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solderless connectors and crimping

To: Shop Talk <shop-talk@autox.team.net>
Subject: solderless connectors and crimping
From: Douglas Shook <shook@usc.edu>
Date: Fri, 25 Jun 1999 08:38:28 -0700


Matt Liggett wrote:

> On Thu, Jun 24, 1999 at 08:50:50PM -0500, Aaron Bergman wrote:
> > On a different topic, has anybody ever seen copper solderless terminals for
> > sale.  All that I can find is the cheap aluminum, and when these are in
> > contact with copper for a few years, bi-metallic corrosion will set up and
> > everything will corrode away.  Does anybody know where one can buy COPPER
> > solderless terminals?  ie, butt connectors, ring terminals, disconnects,
>
> No, don't know where you can get them.
>
> But, in my experience, copper connectors end up all green and corroded
> after [at most] a couple of decades.  Is there a better way?
> Stainless steel?
> --
> Matt Liggett <mml@pobox.com>
> Bloomington, Indiana
> USA

Hi all,

For any connectors exposed to humidity, aluminum and un-plated copper really are
only temporary solutions. Most high quality solderless connectors are made of
tin-plated brass or copper (see the descriptions on page 550 of McMaster-Carr
catalogue #104).

I used to work as a signalman/lineman for the railroad where we would wire the
signals and crossing protection systems, and, of course, circuit failures were
not acceptable. We spent weeks cutting, stripping and crimping wires for each
installation.

I have seen many good, high-quality, solderless connectors fail due to
mis-crimping.  You should use a ratchet crimp (about $55 on page 543) to crimp
connectors, and be certain you insert the connector into the crimp correctly
(insert the wire-side of the connector into the color-coded side of the crimp
(most crimps are made for right handers expecting that you will hold the wire
with your left hand and crimp with your right hand).

It is important to strip and crimp the connectors correctly so that the wire 
will
be firmly supported by the plastic insulation of the connector.  Otherwise,
moisture can enter the crimp and it also encourages the wire to break if there 
is
vibration (motorcycles, etc.) because the wire flexes excessively where the
insulation has been stripped right next to where it is held firmly in the crimp
(the vibration flexing of the wire becomes "focused" right at the entry of the
terminal).

After you crimp the connector, try to pull the wire out of the crimp -- give it 
a
good, strong pull.  If you can pull it out, it was a bad crimp.

doug


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