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Doh! Queston on bad dimple and broken rivet

Reflex

Well Known Member
I've had much higher success shooting rivets than squeezing them. Last evening, while working on finishing up the vertical stab on my -14, the bucking bar slipped while driving a rivet. The damage was to the underside of the dimple (rib).

One side of the bottom portion of the dimple was crushed. The rivet was removed, the dimple resqueezed, and another rivet was set. This time, a "Main Squeeze" squeezer was used. I must say that resqueezing the dimple made little difference in the dent in the dimple.

About 2/3 of the way though the squeeze I felt something give. Upon completing the squeeze, the top side of the rivet (skin side) looked great. But, when I examined the shop head I found a problem.

As seen in the pictures below, it appears that the rivet broke/sheared. In addition, you can see what appears to be a piece of the dimple actually broke off.

On the top side, it's cosmetically perfect. As you can see, the bottom side is a problem.

Issues:

  • Broken rivet
  • Cracked lower dimple

Recommendations?

Broken%20Rivet%20From%20Side.jpg


Broken%20Rivet%20From%20Top.jpg


Thanks,

Fred
 
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First, I might just drill it out to see if the dimple has really broken or it was something else. The photo is not clear for me on that.

Without further speculation, then decide on what the course of action might be based on improved information.
 
BillL...good call!

The rivet and dimple were NOT broken. The removed rivet looks.....for lack of a better term...club shaped. I took additional photos. Hopefully the pictures below will shed some more light on my issue.

Top side before removal
Top%20View%20Clubbed%20Rivet%20Skin.jpg


Hole after 2nd removal
Dimpled%20Hole%20Bottom%20After%20Drill%20Out.jpg


Side view of removed rivet (ugly!)
Clubbed%20Rivet%20Side%20View.jpg



Top view of removed rivet
Clubbed%20Rivet%20Top%20View.jpg


Bottom view of removed rivet
Clubbed%20Rivet%20Bottom%20View.jpg


Hope that helps give more info.

Thanks,

Fred
 
Wow, it looks like a material shear failure! This is not a fact based answer, but since it appears strongly like a rivet failure (still puzzling) just put another rivet of the proper length and set it, then move on. While the "damaged" area is not "perfect" I would doubt there is any reduction in fatigue or static strength.
 
Wow, it looks like a material shear failure! This is not a fact based answer, but since it appears strongly like a rivet failure (still puzzling) just put another rivet of the proper length and set it, then move on. While the "damaged" area is not "perfect" I would doubt there is any reduction in fatigue or static strength.

Nah... no failure, the rivet just "smeared" in the bucking process.

An "oops" rivet would be an easy fix if any of the dimple edge is damaged.
 
Wow, if understand this correctly that is a squeezed and still intact rivet. I knew they could handle a lot of lateral stress without breaking, but that's impressive.

I too get better results bucking, but have never had a rivet do what you describe - especially while being squeezed...?
 
Clinched Rivet

That is what you call a "clinched" rivet. It is normally from using to long of a rivet. If the rivet is to long and you are not straight on the rivet, the rivet just bends over like a nail. Just enlarge the hole to a #30 and put a minimum length 1097 (oops) rivet in.
 
Before enlarging the hole I decided to try one more time. Again, the proper length rivet was put into the hole (3-3.5) and squeezed. I've devised a system that allows me to insure the squeezer is square/perpendicular to the rivet.

Unfortunately, the results were nearly identical. To me, it appears that the rivet is, in effect, being extruded. That is, it's trying to fill in the space with the least amount of pressure on it. Since one side of the dimple is nearly gone, I believe that the rivet is trying to fill that space in.

Before removing and going to the Oops rivet, I guess I should ask what would keep the Oops rivet from doing the same thing? If the dimple is bad on one side, I would think that the Oops rivet would try to smear to "fill" that side. It may not be as pronounced, but wouldn't the outcome be similar?

Many thanks,

Fred
 
Wow, if understand this correctly that is a squeezed and still intact rivet. I knew they could handle a lot of lateral stress without breaking, but that's impressive.

I too get better results bucking, but have never had a rivet do what you describe - especially while being squeezed...?

I agree.

Are you using the recommended rivet length or a size you determined on your own?

Setting rivets with a squeezer is actually the lowest risk and highest repeat-ability process you can use, so I recommend you do a bunch more practicing or maybe even get some help from an experienced builder to critique your technique and give you some tips. A hand or pneumatic squeezer is always the first tool we reach for in our shop.

An NAS1097 rivet would be a good option for fixing this minor problem.
 
Clinched Rivet

The rivet is clinching most likely because the hole is big. Dimpled holes are bad about that sometimes because dimpling the hole also slightly enlarges it. If you ream the hole after its dimpled to a #30 the hole will perfectly fit the #4 rivet you put in it. Use a 1097 4-3. It will look slightly short but i gurantee it will make a perfect butt. Also make sure u slightly hit the dimple with your debur tool because a 1097 head is slightly bigger than a #3 head so it will sit a bit high if not.
 
Hand squeeze

if you are using hand squeezes with a really deep reach, they tend to flex alot when you squeeze them. When the jaws flex they get the sets out of parallel and will cause the rivets to clinch. You will have much better results squeezing rivets if u get smaller jaws that dont flex.
 
Sounds like the general consensus is the damaged dimple has nothing to do with the problem setting the rivet.

Looks like I'll have to resort to the Oops rivet....just not sure why. The length is definitely not to long and the hole is not too big. Plans (RV-14, page 06-05 figure #2) call for a 3.5 length in this spot. All the others have driven nicely.

Have 8 left to drive/squeeze. They're in the spots over the hinges. Not looking forward to that!

Thanks all,

Fred
 
The other thing you can do is take a rivet one length longer than what is spec'd and give it a slight squeeze before you insert it in the structure. That will fatten it up so it doesn't tip in the hole, and may allow you to drive it without further enlarging the hole.
 
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