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Crimping Nicopress Sleeves

snopercod

Well Known Member
I mentioned on the Taxi Testing thread that a Nicopress sleeve on my rudder cable let go on me during taxi testing. After searching the forum, I didn't find any information on properly crimping those sleeves, so I thought maybe folks could learn something from my foolish mistake. That which doesn't kill us makes us stronger ;)

Here is the 3/32" copper sleeve that failed on me.:

sUuoko.jpg


Here is the $54 A-T-S tool (which I have since tossed in the trash) that I originally used to make that bad crimp. I freely admit that I may have not used the tool properly somehow but you can see that it only indents the sleeve on one side by design:

VTtuTo.jpg


Here is the proper tool for crimping Nicopress sleeves ($325 Locoloc hand swager) which a friend loaned me (go/nogo gauge not shown):

eH5JPK.jpg


Here are the 3/32" tin plated Nicopress sleeves which are recommended for use on stainless cables:

wMu0wL.jpg


...and here is what good crimps are supposed to look like:

cFMFn7.jpg


Notice that I used two crimps in series, which some folks say reduces the strength of the assembly. I accepted the possibility of a minor reduction in the 920 lb. breaking strength in favor of the redundancy. I'm funny that way. Flame away...
 
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If you can retrieve the tool you tossed in the trash I will be happy to take it off your hands. :)

I've used that tool for many crimps over the past twenty years and it has worked splendidly. The tool crimps both sides of the sleeve when the bolts are tightened down completely.

The copper sleeve you show just doesn't look right, I can't figure out how you crimped it. A sleeve has to be really mis-handled for the cable to slip out of the sleeve.

By the way, there is a school of thought that using two sleeves close together actually weakens the connection. The cable can not flex between the sleeves and might be subject to fatigue failure. It also appears you do not have a thimble in the cable loop which will further weaken the cable but maybe the thimble just isn't visible in the photo.

No redundancy is necessary when one sleeve is properly installed, the connection is stronger than the cable. Procedure for installing nicopress sleeves is in AC43.13 which every builder should have and use when questions arise about acceptable techniques. Here is a link to the chapter that include cable swaging. Nicopress info begins on page 32:

https://www.faa.gov/documentLibrary/media/Advisory_Circular/Chapter_07.pdf
 
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Methinks you put the nicopress sleeve horizontally in the ATS tool instead of vertically. The figure-8 should be perpendicular to the jaws, not laying across. When you tightened the tool down, the sleeve got trapped between the faces of the jaws and made an interesting "crimp" and never got anywhere near fully seated. The jaws are reversed in your tool pic. It's symmetrical, you just have the bar with the threaded nuts backwards.

Also you might have a look at the eaa video

+1 on adding a thimble. Helps with bend radiuses. Sharp bend coming out of that sleeve.
 
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Don't feel bad John. The subject is more complex than it looks at first glance, with lots of ways to mess up. When researching a Kitplanes article, I found an example in which professionals at a banner company had done it wrong so often that an FAA-required inspection of their fleet resulted in the replacement of 36 swages and 41 cable assemblies on 27 towplanes.

Here is the $54 A-T-S tool (which I have since tossed in the trash) that I originally used to make that bad crimp. I freely admit that I may have not used the tool properly somehow but you can see that it only indents the sleeve on one side by design

The photo of the pulled crimp isn't at a good viewing angle, but it looks like the fitting was in the tool 90 degrees from the correct orientation.

It is possible to get airworthy crimps with a bar clamp (I made and pull tested some), but there's no good reason to use one when the good tool re-sells so easily after completion of a project.

Here is the proper tool for crimping Nicopress sleeves ($325 Locoloc hand swager) which a friend loaned me (go/nogo gauge not shown)

That's a Locoloc 1-SC. Great quality, and the easiest to use of all tested.

Here are the 3/32" tin plated Nicopress sleeves which are recommended for use on stainless cables:

Nicropress-brand bare copper and zinc-plated sleeves are marked "Nicopress". Strangely enough, tin-plated Nicopress sleeves are not marked.

Sleeves from Locoloc and various generic sources are not marked, regardless of plating type.

Our popular vendors are not picky about calling all sleeves "Nicopress" in the catalog, but then sending out Locoloc and generic sleeves.

