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Round file before blind rivet?

Rob H

Well Known Member
I'm working on the tailcone kit. I've found that a lot of the blind rivets don't readily fit in the hole before they are pulled without some coaxing, wiggling, and pushing. I've clecoed everything up, deburred, and visually inspected. In some cases, I've had to run a round file in the hole a couple times and then it works fine. Am I doing something wrong? Or maybe it's normal procedure? Maybe it's because I've primed the interior surfaces and a thin ply of primer takes away just enough tolerance? What's the RV12 builders experience?
 
I'm working on the tailcone kit. I've found that a lot of the blind rivets don't readily fit in the hole before they are pulled without some coaxing, wiggling, and pushing. I've clecoed everything up, deburred, and visually inspected. In some cases, I've had to run a round file in the hole a couple times and then it works fine. Am I doing something wrong? Or maybe it's normal procedure? Maybe it's because I've primed the interior surfaces and a thin ply of primer takes away just enough tolerance? What's the RV12 builders experience?
Almost all of mine were that way. I used the appropriate size drill for the rivet. It just cleaned up the holes a bit ...
 
Awl

Have you tried opening up the hole with an Awl. Don't remove metal, just stretchit a bit if possible. Try an AWL bfore the file.

Here is a copy from the Home Depot site.

Mayhew Model # 46502 Internet # 100202220 Store SKU # 624682 1/4 in. Scratch Awl 5-1/2 in. Blade 6 1/4 in. OAL
 
Its the way the rivets are squeezed onto the mandrel that deforms them enough that they don't slide right in to a properly sized hole. I just used the rivet puller to push them into the hole. I would not be anxious to oversize the hole.
 
I would not be anxious to oversize the hole.
I don't think the holes are being oversized. I think they were slightly undersize to begin with otherwise the appropriately sized drill would simply slip through the hole. My guess is the tool used to punch the holes wears slightly over time making the holes ever so slightly undersize.
 
I had the same experience. If a rivet didn't "dive" right into the hole, I'd try a different rivet. If that didn't work, I'd try an awl the wiggle things around a bit. Sometimes I'd hear the clecoes settle in a bit. If all else failed, I used a 4-flute ream the "round out" the hole. It doesn't enlarge the hole, it just makes it round as opposed the a very shallow 3-lobed hole that a 2-flute drill bit makes. Last, I learned to be very cautious about forcing a rivet into a hole. Those dents you make in a thin skin can be hard to remove.
All the best!
 
What worked for me as part of the deburring process was to run a number 30 reamer thru each hole before even assembly.You would not do that a other kits but on the -12 you can. The last thing you want to do is force a rivet in and get it stuck.
 
I had the same thing happen on about 95% of the holes. Thinking it was an alignment problem, I tried using an awl, but that usually didn't help, so I ended up doing a really short burst with a #30 drill bit. That worked, but the reamer sounds like a better idea.
 
#30 reamer

I second the #30 reamer it is the only way to go. Ream a few holes then cleco and ream the rest. A flie leaves rough rivet holes. I have my drills and reamers in a quick change set up. Good luck
Rich
 
Just re-read the OP. Would recommend against using a round file in the situations you described. No way to control hole size and also makes more "burrs". I did have some cases where the primer prevented easy rivet insertion in holes that had been fine before priming. In most cases the "awl wiggle" did the trick. Think I just invented a new technical procedure!
 
I had the same experience. If a rivet didn't "dive" right into the hole, I'd try a different rivet. If that didn't work, I'd try an awl the wiggle things around a bit. Sometimes I'd hear the clecoes settle in a bit. If all else failed, I used a 4-flute ream the "round out" the hole. It doesn't enlarge the hole, it just makes it round as opposed the a very shallow 3-lobed hole that a 2-flute drill bit makes. Last, I learned to be very cautious about forcing a rivet into a hole. Those dents you make in a thin skin can be hard to remove.
All the best!

I'll second what Dave said. this is exactly the procedure I've used.

Jim
 
I had an old ice pick with a very slight taper. Worked great. Stick it in, twist a little with very light pressure.
 
