#21
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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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Robert |
#22
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Matt it works very well on steel .
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Robert |
#23
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Maple die board-all plies are maple & no voids-
Jamb nuts from any good hardware store
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Karl Heinz |
#24
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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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Bill Tromblay "A sign of a good machinist, is one who can fix his F$@& Ups" My mentor and friend, Gil Zietz Micro Metric Machine. |
#25
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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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Paul |
#26
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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 |
#27
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What a fantastic idea! Well done Robert!
Cheers Charlie
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Why does dust stick to everything, but nothing sticks to dust? |
#28
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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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Robert |
#29
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Quote:
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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Kent http://www.tinmantech.com "All it takes is a little practical experience to blow the he!! out of a perfectly good theory." --- Lloyd Rosenquist, charter member AWS, 1919. |
#30
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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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