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Re: [Shop-talk] Tapping off a crimp connector?

To: Pat Horne <pat@hornesystemstx.com>, shop-talk@autox.team.net
Subject: Re: [Shop-talk] Tapping off a crimp connector?
From: Michael Porter <mdporter@dfn.com>
Date: Sun, 29 Dec 2013 13:22:55 -0700
Delivered-to: mharc@autox.team.net
Delivered-to: shop-talk@autox.team.net
References: <22.F6.21976.3FF7FB25@cdptpa-omtalb.mail.rr.com> <071854D8-15C4-47A9-BE5C-B0F0279E5E1D@me.com> <52C07638.7050000@hornesystemstx.com>
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0
On 12/29/2013 12:21 PM, Pat Horne wrote:
> In the 60s, while in the Air Force, I attended a soldering school that 
> taught us to solder to NASA specs. The problem with soldering wire to 
> that level was with the solder wicking up under the insulation, 
> basically making the stranded wire a solid wire. We used anti-wicking 
> tweezers, which was basically a heat sink that kept the solder near 
> the connection, allowing for more flexibility of the wire.
>
> Either a high quality crimper, spot welding, or minimal amounts of 
> solder would be my choice, in that order.
>

When I worked at the big bus company, we had large customers that put 
crimped soldered connections in their specs, and there was no way to 
avoid soldering. Now, on balance, soldering is more likely to provide a 
positive electrical and physical connection--initially. What we found, 
over time, is that vibration (this problem became more acute once the 
industry changed over from six- cylinder 2-stroke diesels to 
four-cylinder four-strokes) would eventually affect the joint pretty 
much no matter how the joint was soldered (because the problem would 
invariably start at the junction between the soldered joint and the 
unsoldered wires), and the fix was to add support and vibration damping 
to as much of the wire and joint as possible.  We ended up using 
adhesive-coated shrink tubing to about two inches behind the terminal 
and extended over as much of the terminal as possible without 
interfering with the electrical connection, with double layers of tubing 
over heavier wires.  This didn't completely end the problem, but it did 
greatly extend the time to failure.

Engine vibration caused no end of troubles--on one model, we identified 
one maximum amplitude vibration behind the front door which over time 
would crack the vertical structural member horizontally, travel through 
the side destination sign and crack the forward vertical member 
horizontally, crack the upper door header vertically, then travel down 
through the a-pillar and crack it horizontally about halfway down. 
Couldn't change the vibration, so the only fixes were fishplates and 
internal bracing in the a-pillar.  And that's nothing compared to the 
havoc wreaked by vibration on military aircraft. Once knew a guy who did 
avionics repair on carrier F-14s and he said it was a losing battle 
trying to keep the avionics running while on a cruise because the 
vibration would cause the connectors to literally crumble, and there 
never were enough spares.

Cheers.

-- 


Michael Porter
Roswell, NM


Never let anyone drive you crazy when you know it's within walking distance....
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