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TerryPancake

Well Known Member
:confused: After drilling out a few 426-3 rivet how can I tell if I really should use a Van's Oops rivet? I can't tell any damage/oblong on some the holes, others have just a tiny "oblonging". How do I gauge the hole?
Thank you in advance.
Terry
 
My suggestion is to only use a NAS "oops" rivet if you cannot get a regular but "pre-squeezed" 3/32 rivet to set properly and if you cannot re-dimple for a larger 1/8" flush rivet. The NAS rivets are not very strong. My preference is to, if it is possible to redimple, go up to a 1/8" rivet which is MUCH stronger (though such a course might upset the airshow awards purist! :eek: ). Alternatively, one way to increase your odds of getting a 3/32 to set in an enlarged hole is to "pre-squeeze" the next length up which will give it slightly larger diamter. Hope this helps.
 
Steve, thank you. I really don't have any holes that are that bad at all. I forgot about the presqueeze. That is the ticket. Perfect.
Thanks, gotta get back to squeezing. :D
T
 
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Goflyn said:
Can anyone give me more details on what a presqueeze is and how to do it?
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If the rivet hole is a little too big (i.e. you screwed it up by drilling out a rivet or something like that) the rivet will tend to clench over or just not really squash straight down when you squeeze/buck it.

When you squeeze the rivet, it'll get a little fatter. So what you do if the hole isn't TOO bad is take a rivet (one size longer works OK, maybe a half size, but YMMV....experiment with what works for you) and put it in your hand squeezer (don't mash your fingers with the pneumatic, please...I almost did this once without thinking....like, major DUH) and sqeeuze it just a touch before installing it. This will make it fatter and fill the hole a little bit better. This way here, you can go through 3 or 4 rivets in the hand squeezer trying to squeeze it straight with no support and just throw out the screwed up ones. If it's installed and you try to squeeze you still have no support (because the hole's too big), but everyone you clench over will require that you drill it out, messing up the hole even more etc etc etc etc.
 
NAS strength

"The NAS rivets are not very strong."

Steve,

Where have you found that the NAS rivets are not very strong. I'm thinking they are actually stronger since they have a larger bearing surface. (I'm a little concerned because I've used quite a few.) :confused:
 
JCOERS said:
"The NAS rivets are not very strong."

Steve,

Where have you found that the NAS rivets are not very strong. I'm thinking they are actually stronger since they have a larger bearing surface. (I'm a little concerned because I've used quite a few.) :confused:
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Hi John--Sorry to worry you. I should have said that they are "relatively" not as strong. What I've always heard is that the main problem with an NAS is the head of the rivet is not much bigger than the 1/8" shank. Much of the rivet's strength comes from the size different between the factory or shop heads and the shank size. With the NAS you are greatly decreasing the size difference on one end of the rivet.

I've used a few (and will continue to use them where necessary) and Van's says they're OK to use for occassional use. My main point was only that if I can re-drill AND re-dimple, my choice is often to go right up to a AN426-4. In most cases this is not an option, because you often cannot re-dimple. One example where it was possible was on my leading edge near my wingtip light cut-out. Because I could get my squeezer in at the cut-out, I now have a 426-4 right on the top of my leading edge skin. Could I have used an 3/32 NAS? Probably no problem. Not doing so probably cost me my "Grand Champion" award but, on the other hand, I'll never lose a minute of sleep wondering how strong that particularly rivet is! :rolleyes:

If I'm wrong in my explanation or thinking, please do correct me. Sorry again for the over-generalization.
 
Uh oh,

Now I am a little worried. I had trouble getting the flaps leading edge skin clecoed on. I found that the holes were slightly elongated while I was priming, so I decided to drill them out to #30 and used NAS 3.5s instead of the AD-3.5s.

Maybe I should call Vans on this one.
 
The point of the NAS is strictly cosmetic in situations you describe. If you have a bunch of 3/32 rivets, a "4" rivet is going to look out of place. But it does not have the structural integrity of a regular rivet. It's cosmetic. You're trading some measure of structural integrity for a uniform look. That's why you use them in a hole here or there, not in a whole line of holes.

If you drilled a whole line of rivets out to a #30, there's no point in using the NAS rivets, just use all 1/8 flush head rivets (of course yo'd have to redimple). They'll all look uniform, and they have maximum structural integrity.

I don't have any idea what the specific risk is of using a generous helping of NAS rivets as you describe. I think this is one of those times where the only good answer comes from the folks who designed the part.
 
Bummed

Well, I called Vans. Didn't get the answer I wanted.

They said that the NAS rivets do have more shear strength, but that in the leading edge of the flaps, this is not what I need. They suggested CS4-4s as replacements. They also suggested that I try MK319-BS, but I don't see that those would have any more bearing surface under the head than the NAS rivets.

I can't re-dimple the skins unless I completely take apart the flaps. I guess I will have to go with the CS4-4s.

He did say that the plane will not just fold up and fall out of the sky. I will just start seeing stress around that line of rivets after about 200 - 300 hours.

Anyone know of a good way to hide a line of CS4-4s when the skin was dimpled for #40s?
 
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