Author Topic: Any Suggestions For A Knot?  (Read 4139 times)

kryptikk

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Any Suggestions For A Knot?
« on: August 27, 2007, 12:44:58 AM »
Hi, im new here and i apologize for any breach in Etiquette i work for a cable tv contractor and lately ive been having to do underground to pull out the fiber optic cable i usually use a knot similar to an icicle but the undeground has been very tight pulling and it cut the fiber in two i tried a KillickHitch and it had the same result, i was wondering if anyone  knows a knot to pull in parallel  and at a steady tension  with as little binding or kinking in one place it would be best if i could tie the knot in the middle of a span but would accept ones i could only put on the end, any help is greatly appreciated

turks head 54

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Re: Any Suggestions For A Knot?
« Reply #1 on: August 27, 2007, 05:15:35 AM »
Take a couple wraps of electrict tape around the cable and tie a mangus hitch after the tape.
But if that doesn't work try using a constrictor knot.

knudeNoggin

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Re: Any Suggestions For A Knot?
« Reply #2 on: August 27, 2007, 06:26:52 AM »
Take a couple wraps of electrict tape around the cable and tie a mangus hitch after the tape.
But if that doesn't work try using a constrictor knot.
What?  The problem is that he is breaking cable, even though a Killeg hitch
apparently holds!  So beefing up the cable for a better grip isn't a solution.
(And since when does a Constrctor binder not become a gripping hitch?)

But what is the material with which the cable it being pulled?
The most gentle treatment of the cable will come with some soft, flat material
wrapped around it in opposite spirals.  There are even some "stopper" products
sold for such attachment.  There is a soft, thin, flexible polyester tape made for
pulling underground (it is lubricated to aid sliding), and maybe this can be
tied with a knot structure similar to the Valdotain/Machard Tresse--or, simply,
wrapping the tape (tie a starting clove hitch in the middle, perhaps) ends
in opposite spirals and alternating over & under crossings for a good distance,
and then tie this gripping structure to your haul line.

You might even need to help this structure along by using some mason line
and employing a constrictor binder at both ends of your wrapped tape, to
keep it in place (and build some extra friction).  Or you could probably
as well and maybe more easily in tying and untying use a quick form of
common whipping, just wrapping back over a bight relatively tightly and
then lightly binding the wrapping end by the nip of the wrapped bight
(pull on opposite end, but not to pull wrapping end beneath wraps,
as is done for whipping).

*knudeNoggin*

DerekSmith

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Re: Any Suggestions For A Knot?
« Reply #3 on: August 27, 2007, 08:00:11 AM »
Hi kryptic,

Try the KC Sling Hitch, you can wrap it anywhere on the cable you are pulling, but the trouble with all these types of knots is that the harder you have to pull, the more distortion the knot makes on the object it is gripping.

http://igkt.pbwiki.com/KC-Hitch



The least distortion comes from a hollow braid gripping sheath.  They are usually made out of mono filament and are quite springy.  Bunch it up and slide it over the end of the cable, fix the end onto the cable with a cable tie  and then pull the braid sheath to extend and shrink its girth.  then fix the end of the sheath to your pulling line and heave.

PatDucey

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Re: Any Suggestions For A Knot?
« Reply #4 on: August 27, 2007, 08:15:51 PM »
When I worked at a power plant I saw a tool used by cable pullers that might do the job.   It was a Chinese Finger Trick tool tied in steel wire.  The wire was a twisted wire, probably stainless steel, and somewhat thin to be flexible.  I didn't get a good look at it, but it looked like a long turks head.

It was slipped over the ends of the wires to be pulled, and electricical tape was wrapped around the entire lenght of the overlap.  They used a conduit lubricant, which helped a lot.  I don't know if conduit lubricant is acceptable to use with fiber optics, but it sure does help when pulling heavy copper through bends in conduit.

Pat

Dan_Lehman

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Re: Any Suggestions For A Knot?
« Reply #5 on: August 28, 2007, 07:01:36 AM »
The general structure as variously indicated above of an elongated spiralling
gripping mechanism in the spirit of the Chinese finger trap is your best hope.
Derek cautions that his KC knot can impart considerable pressure upon loading,
but if the wraps have a large initial helix angle this effect should be adequately
mitigated.  The practical issue of effecting such an elongated structure is I think
addressed with the addition of special binding structures of the Constrictor or
Strangle knots to hold the elongated hauling gripping material in place.

What diameter of cable is at issue, and how much clearance does it have
through what it is being hauled?

Another similar idea occurs to me:
1) attach your hauling line to a 2-, 3-, or maye 4-armed cord (again, what
diameter & clearance are we working with?);
2) put Overhand or Fig.8 stopper knots in the arms of this cord about
every 4" or so, with those of one arm at a slight (1/4") stagger to each other;
3) run these arms along your cable on different sides;
4) apply that Common Whipping-like binding described above at the points
with the stopper nots such that the knots fall within the whipping (and themselves
are not whipped over, but around--and so protude from the whipping wraps).

.:.  The idea is to have this multi-armed cord take the force of pull alongside
the cable and pull it by the friction of the whippings, part of each of which will
be pushed by the stoppers and then the trailing whipping will be pulled
and should thereby impart some added friction gripping; and the sequence of
(say, three) them one hopes provide sufficient friction grip--yet w/o concentrated
pressure on the cable--to secure the cable.  The slight stagger in the stopper
placements per whipping is to ensure that each stopper pulls/pushes at a
different point in the whipping's wraps (probably better if the positional bias is
towards pushing fewer--stoppers more fore than aft!?

If the cable diameter is such that it might be hard to have thick enough cord-arms
to bear the load and yet leave adequate area for the whipping to bind against the
cable, I think one could say run 4 arms such that only two were whipped at a point,
then the other two at the next point, for a total of 4 whipping points!?  For the cable
to slip out of this, it would have to slide through these four attachment points,
and that should be hard to do.

--dl*
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