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Need some advice on these rivets

WVM

Well Known Member
Hi,

Yesterday a friend helped me with riveting the inboard ribs of the horizontal stabilizer on the frontal spar. I am not really happy with the result and I keep on thinking about it... What should I do with it?

I rather don't have any parts in my aircraft of which I don't have a good feeling. This is one of them. I have contacted VANS about it. They told me that it doesn't look pretty, but that I probably do more damage with drilling everything out, than leaving it. This is a bit double, because actually they are saying it is not good. Main problem is that all six are damaged, it is not just one of them.

Other question I have is, that if I drill it out, would there be a way to do it better? Would a 4 inch yoke be able to set them? I tried with the 3 inch, 2 inch and "spar" yoke, none of them worked, but I don't have a 4 inch at the moment.

I really would like to have your comments on this. Do you also have those in your aircraft? How do they evolve over time? Am I maybe a bit to worried about nothing? ...

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Thank you!
 
I am not going to disagree with Vans.

You have some damaged rivets, but you also have damaged the aluminum sheet around the rivets. I believe that is the spar doubler to the right of the six rivets you are questioning. Almost every one has damage around the rivet. Those "smilies" around the rivets are caused by either the rivet set not squarely on the rivet head or you are using the wrong cup rivet set.

I realize you are not in the US, but if you download a copy of FAA 43.13 and look at page 4-58 you will see what I mean by wrong cup rivet set. If the cup is too large part of the force during riveting is on the skins, which makes those small curved indentations. The more likely problem is the rivet set is not squarely on the rivet, which will also make those marks. I would guess your rivet tails may not be completely square as well.

I suggest you get some scrap material and work on getting the rivet set squarely on the head and tail of the rivet. Do as many as it takes to be able to see and know the rivet set is squarely on the rivet. Then drill out those practice rivets to learn how that works. That will be faster than drilling out multiple bad rivets on your project and you will be happier in the long run.

Look at your first image at the spar doubler, top row, second rivet from the left. The goal is to try to have them all look like that one.
 
They certainly aren't pretty... But they look like they'll do the job.

Getting to those rivets is kind of tough, given the angle that the inboard ribs are at. I used an offset rivet set and a tungsten bar to get at them. I wasn't able to figure out any way to possibly get a squeezer in there.

The rivets that Scott are talking about, in your spar attachment points, show a lot of the same indications of the rivet set not being square. I used the squeezer on those rivets in my plane, but they help to suggest that you work on some scrap material a little bit more for practice.

You should strive for all your rivets to wind up like the top-middle on in your first picture, like Scott said. However, they probably won't all be that way.

If you had one bad rivet in the rib, I would say give it a shot. But drilling out and replacing all three, when they all appear to be functional as is, is just asking for the possibility of more damage.
 
Mine looked almost exactly the same. I drilled them out, but the replacement ones ended up mostly the same. Since then I've gotten better with the offset rivet set and I learned a trick--put 2 layers of masking tape or duct tape on the end of your rivet set.

Here's how my RV-10 rivets ended up in the same location.

2013-10-10%2022.13.46r.jpg
 
Andy those are really nice. Excellent work. I wished all mine looked that good.
 
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Rivets

I agree with Scott. Drilling them won't fix the damage to the doubler. If Vans is ok with them, leave them for now. Maybe when you get past the wings and you have total confidence in drilling rivets, drill the doubler out and replace.
For now, move on and practice. Use a piece of Gorilla tape over the rivet to protect from smileys. I set those with gun and tungsten bar.

Don't stress. I egg shaped one hole drilling rivets for the HS Service Bulletin and had to drill the entire HS apart to replace the forward spar. Glad it happened now but I was really mad at the time. Drilling 500 rivets gave me confidence.

Drilling rivets is a technique. Search or ask how to do it.
 
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I am not going to disagree with Vans.

