What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Newbie riveting question

jlott

Member
I'm currently working on the Practice Kit and should be ordering the empennage in the next week or so. I ran into a small problem today riveting the ends of the practice kit project (the reinforcement/spar/rib combination).

Basically, when the shop head of the rivet is being formed the rib flange wants to lift up off the spar leaving a gap once the rivet is set. I played around with a number of different ideas to prevent this but I'm not sure if its possible.

Is there some way to prevent this gap from forming?

9vcgoz.jpg
 
Last edited:
Try...

Clamping the two pieces together either with a spring clamp or a small u clamp available from most avion tool supply stores.
You just need to keep the metal sandwiched together when riviting, and normally on more lengthly pieces, clecoes in the surrounding holes will clamp sufficiently. I hope this helps. BTW sometimes your local Harbor Freight Aviation Dept ;) has the clamps you need.
Keep on riveting!
 
That shouldn't happen. One way to mitigate the problem might be to bend the rib flange ever so slightly so that when you cleco the middle hole it pulls the ends of the flange up against the spar. Rivet the end holes first (leave clecos in the holes you are not riveting), then do the middle hole.

Usually, squeezing or driving rivets will pull the two pieces of sheet metal together unless the gap is considerable.

Hope this helps.

cheers,
greg
 
You will find it will happen when the shop head is put on the thinner material which is where it needs to be in this case. When you get into your project you can put the manufactured head on the thinner material when possible. Squeezing the rivet just a little too hard will cause the thinner material to lift up, it will take a little practice but take some thin scrap and you can see how much squeezing it will take to distort around the rivet.
 
Clamping the two pieces together either with a spring clamp or a small u clamp available from most avion tool supply stores.

Yeah I tried the spring clamps that I have but the space is so small... cant really get them onto the very corner of the flange. I will try to find a smaller clamp.

... the middle hole it pulls the ends of the flange up against the spar. Rivet the end holes first (leave clecos in the holes you are not riveting), then do the middle hole.

Sadly, there is no middle hole. Just two rivets hold that flang against the spar in the practice project.

Thanks for your responses guys! :)
 
Over driving the rivets

Looks to me that you might be over driving the rivets, a properly driven tail should be 1.5 the rivet dia, another good rule of thumb that someone mentioned above about having the head on the thin side and forming the tail on the thick, the puckering in your photo is a good example of what happens with tails formed on thin material.

Good luck with your build,

Cheers Nick
 
Looks to me that you might be over driving the rivets, a properly driven tail should be 1.5 the rivet dia

I'm constantly worried about that actually. First rivet I ever drove in my life was on the toolbox kit :)

The rivets in the photo measure OK using a rivet gauge for both height and diameter of the shop head. You guys all know a lot more than me though.

Thanks!
 
Bend the flange

You should be able to bend the flange slightly as Greg stated so that it sits firmly against the spar. Give it a try - won't take much.
 
Use that cleco clamp.....

Sometimes you will find that if your triple work is not clamped tightly, when you squeeze the rivet, the rivet shaft expands slightly between layers forcing a bad fit. It is probably the camera lens, but it looks like you are not squeezing perpendicular to the hole, or perhaps the hole was match drilled at a slight angle. Probably just the camera lens, though.
 
Drill?

This is actually a plus if you choose to make it such. Use those rivets to practice drilling them out, you will need to be proficient at it as we all were/are...I remember the horror I felt on my first bad one that I drilled out with shaking hand...

Build on!!!
 
Thanks for all the excellent responses! :) I also got a response on my builder blog directly which poses an interesting answer to the question of why this is happening.

I did in fact drill out twice already, tried various clamp placements and also tried different bucking bar angles. I am going to drill them out again when I'm in the shop next and try one or two twists on the ideas you all have presented.

Thanks again!

P.S. I ordered my tail feathers today. The serious building will begin soon! :D
 
Last edited:
There will be instances where you'll need to rivet a flange that won't lay flat but that for whatever reason can't be clamped. Besides swapping the rivet end-for-end and putting the manufactured head on the thinner material, another option is to place a small rubber grommet/washer/o-ring that is a little thicker than the protruding rivet shaft over the shaft. The rivet die or bucking bar is then placed against the grommet. As you squeeze or buck the rubber will compress this allows you to apply pressure to the surrounding metal and still make contact with the rivet shaft. Set the rivet just enough to hold everything in-place, remove the grommet and finish setting the rivet.
 
A little tip: When riveting thin aluminum sheets together with with AD rivets, it can sometimes be difficult to keep the two sheets tightly together as you squeeze/set the rivet. The result can be a slight gap between the sheets.

I have found that by placing a small (@1/2" x @3/8" x @3/16") piece of rubber with a @1/8" hole drilled in the center (I use old orange silicone baffle material) over the unformed shop end of the rivet and then squeezing/setting the rivet, the rubber piece creates pressure which keeps the two sheets tightly together during the squeezing/setting process.

Be aware - the little buggers have a tendency to fall to the floor and get lost, so make several of them!
 
If the two parts aren't sitting together, you can set them by placing the bucking bar against the outside of the rivet and giving a short burst on the head. The procedure is explained in one of the standard books but I can't remember where off the top of my head.
 
A little tip: When riveting thin aluminum sheets together with with AD rivets, it can sometimes be difficult to keep the two sheets tightly together as you squeeze/set the rivet. The result can be a slight gap between the sheets.

I have found that by placing a small (@1/2" x @3/8" x @3/16") piece of rubber with a @1/8" hole drilled in the center (I use old orange silicone baffle material) over the unformed shop end of the rivet and then squeezing/setting the rivet, the rubber piece creates pressure which keeps the two sheets tightly together during the squeezing/setting process.

Be aware - the little buggers have a tendency to fall to the floor and get lost, so make several of them!

Hunh? I sort of thought that was what I described 3 hrs ago in post 13, except I used a grommet instead of a rubber sheet. :rolleyes:;)
 
So I'm not an expert yet by any means, but I am almost done with my tail section.

Given that disclaimer this isn't normally something I would use the rivet gun on. It's pretty trival to get the squeezer in there and get a good set if you put the spring clamp on along the edge of the tab. Fitting a bucking bar in the same space is much more difficult. I used my manual hand squeezer almost exclusively for these types of things on the empennage pieces. Probably several hundred rivets. Better than going to the gym too. I still don't feel comfortable using my pneumatic squeezer for all of these rivets yet. I just don't get the same level of control. But as you do more rivets you continue to encounter different situations that require different tools. I keep thinking I have all of my tools but that may be silly to even think at this point. I know when I was doing the practice kit I had a very limited set of tools since I was trying to decide if I really wanted to do this type of project so you may not have too many options yet. Just keep working at it and you'll get better. I did a couple of the practice kits before I felt like I was ready to start on the parts that mattered so you might think about that too.
 
You probably squeezed the rivet.

Since it's a test piece, try using the rivet gun and a bucking bar. The rivets do seem to set slightly differently, especially if the holes are slightly oversize.
 
I had put three rivets in on my practice kit, worked out fine on the second side but had to drill out several on the first side!!!!!! Takes alot of practice.
 
Back
Top