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  #1  
Old 09-12-2009, 08:13 PM
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jhnarial jhnarial is offline
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I was a thinking today.

I don't know how to get this question across.

If you had a piece of sheet metal say two inches put a 90dg bend in it so you have one inch on either side.Then you placed little round dimples into one side.Would it put a radius into the piece?Just thinking about it I think it would.I could be wrong but if I'm not ,I would have a use for this.There are a lot of hidden flanges that are never seen.

Would it work or not?
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Old 09-12-2009, 11:00 PM
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Personally, I doubt that dimples would make it curve but tucks certainly will. The dimples, being surrounded by the original metal, would have been formed by stretching (drawing) I'd think. If the dimple was right at the edge it might work.
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Old 09-12-2009, 11:06 PM
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I don't know if this is the answer you're looking for.. I once ran into a problem when rebuilding the aft fuselage frame of a Bell 204 where I needed a to stretch an angle to follow a curve. Pretty easy task with the right tooling, however I didn't have the right tooling. My 'field' solution was to set up a rivet squeezer to press a series of dots into the part causing it to stretch to form the curve.

I have also on occasion needed to form dimples in angled parts to accept countersunk fasteners (because the parts were to thin to cut countersinks) and have not stretched the flange. I suppose if you over pressed the dimples you would cause stretching and end up with a curve.

Sean
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Old 09-12-2009, 11:11 PM
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My thoughts on it was.

When the metal was drawn into the dimple it would pull on the inner edge of the flange.I thought that would be the path of least resistance.

It was just a thought.
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Last edited by jhnarial; 09-12-2009 at 11:14 PM.
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Old 09-12-2009, 11:14 PM
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Try it.

Btw, it's easy to use a door skin type hammer to do a linear stretch on a flange. Well, it's not EASY but it's a simple process.
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Old 09-12-2009, 11:19 PM
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Are you trying to shrink or stretch? Dimpling, like Kerry said, is more of a stretching operation. When you dimple a hole, say .250 in diameter it gets bigger by around .003 to .005
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Old 09-13-2009, 03:57 PM
Sean Sean is offline
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Default Tried it..

I gave it a shot. 2" strip bent 90* with 1" flanges\
First laid out a row of 3/16 holes with minimum pitch and edge distance
056.jpg

Pneumatic rivet squeezer with 100* dimple dies installed
057.jpg
058.jpg
059.jpg

061.jpg

Turns out no matter how hard I pressed the dimples it didn't change the radius
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Old 09-13-2009, 05:47 PM
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Thanks for taking the time to try it.

I was thinking on not having holes in the dimples but I don't think it would have made a difference.

Thanks again.I was hoping when the metal was pushed into the dimple it would pull on the inner flange.I guess I was wrong.
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Old 09-13-2009, 10:12 PM
Barry Barry is offline
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May work if you do it a little closer to the edge Johnny?
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