What's new
Van's Air Force

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

How to dimple rudder ribs?

Michael Burbidge

Michael Burbidge

Well Known Member
The top and bottom rudder ribs (R-903, R-904) get very narrow at the aft end. So narrow that I can't figure out how to dimple the last 2 or 3 holes. How did you dimple yours? Would it be reasonable to counter-sink instead of dimple?
 
Here is what I did on the practice kit ribs in a similar area (at the aft end there is not even enough clearance for the "pop rivet dimpler"):

Cleveland (and probably other suppliers) sell a steel bar about 4" long, 1/2" wide and 1/8" thick that has three screw holes in it and a female dimple die at the far end.

You screw it to your workbench with the female dimple die hanging off. Place the hole to be dimpled over the die.

Put a 426AD rivet through the hole in the rib and the female dimple die. Then hit the rivet with a mushroom set in your rivet gun. The rivet acts like a male die and will form a nice dimple.

You can make a similar tool by taking piece of steel, drilling a hole in it, and countersinking the hole. The piece of steel becomes your "female die".
 
As Mel mentioned, a vice grip dimpler works well. If necessary, you can grind 'em down to fit into even tighter space.

Alternately, you can bend the angle on the rib open slightly, dimple, then bend the flange back to the correct shape.
 
I used a corner of my back-riveting plate and drilled a hole in it, then countersunk it appropriately to act as the female die. Clamp that plate down to your bench with the end hanging off, set your part on it, and use a rivet as the male die and drive it with the rivet gun.

Make sure and put your countersunk hole close enough to the edge of your plate that it won't interfere with the internal bend radius of the rib part.

1001156am0.jpg
 
Cleveland tight fit dimple bar...

Unfortunately I got impatient and counter-sunk the last couple of holes. The material is a bit too thin for counter-sinking. I even had one of the Cleveland tight fit dimple bars. It came with my tool kit. I had forgotten what it was for.

I guess I'll be ordering two new parts tomorrow.

Thanks for the help!
 
I think the first time I ran into the problem with dimpling ribs that get too tight to dimple near the aft end, I used the pop rivet dimpler. However, after the nail broke, I could not find a suitable replacement that would work with my cheap pop rivet tool.

After that, I used the "bend it a little method". You simply bend the flanges out a little so you can get a squeezer in the hole, then you squeeze the dimple. When you are done, you bend things back before riveting.

Ok, ok, before you all jump on me and say "you'll fatigue the part and it will crack", I'll just say that you don't bend the flanges that much, and you only do it once, so fatigue really should not be a problem. Just don't bend the parts back and forth. Also, having said that, I think drilling a countersunk hole in a thin plate is probably a better solution. I just didn't have any plates available when I did this.

Tracy.
 
6d finish nails

I've found 6d finish nails work great, at least for the 3/32" pop rivet dimple dies. Whole box for a couple of bucks, and I can get 2-4 dimples per nail.
 
You could always use pop rivets. The impact to aircraft performance will be zero. The only downside might be a few snickers from other builders who did it the hard way, if they would even notice. I didn't use pop rivets myself there, but I wouldn't be one snickering.
 
[email protected] said:
The top and bottom rudder ribs (R-903, R-904) get very narrow at the aft end. So narrow that I can't figure out how to dimple the last 2 or 3 holes. How did you dimple yours?........
Click to expand...

For narrow, difficult to reach areas you can use a close quarters dimple die set.

 
Rick6a said:
For narrow, difficult to reach areas you can use a close quarters dimple die set.
Click to expand...

Rick,

I must be missing something here. How do you feed the nail into the hole? Your pictures prove that it's possible, but I still don't see how a straight nail about the same diameter as the hole can be inserted in that tight spot. I've attempted this a couple of times and after some head scratching ended up using a different tool.
 
borislav said:
Rick,

I must be missing something here. How do you feed the nail into the hole? Your pictures prove that it's possible, but I still don't see how a straight nail about the same diameter as the hole can be inserted in that tight spot. I've attempted this a couple of times and after some head scratching ended up using a different tool.
Click to expand...

Yes, I would like to know the secret trick to that as well. On the folded skin - sure. But on the rib with the stiff flanges?
 
Not totally "Doh"

I've been using 6d finish nails. Pilots nicely in a #40 hole, but the head won't go through it. I don't like using smaller nails because the heads tend to get forced/jammed into the hole in the die.
 
I align the pop rivet dimple dies using the nail from the outside, then squeeze using some vice-grips that I modified. Sorry the photos aren't better, but you get the idea

squeeze1.jpg


squeeze2.jpg
 
One more idea. You can use your squeezer and a no hole (thin nose) yoke if you temporarily stick the female half of the pop rivet/nail type dimpler to the nose of the yoke. I use fuel lube, but any temporary stickum will do. Then just use the normal male dimple die on the moving part of the squeezer to form the dimple. This worked great for me in many situations where traditional methods failed.

Terry
President; www.eaa1300.org
 
You must log in or register to reply here.
Back
Top