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Rivet length

Reinhold

I'm New Here
Hello everyone!
First post.
I picked up my empennage and wing kit for my RV8 a couple of weeks ago so I'm knee deep in it now. I find myself re-reading and studying the plans over and over again, then practicing over and over before tackling each step......slow going but my skills are getting better I think. I find the hardest part is just figuring out the plans.
Speaking of plans I have a quick question......
Im about to rivet the the stiffener to the rear spar on the vertical stabilizer. The plans state the rivet to be used is a AN470AD4-6. Practicing using that rivet on the same material thickness Im finding the rivet is too long and it starts to fold over. When I use a -5, its right in the specs.
Im starting to second guess myself. Do the plans sometimes get it wrong when it comes to rivet length and leave it up to you make the correct decision?
 
Welcome aboard!

Yes, sometimes you'll need to modify what's in the plans. If the rivet gauge says good, than you're good (both before and after riveting). I've found that I have had to increase the length from say 3.5 to 4 or 4 to 4.5 because the plans spec'd size was a touch short. 95%+, the plans are right on.

In the beginning, there's lots of info to absorb. By the time you're mid-fuse, you can usually guess the right length rivet without looking at the plans.
 
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Welcome

Welcome aboard!

Yes, sometimes you'll need to modify what's in the plans. If the rivet gauge says good, than you're good (both before and after riveting). I've found that I have had to increase the length from say 3.5 to 4 or 4 to 4.5 because the plans spec'd size was a touch short. 95%+, the plans are right on.

In the beginning, there's lots of info to absorb. By the time you're mid-fuse, you can usually guess the right length rivet without looking at the plans.

Welcome
What he said. Rivet gauge is your friend. Don't be bashful about questioning plans.
 
Rivets fold over when you don't hold the bucking bar perpendicular to the rivet. If you don't hold the bucking bar nearly perfectly square, the rivet will fold. I believe the rivet call out in the plans to be correct, I am working on the tail section as well and have only used the recommended length rivet, so far so good. Use a rivet gauge to verify.
 
Good start

Sounds like you are off to a good start with this. Just tow cents here. It is good to question everything as you go in the beginning. Take the time to get the standards by with all this is done. Much of it is in 43.13 or some old books that set things our way back in the 40's or 50's. It will seam as if you are going to take forever at first, but taking that extra time now will help you do things much faster and understand what will be needed later on in the build. As your understanding gets better your creativity and quality will get much sharper and you will like what you can do. Like playing the piano "practice, practice, practice". I like to tell people it's kind of like saying "I do", once you have made up you mind you will see it through to the ends, you are 90% there. Your's R.E.A. III #80888
 
Rivet Cutter

You are correct that a slightly long dash 4 round head rivet can be very difficult to drive properly without having it fold.

Couple of thoughts. First, the kits are not provided with a complete set of half increment rivets. You don't have a AN470 4-5.5 for instance. But in many cases, what you really need is a 4-5.5 or a 4-6.5

The plans will call for the next higher rivet length, but you can plainly see (with experience) when you first insert before driving that it is just a little too long. That half length can make a big difference in setting.

So that's when I pull out my rivet cutter to get the 'before setting' length just right.

Second thought. These rivets are supporting shear loads, not tension loads...generally speaking. As such, the quality of the hole (clean and round) and that the pieces are tight against each other while driving, are more important than the exact size and shape of the shop head of your rivets.
 
Rivets fold over when you don't hold the bucking bar perpendicular to the rivet. If you don't hold the bucking bar nearly perfectly square, the rivet will fold. I believe the rivet call out in the plans to be correct, I am working on the tail section as well and have only used the recommended length rivet, so far so good. Use a rivet gauge to verify.

Thanks......I was using a squeezer to do my tests rivets.....have you started on the vertical stabilizer and riveted the stiffener to the rear spar yet?
 
Sounds like you are off to a good start with this. Just tow cents here. It is good to question everything as you go in the beginning. Take the time to get the standards by with all this is done. Much of it is in 43.13 or some old books that set things our way back in the 40's or 50's. It will seam as if you are going to take forever at first, but taking that extra time now will help you do things much faster and understand what will be needed later on in the build. As your understanding gets better your creativity and quality will get much sharper and you will like what you can do. Like playing the piano "practice, practice, practice". I like to tell people it's kind of like saying "I do", once you have made up you mind you will see it through to the ends, you are 90% there. Your's R.E.A. III #80888

Thanks for the comments Rob.....
It does seem like a long process but Im having a blast learning the ropes!
 
You are correct that a slightly long dash 4 round head rivet can be very difficult to drive properly without having it fold.

Couple of thoughts. First, the kits are not provided with a complete set of half increment rivets. You don't have a AN470 4-5.5 for instance. But in many cases, what you really need is a 4-5.5 or a 4-6.5

The plans will call for the next higher rivet length, but you can plainly see (with experience) when you first insert before driving that it is just a little too long. That half length can make a big difference in setting.

So that's when I pull out my rivet cutter to get the 'before setting' length just right.

Second thought. These rivets are supporting shear loads, not tension loads...generally speaking. As such, the quality of the hole (clean and round) and that the pieces are tight against each other while driving, are more important than the exact size and shape of the shop head of your rivets.

I think you're spot on there.....when I did the formula to double check the rivet length required the result was right between the two rivet lengths that I hand in stock. May have to invest in a rivet cutter. Thanks
 
Found a great app that I downloaded for free.....RivetSizer.com........great design!!
Very easy to use. Just plug in the numbers and it will give you the recommended rivet length.
I think you're spot on there.....when I did the formula to double check the rivet length required the result was right between the two rivet lengths that I hand in stock. May have to invest in a rivet cutter. Thanks
 
Section 5.4 of the manual covers this topic very well. In mine it is also page 5-04. Note that vans specify that rivet call outs may often seem too short, but have been deliberately done this way to avoid difficulty setting a long rivet. They also specify that shop heads need not be 1.5 d minimum, smaller sizes are acceptable.

I also encountered this problem on the VS rear spar, and struggled to set about a dozen rivets before I got a clue. I bought a rivet cutter as a result, and it certainly made me feel a lot better at the time, but now I would simply go down a full size and accept the smaller shop head, provided it is still larger than spec.

Interestingly, my rivet cutter is actually not set up with spacers to cut half sizes, I had to use a piece of scrap .032 as an extra spacer to get the half size. This and the fact that half sizes of AD4 rivets are nearly impossible to buy, leads me to believe that out in the big world they are not considered necessary.
 
Thanks......I was using a squeezer to do my tests rivets.....have you started on the vertical stabilizer and riveted the stiffener to the rear spar yet?

I find it's much easier to "tip" a rivet using the squeezer than using a rivet gun. Some of it may be due to holding the squeezer exactly normal to the surface and some may be connected to wear of the moving parts.

Try your test rivets again with a gun and a heavy bucking bar for 1/8 rivets.
 
Section 5.4 of the manual covers this topic very well. In mine it is also page 5-04. Note that vans specify that rivet call outs may often seem too short, but have been deliberately done this way to avoid difficulty setting a long rivet. They also specify that shop heads need not be 1.5 d minimum, smaller sizes are acceptable.

Correct.

And Section 5 also points out that 1.5 D is a rule of thumb, not a minimum.

The minimum is detailed in the MIL Spec which can be found HERE
 
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