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azav8or

Active Member
:eek: Has anyone had the machined head of the rivet break off while setting a rivet? I am working on attaching my ribs to the main spar and I have had 3 break off. It has looked like it sheared level with the flange of the rib. I am using the double offset. The broken head shows no smilies.

This is the second spar and I had no problems with the first spar but now wonder if there is a problem I should be concerned with. I compared the double offset rivet set to a straight set and it appears the double offset is a little flatter at the bottom of the cup than the straight set. I switched to the straight set and the rivet heads appear to be better.

My main concern is whether or not the ones that didn't break off are structurally sound. They appear a little more flattened (very slightly) but I am cautious about things like this. The thought of drilling out every rivet in the main spar scares me. Any thoughts would be greatly appreciated.
Thanks, Joe
 
Your double-offset set may not be right. If you bought it retail from a reputable supplier, it should be ok.

If it's Boeing surplus it might not be right. It's hard to tell. There are a lot of specialty rivets out there.

I'd also make sure you don't have a bad batch of rivets, and that you've deburred the rib holes properly.

Very strange.
 
Make sure you are not trying to strike the rivet too long after you do the first shot. The rivets work harden and are more likely to crack the heads. If this is not the reason, I'd think it must be a bad rivet set or the set is bounciing on the factory head.

Snap Socs from Avery will work well at protecting the head of the rivets. I used them on my spars and had no drill outs, and not because I'm a great riveter!

HOpe this helps a little. Good luck.
 
Thanks for the replies. I have the books that came with the Avery kit that say to set a rivet in 2 1/2 to 3 seconds. I bought Dan's cd that says he takes average 1 1/2 seconds. Am I hitting them too long? Am I work hardening them?

Thanks again. I greatly appreciate it. Joe.
 
If you are getting the correct size shop head, after a 1 to 2 second burst, or up to 3, 1 second bursts, you should not be work hardening them.
If you have the rivet gun set too low (air pressure) and you are requiring long bursts or longer multiple bursts, then you are. You should either increase air pressure or go to a larger rivet gun.
For the spars, you should have at least a 4X rivet gun or larger, or set them using a heavy hammer in a C frame or arbor press. When I did my -6, I used a 2 lb sledge in the reinforced Avery C Frame. It worked great with no need to drill out any rivets. If you use care in setting everything up, the manual "armstrong" method works well.
Good luck.
 
i think 2.5-3 seconds is too long, especially if your gun is set lower than it should be? 1.5 seconds has worked great for me, but the pressure needs to be adjusted for the size of rivet. if you can count the hits, at the correct pressure you should get about 5-6 at the most.

what size gun do you have, and what pressure are you using? sounds work hardened to me. also, maybe you are pushing to hard with the bucking bar that the head is pushing out and allowed to "wobble" a little?
 
I am using a 3X gun. I have an Avery pressure adjuster at the gun. I used enough pressure to set the shophead properly in 2 1/2 to 3 seconds assuming that must be the right. I am going to remove the adjuster at the gun and use Dan's recommendations unless there is a reason why I shouldn't. I appreciate all of the inputs. The offset I bought was from Avery and they are sending out another for me to compare with my existing. Great folks at Avery.

Thanks all, Joe.
 
It doesn't matter whether it takes 1.5 second or 5 seconds to set the rivet. Just don't stop striking it and then come back later (after 15-20 seconds) and strike it some more. Find a duration for striking and corresponding pressure setting that works is controllable and consistent for you and stick with it. Just my opinion...
 
I'm certainly no metalurgist, but after setting what seems like a billion or so rivets on my now completed airframe, I have had not one single rivet head snap off. I'm sure that I have gone more than 3.5 seconds and less than 1 on a number of occasions. The fact that you've already had several heads come off suggests that something is way off. I'd take a good look at the rivet set. For example, suppose the set had sort of a pimple in the middle. This could focus the hit right through the center, rather than distribute it. Check the rivets themselves. Maybe they're flawed. I had a couple of AN screws with no threads whatsoever. I know this is quite obvious compared to a defective rivet, but there could be a problem. I guess I'm just saying that if rivetting for an extra second or two causes rivets to fly apart, we should all have timing controls on our guns. I think your trouble is equipment/material rather than timing. Just my dopey opinion, of course.
 
I'm not sure I wouldn't try a different batch of rivets from a different supplier or bought at a different time to see if you might have some bad rivets. I have built my empennage and both wings and have yet to have the manufactured head shear off a rivet. I never set a rivet before I started my empennage. :confused:
 
szicree said:
I'm certainly no metalurgist, but after setting what seems like a billion or so rivets on my now completed airframe, I have had not one single rivet head snap off................. .
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Were all of the failed rivets the same length? I say that because many times I have ordered and received rivets that differ in color tone from a previous batch received from the same seller. This suggests to me certain differences in manufacturing and manufacturers from among the seller's vendors.
I have to agree that something is amiss here. Without exaggeration, I have set approximately a half million rivets over 34 years on the shop floor. Not once can I honesty recall a rivet head ever shearing off. One and 1/4 RV's later...still no sheared off rivet heads. One thing a production environment has that the homebuilder does not is a strict quality control department. Bad rivets would never get past the testing labs in the QA department before being stocked into the bins on the shop floor. I have to suspect a bad batch of rivets here. I also believe the hits or lack of hits or the intensity of hits or whatever is a non-issue. Upon inspection, rivets are routinely reshot to conform to Milspec and this could be hours or many days even weeks later. The fact that you experienced this unusual phenomena 3 times over such a short period leads me to suspect a defective batch of rivets.
For rivets to demonstate failure by shearing so readily and long before any flight loads are imposed upon them would certainly give me reason for concern. Sadly, I suspect little would be gained from contacting Van's regarding this matter. After all, it is unlikely they are equipped with and have the necessary tools to test and certify the fasteners they sell are indeed defect free.