Sound like trouble? The good news...the major brands are all made at the same copper-forming plant in Pennsylvania, with slightly different specs (like 0.002") for each brand. Each manufacturer insists that only their sleeve be used with their tool, but it appears to be CYA thing. Pull tests of multiple combinations, plus a lot of measuring says the sleeves are interchangable.

The bad news? There's nothing to stop imports from some third world toilet, which is why buying sleeves at a big box store is totally nuts. Same for a crimp tool.

Notice that I used two crimps in series, which some folks say reduces the strength of the assembly. I accepted the possibility of a minor reduction in the 920 lb. breaking strength in favor of the redundancy. I'm funny that way. Flame away...

cFMFn7.jpg


No flames, but there are a few interesting things here.

Yes, two sleeves in series are unnecessary for a loop end (the exception is a lap splice). The correct sleeve installed correctly does not slip. I built and broke a bunch of them, both crimped correctly, and with various levels of error.



As for number of crimps...if those are 3/32 sleeves, each would get two crimps (as pictured) when using a Locoloc 1-SC, but one double width crimp if using a Nicopress 64-CGMP. You really need the specific instructions for each crimp tool.

The assembly shown is unusual. It appears to be a loop around an AN111 cable bushing inserted into a standard AN161 fork. Should be ok with a bushing, but without a bushing (just looped around the bolt) it's wrong for sure.

The assembly may not test as well as the conventional method, which is to use an MS21255/AN170 cable eye in the turnbuckle, and an AN100 thimble in the cable loop.

Here are two 1/8" cable ends made with AN100 thimbles. Which one is not airworthy, and why?



One more detail....the Nicopress table is AC43 is wrong.

A lot more in Kitplanes, December 2013, if you want to know.
 
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Here are two 1/8" cable ends made with AN100 thimbles. Which one is not airworthy, and why?

Not having worked with Nicopress cables or their ilk, other than to install balustrading on my veranda, I am thinking the bottom one looks to have been over-squeezed for the size of the swage.

ISTR reading the KitPlanes article, or another story on a similar topic, and it was stated that oversqueezing was almost as bad as under-squeezing the swage in terms of joint strength.
 
Not having worked with Nicopress cables or their ilk, other than to install balustrading on my veranda, I am thinking the bottom one looks to have been over-squeezed for the size of the swage.

ISTR reading the KitPlanes article, or another story on a similar topic, and it was stated that oversqueezing was almost as bad as under-squeezing the swage in terms of joint strength.

In general, it's not a concern because the tools won't allow an over-squeeze when working with the correct sleeve and tool groove. However, you were close.

That's a 5/32-size sleeve (28-4-P in Nico-speak) crimped on a 1/8" cable. Normally, on a 5/32 cable. it would be squeezed using the P-groove in the 64-CGMP tool, and the finished appearance would look a lot like the top example, just a wee bit larger.

However, if a fella thought he was working with an 1/8" sleeve he would use the M-groove, thus the overly-squeezed appearance.

Point is merely that an inspector or mechanic must look close, because a lot of sleeve errors are not real obvious.
 
I It also appears you do not have a thimble in the cable loop which will further weaken the cable but maybe the thimble just isn't visible in the photo.
There's an AN111 cable bushing in there (not visible in the photo).
 
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Thanks for the lengthy and informative reply

Sleeves from Locoloc and various generic sources are not marked, regardless of plating type.
I noticed that. The only place I could find the tin-plated sleeves (or swages) was at VERsales in Burbank. The bad news is that I had to buy 250 of the little buggers to meet their minimum order requirements (anybody want any?). Come to find out that aircraft spruce carries them but they're not listed under "nicopress sleeves", but rather off by themselves under "swages". Go figure...

I'm impressed that you took the time to load various configurations to failure.
 
Come to find out that aircraft spruce carries them but they're not listed under "nicopress sleeves", but rather off by themselves under "swages". Go figure...
I just bought some of these from Spruce a few months ago. They are indeed listed under the Nicopress sleeves page along with the plain ones.

https://www.aircraftspruce.com/catalog/appages/nicopress.php?clickkey=4330

The plated ones have part numbers beginning with 2 rather than 1, with all other digits being the same. Per AC43.13 they are indeed required for use on stainless cable. Guess who found the out after completely rigging the aircraft using cables made with the copper sleeves? Live and learn.
 
