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Adding extra rivets instead of drilling out

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prkaye

Well Known Member
When I first started, I was usually inclined to drill out rivets that didn't look right. This has been a hard impulse to ignore, even now. However both my inspector, and an email from Vans, both stressed that usually drilling-out a rivet is not the thing to do, because the result is usually worse than the orignal rivet. Still... it is a hard habit to shake.
The approach I'm shifting towards now (right wing skeleton) is when I set a rivet poorly, to add an extra rivet nearby (often a blind rivet), if there's room. I think the allowed inter-rivet spacing is pretty tight, so there almost always is enough room. Adds a bit to weight, I guess.
Just wanted to survey the community on this, what are most people's biases out there... do you typically drill-out your bad rivets (sometimes more than once), or do you take the approach of adding extra rivets when you are in doubt about some of the ones you've set?
 
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Additional Rivets

Every time you add an additional rivet you are devaluing your plane.

Don't be overly crtical of your rivets. Over simplification but true...Ask yourself, "Will it fall out"? If not, press on.

Best advice I can give you is...Learn how to rivet.
 
Replacing Rivets.

Occasionaly I replace rivets that have for one thing or another bucked ugly.

I do not think it is detrimental to do this, WHEN not IF, you do it correctly.

Th longer the rivet is the more difficult it is to do its successfully.

Don't drill it all the way through, unless you know you are going to put in a bigger dia rivet.

If you don't have the eyesight and the coordination to drill the head of dead center, don't do it.

Try to drill the head only deep enough to crack it the rest of the way with a pin punch.

When taking the rest of the rivet out, back up the skin with a small socket or bucking bar with a hole in it, then with a small hammer drive it out with a punch that is a little smaller than the rivet dia.

Usually in the 3/32 MS20426AD3-? holes that this is done to the hole of the skin has expanded and will require the 7/64 (first oversize) rivet # NAS1241AD3-? use a # 35 drill for this one.

If it is really gee'd up then you will need to drill it out with #30 drill and install what Rv'ers call an oops rivet. # NAS1097AD4-?

We stock a fair amount of both of these in 1/4# increments.

See the tech info wrenches under Rivets / Solid Rivets / Standard Diameter and Oversize Diameter. When these are clicked on it will bring up a page from our Hardware Reference Book.

As said before the best method is to learn how to buck rivets.

Practice pieces thrown away are cheaper than throwing away actual assemblies or parts you paid for.
 
Every time you add an additional rivet you are devaluing your plane.
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Why? Or is this just referring to the cosmetic effect of adding extra rivets in places that are visible (like skins)? If you add extra rivets say from wing spar to ribs, nobody will ever know they're there.
 
I don't think there is a problem with ocassionally adding additional rivets assuming you observe the appropriate rivet pitch. I agree that in most cases it is probably not necessary--remember that part in section 5 of your manual from Alcoa that says something like a poorly set rivet is 95% as strong as a well set rivet (very ROUGH paraphrasing--don't have the manual here to check it)--but if it really makes you feel better to have the occasional extra rivet in there, I'm not sure why it would hurt. I've added a couple rivets here or there, but I think in all cases I checked with Van's first to make sure it was OK. Their general answer was usually, "not necessary but if it it makes you feel better OK."
 
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Best advice I can give you is...Learn how to rivet.
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I know how to rivet, even experts make mistakes from time to time. I'm just interested in finding out how others usually deal with these mistakes.

Also, even with a lot of practice drilling out rivets (i've had my share), it can still go wrong sometimes (resulting in enlarged holes or deformed parts). This is probably why Vans says that it's usually better to leave poorly set rivets alone.
 
Consider OS CherryMax

prkaye said:
.....
The approach I'm shifting towards now (right wing skeleton) is when I set a rivet poorly, to add an extra rivet nearby (often a blind rivet), if there's room.
......
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One good option is to replace those hard to set screwed up rivets with a pulled rivet as you say, but drill out the old rivet and use an oversize CherryMax rivet.

The oversize ones are about 0.015 larger diameter and take a #27 drill. This larger drill size will usually clean up a hole from a poorly extracted solid rivet.

The CherryMax meet the structural requirements to replace a solid rivet, and are useful in the location that you describe (wing rib attach) where builders find it difficult to get both the rivet set and bucking bar square to the work and create a tipped over rivet.

The CherryMax are expensive, but you usually only need a few.... :)

http://www.aircraftspruce.com/catalog/hapages/cherrymax.php

Specifications and installation tips here...

http://www.peerlessaerospace.com/pub/Productimages/TAF_CHERRYMAX.pdf

...hope this helps...

gil in Tucson
 
Why fix ugly?

prkaye said:
Also, even with a lot of practice drilling out rivets (i've had my share), it can still go wrong sometimes (resulting in enlarged holes or deformed parts). This is probably why Vans says that it's usually better to leave poorly set rivets alone.
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IMHO, the occasional ugly rivet is Ok as long as it's not a real structural problem. I'm building a working airplane, not a showplane. Some will disagree; that's Ok. As the saying goes, yous pays your money and yous makes your choice.
 
az_gila said:
And learn how to properly drill out a rivet..... :)

This old thread may help.... check the link in the first post...

http://www.vansairforce.com/community/showthread.php?t=10533

gil in Tucson
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That technique does work for some bad rivers, after all if our rivet looked like that one in those diagrams, we would not be drilling them out. Some poorly set and then drilled out rivets tend to lead to worse damage to the holes than others.

