'cheater' pop rivet question

[dbhill916]

Hi guys,

I'm looking for confirmation (or not) that I'm doing a repair correctly. I screwed up the landing light cutout on the R outboard leading edge wing skin, thus I spent all day today removing said skin in order to replace it. I have drilled out all of the rivets and removed the skin itself. Not surprisingly, some of the drilled out holes are out of tolerance for being re-riveted.

Question #1: I'm using 50 % out of round as my upper limit of acceptable for re-riveting. Is this reasonable? I can't remember where I learned it, and haven't had much luck finding the original reference (if it exists.)

Question #2: Assuming the above criteria, I have about 20 holes that will need something other than an LP4-3. I have some 5/32" rivets from the local hardware store. Is it acceptable to match drill the new skin with a 5/32" bit and use those rivets?

Thanks for any feedback,
-dbh

 

[Mel]

Do NOT under any circumstances use hardware store rivets. Normally they are not made to any "specification".

Pulled rivets need to specced. If you can't get the oversize rivets you need from Vans, Aircraft Spruce carries Cherry "N", commercial grade rivets that are specced similarly to the rivets that Vans uses.

 

[skydiverlv]

The best way to remove the pulled rivets is lightly drive the mandrel out with a punch, use a #40 bit first and then use a #30 bit. If you leave the mandrel in, the drill bit will contact the mandrel causing the bit to wander off center.

 

[RFSchaller]

David,

When I started building my 12 I wondered just how different the Lp4-3 rivets were from commercial grade, so I pulled a few of each on some scrap. The commercial grade shop heads were inconsistent and smaller than the LPs, and sometimes the mandrel was not captured so the final rivet was essentially a hollow tube. My conclusion was use the commercial rivets in non-structural applications ( maybe your headset hook) but spend the extra money if your skin is at stake.

Rich

 

[dbhill916]

OK, the consensus is pretty clear to stay clear of rivets from Harbor Freight or Home Depot. I'm unable to find any kind of technical reference to Van's LP4-3's, thus I'm not comfortable guessing at what are adequate replacements.

From Van's website, the only candidate is
5/32 N RIVET BSPQ-5-4.

Looking at Mel's advice, I searched Aircraft Spruce and found a 5/32" 'N' type Cherry Rivet
MSP-54

Do either of those represent an adequate replacement for the LP4-3?

Does anyone have any comment on my original question #1, regarding the use of 50 % out of round as a criterion for upsizing the replacement rivet?

Thanks again for the feedback,
-dbh

 

[Mel]

From Van's website, the only candidate is
5/32 N RIVET BSPQ-5-4.
Looking at Mel's advice, I searched Aircraft Spruce and found a 5/32" 'N' type Cherry Rivet
MSP-54

The BSPQ rivet has a higher shear strength than the MSP because the mandrel is designed to break off and stay in the rivet. Give A/S a call. They used to carry the BSPQ rivets. Not everything they have is listed in their catalog.

Check to be sure, but I'm pretty sure that the MSP rivet exceeds the LP4 specs.

 

[John-G]

David - The LP4 rivets sent out by Van?s for my RV-12 kit are manufactured by Gesipa and while researching flush rivets for my project discovered they are called a poly-grip multi-grip rivet. The Gespia part number as on my box is GSMD41-43APG. As MMiller posted earlier, the link to that page with the specs is:

http://blindrivets.gesipausa.com/vi...polygrip-multi-grip-blind-rivet-steel-mandrel

But basically you are looking for a rivet that has a grip range of .039 to .197, a tensile strength of 236 lbs or better and shear strength of 162 pounds or better.

I see Gespia makes a Poly-grip in 5/32? ? part number GSMD51-54APG with a grip range that should work nicely for you ? needs a #20 hole.

Good luck and happy building,