be worse.

Jim Sharkey
RV6

 

[WilburD2]

Happy rivets

Tim, if that one is the worst of them, I don't think you have anything to worry about. I've seen worse actually flying on commercial airliners. The key is the two next to the one in question. Since they look passable, the bad one is pretty well covered.
That having been said, it boils down to your personal comfort. Will it continue to nag at you once you've closed up and moved on. If it will, remember, smaller drill bit, slow starting speed, and deepen the center dimple of the rivet with a center punch before you start drilling.

 

[ditch]

Well, Brantel, you saved me hundreds of hours of sleep. That was the best article that I've seen on rivet strength and I now feel fully comfortable with my work. Lets just say you saved the day It would be really interesting to know how many pounds are exerted on the rivets at say, 6 G's ? Can't be anywhere near failure. I think that this article should have its own permanent heading on the forums so that anybody who starts a rv project can read this. This really is the only issue, to me, about building an rv ofcourse until you get into the FWF and instruments. But as far as the plane structure itself, with match hole construction and a bit of care when working with the aluminum, if you can buck a rivet fairly good, you shouldn't have to worryabout rivet failure. Thanks again for the article. I actually stopped working on my wings a week ago and had no interest in continuing until I had some concrete reasurrance of my work. Guess I'll be bucking shortly again.