Years ago, i attended a seminar put on by Bob Nuckolls, who writes The
AeroElectric Connection. He started out by taking a wire, crimping on a
push-on connector, then connecting it to an item by pushing it on that
had a little weight, then spinning it around by the wire. The push-on
connector held. He went on to point out that the space shuttle and many
other aerospace vehicles use them, and they work fine under heavy
G-loads and vibration.
Bob, if you're familiar with his career, worked for various airplane
companies on electrical systems until he retired, and has a great deal
of experience troubleshooting electrical problems for aerospace
applications.
There are some caveats to using crimp connectors. First, only get good
quality connectors, and only the ones that both crimp to the wire as
well as the insulation. Cheap connectors, (and I've used them in
non-aeronautical, non-critical tasks) do not make good connections
between male and female spade connectors. The cheap ones don't grip the
male connector firmly and they only grip the wire itself. I've had some
connectors pull apart as I moved the wire, they gripped that loosely.
Subsequently, I took a pliers to the unconnected female connector and
reshaped the "curls" that slide over the male connectors, so they
gripped better. Needless to say, I'd never use a connector like that in
an airplane.
Good quality female spade connectors cut a groove into the male
connector as they are pushed together, in essence, mating the two
electrically as well as making a firm mechanical grip.
Having crimp connectors that both crimp on the bare wire and the
insulation provide mechanical support to the wire itself.
Using the proper tool to make the connection is necessary. The good ones
crimp the connector to both the bare wire and the insulation with a
measured amount of force, then release.
It is true that careless soldering can wick up stranded wire, stiffening
it so that it breaks easily, but careful soldering avoids that. There is
one other disadvantage to soldering, and for the great majority of
connections, it is not a factor: solder introduces a tiny amount of
resistance to the connection because it has higher resistance than copper.
On a microscopic level, properly crimped copper wire is crushed to the
point that electrically, it unites with the crimp connector: the wire
and the connector are crushed to the point that they become one, with no
resistance between them. The copper, stranded wire also becomes a single
piece.
Careful soldering makes good connections, but a good crimp connector
that grips both the wire and the insulation is, IMO, is just as good, if
not better.
As for my soldering experience, as a teenager, nearly 60 years ago, I
had a job soldering and unsoldering wires on a huge frame in a telephone
exchange as a "frameman" for Pacific Bell. When someone moved, we had
to connect the pairs of wires that came in on the trunk line to a
different place. The wire frame I worked on was at least 50, if not 70'
long. The job no longer exists. The building I worked in was the size of
a small supermarket, but at least 3 stories tall, and used step
switching for the phones. The size today of a new exchange that size for
wired land lines is now the size of a garage, and changing the service
from one place to another is simply done electronically.
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