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July 2005
heat shrinking metal with a torch?///////

Procedurte is basically to heat an area of the streched metal about the size
of a dime to a dull red.  When the metal begins to dome up, you know you've
added enough heat.  Immediately set the torch aside ( a helper or stand
makes it easier), then you place a dolly directly under the domed part and
hammer, forcing the metal into itself.  Then cool with a damp rag or sponge.

Lots of good information on the web:
http://www.metalmeet.com/index.htm
http://www.allshops.org/

Do a search on the forums at either site and you'll find info and pics.
Also consider searching on "shrinking disk".
The back panel on the Roadster I'm just finishing up was rumpled pretty
good, with the metal quite stretched.  I made a shrinking disk out of a
stainless steel pot lid, and was amazed at how well it worked compared to
the old torch method.

You can see the tool on a page on my site
http://www.mildevco.net/chevypowereddatsuns/bodywork.htm
and check out the other body and metalworking stuff on rest of the site
using the links on the left http://www.mildevco.net/chevypowereddatsuns

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As Eugene said in his reply, you run the spinning disk over the high spots
until they turn straw color - almost but not quite blue.  Keep the disk
moving in small circles over the high spots, almost like using a disk
sander.  When the metal is hot enough, quench it.  Unlike the torch method,
where you are using localized heat to expand a small spot of metal and
hammering to force it together, the disk heats a larger area and quenching
pulls it in.  In between disk passes, you can do some light off-dolly work
to bring up the lows.  One of the sites I gave you the links for has a video
of a guy using one.


The shrinking disk is just a stainless pot lid attached to your grinder. You
touch the high spot with the spinning disk for about 5 secs. The metal may
or may not turn blue but you definitely don't want it any color or shade of
red. Immediately, quench the area with a wet rag - it should sizzle. If it
didn't shrink enough, do it again. It's very easy and that's where the
amazing part comes from...`