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  #21  
Old 06-03-2019, 10:20 AM
rkolenda rkolenda is offline
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"One thought: temps seem to be 500F to 650F so annealing happens at the shrink point. What do you do with the softness in your panel?" Kent you bring up an interesting question . So far I have not had any problems using this method with overly soft /mushy panels . You have many more years of repairing old aluminum bodied cars . Do you have any recommendations ? Does the temper return thru aging?
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  #22  
Old 06-03-2019, 10:22 AM
rkolenda rkolenda is offline
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Matt it works very well on steel .
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  #23  
Old 06-03-2019, 11:32 AM
Secant Secant is offline
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Maple die board-all plies are maple & no voids-
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  #24  
Old 06-03-2019, 12:17 PM
BTromblay BTromblay is offline
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Hi,

When I aluminum shrink with a wood disk, I use a Sharpie and put marks on the surface to use as temp marks. So far, shrink is happening below the 650 deg F anneal temp, as the sharpie marks does not burn away. I don't know what the current temp is, but it is allowing the surface to be shrunk. Much like torch heating the panel to 300 deg F for easier shrinking.

I tend to over shrink the panel, and planish back to size and contour. The planish process is re-work hardening the shrunk area like wheeling or planishing after welding.

B
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  #25  
Old 06-03-2019, 02:38 PM
hot rivet hot rivet is offline
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Just a thought on the temperature i would imagine that it is mainly a factor of force and disc speed-if it should prove a problem you could experiment with angle drilling an asymmetric hole pattern through the disc to give some air flow and reduce it's efficiency...asymmetric so it doesn't sound like an air raid siren!
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  #26  
Old 06-03-2019, 02:58 PM
Stretch Stretch is offline
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Thanks Reno/Robert. When I get some time I'm going to make a hardwood disc and give it a try.
Cheers, Matt
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  #27  
Old 06-03-2019, 05:49 PM
Charlie Myres Charlie Myres is offline
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What a fantastic idea! Well done Robert!

Cheers Charlie
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  #28  
Old 06-04-2019, 07:49 PM
rkolenda rkolenda is offline
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Thanks Charlie . I would like to give the credit for this idea to Cass Nawrocki . When we visited his shop a few years ago he showed us a wood dowel mounted on a shank that he used for spot shrinking.I made one when I got home for shrinking a spot and it worked well . I decided to scale it up and this is what I came up with.
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  #29  
Old 06-06-2019, 11:52 AM
crystallographic crystallographic is offline
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Quote:
Originally Posted by rkolenda View Post
"One thought: temps seem to be 500F to 650F so annealing happens at the shrink point. What do you do with the softness in your panel?" Kent you bring up an interesting question . So far I have not had any problems using this method with overly soft /mushy panels . You have many more years of repairing old aluminum bodied cars . Do you have any recommendations ? Does the temper return thru aging?

Only if you are using heat treatable aluminum - 6061, 2023, etc.
Otherwise the aluminum may only be hardened back up by working it.
This is a common problem with the old aluminum auto bodies (3003, 1100), as when they are softened for shrinking they remain soft in that area, because to harden back up means hammering out the shrink, which removes the shrink, making it a "zero sum game."
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  #30  
Old 06-06-2019, 04:57 PM
Ken Hosford Ken Hosford is offline
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I also share the concern of exploding a disc. But would not worry if you banded it with 14 ga or even 16 ga , measure dia add 1 material thickness to get C/L multiply by PI 3.141 subtract .03" - 06" ? depending on roundness and surface finish of disc and ring for shrink fit . Cut a strip to this length roll carefully till round , fusion weld . Heat the ring dull red and drop/pound over wood followed immediately by lots of water . This is the way wood wheels were shod when horse power had four legs and ate grass not wheels and gas.
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