Tip: Outie Dent Removal

[Stewie]

Hi all-
Dropped my bucking bar while riveting the wing tank the other night and after a few choice words, I came in to search VAF and the internet on dent removal and see if I couldn't learn a new skill. Based on various ideas, I came up with a method that was able to work the two outie dents (on the upper skin of course!) mostly away. Here's what worked:

1. Sharpie cross hairs on your dent.
2. Get a 3 inch length of clear packing tape, fold a corner over on itself (so you can remove when finished), and center over the dent. Do this again (2 layers of tape).
3. Use a spoon and push on a radial from about 1 inch out into the center of the dent. Work in a radial motion, moving about 10 degrees per stroke (ie, after approximately 36 strokes you will have made a complete circuit around the dent).
4. For the big outie, I held a concave dolly (OK, a spoon with a bucking bar under it!) under the skin and hit the outie from the protruding side with a mushroom head (flush set) in the rivet gun. Pressure was set at 20 psi. I was very careful to only get 2-3 hits doing this before returning to step 3. For the smaller outie, no hammering was necessary. I hammered the big outie 4 times with the gun, with 5-10 minutes of spooning between each hammering.
5. Keep repeating step 3 until outie is gone.


I spent about an hour on the big outie and 20 minutes on the smaller one. The big one is still barely perceptible to the touch but I began the experiment spoon to metal and the aluminum is a bit scratched up at the moment. I'm planning to polish the plane, so once I've polished out the scratches, I may keep working on it depending how it looks. With the smaller outie, I used the packing tape from the start and no scratches. The dent is no longer perceptible to the touch, although in reflected light I can see a small wave.

Just thought I'd pass along something that worked for me. Takes time, but it is doable. In my newfound power, I went out and did this on an old outie in my Grumman Yankee and it worked great and did not lift the paint (just be sure not to forget to use the packing tape).

You want pics, I know. Sorry, the camera is on the charger and I didn't feel like waiting to do before and after pics.

Eric

[Wesael]

Thanks for the tip!!!!

[David Paule]

Good for you!

Years ago I watched a guy from a car body shop unbash a leading edge that had been pushed into a hangar door. It was similar to your description.

In both cases, his and yours, it took a lot of good old-fashioned craftsmanship. Excellent.

Incidentally, he held a solid round bar inside the leading edge, and gently tapped, with a suitable hammer on the outside while pushing with the steel bar. That is, it was a lot like riveting: the hammer added energy and the steel bar did the work. The hammer had a slightly convex surface but was basically flat. It wasn't very big.

Dave

[KRviator]

Thanks for the tip, Stewie.

I've got a doozy to Smooth over on the rear deck where I let the bucking bar slip... so this might be just the thing to get it looking semi-reasonable.

[fixnflyguy]

Eric,
Sounds like you did a good job on your re-work...to put it in perspective, at my day job, I manage a re-skinning project for a 737 operator ,and we work with skin panels approximately 23'X5'x.036" in size...one single "outie" or "innie" over .004" in depth is cause for rejection(cant re-work them on pressurized skin)...at the cost of $60K-$100K per panel !!. On each aircraft, we change 10 panels. Ask me how I know the price !! ugh. My -4 has a little re-worked outie, but it hasn't bothered me a bit since the first flight !

[videobobk]

For more tips on this, search on "paintless dent removal" and you will probably find some good stuff. I did this the first time when my black lab stepped (pounced) on my 9A rudder skin I had stupidly laid on the carpet. I can't find the five dents, even though I know just about where they are. I have done this on a few spots on the 12 we are building, and the painter looked at them this week and said we are good to go. I work in a circle, from the outside in, but either technique would probably work on most dents. Good tip!

Bob

[aerhed]

This is why my wife won't rivet with me any more. I was fixing a B36 gear-up and did most of the big belly skin by reaching in and riveting my way out. When I got beyond that point she was inside bucking away. With half a dozen rivets to go she knocked a buck bar off the spar and it of course landed in the middle of the skin and left a triangular outie right in my face as I was laying under there with the gun. I spazzed and now she won't go near a bucking bar. Keyword for a happy marriage is "restraint". Something I'm still learning.

[Stewie]

Originally Posted by David Paule

Good for you!

Years ago I watched a guy from a car body shop unbash a leading edge that had been pushed into a hangar door. It was similar to your description.

In both cases, his and yours, it took a lot of good old-fashioned craftsmanship. Excellent.

Incidentally, he held a solid round bar inside the leading edge, and gently tapped, with a suitable hammer on the outside while pushing with the steel bar. That is, it was a lot like riveting: the hammer added energy and the steel bar did the work. The hammer had a slightly convex surface but was basically flat. It wasn't very big.

Dave

I like this idea even better than hitting it with the gun. Think I am going to buy the beginners metalworking kit from tinmantech.com.
Their 4-day metalworking class looks pretty nice, but spendy ($1500). Maybe I'll try to organize a VAF group-buy when I'm finished with my -4...

[Stewie]

Originally Posted by videobobk

For more tips on this, search on "paintless dent removal" and you will probably find some good stuff. I did this the first time when my black lab stepped (pounced) on my 9A rudder skin I had stupidly laid on the carpet. I can't find the five dents, even though I know just about where they are. I have done this on a few spots on the 12 we are building, and the painter looked at them this week and said we are good to go. I work in a circle, from the outside in, but either technique would probably work on most dents. Good tip!

Bob

Bob-
I read your posts when researching this topic. I tried both concentric and radial spooning, but found it hard to move in a nice concentric motion. But agreed that they are basically both pushing metal in. Appreciated your previous posts on this, very helpful.

[Av8torTom]

Having the metal bar on the inside to backup the tapping on the outside is key. It's easy to turn a small outie dent into an even bigger innie dent. I also watch a guy fix a leading edge this way; when he was done there was no sign of the dent... amazing.