Rick Galati RV-6A "Darla"
 
Thanks for the replies. I cannot trust that these rivets are sound. I am in the process of driling out 130+ rivets from my main spars. I can't in good conscience not remove them all. Wish me luck. I will purchase other rivets and try again. I contacted Vans and they have never heard of it happening. I contacted some local builders and 1 stated he only had it happen once in several hundred thousand rivets driven. One thing I have noted is that it takes several hard hits on the punch with a 16 oz hammer to drive the shop head out after getting the manufactured head out. Is this customary? Thanks for all of your patience with me on this.

Joe Manning
 
Can you post some pictures? I did some asking around today with some of the Boeing guys I work with, and they've never heard of such a thing. The only thing they could think of is if the set or rivet head were shaped improperly (i.e. you were only driving on the sides of the rivet) you could concievably make the rivet "wobble" as you were driving it which maybe sorta could cause it to snap off. You would probably be able to see evidence of this on the rivet head and the the piece you're rivetting, though.

Sounds hokey to me, and sounds hokey to them too, but that's all they could come up with.


edit: I should mention that they also thought it might be bad rivets....the hokey rivet set theory was all they could come up with OTHER than bad rivets. Everyone agreed that there's just no way to do what you're describing with some sort of technique, or lack thereof. I personally don't know much about this....just relaying info I got from the pros :)
 
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azav8or said:
Thanks for the replies. I cannot trust that these rivets are sound. I am in the process of driling out 130+ rivets from my main spars. I can't in good conscience not remove them all. Wish me luck. I will purchase other rivets and try again. I contacted Vans and they have never heard of it happening. I contacted some local builders and 1 stated he only had it happen once in several hundred thousand rivets driven. One thing I have noted is that it takes several hard hits on the punch with a 16 oz hammer to drive the shop head out after getting the manufactured head out. Is this customary? Thanks for all of your patience with me on this.

Joe Manning
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They'll come out easier if you take a smaller size drill and VERY CAREFULLY put a little hole down the middle of the shank after you pop the head off. It relieves the pressure a bit. But yeah, they can be a bear to get out sometimes....be sure to back it with something so you don't turn your spar into a pretzel.
 
This may be a longshot, but aren't there lots of different types of rivets that pretty much look the same? I have some of the "soft" ones and you can damned near squeeze 'em with your fingers. I seem to recall seeing a table listing all the different types, along with the markings (The soft ones have no dimple in the top). I guess I'm just wondering if all such rivets are designed to be shot with a rivet gun. I know it's unlikely, but I thought I'd throw it out there.
 
azav8or said:
Thanks for the replies. I cannot trust that these rivets are sound. I am in the process of driling out 130+ rivets from my main spars. I can't in good conscience not remove them all. Wish me luck. I will purchase other rivets and try again. I contacted Vans and they have never heard of it happening. I contacted some local builders and 1 stated he only had it happen once in several hundred thousand rivets driven. One thing I have noted is that it takes several hard hits on the punch with a 16 oz hammer to drive the shop head out after getting the manufactured head out. Is this customary? Thanks for all of your patience with me on this.

Joe Manning
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Joe, I am assuming here that you are talking about the 1/8" universal rivets that are used to rivet the wing ribs to the main wing spar.

If you are going to drill out 130 rivets (and it seems like you probably should) then I would highly recommend that you buy the Avery Rivet Removal Tool Part # 40053.

This tool will remove universal rivets consistently and without any possibility of damaging the spar. It's one of the nicest tools that I have and I wish I'd bought it earlier than I did.

Using a standard drill it's very easy to get damage removing universal rivets and on the wing spar that would be critical.

The only problem is that the Rivet Removal Tool will not work in tight spaces. So if you installed all the rivets with the factory heads on the rib side using an offset set you have a problem....the tool will not get in to the rib flange. If on the other hand you have the factory heads on the spar side you can get the tool onto most of them.
 
azav8or said:
.......One thing I have noted is that it takes several hard hits on the punch with a 16 oz hammer to drive the shop head out after getting the manufactured head out.................Joe Manning
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Joe,
It is considered good practice to always back up the work prior to punching the rivet out. If possible, have someone hold a bucking bar firmly against the shop head side right next to the rivet as you strike it with the hammer and punch. This practice minimizes the chances of deforming the material locally and reduces the stresses radiating through the structure. By focusing the hammering energy around the rivet, it usually makes removal much easier.
Rick Galati RV-6A "Darla"
 
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