At 07:35 PM 7/12/2010 Monday, Raymond Paquette wrote:
>But, when I solder stranded wire on a car, my connection often breaks
>off (after a time).
>
>The wire is flexible, with strands that move independently from each
>other, so there's no one spot that takes all the flex.. The solder
>creates a solid mass with one flex point where the solder ends.
>
>FWIW, and not diminishing my overall awe at the wisdom of the collective.

Rem acu tetigisti.

Your observation is correct (and you have opened up a can of
worms).  The pros and cons of soldered vs crimped connections, and
the correct technique for soldering a wire that will be used under
vibrating conditions can be researched voluminously on the web; and
you've put your finger on exactly the trouble spot.

Let the contest begin...in gentlemanly fashion of course.  I'll throw
my hat in and say that it takes a great deal less specialized
knowledge to make a good crimp joint than a good solder joint in
wires that will be subjected to mechanical stresses, particularly
vibration and bending stresses.

Yours,
David
ps -- many years ago I had a catalog which listed a thirty-dollar
pair of beryllium-copper "anti-wicking tweezers" to clamp around
20-ga stranded wires for soldering to NASA specs.  Thirty dollars was
quite a bit more then than it is now.