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

From: Jim <[email-masked]>
Date: Sat, 28 Dec 2013 21:10:31 -0500

> But if you make the joint quickly enough (and without overheating), it won't
penetrate all the way through the crimp to the other side.

Randall: the way you wrote this sounds like you don't want the solder to go
all the way to the other side. Is that correct?  I made sure all of my
connections flowed through the ferrule, assuming that would be best. Was that
wrong?

Sent from my iPhone

> On Dec 28, 2013, at 8:50 PM, "Randall" <[email-masked]> wrote:
>
> But if you make the joint quickly enough (and without overheating), it won't
penetrate all the way through the crimp to the other
> side.
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From: ml <[email-masked]>
Date: Sun, 29 Dec 2013 13:06:14 -0500

I won't enter the fray regarding solder or crimping or both - not enough
experience on my part to be expert. But Randall's comment below is wrong. If
done properly - admittedly a big "if" - crimps have full  (100%) contact
between the wire strands and the connector with minimal or no air gaps at all.
The crimp should deform the wire strands as it deforms the connector leading
to a solid mass of metal in the area of the crimp.

To see what I mean check out this link:
http://www.epp-europe.eu/archive/-/article/32536727/35088948/Different-specif
ications/art_co_INSTANCE_0000/maximized/

Whether you can achieve this level of quality consistently with DIY tools is
another question. For me, investing in the proper tooling for each of the
connectors that I use has been worth every penny. In many cases that's meant
tooling in the low hundreds of dollars rather than $3 or $30 though. But I've
never had a crimp fail yet.

Michael

On Dec 28, 2013, at 8:50 PM, Randall <[email-masked]> wrote:

> With a crimp, you get basically a few lines of contact between the wire
strands and the terminal, a few thousandths wide at best.
> In between are air gaps.  With solder, you get 100% contact, no gaps.

[email-masked]

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From: Pat Horne <[email-masked]>
Date: Sun, 29 Dec 2013 13:21:28 -0600

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.

Peace,
Pat

Thusly spake ml

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From: Jeff Scarbrough <[email-masked]>
Date: Sun, 29 Dec 2013 15:18:04 -0500

I think sometimes we might lose sight of the fact that we aren't
driving to the Moon in our cars.

Yes, MilSpec connecting is a critical science, and must be done
exactly as specified.  Yes, it works great under severe circumstances
where lives are at stake.  Yes, sometimes soldering can lead to
problems, and sometimes inadequate crimping can as well.

But, I've done all sorts of automobile wiring connections over the
last 40 years, including twisted wires under black electrical tape,
and the only kind I've had fail was the IDCs that Volkswagen used in a
fuel pump relay recall campaign.  And even then, it was probably less
than 10% failure.

Given a preference, I'd use a $300 crimper to make my connections.
But, I'm too cheap to spend $300 on a tool I'll use rarely -
especially when that task can be carried out quite adequately with a
lesser crimper, solder, and heat-shrink tubing.

Put some thought into the connection, and how it will be used,
protected, and secured, and you'll likely be just fine.

Jeff Scarbrough
Corrosion Acres, Ga.

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From: Michael Porter <[email-masked]>
Date: Sun, 29 Dec 2013 13:22:55 -0700

On 12/29/2013 12:21 PM, Pat Horne wrote:
> tweezers, which was basically a heat sink that kept the solder near 
> the connection, allowing for more flexibility of the wire.
>

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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From: "ElanS4" <[email-masked]>
Date: Sun, 29 Dec 2013 23:31:19 -0500

> But Randall's comment below is wrong. If done properly - admittedly a big
"if" - crimps have
>  full  (100%) contact between the wire strands and the connector with
minimal or no air gaps at all.
> The crimp should deform the wire strands as it deforms the connector
leading to a solid mass 
> of metal in the area of the crimp.

Exactly correct.

> Whether you can achieve this level of quality consistently with DIY tools
is another question. For 
> me, investing in the proper tooling for each of the connectors that I use
has been worth every 
> penny. In many cases that's meant tooling in the low hundreds of dollars
rather than $3 or $30 though.

Ignore the cheap tools - the crimp, cut wires, and cut bolts to the proper
length (the cheap tool).

But you can go to Lowes and buy a large pair of wire working pliers for less
than $20 - they cut the wire and have a couple of crimp positions (make sure
you get one that crimps the size crimps you need to use).  The secret is to
not just get the cheap crimpers that squeeze the crimp flat, but get the
type that indents one side into the other - actually make a dent into the
wire (makes the finished crimp slightly "U" shaped.  That works as well as
the several hundred dollar types I've have from various jobs.  

For crimp connections on typical computer type connections, make sure you
get the type that takes the open "U" shaped crimp and curls the "U" over and
into the wire as it squeezes them.  Again, I never had one fail, and as far
as I know the wiring harnesses (all crimped)  I used to make for on-board
weapons control for Navy Destroyers are still working fine.

> But I've never had a crimp fail yet.

Me either.  But I have had soldered and crimped connections fail - actually
the wire near to the crimp.  That was before I learned how to do the MilSpec
stuff - basically crimp only unless there was absolutely no other way.

Tim

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