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nuckolls.bob(at)aeroelect
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 Posted: Fri Dec 06, 2013 7:01 am Post subject: Studies in the fine art of worrying |
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Just received a heads-up on this new product . . .
Someone has apparently studied the state of current
arts for joining of wires (and protecting the joint)
and found the practice lacking.
http://tinyurl.com/kz5c48h
They've even produced a video . . .
http://tinyurl.com/kmdfygt
"When there is no margin for error" says the narrator,
this product is the right choice. What is not said
is that the use of the right crimp tool produces a
gas tight joint that does not improve with the addition
of solder.
Had they offered the crimp+solder process as a hedge
against poor selection of tools or technique, this would
begin to make sense.
In this case, the crimp tool is nothing more useful
to the process than fixturing the wire and terminal
while solder is applied to finish a task that the crimp
tool missed.
The promotional materials do not cite reliability and/or
service problems that begged for this solution. Nor
does it suggest that with more understanding and
exploitation of legacy materials and processes, the
"need" for this product becomes less convincing.
Throughout the OBAM aviation forums there are examples
of advice to 'crimp and then solder' for improved
joint integrity. This company has taken that advice to
an new level . . . and perhaps fueled the fires of
new constellation worries amongst our brothers.
Without a doubt, this product offers an opportunity
for improved integrity of joints which are the outcome
of under-educated or careless craftsmanship. Perhaps the
accident chronicled here http://tinyurl.com/mwbk9qs
would not have happened had terminals/wires cited in last
paragraphs of page 3 had be crimped+soldered with this
not so revolutionary new product.
The point of this missive is to re-enforce the idea that
system reliability will be greatest when the designer/
builder possesses a degree of understanding about the
simple-ideas that make all the pieces fit and perform
with confidence. This understanding cannot be secured
from a simple review of promotional literature and data
sheets for products . . . the greatest reliability
doesn't come off the display racks in a blister-pak.
I would not discourage anyone from exploiting such
a product if their budget is not strained . . . without
a doubt, the product performs as advertised. But just
as we've discussed $high$ contactors and fuses in
bus feeders, the question to be asked and answered,
do understanding and rudimentary skills make this
unnecessary or a poor return on investment?
As a side note, in the Utopian lead-free world, what
is the melting temp for the solder? I note that they
did not use a heat-gun but a butane flame, easier
to 'point' the energy but also MUCH hotter. Most
insulations outside the aviation community are
gong to be pretty stressed at temperatures required
to flow lead-free solders which melt at about 100F
hotter than 63/37 tin-lead.
It takes a whole new skill set to apply these
terminals with results that match the demonstration
video . . .
Bob . . .
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nuckollsr
Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS
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| Posted: Tue Dec 10, 2013 6:49 am Post subject: Re: Studies in the fine art of worrying |
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| Quote: | Just received a heads-up on this new product . . .
Someone has apparently studied the state of current
arts for joining of wires (and protecting the joint)
and found the practice lacking.
http://tinyurl.com/kz5c48h
They've even produced a video . . .
http://tinyurl.com/kmdfygt
"When there is no margin for error" says the narrator,
this product is the right choice. What is not said
is that the use of the right crimp tool produces a
gas tight joint that does not improve with the addition
of solder. |
I've been pondering this product and my first impressions . . . I didn't realize how close I was to the truth when I suggested that the crimp was not expected to achieve any degree of electrical integrity but simply a way to fixture the two wires so that the solder-sleeve technology could 'do what it does best'.
A number of readers have commented on the utility of the legacy solder sleeves for joining two wires . . .
http://tinyurl.com/nvu5zub
It takes three or four hands to hold all the pieces in alignment while heat is applied to make up the joint.
I even acknowledge this 'short coming' in the article on Poor Man's Solder Sleeves . . .
http://tinyurl.com/dgg2nb
. . . where I suggest that the wires be fixtured by wrapping a strand or two of wire around the lap-joint to hold alignment while soldering takes place.
I also recalled an evaluation I made on some low cost, butt splices with heat-shrink covers. REALLY inexpensive in boxes of 100 at Lowes, Menard's, et. als. I dug some of those samples out for a second look and recalled that it was nearly impossible to craft a crimp that would offer a decent pull-test. I.e. no gas-tight joint was being created. The plastic heat-shrink was so soft that it was impossible to put sufficient crimp-forces on the splice without making a mess of the heat-shrink overlay.
So, getting back to the Dell ad for crimp-solder sleeves . . . this now appears to be an elegant solution to the difficulties cited earlier. When you add solder on top of the crimped joint, gas-tight electrical integrity is achieved.
Aggressive crimp forces are not necessary, the crimp is only there to fixture the wires in place to await solder.
The lighter crimp forces don't trash the sleeve so that the finished joint stays pretty.
If anyone elects to try these, let us know what your impressions are. I note that the small red butt splice is rated down to 20AWG . . . I did notice that similar products did not shrink down tight enough to offer insulation support or hermetic sealing of a joint on 22AWG Tefzel.
Bottom line is that these things may be a better product than first blush and past experiments suggested . . .
Bob . . .
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