What I did, I used an old #30 bit, chucked the drill end into an old mini-chuck I had. Using a grinder then the Scotcthbrite wheel, I tapered the end. You hold the mini-chuck and insert the tapered bit to align the holes. To insert the rivets, I actually cut about three inches off a broom handle and drilled a small hole into the rounded in. Make the hole deep enough so the entire rivet shank goes in.
 
Almost all of mine were that way. I used the appropriate size drill for the rivet. It just cleaned up the holes a bit ...

Agree.

Holes are holes, no matter the airplane.

Matched drilling is wonderful but the holes do not line up perfectly. Run an appropriately sized bit through and rivets will not hang up.

Press on. :)
 
Maybe I'm not understanding exactly what the OP was encountering, but if you're using LP4-3, CS4-4, or other rivets that have small external stamping burrs on their bodies, the easiest thing to do to correct the issue is to simply remove the burrs.

Do this by grasping the rivet stem and spinning the body of the rivet lightly against your running Scotchbrite polishing wheel.

That's far easier than enlarging the rivet hole!

For MK319BS rivets, those are 7/64" shank and won't fit a #40 hole!

If in doubt, buy a cheap Harbor Freight dial caliper and measure your rivets and drill bits.
 
Thanks for all the tips. I will stop using the round file, and whatever I try, will not be creating more burrs.
 
I should probably stay out of this, but I just need to make a couple of comments. Our RV-12 kits contain pre punching that is extremely accurate. Before reaching for a drill, or a file, try realigning and changing your cleco sequence. I found that almost always, if a rivet won't go in, I needed to do a little realigning. Opening up a whole should be your very last resort. You need a half dozen small tapered punches, awls, ice picks, anything to aid in accurate alignment. Then, before grabbing clecos, see if you can drop in a few rivets, then go back and cleco it up. ......Tom
 
I gotta go along with todehnal here. If you're having trouble getting a rivet in, try wriggling the adjoining cleco a bit. Most times this will allow the hole to properly align and the rivet will go in.
Remember, pulled rivets don't expand in the hole like driven rivets do.
Hole size and shape is more critical with pulled rivets.
 
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Anyone seen this tool?

I go along with critical aligning, whether more clecos, or whatever it takes. There are cases where it just doesn't work, and I have an old tool that really does the job. It is basically a five-sided ice pick with a very slight taper, about five inches long. It acts as an alignment tool, or a reamer that does not remove metal with just a twist of the wrist. Has anyone ever seen these? All I know is that the one I have was used in the old Aero Commander twin factory, many years ago, and beats an awl in every way. They came in various sizes. I would love to find a source for them, as I think they are the very best option.

Bob
 
I post my experience about this when this subject comes up.
On my 12 I checked literally 100 tight fits and the shank of a # drill bit would not fit into the hole of either piece. You need a reamer. It is usually not misalignment.ream the holes individually and put them together and the river will fit. After proving that to myself the reamer became part of the process just like the deburring.
I think vans punch got smaller.
 
I post my experience about this when this subject comes up.
On my 12 I checked literally 100 tight fits and the shank of a # drill bit would not fit into the hole of either piece. You need a reamer. It is usually not misalignment.ream the holes individually and put them together and the river will fit. After proving that to myself the reamer became part of the process just like the deburring.
I think vans punch got smaller.

As has been posted in the past, there is a tolerance range for the diam. of the holes.
Over time, as the punch tools get dull, etc., the hole diam. can drift towards the smaller end of the tolerance range.
The punch tool may then get sharpened or replaced when another production batch of a particular part is produced so some people might get parts that are fine, and other may get parts that are a little tight.

A cause for rivets not going in the hole can definitely still be hole misalignment. A common cause for this is parts requiring fluting and/or small adjustment in flange angles, not having this work completed properly.
It can make a big difference when we are only talking about .001-.002" beibng able to prevent a rivet from inserting.
 
It is basically a five-sided ice pick with a very slight taper, about five inches long. It acts as an alignment tool, or a reamer that does not remove metal with just a twist of the wrist. Has anyone ever seen these? All I know is that the one I have was used in the old Aero Commander twin factory, many years ago, and beats an awl in every way. They came in various sizes. I would love to find a source for them, as I think they are the very best option.

Bob

Sounds like a great tool. Let us know if you find a source or remember what it's called. I'd like to find one, too.
 
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