The plated ones have part numbers beginning with 2 rather than 1
The P/N for the 3/32" tin plated copper sleeves that I used is 428-3-VG. See: Nicopress Oval Sleeves. I haven't quite figured out the Nicopress naming convention but the "28" in the P/N seems to signify tin plating, the -3 is the size in 32nds, and the VG is (who knows?).

AC 43.13 is no help at all and I believe it to be incorrect in this case. Table 7-6 has a note that (for 3/32" cable), P/N 28-2-G is "Required on stainless cables due to electrolysis caused by different types of metals". But that P/N is zinc plated copper which Nicopress tells us is intended for use on galvanized cables (see link in 1st paragraph). You can also go to MS 51844 itself. Table 1 tells us that the tin plated sleeves are "for use on CRES cable". The P/N they call out for 3/32" cable is MS 51844-83 which cross references to Nicopress P/N 428-3-VG

I went round and round over this when ordering Nicopress sleeves to replace the failed plain copper one that came with my kit. I finally decided to ignore AC 43.13 and go with the manufacturer's and the Mil Spec's recommendation. "It's experimental :confused:" Unless the Nicopress sleeve is out in the weather (mine aren't) I personally don't see how dissimilar metal electrolysis would be a concern.
 
I just bought some of these from Spruce a few months ago. They are indeed listed under the Nicopress sleeves page along with the plain ones.

https://www.aircraftspruce.com/catalog/appages/nicopress.php?clickkey=4330

The plated ones have part numbers beginning with 2 rather than 1, with all other digits being the same. Per AC43.13 they are indeed required for use on stainless cable. Guess who found the out after completely rigging the aircraft using cables made with the copper sleeves? Live and learn.

Happens all the time Jeff. I hope what follows doesn't ruin your day. The correct sleeves for stainless cable are tin plated and start with "4".

There are two kinds of sleeve plating, zinc (part numbers start with 28) and tin (part numbers start with 428), in addition to bare copper (starts with 18). It's darn near impossible to tell zinc-plated sleeves from tin-plated sleeves after they've been floating around in a parts pin for a while. So what to do?

Bare copper is legal on carbon steel cable, and tin-plated sleeves are correct for stainless cable....so don't ever order zinc-plated sleeves. Just keep them out of your inventory.

Now remembering which sleeve goes with what cable is simplified. All you need remember is that you want a layer of sacrificial plating between the cable and the copper, just like we want cadmium on bolts.

With carbon steel cable, the plating is already on the cable (zinc or tin, either is fine by spec), so you can use a bare copper sleeve.

With stainless cable, the plating must be on the sleeve, as the cable has none.

I don't think there is any FAA document so misunderstood as AC43. Read page 3. Information in AC43 is to be used only in the absence of manufacturer's information. Put another way, if you do something using data in AC 43, and the manufacturer of whatever you were working with has published information available, you are wrong.

This is what I wrote for Kitplanes...

Information specific to
Nicopress-brand oval sleeves is found in
Chapter 7 and Table 7-6 (Fig. 1). Like
much of AC43.13, the entire Nicopress
section is old—so old it may have come
directly from a CAM document when
AC43 was first created. Although often
cited by mechanics as their reference
source, much of the information is outdated
or incorrect.
For example, the “Tested Strength”
values listed in Table 7-6 are too high
for design and do not reflect the notable
strength difference between carbon steel
cable and stainless steel cable. (Oddly
enough, the correct values, 2000 and
1760 pounds respectively, are found in
Table 7-3 in the same chapter.)
Note the asterisk next to the word
“plated.” It means (per the note at the
bottom of the table) that a plated sleeve is
to be used on corrosion-resistant (stainless)
cable. However, the listed 28-series
Nicopress part numbers are zinc-plated
sleeves. Zinc-plated sleeves on stainless
cable has been an obsolete recommendation
for more than 40 years.


Assuming you are using Nicopress-brand sleeves and tools (marked or not), you want "Nicopress Data Sheet - Oval Products" for product selection, and "Nicopress Instruction 32" for tool use and number of crimps.
 
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Happens all the time Jeff. I hope what follows doesn't ruin your day. The correct sleeves for stainless cable are tin plated and start with "4".

There are two kinds of sleeve plating, zinc (part numbers start with 28) and tin (part numbers start with 428), in addition to bare copper (starts with 18). It's darn near impossible to tell zinc-plated sleeves from tin-plated sleeves after they've been floating around in a parts pin for a while. So what to do?

