Wire rope Q


Awl --
You know the loop at the end of wire rope, with a crimped-type band, often
around an "eye", maintaining the loop?
For the life of me, I cain't grok how that crimp holds, at such high load
ratings. It amazes me. It looks inherently weak, but apparently does the
job.
AND, if I have seen correctly, it seems that some of these crimps are
aluminum!
I would have thought some exotic-type brazing or welding would be required
for reliable strength.
Is this crimp method readily performed in a shop with a simple arbor press?
I may be requiring some of this to be done, but it just gives me the
willies, from a liability pov.
Reply to
DrollTroll
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Not "crimped", try "swaged". Search on that and see the difference.
Reply to
Pete C.
"DrollTroll" fired this volley in news:48ebb42a$0$4960$ snipped-for-privacy@cv.net:
The "eye holder thingy" is called a "thimble".
If the crimp is properly done, deforming the ferrule and embedding it into the fabric of the wire rope, the joint is as strong as the shear strength of the ferrule times the effective 'tooth' area, or the tensile strength of the rope; whichever is weaker.
Try looking up the shear strength of common aluminum alloys, then figure (say) a 1/4" wire rope having about 1/4 square inch of effective gripping area of the ferrule embedded into the rope.
LLoyd
Reply to
Lloyd E. Sponenburgh
"Lloyd E. Sponenburgh" fired this volley in news:Xns9B309E6F27E88lloydspmindspringcom@216.168.3.70:
And Pete C. is correct. The "crimping" is called "swaging".
LLoyd
Reply to
Lloyd E. Sponenburgh
Nicopress is the trade name.
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Reply to
cavelamb himself
The aluminum ferrules and stops are not rated for lifting overhead.
It is done with a hand tool that swages the ferrule and snaps 'over-center' to assure the correct crimping. A ferrule may require two or more swages to obtain the rated strength.
Reply to
MacD
When the wire rope loops around the thimble, the friction force reduces the pulling force of the opposing end by a great deal.
Reply to
Ignoramus13707
When I worked in boatyards we called applying Nicopress sleeves "crimping," as does Nicopress. "Swaging" was reserved for this process:
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Reply to
Ned Simmons
I don't think so. Many wire rope slings are sold with swaged thimbles, that do not have the loop forming insert (not sure of the proper name). It is the swaging which flows the thimble material into intimate contact with the wire rope that makes the difference. In any case, the doubling of the wire rope nominally halves the load on either side of the loop.
Reply to
Pete C.
DT
Your eye splice, with just an aluminum Nicropress sleeve, is possibly a Molly Hogan. Take a look at
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After the eye is fully formed, the two ends can be put back in lay, and the Nicropress sleeve put over that, and it would be hard to tell that from just a bent eye.
Don
Reply to
Don Murray
The "loop forming insert" is the thimble.
Reply to
Ned Simmons
Hmmm.... when I worked for the phone company we had a straight connector for solid open wire called a Nicopress also. It was pretty cool. It came filled with an abrasive. You would slide it on and off the wire which would polish off surface oxidation and knock the abrasive out of the tube. Then we would crimp it in place. Basically a glorified butt connector with enough strength to support a couple hundred feet of open wire under most weather conditions.
Reply to
Bob La Londe
I see:
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Reply to
Pete C.
I bought the swaging tool in Home Depot for $20. It looks like bolt cutters with semicircular cutouts in the jaws.
Some say that copper crimp sleeves are best.
"Spelter" sockets which hold the wire with cast-in-place zinc or epoxy are reputedly the strongest.
Reply to
Jim Wilkins
I was in a place in nocal that specialized in rigging and watched it being done.The press was a very large,probably in the range of 200 tons
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Reply to
DaveB
"DrollTroll" (clip) I would have thought some exotic-type brazing or welding would be required
^^^^^^^^^^^^^^^^^^^^ Welding a stranded cable would be virtually impossible. Brazing or silver soldering, if done very carefully in a temperature controlled oven, might work. If done by me, with a torch, the filler metal doesn't properly wet all the strands, and the outer strands get so hot the strength is shot.
Swaging or "crimping," or whatever you want to call it, works because the length of the collar has made long enough to to match or exceed the strength of the cable itself.
Reply to
Leo Lichtman
You have discovered the proper way to inter-lay the end together prior to crimping anything on the wire rope, congratulations. I have done this many times. I used a hydraulic hose crimping press and dies to crimp the sleeve.
I have a number of chokers that I have made this way.
The end is separated in adjacent strands of three and strands of four strands due to the wire rope having seven bundles of wire. Then tied in an overhand knot with the ends and pulled until they interlock. Then the ends are continued to be re-looped through the eye and interlock each time. If done right the ends blend together at the main length of the wire rope and the sleeve is pulled over the end and crimped so the sleeve covers as much of the intertwined loop as possible and still covering the ends. The size of the loop must be the length of the sleeve and the finished loop combined to be strong. Then crimped.
Then there is a Liverpool splice.
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This was covered not long ago in a article in Woodenboat Magazine on standing rigging. A true art in my opinion.
Reply to
RLM
Brazing/welding would anneal the wire and cause serious loss of tensile strength. JR Dweller in the cellar
Reply to
JR North
Zinced endings: There are three types of zinced endings: A cone is formed from molten zinc poured into a mold in which a frayed rope end has been inserted; sometimes a ferrule is used as mold and stays on after pouring the zinc; or sockets are used instead of the ferrule. An open socket has ears to hold a pin and cotter. A closed socket has a loop or "bail." Both are heavy forgings and find widespread use.
All three zinced on endings need a good deal of preparation. The rope's end must be broomed out, cleaned with acid and straightened. Special endings: such as thimbles, clips, and clamps are quicker and easier to apply than a zinc socket, but efficiency is not as high as with other attachments. These are filed attachments and inspection is necessary during service to make sure the nuts on the clips remain tight and provide proper holding power. Clips are U-shaped bolts with a grooved base and nuts to tighten-these and other grooved devices fit around a rope to form loops, or to provide endings similar to zinced sockets. In some cases, special thimbles and bolted clamps are used instead of clips.
Mechanical endings: A mechanical splice consists of a loop in the end of a rope and a sleeve pressed on the rope at the base of the loop to hold the end of the strands in place
Swaged endings: Swaging is the cold-flowing, under pressure, of metal fittings into the rope body, between strand sand wires. This pressure, applied by press or by rotary swagers, elongates the fitting but forces its metal inward so that the bond becomes permanent and compact, yet as strong as the breaking strength of the rope.
DaveB
Reply to
DaveB
[Flemish bend...]
How do you equalize the tension in all seven wires?
Somewhere I read a suggestion to load the eye enough to move the wires before completely swaging the sleeve. Without a rigging vise to hold the eye tight against the thimble I found it difficult to do.
Jim Wilkins
Reply to
Jim Wilkins

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