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?

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

"Joe Landau" wrote in message
. ..
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?

"Joe Landau" wrote in message
. ..
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?


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

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

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
:

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?

On Wed, 08 Mar 2006 09:35:43 +0100, Steve Lusardi wrote:

On Wed, 08 Mar 2006 09:35:43 +0100, Steve Lusardi top-posted:

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

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


"Joe Landau" wrote in message
. ..
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?

In article ,
says...


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?

By the time the steel is hot enough to "relax" the aluminum will be
downright runny.

Ned Simmons