Jim Wilkins wrote:
"rangerssuck" wrote in message
...
On Thursday, June 4, 2015 at 8:06:17 AM UTC-4, John B. wrote:

It is easy to do,
just paint the area with a marker - permanent or white board - and
then heat the area with a torch until the marker goes away.

Interesting - i'd never heard of using a marker as a heat indicator.
Any idea what temperature that "vanishing point" would indicate?

I've always used these:
http://www.tempil.com/products/tempilstik-original/

Supposedly around 800F, which isn't too far below the
(alloy-dependent) melting point. Aluminum melts without glowing red,
so don't heat it much past that vanishing point or you'll reach
another one.

I'd practice on a piece of 6061 sheet first, especially if you don't
have hands-on experience forming metals that work-harden and crack.

-jsw

Chances are that the case was drawn/stamped in a single op , if so
work-hardening shouldn't be a problem .

--
Snag