Also, for the one that said to learn to rivet, experts that rivet 8 hrs a day for a living also get bad rivets from time to time. Sometimes the materials, holes, angle, rivet etc. lead to a bad rivet no matter who shoots them.
 
Learning when to say....

I think one of the biggest things I've had to learn on this project is being able to judge if a less than perfect rivet is worth the risk to replace it. At this point in the project if I screw up a rivet, it's usually in a hard to reach location. That means I'm even more likely to screw up the replacment rivet since the hole is usually enlarged from not only drilling out the offending rivet, but the expasion resulting from setting the original rivet.

When I was building the empennage I was worried about every rivet. Now I look back at the tail and know that I should have left 70% of them alone.

I look in my spam can and see ugly shop heads all over that thing and think to myself.... Well those have held for 30 years and 4000 hours......HMMMM
 
No judgement being placed here but. .

prkaye said:
I know how to rivet, even experts make mistakes from time to time. I'm just interested in finding out how others usually deal with these mistakes.

Also, even with a lot of practice drilling out rivets (i've had my share), it can still go wrong sometimes (resulting in enlarged holes or deformed parts). This is probably why Vans says that it's usually better to leave poorly set rivets alone.
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Hey Phil, I would like to give my .02 worth here but before doing so I want to emphasize that this in no way is intended to be a judgment of your, or anyone else's, character or riveting competence. :D

It sounds to me like you are working on the premise that perfection is an achievable goal that you should diligently strive for in absolute terms. With this idea motivating us the only real result will always be absolute frustration. All of us have heard that very old adage "No one is Perfect!" In fact we hear it so often that in some respects it has become meaningless. But the truth of the matter is that by allowing ourselves the right to not be perfect empowers us to push ourselves toward accomplishing things that we would never be able to achieve if we forced perfection upon ourselves.

Design wise these airframes are so well engineered that even with our imperfect construction practices they are extremely strong structures. I believe the design standards have to incorporate some human error "swag". If it were not so, I do believe there could not be an amateur built airplane flying anywhere in the world.

The overwhelming drive you feel to replace a rivet you deem questionable is in all likely hood driven by either the above mentioned desire for perfection or by a sense of fear that, if you do not create a perfect rivet every time, something bad will happen down the road and the wing, tail, engine, or some other important part will come flying off of your airplane while you and your loved one are high over the Sierra Nevada mountains or over the Gulf of Mexico or somewhere else just as hairy.

I do believe to overcome this type of fear we all must put trust; first, in the engineer(s) who designed our airplanes; second, in the manufacturers who produced the materials we use to build them; and lastly, but I do believe most importantly, in ourselves. We need to have faith in ourselves that we do indeed have the necessary knowledge, skills and abilities to construct this fantastic piece of machinery and that we can successfully do so.

Again, I am not saying this to be disrespectful to you or anyone else. I just feel that, as amateur builders, we need to give ourselves much more credit than we sometimes do. We need to stop obsessing on the mistaken idea that our errors are always of such dire consequences that everyone of them will have such catastrophic results that they stop us from achieving our intended goals.

Live Long and Prosper!
 
I too have done a mess up on a rivet or two or three. I fix the situation and look at it and find myself really critising my work. I find the best thing to do after working on a section is to walk away, don't do anything more, if you do you may end up screwing it up real good. Go back to it another day and look it over, chances are you will find that everything is just fine and you just got supper critical of the work that was done.
 
GAHco said:
Occasionaly I replace rivets that have for one thing or another bucked ugly.

Usually in the 3/32 MS20426AD3-? holes that this is done to the hole of the skin has expanded and will require the 7/64 (first oversize) rivet # NAS1241AD3-? use a # 35 drill for this one.
Click to expand...

OK, this is a new one for me; I had never heard of these. I thought the next size up to fix an enlarged hole was an "oops" rivet. What size is the head of these rivets? The same as a regular 426AD-3?
 
Was getting on a Northwest plane Friday (for a weekend trip to Cleveland that someday i hope I can fly in my RV) and while waiting decided to check out the rivet job on the universal head rivets around the door - gap seal area I believe. I counted a smiley on about every 4th rivet.

It made me feel unusually good.
 
Bob Collins said:
.....check out the rivet job on the universal head rivets around the door - gap seal area I believe. I counted a smiley on about every 4th rivet...It made me feel unusually good.
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I doubt those smileys were generated during initial production. In the case of a commercial airliner, those gap seals may well have been replaced more than once while the a/c is in revenue service.

There may be significant differences in QC between commercial and military aircraft production. A smiley around a rivet head on a combat aircraft is almost always cause for the rivet's removal and the smiley must be blended and/or polished out of the structure before a new rivet is reinstalled. Navy and Air Force auditors are a constant and overseeing presence on the shop floor and would not have it any other way. Once the a/c is "out the door" though, all bets are off concerning quality standards of repair work, especially in the field.
 
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I also have found, especially with the Universal head, the quality of the rivet set has a huge effect on rivet quality. I have about 4 different AN470-4 sets and only use 2 of them. The shape of the head wasn't the problem, but the lip the set really made a difference.
 
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