On Oct 7, 11:04 am, "Ed Huntress" wrote:
"John Doe" wrote in message

...



cavelamb himself wrote:
Harold and Susan Vordos wrote:

Is there any difference between 6061 aluminum and aircraft grade
aluminum for that purpose?

Certain grades of aluminum were developed from need of the
aircraft industry. They are, in general, very much stronger when
heat treated (or aged) than other grades of aluminum. 7075 is
likely the strongest (it rivals mild steel in tensile strength
when aged to a T6, or T651 condition, with 2024-T351 being quite
good as well.

7075T? also considerably less ductal that 6061-T6...

If that matters in this application.

Besides price, yes that matters. I'm probably going to struggle just
to get the fit right without grinding the motor gear, so being
ductile is potentially important. I'm also looking at some sort of
nylon/whatever thin tubular spacer if necessary to decrease the
inner diameter of the aluminum tube.

But I'm curious about aircraft grade aluminum too. So far I picked
up at least two different numbers (2024, 7075) designating aircraft
grade aluminum, and the idea that metal can be hardened with aging
(didn't know that one).

Thanks to the replies.

Look up precipitation hardening of aluminum. That's a more precise name for
"age hardening." Some grades harden that way. Others don't.

--
Ed Huntress



Ed,

The story of the development of precipitation hardening aluminum
alloys is quite interesting.

Recalling from memory... One investigator was showing two visually
identical strips of copper-bearing aluminum alloys to a colleague and
asked him to bend them by hand. Although identical in size and alloy,
one could be bent and one could not. The difference was the
precipitation hardening.

The discussion turned to the % composition. Much of the early work
was based on experiences with copper alloys such as brass and bronze,
where the alloying constituent may be from say 5% to 40%. And
aluminum bronze is an alloy of approx. 10% Al and 90% Cu, forming an
exceedingly tough and abrasion metal.

The investigator stated that the copper content was less than 1% and
closer between .25% and .5%. The colleague asked "why so little" and
the reply: "In steel alloys you only have carbon content at typically
less than 1% also. When I first read this tale in a book entitled
"Metall" 40 or 50 years ago I was fascinated.

Wolfgang