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Old 09-01-2021, 12:00 PM
DavidHarris DavidHarris is offline
Join Date: May 2018
Location: Upland, CA
Posts: 152
Default Hole Tolerances

I have a question about RV-12is hole tolerances. I'm starting with the wing and frequently fighting to insert pop rivets into holes. It's a particular issue on the LP4-3 rivets joining wing skins ribs, where there are a lot of rivets to insert. I'm always able to get the rivet in, but often have to put it in a hand rivet tool and push pretty hard while twisting. Occasionally I have bent the flange on the underlying substructure and have to remove the rivet and rework the flange. Whatever misalignment exists is too small for me to casually observe without magnification.

I would like to better understand why this is so difficult. The RV-12is holes are all CNC drilled to final size so I haven't been match drilling. I just debur, cleco, and rivet. The clecos are slightly smaller than the holes so that could allow a tiny bit of misalignment. I've installed rivets about every 5th hole, which I hoped would force everything into alignment, but inserting the other rivets remains difficult.

I don't recall nearly this much difficulty on my RV7 wings, but those were AN426 rivets in match-drilled holes. I was also accustomed to occasionally run a reamer through the holes again whenever a rivet was hard to install.

I'm contemplating reaming the RV12 wing skins on the ribs now with a #30 reamer to solve the problem, and then debur the rib after reaming.

I would appreciate any insight into whether other people have this difficulty, whether it's due to something about my construction technique, and whether there are drawbacks to reaming all the wing skin holes.


David Harris
David Harris
Vans RV-7A N47HM
First Flight March 2020
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Old 09-01-2021, 12:18 PM
Bob Y Bob Y is offline
Join Date: Jul 2017
Location: Piedmont, SC
Posts: 287

If you search the site youíll find several threads on this subject. Iíll go out on a limb here and say weíve all had to do something to get holes to align for rivet insertion. Variation in rib fluting and stacked tolerances will result in holes that arenít perfectly aligned. I used reamers when this occurred. And my understanding is that if you ream vs. drill, it negates the need for deburring in most cases.
Bob Y - builder 12iS E-LSA
N569TT first flight 2/9/2020
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Old 09-01-2021, 12:52 PM
rvbuilder2002's Avatar
rvbuilder2002 rvbuilder2002 is offline
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,597

Here is one of the more recent threads that has a lot of info.
Rather than repeat, look at my posted #18.

As for reaming all of your holes #30... if a rivet will slip into the holes in the skins or ribs individually, then you have a hole alignment issue as described in the other thread.
If not, then reaming might be the way to go.

For a strong rivet joint, a close fit of the rivet to the hole is required, because the rivets done swell in diam. as much as solid rivets.
Solid flush rivets fit into the holes easily because when the holes are dimpled, the hole diameter actually gets larger.
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Hubbard, Oregon
Van's Aircraft Engineering Prototype Shop Manager
RV-6A (aka "Junkyard Special ")
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Old 09-01-2021, 01:12 PM
DavidHarris DavidHarris is offline
Join Date: May 2018
Location: Upland, CA
Posts: 152

Thanks, Scott! Very helpful.
David Harris
Vans RV-7A N47HM
First Flight March 2020
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