On Tue, 30 Nov 2010 11:26:23 -0800 (PST), harry
wrote:

On Nov 30, 7:11Â*pm, wrote:
On Mon, 29 Nov 2010 22:52:32 -0800, Smitty Two





wrote:
In article ,
wrote:

You have inspected millions of solder joints. I won't dispute that.
What were these joints on?
On circuit boards you are correct - and I stated that.

What kind of joints between 2 wires do you inspect that do not have a
mechanical connection component other than solder? On what?

Educate us please.

If they were not joints between 2 wires, what kind of joint were they?
( am assuming we are on target here and they were electrical
connections - although even most (although certainly not all) tinwork
has some crimping involved before soldering)

Wiring onto terminal strips GENERALLY involves a "hook" of some sort
on solid core connection wires.

I'm not saying you are wrong and I'm right - I'm just asking what
connections, and what kind of connections, on what, do you consider to
be adequate with no mechanical component to the connection other than
the solder.

It's true that most of those joints are components on circuit boards;
through hole and surface mount. But we regularly solder wires to flat
pads on circuit boards. No mechanical connection whatsoever, other than
the solder. We also solder wires to speaker terminals, again, no
mechanical wrap at all.

ALL the high end speaker equipment I've worked on has had the wires
bent around the tabs on the speakers. Most of the junk chinese stuff
I've had to resolder has not - - -



We solder wires to switches and other chassis mounted controls; some of
them are wrapped but many of them are not. A wire to a turret terminal,
sure, it should have a 75% mechanical wrap. But not everything benefits
from that.

As far as wire to wire, lap splicing is common in wiring, almost always
protected by shrink tubing, but that is more for electrical insulation
than mechanical reinforcement. Twisting is great for electrical work,
capped by a wire nut. Lap splicing is more common in electronics, as it
takes up far less room, and is easier to cover with shrink tubing.

I was taught to twist lap, at the very least, and "western union"
joint every soldered splice before soldering and taping, or heat
schrinking, a joint, and to heat shrink at least half an inch past the
joint in both directions on 18 guage wire. A bit less (proportionally)
with decreasing wire guage. (for vibration/bending protection)



We make high end audio gear, communication components for the
professional dive industry, optical encoder sub-assemblies used in all
manner of automated equipment, and virtual reality electronics, among
others. These are not garage shop customers, they're real companies with
world-wide markets, and actual engineers designing the stuff, and
ultimately approving our workmanship.

I guess as long as it's better than the chinese, and not too much more
expensive - but it's still not "best practice"



Solder, done well, is damn strong. It's true that some things are poorly
engineered, and I'll argue against a customer asking me to add solder to
a crimped connector.

In mnost cases that is definitely correct. I will, on occaision, po]ut
a spot of solder on the terminal end (where the wire end comes
through) but it has to be a Â*quick shot, not allowing ANY solder to
wick to the outer end of the crimp. Sometimes required for corrosion
protection (to keep fluid or corrosive gas from "wicking" up the
conductor) and always combined with a good heat shrink sleave on the
crimped end.

I'm going to do a little test for our a.h.r. homeboy in Texas: I'm going
to take some 18 AWG wire, and hang weight on it until it breaks. Then
I'm going to cut the wire in half, and butt splice it with solder, and
test it again.

Â*If you can GUARANTEE you always make a perfect joint, and it will not
be subjected to undue vibration/stress, in theory the joint will work.
Tensile strength of 60/40 solder is 6400 lbs, shear is 5700.
Tensile strength of 63/37 is 6700, and shear is 6060.

In comparison, drawn copper wire is 12,500 and rolled is 32,000

None of your applications are particularly "safety" items - like
aircraft wiring and even automotive electronic control wiring.

For your applications, solder without independent mechanical
connection appears to be "good enough" Â*- in most of my applications
it is NOT.
Best practices for soldered electrical joints involves a mechanically
secure joint which is THEN soldered to assure a permanent low
resistance electrical connection.- Hide quoted text -

- Show quoted text -

The wire connections to motor armatures are soldered (or were in the
past). Including automotive starter motors and dynamos. Plenty of
stress there.
And the wires are also tied - wrapped with string and varnished - in
MANY, but not all applications.
And I've seen many an armature unwound from overspeed.