You have some damaged rivets, but you also have damaged the aluminum sheet around the rivets. I believe that is the spar doubler to the right of the six rivets you are questioning. Almost every one has damage around the rivet. Those "smilies" around the rivets are caused by either the rivet set not squarely on the rivet head or you are using the wrong cup rivet set.

I realize you are not in the US, but if you download a copy of FAA 43.13 and look at page 4-58 you will see what I mean by wrong cup rivet set. If the cup is too large part of the force during riveting is on the skins, which makes those small curved indentations. The more likely problem is the rivet set is not squarely on the rivet, which will also make those marks. I would guess your rivet tails may not be completely square as well.

I suggest you get some scrap material and work on getting the rivet set squarely on the head and tail of the rivet. Do as many as it takes to be able to see and know the rivet set is squarely on the rivet. Then drill out those practice rivets to learn how that works. That will be faster than drilling out multiple bad rivets on your project and you will be happier in the long run.

Look at your first image at the spar doubler, top row, second rivet from the left. The goal is to try to have them all look like that one.

It is actually the damage around the rivets that I am talking about. The rivets itself are not that bad to my opinion. According to the builder how set those rivets for me the reason is the offset rivet set that seems to turn in between two hits of the rivet gun.
I had to attach the assembly with the lead on the elevators and don't have this damage, but I really hate to set those rivets with a gun. Would it work with a 4 inch yoke to set them with a rivet squeezer? Tomorrow I have an inspection planned from the aviation authorities. I am going to see what he is going to say about it.
 
Mine looked almost exactly the same. I drilled them out, but the replacement ones ended up mostly the same. Since then I've gotten better with the offset rivet set and I learned a trick--put 2 layers of masking tape or duct tape on the end of your rivet set.

Here's how my RV-10 rivets ended up in the same location.

2013-10-10%2022.13.46r.jpg

Hi Andy,

That indeed look really nice! Would you have a picture of the rivet set because I am not 100% sure that I understand how you put the tape around it.
 
I agree with Scott. Drilling them won't fix the damage to the doubler. If Vans is ok with them, leave them for now. Maybe when you get past the wings and you have total confidence in drilling rivets, drill the doubler out and replace.
For now, move on and practice. Use a piece of Gorilla tape over the rivet to protect from smileys. I set those with gun and tungsten bar.

Don't stress. I egg shaped one hole drilling rivets for the HS Service Bulletin and had to drill the entire HS apart to replace the forward spar. Glad it happened now but I was really mad at the time. Drilling 500 rivets gave me confidence.

Drilling rivets is a technique. Search or ask how to do it.

I did not yet set the rivets in the ribs on the other side of the spar. If I would replace it, I would simply reorder a set of 4 ribs, 2 nose and to inner ribs. Eventually with the spacer. The only drilling that needs to be done is the 6 rivets and the nose rivets. I am quite confident in drilling out rivets as I did so a lot already, but I need a better technique to redo it when I drill them out. I was hoping that some had experience with the 4 inch yoke on those? The 3 inch, 2 inch and special spar yoke don't work because the skin is always in the way.
 
...
According to the builder how set those rivets for me the reason is the offset rivet set that seems to turn in between two hits of the rivet gun.
....

Either hold the rivet set with your other hand or use duct tape to tape the rivet set to the rivet gun to prevent turning.
 
Hi,

The inspector from the aviation authorities accepted the rivets based on the comment from VANS that it would probably do more damage by drilling them out and replacing the ribs. But also because that location remains accessible and will be yearly inspected by them. I am still not sure that I will keep them in or not. I did not rivet the main rib to the skin yet. And the rear spar is also not yet in. I only would drill it out when I am sure that I found a better method to rivet them in place. I am going to put it aside for a while.

Thanks
 
Hi,
...

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...

Hi,

You might remember this post... I drilled those out today after reading this comment on the forum about drilling out rivets or not.

The second reason I did is because I noticed that my new yoke is able to reach all those rivets.

