Author Topic: Whatever Bend  (Read 2427 times)

SS369

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Whatever Bend
« on: February 11, 2014, 10:10:22 PM »
Whatever Bend

First tie a Whatknot with the tails opposing. (exiting from the central area in opposite directions as Ashley shows in the first sequence for #1408.
Then take the tails around the Standing parts as shown in the attached pictures and drive them through the central opening between the two parallel strands.

Dress till the tails partially encircle the oppose sides of the Standing parts and further tighten, alternately pulling the tails individually, while holding the body of the knot, and then the Standing parts.

In the small diameter Dyneema I have it draws up very compact and holds well at a 300 lbs load.
Untied easily with the aid round nosed pliers, used due to my inability to grab the interwoven strands.
The larger rope was less needful.

As well, it can be tied as an eye, though bulky.

SS

xarax

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Re: Whatever Bend
« Reply #1 on: February 11, 2014, 11:10:12 PM »
  I have never seen or tied this bend - which seems a pretty secure one ! In fact, the interwoven "8"-shaped links are so well nipped by this wefts-and-warps over/under pattern, that it is difficult to dress the bend in ordinary material. The friction is so much that the pull from the Standing Ends can not reach the Tail Ends - so the hand-induced tensile forces are absorbed before they "fold" the knot. That is an indication it would be a quite secure bend, even if tied on slippery Dyneema...
   I also find it interesting that the links are topologically equivalent to the unknot - so the end-to-end knot can serve as a PET eyeknot - although I do not believe we would ever really need such a convoluted eyeknot.
   Adding an easy, straightforward further retucking, we can make the Tails run adjacent and parallel to the Standing ends, so the knot becomes more streamlined, and can be inspected even more easily.
   For the most "similar" bends to this I can think of, have a look at (1),(2) (3) and (4), and at the three bends shown in the attached pictures, by Valentine, Luca and me.

1. http://igkt.net/sm/index.php?topic=3148.msg18834#msg18834
1. http://igkt.net/sm/index.php?topic=3225.msg19239#msg19239
2. http://igkt.net/sm/index.php?topic=4662.msg30153#msg30153
3. http://igkt.net/sm/index.php?topic=3148.msg30777#msg30777
« Last Edit: February 11, 2014, 11:13:01 PM by xarax »
This is not a knot.

xarax

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Re: Whatever Bend
« Reply #2 on: February 12, 2014, 03:39:09 AM »
   This knot is truly wonderful :
 
   1.  The segments cross each other at the optimum, the right angle, so the saddle-shaped local deformations around the areas of mutual contact are maximized, and the lines do not run the danger of sliding easily on their sleek surfaces.
   2.  The cross section is reasonably wide : assuming that the lines follow an orthogonal grid, around four rope diameters.
   3.  The pattern of the 2D tying diagram does not differ much from the pattern of the tighten 3D  knot - a rare great advantage regarding the learning, memorizing, remembering, tying and inspecting the knot.
   4.  This pattern is the most simple possible : an alternating orthogonal grid, where the lines of the one link lie in between the lines of the other. See the "yellow" or "light", and the blue" or "dark" lines of the knot as shown in the attached pictures.
   5.  It is side-symmetric, just like the Zeppelin bend : the flat surfaces are symmetric, so one picture or mental image of it is sufficient to describe it completely.
   6.  It is very easy to untie, again just like the Zeppelin bend, and all the bends where the lines play the role of "pivots" in a nub resembling a rope-made hinge mechanism.
   7. Although I had not the means to test it on slippery material, I believe that even if the Standing and the Tail ends are swapped, the bend would be equally - and perhaps even more - secure.
   8. As the links are topologically equivalent to the unknot, it can serve as a PET eye-knot, and/or an end-to-middle knot.
   9. The Tails run parallel to the Standing Ends, an advantage in many practical applications, which also makes this bend, although based on a flattish, textile-like pattern, look streamlined.
 10. Although we can not just pull the free ends and wait the knot to become tighten all along its nub and compact ( there is too much inner friction, and the tensile forces are absorbed before they reach the Tail ends ), we can nevertheless dress it easily and properly, with a trick : we can first push the one collar towards the other, and take the remaining slack only afterwards, by pulling various pairs of opposite ends. Doing this two or three times in a row, the knot almost self-dresses itself : it becomes very compact, and settles in a very symmetric form, with all the lines parallel or perpendicular to each other.

   I am sure that if one examines this knot a little more, he/she will discover many more advantages - because it seems that this classic warps-and-wefts pattern has many more aces in its nub.
This is not a knot.

