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Substituting rivets

ScottK

Active Member
Hypothetically, if someone were skinning a horizontal stabilizer, got the front spar riveted, then switched to riveting the ribs but forgot to switch to the shorter rivets called out on the plan...thereby installing 426-3-4 where the plans say 426-3-3.5 ... could such a person reasonably say that it's close enough, and honestly they look pretty good anyway, and it'd probably do more harm than good trying to drill out 30ish rivets. Hypothetically. Asking for a friend. :rolleyes:

I did learn today that you can nicely buck a rivet that's too long to squeeze without clinching. So there's that.
 
longer yes

In my view, rivets can be longer than specified in almost all cases, as long as they don't clinch over. A few times I had to go longer to make a nicer rivet. sometimes I think my plane is a work of art. Others probably think it is just a finger painting.
 
Well, you might have totally screwed up your weight and balance with all of that extra weight. :)
 
It's fine, build on. If the only mistakes you make are accidentally using a few 1 size too long rivets, you're going to have an amazing airplane.
 
There are lots of places where I use Van's plan rivets as a "recommendation". There are plenty of times where there is a layer of tank sealant inside the rivet row, or you are riveting something where fiberglass is involved (where the thickness varies by an amount observable with the naked eye.) Or, frankly, where two bent pieces come together and there is a bit of a gap, and no amount of clecos or clamps holds things tight enough, so a longer rivet helps to pull things together.

Going long is always preferable to going short, as long as the shop head is pretty and not a leaning tower. The next time you order anything from Aircraft Spruce, buy a quarter pound or half a pound of every single 426-3 rivet from 4 to 6, at 0.5 intervals, to keep on hand.

And as soon as the "in my day, we had to smelt our own aluminum" crowd weighs in, they will tell you that the older models are all on your own and the builder always picks his or her own rivets.
 
Agreed - as you build on you'll find several more places in the airplane where you put the indicated rivet in the hole and it just obviously doesn't look right, and you adjust up or down as needed to get it right.

After a few hundred rivets you can eyeball it before setting the rivet and know if it's going to be right or not.
After a few thousand rivets you can feel the shop head with a fingertip in a blind area without the ability to see it and know if it's OK or not.
 
OK, I feel better now. My friend does, I mean. Yes. He feels better.

I did get a bunch of extra rivets, only 1/8lb each but that seems like plenty to start. At least it helps offset the surprising number of them that I drop on the floor where they immediately vanish never to be seen again.

For the record - and thank you Bruce for putting the idea into my OCD-prone head - if I mathed this correctly, the too-long rivets have added 286 milligrams of extra mass to the empennage. Obviously I'll need to compensate, maybe I could stick a wad of bubblegum under the instrument panel. :)
 
Obviously I'll need to compensate, maybe I could stick a wad of bubblegum under the instrument panel. :)

Be careful. The instrument panel is VERY close to the Center of Gravity. It would take less bubblegum if you put it on the engine mount. Of course an ample piece of fire-sleeve will be appropriate.
 
I keep rivets in empty plastic water bottles. When I need some I use a plastic tray from some microwave stuff to hole those few. It drastically cut down the loss rate.

Dave
 
Lost rivets?

Nope, not lost. They'll come back. All ya gotta do is just kneel down. You'll know when you find one.
 
Nope, not lost. They'll come back. All ya gotta do is just kneel down. You'll know when you find one.

Yes, and so will my neighbors. Dirty looks for days, too, as if I invented those special words. No, just repeating them. Loudly.

Anyway, there's as many ways to manage rivets as there are riveters. I found a bunch of these clear 8oz plastic screw-top jars on clearance somewhere. Tip a few out into the lid to work from, leave the jar safely away from the work zone, helps to minimize the spill damage. So far I haven't been spilling trays of rivets, I tend to lose them one at a time - slipped from my fingers, or jumped out of the hole before I could bring the gun/squeezer to bear. Odds of recovery improve if the floor's clean, I try to sweep up a couple time a week, though single rivets are not costly.
 

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The guys are having a little tongue in cheek fun on some of the previous posts. I hope you realize that.

I often find that I have to adjust the rivet lengths slightly from what the drawings call out. If the rivet gets too long it is likely to bend over instead of forming a proper head (I work with the Brits). If it is too short you won't have enough material to form a proper head. As long as the head is formed properly you are fine. If you don't have rivet gauges to check the length of the extended rivet and a go no-go gauge for the finished head you should buy them. After a while you can pretty much tell if the finished head is good by looking at them. However, I still check every single rivet head with the go no-go gauge.
 
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