Oops Pop Rivet?

[lr172]

The previous builder didn't drive the rivets on a wing skin properly. Most of the rivets I was able to reach with a bucking bar and drive properly. However, there are two rows that I cannot reach and am replacing the under-driven rivets with MK-319BS rivets. I have found a few holes that he over-drilled to 1/8". I think he used the Oops rivets here (4 shank with 3 head).

Do they make such an animal in pull rivets? I took a stainless rivet on the drill press and sanded it down to work, but it was a chore.

Thanks for your help with this.

Larry

[bugsy63]

Hi Larry,

I believe a Cherrymax CR3214-4-xx is equivelent to the 1/8th NAS1097 (oops rivet). They are available in several grip lengths. The "xx" represents the grip length and is determined by reference to Cherrymax catalogue .

[vfrazier]

I use the MK-319BS rivets frequently, but I'd really pause for thought before I'd use them for two entire rows on a wing skin. Even if they were strong enough, the potential for galvanic corrosion along the joint would give me the willies.

Perhaps someone with a better memory can show you the Alcoa reference that talks about how even poorly set rivets that look like heck still develop something like 90% of their intended strength.

[BillL]

Originally Posted by bugsy63

Hi Larry,

I believe a Cherrymax CR3214-4-xx is equivelent to the 1/8th NAS1097 (oops rivet). They are available in several grip lengths. The "xx" represents the grip length and is determined by reference to Cherrymax catalogue .

I can confirm the existence of this size rivet. It has a head of the -3 but shank of -4 (1/8") They lay flat nicely. Not cheap but a good solution option.

+1 = look in the Cherrymax catalogue for the correct part number.

[ccsmith51]

Originally Posted by vfrazier

I use the MK-319BS rivets frequently, but I'd really pause for thought before I'd use them for two entire rows on a wing skin. Even if they were strong enough, the potential for galvanic corrosion along the joint would give me the willies.

Perhaps someone with a better memory can show you the Alcoa reference that talks about how even poorly set rivets that look like heck still develop something like 90% of their intended strength.

This link might help:

http://www.vansairforce.com/communit...hp?t-6903.html

Chris

[az_gila]

Originally Posted by vfrazier

I use the MK-319BS rivets frequently, but I'd really pause for thought before I'd use them for two entire rows on a wing skin. Even if they were strong enough, the potential for galvanic corrosion along the joint would give me the willies.

Perhaps someone with a better memory can show you the Alcoa reference that talks about how even poorly set rivets that look like heck still develop something like 90% of their intended strength.

Vans early RV-6 instructions allow an entire wing surface to be riveted with MK-319BS rivets as an option.

[lr172]

Thanks for all the help and guidance here. I have found articles by Van, indicating that the MK-319 could be substituted and have equal strength or at least strength up to the job on the wing skin.

My issue here is not poor looking rivet sets. I would accept them on the center wing skin rivets. Many of the rivets on one wing were barely hit. The shop head was very long and very thin and in many cases could see the exposed edge of the hole. A few were even loose and in some spots the skin wasn't tight to the rib. These HAD to go and I really didn't want to pull the whole skin again (P/B did it once, hence all the problems). I would accept an ugly rivet if sound.

Even if they corrode over time, I still think that I am better off than what I had. I believe that these two rows in the center of the skin are not highly structural. I believe that the rivets on the four edges of the skin really hold the shape (attached to stronger elements) and the center ribs really hold the skin flat to allowing the skin to hold the structural shape.

After more investigation, I found that most of the 1/8" holes had been dimpled for -4 rivets, so I can use -4 cherry's of similar or greater strength of the MK-319's.

Thanks again.

Larry

[az_gila]

Originally Posted by lr172

......Even if they corrode over time, I still think that I am better off than what I had. ......

Larry

Dip the rivets into zinc chromate and install them wet...

[lr172]

Originally Posted by az_gila

Dip the rivets into zinc chromate and install them wet...

Good idea, Thanks!