This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com