I have an issue after drilling them out. As I used a smaller drill size, I have some remains of the rivet in most of the holes. They don't want to come out as the outside part is larger than the rivet hole (on both sides). The most logical idea was to use a pliers, but this fails. Another idea was to drill them out, but as the remains are not evenly around the hole, they tend to swirl around rather than drilling away and chances are there that the drill will damage the hole as it is not perfectly aligned with it.

rivet-remains1.jpg


rivet-remains2.jpg


rivet-remains3.jpg


Any advise?
 
Nail punch

Just get a small nail punch and a light hammer to tap the edge of the rivet (inward toward the hole) in a few places. You can then give them a tap to drive them through the hole. Doesn't take much force. Avoid the spar and other parts with the punch.
 
Drilling too deep with a small bit and leaving the shell is a lesson learned. Like said, take a proper size punch and knock them out. If you end up with some discarded parts, practice rivet removal on them. You will get there, and be able to use a standard bit and make it work.

Rivet removal is mostly technique, not skill. You have to be able to see a human hair down there so good eyesight, cheaters, or optivisor should be used. I drill the head in several steps, a few revolutions per step. If the hole is not in the center, then walk it. Take a bunch of universal head rivets and learn to walk your drill point. This will keep it in the center. Using an angle drill is a whole other skill set!

For a long time I could not drive a universal head rivet without a smilie to save my life - not one. Set out research program of variables and now it is easier. Offsets, arrrrggghh.

Happy building.
 
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Next time put some duct tape over the end of the rivet set. It helps keep the set from jumping off the rivet and reduces the chance of damaging things like what happened to you.

FWIW, I agree with Van's.
 
For the occasional universal head removal, the procedure Bill describes of "walking" the drill bit works. This also works for flush heads.
However, if you have a lot of them to remove, or want a more fool proof method, buy this tool;
http://www.aircraftspruce.com/catalog/topages/rivetremoval.php

In my restoration work, I have had the occasion to remove literally thousands of rivets. When properly set up, this tool allows you to move quickly and safely. At one point in time, I was removing on average over ten rivets per minute. I burned through several drill bits.

Even if you don't have hundreds to remove, this tool makes clean work of it, and we all need an excuse to have one more tool right?
 
Just get a small nail punch and a light hammer to tap the edge of the rivet (inward toward the hole) in a few places. You can then give them a tap to drive them through the hole. Doesn't take much force. Avoid the spar and other parts with the punch.

You could consider grinding a special punch, kinda like a prow on a boat, to collapse the "tube"

I try to avoid "drilling through" I'll use a standard size drill to get close to the junction between the rivet head and barrel. The head can be removed mechanically, either by putting a punch in the hole and wiggling, or shearing off (470s) with a drift or other punch. You can "punch through as stated above, but I sometimes "draw" the barrel out of the hole by drilling the barrel (not through drill) with a smaller drill. After which I use fine punches I made up on my surface grinder. If the barrel is drilled to the thickness of the parts clinched, the thin punch will pull the rivet out easier I think it may actually stretch the barrel and reduce the diameter (slightly?). Less risk of structure damage if you aren't concentric in your drilling.

FWIW
 
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For the occasional universal head removal, the procedure Bill describes of "walking" the drill bit works. This also works for flush heads.
However, if you have a lot of them to remove, or want a more fool proof method, buy this tool;
http://www.aircraftspruce.com/catalog/topages/rivetremoval.php

In my restoration work, I have had the occasion to remove literally thousands of rivets. When properly set up, this tool allows you to move quickly and safely. At one point in time, I was removing on average over ten rivets per minute. I burned through several drill bits.

Even if you don't have hundreds to remove, this tool makes clean work of it, and we all need an excuse to have one more tool right?

I got one of these cool tools after watching the HS-spar crack-SB video where it was used. It was really quick!! I even tried it on the shop head with a nicely fitting guide.

BTW - I only suggested universal heads for drill-out-practice as they give more drill practice time. It is rare for me to use a center punch until time to knock out the husk. The updated Section 5 is pretty good on this now. Everyone should drill out 10 a day just too keep in shape:eek:
 
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