How to relax sheet metal?

I have a piece of sheet steel that looks to be tinned, about 8x7", that is
part of a 70 year old box I'm refinishing. It has acquired some stresses,
and won't lie flat, though it will spring into several stable states, like,
boing!. How can I get it to relax, so I can rebuild the box without
stresses?
Reply to
Joe Landau
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Joe, It is mild steel. It is not stressed. It is stretched. You have two choices. You can stretch the rest of the panel or shrink what is streched. . The difficulty is determining where the stretch is. That takes a lot of talent and experience. The corrective action for creating stretch is hammering on an anvil and for shrinking, the use of special rolls or heat and quenching. In all of those cases the finish will be damaged. One possible method that might work and not damage the finish is to use a flat roll and curve the panel one way and then reverse the the panel and curve it the other way. Then open the rolls a bit and roll it back to straight. The panel will be slightly larger than it was and will have to be trimmed. This only works if the panel is flat. Steve
Reply to
Steve Lusardi
I have used a slapping technique to straighten sheet metal. I have a piece of 1" steel -12" X 24" that lays on my benchtop. I take the offending sheetmetal and in a slapping motion strike down on the plate. Be carefull not to hit the edge of the plate for obvious reasons. Light hits seem to work best and if the plate is free of burrs you shouldn't harm your tinned sheet. Steve
Reply to
its me
Try a rubber or hide mallet against a flat steel surface. Maybe get a practice piece and induce some warp, beat on that one or two to get the feel of it
Reply to
daniel peterman
Auto body hail and general bumps are alike.
I'd put it in the sun to heat the metal nicely - but not an oven... Could get that hot but not yet anyway.
Once hot - then press ice - dry ice is colder - into the center of the bulge. The metal will contract (like you if you had ice on a hot body) and with luck re-gain the alignment it once had.
I have taken out a number of ugly hail dings this very way.
Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder
Joe Landau wrote:
Reply to
Martin H. Eastburn
Thanks, guys--I'll try these suggestions. Worst case I might end up looking for a new piece of sheet metal!
Joe
Joe Landau wrote in news:Xns977FEB56E4E3Ajrlversaformcom@199.45.49.11:
Reply to
Joe Landau
On Wed, 08 Mar 2006 09:35:43 +0100, Steve Lusardi top-posted:
How about, get a couple of flat pieces of aluminum plate, 1/2" thick or so, sandwich the steel between them, and heat the whole assembly until the steel relaxes enough to go flat, then let it cool while the steel is being held in place by the aluminum?
Albeit, it'd probably be cheaper to buy a new piece of sheet steel. :-)
Good Luck! Rich
Reply to
Rich Grise

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