Pop rivet question

[SgtZim]

I messed up - attaching the leading edge on the left wing spar with pop rivets as Van support suggests. Though I used shorter rivets LP 4-3 instead of LP 4-4 - wasn't thinking about correct grip length the first time around.

After knocking out the mandrels and drilling out the short rivets, I did a bit of testing on scrap. Even with the LP 4 3 rivets in a .25 in. part - a small collar still formed and (barely) trapped the end of the mandrel. However, in most of the rivets I removed and the test pieces, only a very short piece of mandrel remains in the "shop side" of the rivet after setting. I thought the mandrel was supposed to break at the "manufactured head" side leaving the steel core to help bear shear loads?

Without the core - you only have a small aluminum tube taking the shear load on those leading edge ribs.

I hope the cherry max rivets I ordered will form a stronger joint than the LP rivets. If I had to use the LPs on those parts, I think I'd try intentionally bending the tool as I set them to make the stem break off at the surface of the rivet.

I have a few pictures of the tests on my facebook page if anyone is curious.
https://www.facebook.com/BZsRVproject/

[SgtZim]

I tested a couple of LP rivets to failure. Both failed around 200 lb in shear. Test was very crude, but I'm satisfied that these rivets are up to the job.

https://www.facebook.com/BZsRVproject/

[bobnoffs]

the lp rivet mandrel is not designed to add ANY strength to the rivet.

[N546RV]

I used MSP rivets from Spruce to attach the leading edge. Three different lengths were required: (ribs are numbered from inboard to outboard)

• MSP-42 for ribs 4 & 5 where there's no reinforcement on the spar web
• MSP-43 for rib 6 which rivets in assembly with the main rib
• MSP-44 for ribs 1-3 where there's the additional spar web reinforcement

One of the reasons I went with these rivets is because there are clear specs on the allowed grip lengths, which gave me a little extra peace of mind. For all I know, it might be overkill, but I'll sleep better at night.

[longranger]

Originally Posted by N546RV

I used MSP rivets from Spruce to attach the leading edge. Three different lengths were required: (ribs are numbered from inboard to outboard)

• MSP-42 for ribs 4 & 5 where there's no reinforcement on the spar web
• MSP-43 for rib 6 which rivets in assembly with the main rib
• MSP-44 for ribs 1-3 where there's the additional spar web reinforcement

One of the reasons I went with these rivets is because there are clear specs on the allowed grip lengths, which gave me a little extra peace of mind. For all I know, it might be overkill, but I'll sleep better at night.

Plus one. I did exactly the same thing.

[SgtZim]

Thanks for your comments and info. I got it all straightened out I think. I tested a couple of Van's LP 4 3 rivets with a crude workshop rig. They both sheared at around 200 lbs, which at a wag should be a lot more than double the design strength of the nose rib - spar connection.