Wing skin dimples... too deep?

[RV7Factory]

Today, in a moment of inattention, I dimpled one of my top wing skins before I realized I was using the Tank Dimple Dies in the C-Frame. D'oh!

Ok, probably not a big deal, but it is the top skin... grrrrr.

Please somebody tell me I am being OC about this. I might use my regular dimple dies to try to lessen the current dimple, but I suspect when painted, nobody will know the difference anyway.

I just hate when I do stupid things.

[tshort]

I don't know that I would "redimple" them - not sure what the outcome would be. I guess you could try on a piece of scrap and see.

The only thing I can think of that might be bad is if the rivets sit down in the dimple then when set with the flush set there might be a small space between the head and the dimple (where the proseal would normally be). Might test this out on a piece of scrap, too. I bet it will look OK.

Thomas

[captain_john]

naaaaah, fuggetaboudit!

You will be fine! Such a non-issue, really...

Press on!

Those tank dies should be in the hands of the next tank builder in your area anyways! You are done with them until you do your next plane!

CJ

[Wicked Stick]

Without the proseal in the holes, I think you might actually end up with a gap like Thomas speaks of...

The only way to really tell, is to try a few samples on scrap.
Also, try the re-dimple with regular dies on scrap too, then rivet to see.

Did you do the entire skin with them, or just a couple of holes ?

[Lorin Dueck]

I agree with CJ. It should be fine. The thinner skin will pull into the contour of the thicker rib flanges when riveted.

For what it's worth - I know of a Tech Counselor who was helping someone else (not me!) work on their fuselage skins. This person dimpled one panel on the wrong side.
Their solution was to go back flatten all the holes with a flush rivet set and then re-dimple the other side.
I asked him about work hardening & possible stress concentrations.
He said there was not a problem if you only did it one time.
This would lead me to believe you could redimple with the proper dies if you felt strongly about it - but.. again - I wouldn't wory about it!

Lorin D
9A Wings

[svanarts]

That is also what Van's support told me. You can re-dimple...ONCE.

[RV7Factory]

Thanks for all the suggestions guys.

I should have been clearer... I wasn't going to remove the dimple then redimple, I was thinking about just dimpling again with the regular dies. I thought about this overnight and I came to the conclusion that it won't do any good... it just won't do anything.

Anyway, my A&P neighbor came over today and we devised as solution. It involves using my DRDT-2 with a flat set to lessen, not remove, the dimple then redimpling with the correct dimple die. We tested this theory on some scrap today and it really seemed to work well. We are setting up the DRDT-2 so that the flat set only extends to the stops of the DRDT-2. Anyway, its kinda hard to explain in just a few words, so I will post a pic in a day or two.

I would normally leave this alone, but I planned on back riveting the top wing skins, and I do not want a deeper dimple or in this case the rivet might sit proud.

[captain_john]

Ahhhh, the rivet WOULD LIKELY sit prou in those holes and cause a problem in backriveting. Good call on that. I would be more concernned about work hardening the area with all the undimpling and redimpling.

Traditional bucking works pretty good in my book for installing these rivets. It is a 2 man job for sure, but quality is great!

CJ

[RV7Factory]

I would be more concernned about work hardening the area with all the undimpling and redimpling.

Yea, I agree. That's why I brought in the expert (A&P). It was his first concern too, but since we are just lessening the dimple a *tiny* bit rather than removing the dimple completely, he felt it wasn't an issue given the skin was T3 AL. We will see... I sure hope this works.

NOTE TO SELF: Borrow wife's nail polish and put some red dots on the tank dies!

WS... this was the entire outboard wing skin... Grrrrrr!

[JohnR]

Bummer Brad. Good luck in re-dimpling. I almost made the same mistake on one of the tail skins but caught it right before I started.

[RV7Factory]

I said I would post pictures of the fix, and here they are...


First I inserted a piece of solid AL between the frame of the DRDT-2 and the set holder. This was done to bring the set holder up to level with the table surface so that I could use it as a working surface. You will also notice I turned the set holder around.


I then inserted a flat set into the DRDT-2.


I then set up the DRDT-2 so that the flat set only extended to a point where it would lessen or remove the dimple slightly and squashed the dimples between the set in the ram and the flat surface of the set holder below. I set it up so that the DRDT-2 hit its limit before the dimple was removed or squashed completely (as pictured above). I had to remove the handle of the DRDT-2, but hardly any pressure was needed so the little stub that stuck out proved adequate. Basically I barely kissed each dimple with the flat set, and if I hadn't told you, you would never have tell the diples had been squashed a little. You had to insert a rivet to see that the dimple was shallow. In the picture above, only the dimple on the camera side of the set/ram had been squashed, and you can only tell the difference if you look real close.

Once all the sqashing was done, I set up the DRDT-2 for regular dimpling, and redimpled the skin. It felt like it wasn't doing anything, but when it was all done, it the dimples were all the correct depth. Another problem solved!

[Lorin Dueck]

EXCELLENT!!!
... and thanks for the pics!

Lorin D
9A Wings
N194LD reserved