Bare copper is legal on carbon steel cable, and tin-plated sleeves are correct for stainless cable....so don't ever order zinc-plated sleeves. Just keep them out of your inventory.
[snipped]

Well shucks. I just ordered some sleeves for stainless cable from Spruce for another project, and ordered based on this, from the Q&A section on their nicopress sleeves:

"Which nicropress sleeve are used for stainless steel control cable?
The Zinc plated copper sleeves are commonly used with stainless cable because of the corrosion resistance, but plain copper can also be used."

Who can tell Spruce that they're wrong, and speak with authority?
 
I'll send the appropriate Nicopress document to Jim Irwin. I'm confident he will get it corrected.
 
Happens all the time Jeff. I hope what follows doesn't ruin your day. The correct sleeves for stainless cable are tin plated and start with "4".
Nah, didn't run my day, but did cause me to do more research. You are of course right about the tin plated vs. zinc plated sleeves. My apologies to Snopercod as well- that's what I get for posting before coffee.

So, I now know that the current correct sleeve for stainless cable is the tin plated. What I am trying to discern is whether the use of zinc plated sleeves is verboten, or just an outdated standard. Unless it's a typo, the 43.13 reference had to come form somewhere. In other words, are my cables acceptable, or must they be remade (again.) It wouldn't be the first time I've remade a part three times. Fortunately I can use each old cable to remake the next shorter cable after lopping off the ends, so material wastage is minimal.

I might be taking Snopercod up on the offer to sell some of his excess 250 tin sleeves.
 
I might be taking Snopercod up on the offer to sell some of his excess 250 tin sleeves.
Since I haven't been able to sell them on eBay or here on VAF, I'd be glad to send you (or anybody) however many you want for the price of shipping. PM me your address and how many you want. (These are the 3/32" size. Offer good while supplies last :D )
 
Nah, didn't run my day, but did cause me to do more research. You are of course right about the tin plated vs. zinc plated sleeves......
I might be taking Snopercod up on the offer to sell some of his excess 250 tin sleeves.

Jeff and I discussed the zinc vs tin plating issue offline. I was curious, and I had made industry contacts while researching for Kitplanes, so I promised to make some phone calls. The questions were (1) when did the standard change from zinc to tin, and (2) why?

Turns out one of my contacts is the fellow who actually wrote and submitted MS-51844, with the then-new tin requirement, way back in 1968. The change was made (as one might expect) to reduce the possibility of galvanic corrosion. Zinc is an excellent sacrificial anode. Tests found that given an adverse environment (electrolyte exposure, notably salt water), tin plated sleeves on stainless cable were superior. As a bit of trivia, nickel plated sleeves also tested well, but cost more and never gained acceptance.

Ok, so what about Jeff's problem, a bunch of stainless cables already made for a Breezy, using zinc plated sleeves? Unofficially, no difference in strength, and many, many in service, both on purpose and by accident. The issue is strictly corrosion. Given the application is a Breezy in Wisconsin, and thus unlikely to ever be flown in the rain or dunked in the ocean, a builder might make a reasonable decision to use the existing cables, rather than build a whole new set. The smart guy might squirt a little penetrating spooge on them from time to time to keep moisture out, and note the zinc sleeves in the build log, just in case it winds up on floats many years in the future. It would arguably be an unwise decision on an all-weather airplane, including an RV.

Remember, in the case of a certified airplane, you may use AC43 information only in the absence of manufacturer's guidance. Instructions from both National Telephone (Nicopress brand) and Loos & Co (Locoloc brand) are specific; the current standard is tin plated sleeves on stainless cable. The same is true for all the MIL specs. Bottom line, for certified, it's tin plated sleeves on stainless cable, no exceptions.
 
Dan,

Did you also speak with A/C Spruce? This thread popped up a day or two after I placed an order for sleeves. I emailed Nicopress, because Spruce's page (at that time) said use either plain copper or zinc plated for stainless cable. The tin plated version was on another page, under a different name, with no reference on use.

I called them, then swapped a few emails, as they researched. Last response was that they would move the tin plated to the same page with the plain & zinc plated (which they've done). The Q&A now simply says that plated is required with stainless (which plating is still unspecified).

Charlie
-7 FWF in progress, paused to restore a Kolb Twinstar
 
update to add new info:
Just got an email from Spruce; they will be working with marketing to update the website, reflecting milspec data.

Charlie
 
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