"T.Alan Kraus" wrote in message
...
On 8/1/2011 11:24 PM, Gunner Asch wrote:
On Mon, 1 Aug 2011 22:34:56 -0700 (PDT), "
wrote:

I want to make an adjustable cheek rest for a rifle stock.

I want to bend the 1" wide Aluminum around a 2" pipe for 180 degrees.

Do I need to anneal it?
Do I need to do it while it is hot?

Thanks in advance.

What kind of aluminum are you planning on useing?

I think if you were going to use the common 6061..you can simply heat it
up, which softens it up, bend it and reharden.

http://www.cnczone.com/forums/bendin...3_16_inch.html

"found the best way to anneal aluminum is with an oxy/ acetylene rig.
Use the biggest rosebud you have, a #8 is plenty big, burn the acetylene
without the oxygen, cote the aluminum with that black nasty soot, turn
on the oxygen to a nice neutral flame, and apply just enough heat to
burn away the soot from the aluminum. Let it cool naturally and your
medium is back to moving like butter. "
--
"The danger to America is not Barack Obama but a citizenry
capable of entrusting a man like him with the Presidency.
It will be far easier to limit and undo the follies of an
Obama presidency than to restore the necessary common sense
and good judgment to a depraved electorate willing to have
such a man for their? president.. Blaming the prince of the
fools should not blind anyone to the vast confederacy of
fools that made him their prince".

Make a carburizing flame with the oxyacetylene torch and deposit a soot
surface onto the aluminum. then flow more oxygen for a hot flame and heat
the aluminum evenly until the soot disappears, then you know the aluminum
is annealed and soft

0.130" 6061, if it's T4 temper or below, shouldn't require annealing to bend
around a 2" pipe. If it's T6, all bets are off. But I'd still try it before
doing some kind of spot anneal without temperature control.

If you anneal it with a torch, some of it will be heated to solution
temperature and some won't. That which isn't will be left partially softened
forever. That which is will eventually return to something close to T4
through age hardening. To achieve T4 (20 ksi yield) requires a little over
400 days of natural age hardening.

Two other things to think about: The yield strength of 6061 falls off by
about 2/3 at 500 deg. F. That's well below solution temperature, so you can
heat it in a kitchen oven and bend it quickly without causing big strength
problems.

The other thing is that local heating with a torch is going to create a
heat-treatment mess in a hardenable grade of aluminum. The strength will
vary all over the piece, and, as I mentioned, it will change over time.
Torch annealing is something that's commonly done to anneal
non-heat-treatable alloys (3XXX and 5XXX series alloys) while you're
hammer-forming it, or otherwise cold-working it. But it's not usually a good
idea with 2XXX, 6XXX, or 7XXX series alloys that have been heat-treated to a
T4 temper or above.

--
Ed Huntress