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Tin Bender question
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Author:  N3Njeff [ Sat Sep 06, 2008 4:04 am ]
Post subject:  Tin Bender question

An old time mech that I am trying to find so I can ask him this again. Since I have had no luck, I will post here.

If you have a dent in a skin, how do you pop it out with dry ice and heat. He told me the way but I dont remember it. I am thinking about buying a airplane with minor hail damage.

Author:  Second Air Force [ Mon Sep 08, 2008 10:03 am ]
Post subject: 


I learned this on auto sheetmetal, not aluminum, but I assume the theory is the same but with lesser amounts of heat needed.

First you warm up the dent area of the metal with a heat source (a heat gun would likely work best on aluminum, and I'd guess not much heat would be required) and then apply the ice directly on the dent. I actually used regular ice on the vehicles I used it on, and it did remove small dents that hadn't stretched the metal too far. I've never tried it on 2024, so other inputs would certainly be welcome.


Author:  Greg87 [ Mon Sep 08, 2008 10:52 am ]
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Wouldn't you risk altering the heat treatment properties of the 2024? Just curious.

Author:  Second Air Force [ Mon Sep 08, 2008 11:06 am ]
Post subject: 

Good question, Greg.

The warming temperatures that I think would be useful for this process wouldn't be hot enough to cause any problems I don't believe. The rapid cooling was the real driver in the process with steel, but I don't know if that would "shock" 2024 and cause problems. It's something I just might try on a piece of scrap .032 tonight just to see what happens. Aluminum stretches easier than steel, so the idea may not work at all.

We used to have an airplane on leaseback at my old flight school that looked like a golf ball. I should have tried the hot/cold treatment on it!


Author:  Dan K [ Mon Sep 08, 2008 3:22 pm ]
Post subject: 

I Googled a number of autobody remedies. I'm definitely going to experiment on scrap 2024. Try scrolling through the following videos:

http://www.wisebread.com/remove-car-den ... nd-cheaply

Author:  bdk [ Mon Sep 08, 2008 5:45 pm ]
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Greg87 wrote:
Wouldn't you risk altering the heat treatment properties of the 2024? Just curious.
It takes a while for the grain structure to change when exposed to temperature. Short durations (like 30 seconds) should not have a measurable affect under probably 500 degrees C/932 Degrees F, which is the approximate solution treatment temperature which is applied for some hours. You'd never get that out of a hair dryer and probably, because of conduction, might have trouble getting that out of a commonly available industrial electric heat gun.

That's not to say that putting the tailboom of your P-38 in a furnace at 1000 degrees F for 30 seconds would be a good idea though. It might permanently twist like a pretzel from residual stresses, but at least the heat treat would be OK.

Author:  tinbender2 [ Sun Sep 14, 2008 3:26 am ]
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good luck with that.

I've tried it twice without enough improvement to bother continuing. This was on small aircraft, 2024T3. The technique works fine on thin steel automobiles though.

It simply wasn't cost effective, labor-wise, to try to remove dozens of hail dents.

Author:  Broken-Wrench [ Sun Sep 14, 2008 9:17 am ]
Post subject: 

I have done it with 737 nose ring cowlings but it only worked about half the time. The cowling metal is thicker and has a memory. I did some work on a airbus that was chaught in a hail storm. I Purchased a $80,000.00 machine that produced a vacuum to suck the dents outs and bring them within acceptable tolarances. maybe you could make a machine to suck the dents out in a localized area. It is going to take some out of the box thinking. First I would find out what the tolarances are and measure and number each dent. Some you might be able to work out some on the back side.

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