Author Topic: A Simple Tool to Help Understand Knots  (Read 407 times)

DerekSmith

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A Simple Tool to Help Understand Knots
« on: August 19, 2018, 08:24:20 PM »
If we pull a knot open, we can study the lacing patterns, but not the structure of the knot at work.

A simple tool to help study the operational structure of a knot is to skeletonise it.

Tools:-
Cord - I find 6mm Nylon braided Sash Cord to be an ideal compromise.
Marker Pen
Superglue - liquid not gell

Method:-
Tie, dress and set the knot to your satisfaction.
Repeat so that you have a duplicate pair of knots.
Start with the SP and dot with the marker pen to follow the path of the cord around / through one of the knots.
Using the Superglue, follow the tracer dots around the knot applying small dots of Superglue to the traced cord.  Do not apply too much glue or it could soak out and glue adjacent cords together.  The objective is to only apply sufficient glue to solidify the traced cord.
Set aside to set.
Now carefully draw the counter cord out of the knot to leave only the solidified cord.  If parts of the skeleton are 'floppy', match the structure to that of the duplicate and apply more dots of Superglue to rigidify the missed portions.
Now using the duplicate knot, follow the counter cord through the knot with the marker, then the Superglue in order to petrify it, then once set, remove the counter cord and patch up any 'floppy' areas.

You should now have the two skeletonised components in exactly the conformance they held within the dressed and set knot, ready to perform as intended.

Tie a third example of the knot and use the component skeletons to visualise and understand how the components enmesh with and react with one another.

Happy petrification.

Derek

Dan_Lehman

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Re: A Simple Tool to Help Understand Knots
« Reply #1 on: August 19, 2018, 08:43:39 PM »
Except that in many cases, there will be some significant
change of knot geometry with serious load --a tensioning
(and tightness/jamming) that might be too much for simple
glue.  Which is just to say that one can go wrong in analysis
if the hand-set-only geometry is regarded and not what
obtains with serious loading.  --depends on one's objectives.


(I forget what method Barnes used in sort of freezing some
broken blood knots so that he could cut them and see
where the break came (middle of knot where SParts run
around tails on opposite sides, NOT at the hard, single-diameter
turns-into-wraps at the opposite ends of the nub!).
)


 :)

DerekSmith

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Re: A Simple Tool to Help Understand Knots
« Reply #2 on: August 19, 2018, 09:05:40 PM »
Indeed Dan, I agree with your comment.

The cord I use is suitable to enable the provision of modest loading, yet still be 'petrifiable'.  For knots which heavily transmute or jam under load this tools is of limited or no value, leaving us in the dark as to their structure, but it does give us a view into the dressed, set and modestly loaded knots.

Derek

Dan_Lehman

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Re: A Simple Tool to Help Understand Knots
« Reply #3 on: August 20, 2018, 11:56:11 PM »
Which is just to say that one can go wrong in analysis
if the hand-set-only geometry is regarded and not what
obtains with serious loading.
I sometimes wonder at the ranking of knots, maybe
esp. of anglers knots, looking at one that's said to be
so much stronger than some other(s) and thinking
"but they all do THIS, after which why will it much
matter ... ?! " !  The Palomar knot e.g. is one
that puzzles me at being so strong.
(I think that with anglers knots part of the answer
is that they are able --given weakness of line-- to be
manually set to much higher % of break strength.
(And knots images typically show only an indecipherable
squiggle for the completed knot; one has to be attentive
in the tying steps, where pulling on "the tag end" (= tail)
is often specified.)

 ;)

DerekSmith

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Re: A Simple Tool to Help Understand Knots
« Reply #4 on: August 21, 2018, 04:56:10 PM »
@Dan

Quote
The Palomar knot e.g. is one that puzzles me at being so strong.

I think the strength of the Paloma can be deduced from its dressed, then loaded structures (they are the same).

The loaded SP approaches the hitch through three parallel wraps - there is no linear distortion, nothing to act as a compression or weakness inducing point.  It then makes a clean unobstructed turn around the hitch object, shedding a substantial amount of load against the stable hitch component.  It then leaves the hitch component and returns parallel to the SP but separated from it by one diameter until it shoulders over itself to form the three encircling wraps and the final closing loop.  The residual forces act compressively on the collar (which in turn bears on the hitch component), not on the heavily loaded SP.  The WE meanwhile flows in the opposite direction through the three wraps, offering a small degree of negative cogging support.

The absence of cord compression, nipping or distortion forces should, and clearly does, offer maximum strength to this knot.

Whoever discovered this delightful noose hitch deserves a knotting medal.

Derek