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Old 02-27-2016, 11:20 AM
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32chevy 32chevy is offline
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Default Shrink with hammer. Trap perimeter & work center into surrounding

Can an over stretch area of a panel be shrunk with a hammer and proper technique. I just built a shrink stump and it is highly effective but only useful on panels edges. I have had success with shrinking with heat and proper hammer technique. But now would like to know about other options for shrinking

I think a series of small dents around the perimeter of an over stretched area would be the way to trap the metal so that you can work the center into surrounding area.

How is this done , and good references
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Last edited by 32chevy; 02-27-2016 at 11:26 AM.
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Old 02-27-2016, 12:19 PM
crystallographic crystallographic is offline
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Yes, it is a useful technique, and can be accomplished on different metals.
Steel is probably better done in the blue heat, going towards the black heat.

I've noticed that getting the trap started around the perimeter is a sensitive thing, because stretching should be avoided.

I learned over the years that some fast working is helpful, so it was better for me when I got my machine trained to do it for making repairs to severe damage.

shrink to reduce crown.jpg
shrink to reduce a crown.jpg
This is doing aluminum cold.
The metal is black when doing warmed steel.

Maybe this helps?
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Old 02-27-2016, 08:26 PM
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Kent thanks for your reply. I don't have a power hammer. I was looking to apply this over a sand bag with panel and hammer
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Old 02-27-2016, 09:58 PM
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Kerry Pinkerton Kerry Pinkerton is offline
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Donut dolly is a useful way to do an internal shrink. The process is similar to doing off dolly shrinking but you use the circular donut dolly to support everything in the center and as you gently tap it, it pushes inward and shrinks. Not fast but effective. I believe if you search for donut dolly you'll find some threads.
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Old 02-27-2016, 11:10 PM
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I would think that anything you can do with Kent's air hammer you can do by hand, just much slower, and you need to use the right tools so you don't stretch the metal.
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Old 02-28-2016, 04:24 AM
Oldnek Oldnek is offline
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Localised stretch is pretty hard to get back without heat shrinks, I have tried on numerous occasions to remove stretch in a large panel using a similar devices as a donut dolly, it appears to work , but it is pretty deceiving because is just move the area of stretch around.

Flamed heat or Shrinking disc is a better option and let air cool

Now if you take a look at Kent's images, he has a large area of stretch beyond the panel, where he can shrink back, because you can trap the tucks and eventually planish back out.
Working around a perimeter is easy to shrink cause your trapping the metal and hammering onto itself, a large flat panel is a different piece of cake.
The metal needs to pull to shrink effectively.

I can see I going to cause a few arguments here.
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Old 02-28-2016, 09:02 AM
John Buchtenkirch John Buchtenkirch is offline
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I’ve had decent results pounding soft aluminum back into itself (shrinking it radially) but doing the same on steel is certainly more limited but still somewhat doable. I’m semi old now and admittedly somewhat impatient (who knows how many working years I have left) so I’m quick to fall back on what has worked well for me for 45 years, shrinking steel with a torch . ~ John Buchtenkirch
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