[Amps] Bend allowance

[W0UN -- John Brosnahan]

At 03:42 AM 8/4/2005, Peter Chadwick wrote:
>Ian asked:
> >Staying on-line... what's the trick to prevent alumin(i)um from
> >splitting on the outside edge of a bend where it is stretched?
>
>
>As Will said, use a softer aluminium. Or heat treat what you have. 
>Problem is that that heat treating aluminium is a pretty specialist 
>subject needing good heat control. However, I have successfully 
>managed to soften some aluminium sheet of unknown mix (obtained 
>cheap at a model engineering show) by the old trick of rubbing some 
>soap on one side, and heating the other until the soap turns brown.

Interesting comment about using soap for heat treating aluminum.

I have found one part of the "equation" for bending aluminum is the AGE of
the aluminum.  Aluminum alloys (in some cases) are aged or artificially aged.

Needing T-match rods for some 400 MHz Yagis I decided I wanted to
put a 90 deg bend in the 6061-T6 material I was using, rather than use
shorting bars.  6061-T6 is not really any good for bending, but I decided to
heat it and try, and it bent just fine.  BUT the same rod that was a couple
of years older (when I tried it again) would not bend without cracking.

6061-T6 is artificially aged by holding it at 320 deg F for 18 hours.  But the
aging process continues just having it on the shelf.  So what works when
the alloy is new may not work that well when it is a few years old.

This seems to have significant relevance for not only amplifier sheet metal
but also for antenna systems.

73  John  W0UN