Rivet questions

Post by **Spike** » Thu Mar 30, 2006 2:22 pm

For me the magic question is this, "Will I do more damage by drilling and redoing the rivet?" Unless the rivet is really bad, this question guides my decisions. Frankly the picture that you posted, if you were to question that rivet I would leave it. Remember to try and think how the rivet is stressed. Generally its always in shear, not in tension.

Wicked Stick · Post by **Wicked Stick** » Thu Mar 30, 2006 10:15 pm

prestwich wrote:I thought I'd reopen this thread now that I'm actually riveting. I finished the HS rear spar on my 7A, and I'm happy with almost all of the rivets. Most of the rivet length callouts were a tad on the short side and I managed to squeeze 'em straight. But, the last couple of brackets had more free length on the rivet (yes I'm sure I used the correct ones) and I got at least one rivet that's a bit "clubbed." How do you know when it's OK to leave it as is? The finished height and diameter are fine.

Also, why the hell are my flat squeezer dies crowned? Seems like they should be dead flat, or even slightly concave. Having that slightly convex shape to them seems like an invitation to clubbing the rivets.

To me, looking at the picture, I would say they need to be squeezed, or bucked just a tad more. Van's callouts are usually a tad shorter than what the rivet gauge calls for, but sometimes they are a wee bit long as well. These in the picture look like they started out as rivets that were too long to begin with. Since it's not a dimpled hole, you can more easily drill them out and re-buck with a correct length rivet.

When drilling out rivets, I like to use the next smaller size drill bit so that I don't enlarge the hole if I'm slightly off center. (example, a #31 or #41 to drill out -4 and -3 rivets)

If it were me, and I've been known to be anal about my project, I'd try drilling one out and using a slightly shorter universal rivet. sometimes if the length only has to be shortened by a little then just touch it to the scotchbrite wheel to grind off the small amount you need to get it the right length.

The two on the right hand side of the picture look fairly straight, so just givem a bit more squeeze and leave them. The two on the left, especially the bottom left, I'd redo. Just my opinion mind you.

I have two sets of dies, one that came in the avery kit, which seem to have the crown you speak of, and the other sets are flat that came with my pneumatic squeezer. I hardly ever use the crown'd set now that I have the flat sets.

prestwich · Post by **prestwich** » Thu Mar 30, 2006 11:08 pm

They *were* too long to begin with, now that I do the calculations. They "should" have been -4.5 (.281) rather than -5 (.312) as the plans call out. Wish I'd checked that first.

I also emailed Van's tech support, and was told that the clubbing wasn't too much of an issue here, but he also said they needed to be squeezed down a bit more.

The thing is, they are correct as far as diameter is concerned, so do they really need to be shorter? I'm afraid it will increase the clubbing.

As far as the crown in the squeezer set, I was told that it's to keep from marring the skin when setting the flat heads. Jeez, that makes total sense, but then the tool makers ought to make two different styles of sets. A tiny bit of curve the other way seems like it would sure make for better shop heads.

Oh, jeez Dave, I was in such a hurry that I just now read the last sentence of your post. Guess I need to find some dead flat sets for this work.

tshort · Post by **tshort** » Fri Mar 31, 2006 4:54 am

I was gonna say the same thing as WS - it could be the picture, but they really do look undersqueezed to me, too.
Do you have a guage for checking them? It may not work really well if the rivets were a little long to begin with (extra material in both dimensions) but it gives you an idea what you're looking for.
I would say, though, (unless the picture is deceiving) that those need to be squeezed more.

Thomas
-8 wings

captain_john · Post by **captain_john** » Fri Mar 31, 2006 6:40 am

I will "third" the motion. They DO look under squeezed.

They could take better shape when they are completely squeezed and may not have to be redone.

CJ

cjensen · Post by **cjensen** » Fri Mar 31, 2006 9:50 am

a fourth motion here. pwich, i know EXACTLY how you feel about those...i did the same thing, except mine were on the HS stiffeners and come to find out, it was my hand squeezer being out of alignment, not incorrect length rivets (you probably read that earlier). i did drill out 38 rivets, and sweat bullets the whole time. yours aren't so bad, so i would just squeeze each one a little farther, and they should be fine with the exception being that lower left one-i'd probably drill that one regardless.

i'm a little late in responding to this, so perhaps you've already worked it out, but i thought i'd throw my thoughts in FWIW (not quite .02

)

prestwich · Post by **prestwich** » Fri Mar 31, 2006 11:52 am

OK, I think I hear the crowd voting for more squeezing! I gave the little fellows a bit more. Thomas, you're right, they're a bit big in both dimensions. They're still beyond the max height, but they're starting to not fit through the max width gauge. Anyway, I hope these will hold the damn airplane together.

One thing the guy at Van's said was they don't like to drill out rivets just to put in another rivet. I think I agree with that sentiment. I'm not seriously deluding myself into thinking I'm going to build an airplane without drilling any rivets, but I don't want to start quite this soon.

Post by **Spike** » Fri Mar 31, 2006 1:02 pm

Hmmm, something just caught my eye, and I hope you dont mind me inserting myself a bit. I personally would suggest that you take your edge preparation a bit further. your spar edges seem to be a bit "rough"

-- John

prestwich · Post by **prestwich** » Sat Apr 01, 2006 2:07 am

Hmm, thanks for that suggestion, John. I had thought that I'd been pretty good with the edge prep. They do look a bit rough in the close-up shots. But they sure aren't sharp. I deburred them pretty thoroughly with the burr knife, and then gave 'em a good workover with the small scotchbrite wheel in my air drill. (Boy does that swallow a tank full of compressed air in a hurry!)

I actually think they look better in person than in the photos, but I'd welcome more feedback on that, or visual comparison. Anybody have a close-up photo from similar angle, etc?

Jeez, I've *got* to get outta the house and find a tech counselor or something! (Not to mention a rivet bucking girlfriend ':evil:' )

johnk · Post by **johnk** » Sat Apr 01, 2006 7:57 am

I agree that the edges feel smoother than they look under magnification, mine were the same way, when I looked closely, they still looked ragged. To remove the ragged edge, before using the scotchbrite, I run a fine file all around the edge which removes the larger roughness. Then I finish with a blue scotchbrite disk in my airdrill, which leaves a very smooth edge. Don't know if this is more than required. It's hard to know how smooth is smooth enough.

JohnR · Post by **JohnR** » Sat Apr 01, 2006 11:20 am

I'm going to look at my edges and see what they look like. My tech advisor uses the thumbnail test on the edges. If the thumbnail doesn't catch and there are no sharp edges they are good. I do trust his opinion and am glad to have him available to review my work.

A week or so ago he looked over what I had done and studied the parts for a while which was making me a little nervous. Then he turned to me and said "Looks good, I'll do rolls and loops with you in it any day"

That was a great confidence builder.