"Meanie" wrote in message ...

A few weeks ago I asked about bending a 2" wide x 1/4" thick x 3' length
flat stock 6061 aluminum bar into a U shape with a 7" radius. I was
concerned about the bar springing back and thus did an experiment. I
made a die using wood to form my radius.
https://www.flickr.com/photos/18223943@N06/14635585195/ and tested a
piece of 1/8" thick aluminum bar.
https://www.flickr.com/photos/182239...n/photostream/
Though, I realize the 1/8" bar is more resilient than the 1/4", the
concern of springing back presents itself as you can see
https://www.flickr.com/photos/182239...n/photostream/

Therefore, what are the possibilities of the 1/4" bar springing back and
what can I do to prevent this? Heat? It's important the bar retains it's
shape after bending.

Thank you

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In commercial press-brake work, springback is compensated by overbending. If
you have one of the fancy new CNC press brakes with databases of materials
and their springback properties, you can program it all in and you'll come
quite close. Otherwise, you do it the old-fashioned way: keep bending it a
little more until you get the bend you want.

That's how I do it with my sheet-metal equipment: a very big vise, some
angle iron, wooden forms, and some really big hammers. d8-)

Heat and 6061 are not a happy combination, because 6061 age-hardens and
moves, and can drive you nuts. You'll also never quite recover the
pre-heating strength, unless you put it through a carefully controlled
heat-treating cycle afterwards.

--
Ed Huntress