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
AND, if I have seen correctly, it seems that some of these crimps are
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.
"DrollTroll" fired this volley in
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.
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.
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.
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
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.
"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.
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
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.
This was covered not long ago in a article in Woodenboat Magazine on
standing rigging. A true art in my opinion.
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.
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.