Dan_Lehman

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Re: Whatever Bend
« Reply #3 on: February 12, 2014, 04:28:29 PM »
Whatever Bend

First tie a Whatknot with the tails opposing.
Which at this point is a knot that can hold
given the proper orientation/dressing, just
the grass (half-hitch) bend can --tails placed
farther from their U-turns, each tail nipped
within the loop formed by the other's U-turn.
(I think that Desmond Mandeville showed this
knot in some Knotting Matters long ago.)

Quote
In the small diameter Dyneema I have it draws up
very compact and holds well at a 300 lbs load.
And is this pure Dyneema (HMPE), or a sheathed cord?
(I think that you have some of the latter, but show the
former in your photo?)
What's its tensile strength?

(I'm having trouble seeing that small cord having
the same knot as the red (and as what I've played
with) --it looks different!?)

--dl*
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SS369

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Re: Whatever Bend
« Reply #4 on: February 12, 2014, 04:54:30 PM »
Hi Dan.
Yes I do have some Titan also with Dyneema core and Nylon outer sheath. Different animal.

The Blk/Gray cord is 100% Dyneema.
 Specifications:

    Line Diameter: 1/8" (3 mm)
    Material: 100% Dyneema fiber
    Color: gray
    Average Tensile Strength: 2,500 lbs
    Weight per 100 ft: 0.5 lbs
    Splicing: Class II 12-strand splice

It is slippery as all get out, feels like it has a graphite coating. In fact the Black/gray does come off on your hands when tying and tightening.
It is very soft and flattish. This makes it hard to see the parts of the knot when dressed and loaded. The sheen obscures this as well.
I assure you that the two bends in the photo are tied the same and I believe that even were it in your hands it would be no more clear.

BTW, it happens that the grass bend holds at the same load I subjected the other, as well, using the pure Dyneema!


Quote
(I think that Desmond Mandeville showed this
knot in some Knotting Matters long ago.)

Are you saying in the above that the "whatever bend" or xarax's modification were previously shown or the grass bend? If so, can you give the reference pages or the name used?

SS

Dan_Lehman

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Re: Whatever Bend
« Reply #5 on: February 12, 2014, 05:38:30 PM »
    Average Tensile Strength: 2,500 lbs
So, you got > 10%, at which point one might
expect troubles to show; but there is of course
more to go!

Quote
It is slippery as all get out, feels like it has a graphite coating.
The blue NER 5/16" stuff I was given by them
to use has a urethane coating, which makes
one wonder about having that as an additional
factor to consider.


Quote
BTW, it happens that the grass bend holds at the same
load I subjected the other, as well, using the pure Dyneema!
Which certainly puts doubt into one's testing
--that sufficient force has been delivered.
I has some supple, gray, SPectra in which some
mid-line eyeknot (pulled w/eye slack, IIRC) held
in it, yet showed some movement in supple, soft
solid-braid nylon !?  Ha.  (Not given huge loads.)


Quote
Quote
(I think that Desmond Mandeville showed this
knot in some Knotting Matters long ago.)

Are you saying ...
... that the base formation --like a grass knot--
was presented, ends going opposite directions after
a simple turn of each (and careful dressing & setting).


--dl*
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SS369

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Re: Whatever Bend
« Reply #6 on: February 12, 2014, 05:56:29 PM »

Quote
So, you got > 10%, at which point one might
expect troubles to show; but there is of course
more to go!
More like 12%.  ;)

Quote
The blue NER 5/16" stuff I was given by them
to use has a urethane coating, which makes
one wonder about having that as an additional
factor to consider.
I feel positive that the coating plays into this strongly, along with the easy to deform qualities. Try the offerings of this post using that NER stuff.


Quote
Which certainly puts doubt into one's testing
--that sufficient force has been delivered.
I has some supple, gray, SPectra in which some
mid-line eyeknot (pulled w/eye slack, IIRC) held
in it, yet showed some movement in supple, soft
solid-braid nylon !?  Ha.  (Not given huge loads.)
I'll load more heavily in the future since I have such a limited supply on hand now and continue light testing till my list is pared down.


Quote
... that the base formation --like a grass knot--
was presented, ends going opposite directions after
a simple turn of each (and careful dressing & setting).
Cleared it up...

SS

SS369

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Re: Whatever Bend
« Reply #7 on: February 12, 2014, 11:07:39 PM »
Here's another picture of it loaded (not maxed) using 3/8 inch Vectran 12 strand braid.  Slippery stuff with no coating I can discern.
It shows the compactness and the parts better than the small Dyneema, with it being of the same construction.

SS