nicopress sleeve for stainless steel cable

[ls]

I have some questions regarding swaging stainless steel a/c cable with
nicopress sleeves. Specifically, several sources I've seen say that zinc
plated copper sleeves should be used on SS cable (I.e. 28-2-G for 3/32"
cable). Many suppliers that I know of sell SS cable and the zinc plated
sleeves, so presumeably there are a lot of aircraft out there rigged
with these sleeves.

However, National Telephone (www.nicopress.com) appears to require a
special tin plated copper sleeve be used for swaging SS cable ends
instead (i.e. 428-3-VG for 3/32" applications). This one appears to be
harder to find among various suppliers (though I havn't really looked
that hard yet).

My questions are:

- what is the hazard of using the wrong sleeve on SS cable: is it a
strength or corrosion issue (or both)?

- what's the real story anyway? I.e. are the zinc plated copper sleeves
or even bare copper OK on SS cable, or ?

- where's a good source for the tin plated ones in the event that's
required?

I have some SS cables I made up with regular copper sleeves and am
trying to assess when I need to remake them with the correct sleeves
(i.e. immediately or when I get the materials). They appear to be as
strong as the galvanized cable ends I've made elsewhere so there's no
immediate problem that I can see.

But I do want to know what the correct sleeve is to be used, at which
time I do plan to remake the cables...

Thanks,
LS
N646F

[Drew Dalgleish]

my murphy rebel kit shipped with plain copper sleeves. that's what I
used and the inspector passed it. AFAIK it's a corrosion issue as
plating can't offer any measurable strength.

>I have some questions regarding swaging stainless steel a/c cable with
>nicopress sleeves. Specifically, several sources I've seen say that zinc
>plated copper sleeves should be used on SS cable (I.e. 28-2-G for 3/32"
>cable). Many suppliers that I know of sell SS cable and the zinc plated
>sleeves, so presumeably there are a lot of aircraft out there rigged
>with these sleeves.
>
>However, National Telephone (www.nicopress.com) appears to require a
>special tin plated copper sleeve be used for swaging SS cable ends
>instead (i.e. 428-3-VG for 3/32" applications). This one appears to be
>harder to find among various suppliers (though I havn't really looked
>that hard yet).
>
>My questions are:
>
>- what is the hazard of using the wrong sleeve on SS cable: is it a
>strength or corrosion issue (or both)?
>
>- what's the real story anyway? I.e. are the zinc plated copper sleeves
>or even bare copper OK on SS cable, or ?
>
>- where's a good source for the tin plated ones in the event that's
>required?
>
>I have some SS cables I made up with regular copper sleeves and am
>trying to assess when I need to remake them with the correct sleeves
>(i.e. immediately or when I get the materials). They appear to be as
>strong as the galvanized cable ends I've made elsewhere so there's no
>immediate problem that I can see.
>
>But I do want to know what the correct sleeve is to be used, at which
>time I do plan to remake the cables...
>
>Thanks,
>LS
>N646F

[[email protected]]

This is from High School chemistry and that was a LONG
time ago.

I agree that it will be a corrosion issue.

When water enters such a joint two different metals make
up a battery. This can enormously accelerate corrosion
and is what happens to, for example, chrome plated parts
on cars. They get badly pitted quite quickly (not though
in Arizona). Modern cars do not use chrome I don't think.

Of the metal pair, the less "active" one is preserved and
the more active one suffers.

In order of activity Chrome is lower than Iron.

Copper is likely a nice material for such sleeves since
it is ductile and can 'flow' (I guess) into the wire without
too much pressure or too much damage to the original wire.
(You wouldn't want a sleeve that cut through the wire).

However, Copper has a lower activity than Iron and
so Zinc plated sleeves are use. In this case the Zinc
has an even higher activity than Iron or Copper and
so it is 'sacrificed' and the integrity of the cable is preserved.

For some reason, (I have no idea at all) the zinc must cause
some problem with the stainless steel (Iron, Nickel, Chrome and
maybe other bits alloy)


http://www.qsl.net/n9zia/electrochemical.html

http://www.lytron.com/support/galvanic_corrosion.htm

Google for [tin copper aluminium electrochemical potential]

[Stealth Pilot]

On 5 Dec 2005 13:08:53 -0800, wrote:

>This is from High School chemistry and that was a LONG
>time ago.
>
>I agree that it will be a corrosion issue.
>


surely a smear of duralac would solve most of these issues.
duralac being a zinc chromate paste designed for killing off
electrolytic corrosion problems.
Stealth Pilot