Dimpling the Fuselage - Flush vs. Dimpled

[psalter]

The technique varies depending on the area of the fuselage. For the 5/8 tubes with no obstructions we use a standard rivet squeezer with a 100 degree male die. (In tests we found the 100 worked slightly better than 120 degree ones). Then set the depth based on a test sheet of .032 aluminim dimpled for the rivets.

For the 1.5 tube, if you had a large enough frame for the squeezer, you can use the same technique.

The problems come in where multiple tubes meet and you cant get a squeezer in. In those cases, i used a bucking bar (cylindrical steel about 2 in in diameter with a hole at the end for a dimple die) and again used a 100 degree dimple die and struck the bucking bar with a hamer against the frame to form a dimple. I tried to keep the blows light, and was conservative with the depth. We have also used a center punch and created the depression.

[rlweseman]

From Tony Spicer:

First, a question about your last sentence. What’s your definition of a “normal builder”? Didn’t know there was any such animal

Yep, the depressions bother some people.

I used a piece of .035 wall square tube and did some testing to see first-hand what a depression looked like.

https://picasaweb.google.com/tonyboytoo ... 1682927730
https://picasaweb.google.com/tonyboytoo ... 4545013122
https://picasaweb.google.com/tonyboytoo ... 3618957538

Based on that, I elected to go with protruding head rivets in the cage. The very last rivet was pulled about two hours ago.

Tony

[rlweseman]

From Rick Holland:

Lynn Dingenfeller described a very interesting method of dimpling the cage steel tubing (which worked for him) at the SNF Panther party. Lynn, if you are listening do you want to share that with us?

Rick H

[rlweseman]

From John Steere:
Paul,

I am in the process of deciding between protruding or flush rivets on the forward fuselage. Everything else on my plane will be flush, so for appearance purposes, I prefer to stay with flush.

However, the critical piece of information that I am missing is exactly what tools and what process is used, and without the mating die piece, how do you control the dimple depth for consistent results. I have searched through the BM several times, but find no description or photos of the steel tube dimpling process.

Any input you can provide about the process, and especially depth control would be greatly appreciated.

John Steere
Panther #039

[rlweseman]

From Paul Salter:

The difference between protruding and flush is mainly for looks at the speeds, the Panther flies. The steel tubing is harder to dimple than aluminum. And the dimple is just a depression and not fully formed dimple as in aluminum sheet. Which bothers some people, because the depressions don't really look that great.


Either way is acceptable.

The prototype and mine are flush rivets.

[rlweseman]

From Christopher Braun

Yes, I am replying to everyone just to get feedback. I only need to order the forward fuselage hardware kit. Have the others. While I have used the flush everywhere, there have been a few places (trim tab) where I went with protruding. Is the consensus that dimpling cabin frame is not worth the work? In other words, unless you are building the Hughes Racer, are most normal builders using protruding?