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Since one of my Nicopress sleeves failed, I've learned more than I
want to know about these things. Nicopress recommends using the 428
series tin-plated sleeves on stainless steel
cable, but Lancair sells the 18 series plain copper sleeves.
Aircraft Spruce doesn't sell the tin-plated sleeves in America (they
do in Europe), but instead they sell the 28 series zinc-plated
and the 18 series plain copper sleeves. The only
company in America that I can find who sells the Nicopress
tin-plated sleeves is VER, and they have a $50 minimum
order so I would have to buy 200 sleeves. Grainger sells some off
brand tin-plated sleeves made in China. Do I really want to use
those? I don't think so. The copper alloy is crucial to the
longevity of the crimp, I think, and who knows what I would be
getting. McMaster-Carr sells some "TIN-Plated Copper Oval
Compression Sleeve for 3/32" Rope Diameter, 3/8" Sleeve Length". No
Country of origin listed, but they do say "All sleeves meet MIL-STD
51844". Unfortunately, the length before crimping is listed at 3/8"
rather than the 7/16" that MS51844 Rev. E calls for. So I'm
flummoxed.
Does anyone know of a source for the authentic, Mil spec. Nicopress
428-3-VG tin plated oval crimp sleeves for 3/32"
stainless steel cable?
OTOH, does the plating really matter? Is galvanic corrosion really a
concern in the foot-well? I noted that my failed copper crimp sleeve
had blue copper corrosion all over it. Sure, I used the wrong tool
originally, but could corrosion have been a factor in the failure?
Possibly, according to this Kitplane article The
Big Squeeze. It's a great article from 2013 answers a lot of
my questions, including:
Why three types? The idea is to match sleeve
and cable finish for the least damaging galvanic potential between
components. While any copper sleeve choice will initially
withstand the rated load when installed on either galvanized or
stainless cable, corrosion will weaken the mechanical joint given
time, the wrong environment, and the wrong combination of
materials. The specifications are quite specific. Bare copper or
zinc-plated sleeves are used on galvanized carbon steel cable. Tin-plated
sleeves (or as noted previously, stainless steel sleeves) are
used on stainless cable. There are no exceptions.
and...
Zinc-plated sleeves on stainless
cable has been an obsolete recommendation for more
than 40 years.
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