Author Topic: Non slipping bend in Dyneema  (Read 67057 times)

SS369

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Re: Non slipping bend in Dyneema
« Reply #135 on: January 30, 2014, 04:48:15 PM »
Hello Allen.
Thank you for the video. It made it very clear.
I am supposing that prior to use/testing you would pull the tails to further condense the bend and eliminate movement.
Looking forward to the update from Estar.

SS

allene

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Re: Non slipping bend in Dyneema
« Reply #136 on: January 30, 2014, 05:00:42 PM »
^^ In Dyneema, the knot tightens itself up so I have never done more than what I show in the video.  The variation of the knot, with the tails going out parallel to the standing ends, can be tightened up and will not slip if you do so.  The main version, the one you can untie and is simpler to tie, you want the tails snug but it is not clear to me that pulling them actually tightens the knot.

Allen

allene

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Re: Non slipping bend in Dyneema
« Reply #137 on: January 30, 2014, 11:08:38 PM »
We have some data.  The first bend slipped at 32% of line strength.  The variation, with the tails coming out parallel to the standing ends, did not slip and broke at 39% so it is about 20% stronger.  By comparison, the triple fisherman's knot slipped at about 25% of line strength.  Amsteel and other Dyneema is considered a line that you cannot tie knots in so I am pleased with both these results.  I created a video for making the variation.  For making a shot loop, the variation might be a better candidate as you would not want to untie it, the added strength is a plus, and having the tails come out parallel to the standing ends is nice.

Another way to get a knot that will not slip is to use the first bend without the variation and pull it until it slips, then wait an hour or so and it will not slip when pulled again.

http://youtu.be/i8DTAw7dwV0


xarax

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Re: Non slipping bend in Dyneema
« Reply #138 on: January 30, 2014, 11:52:43 PM »
    There are two remarkable things here, for knots tied on pure Dyneema :

1. The retucked-through-the-centre alternative Carrick bend ( ABoK#1428 / M. A5 ) slip less than the similiraly retucked classic Carrick bend ( ABoK#1439, M. A6 ).
2. The retucked-through-the-centre alternative Carrick bend ( ABoK#1428 / M. A5 ) slip less than the triple fisherman s knot.

   So, the main question is : How much ?. And the secondary question is : What is the MBS of the knotted line in each case ?
   I would like to see more data from more tests on those three knots, to get a more clear image. Oftentimes, more is more  :)
   
 
« Last Edit: January 31, 2014, 01:19:55 AM by xarax »
This is not a knot.

allene

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Re: Non slipping bend in Dyneema
« Reply #139 on: January 31, 2014, 12:31:36 AM »


I see no resemblance to either of my knots to 1429.


allene

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Re: Non slipping bend in Dyneema
« Reply #140 on: January 31, 2014, 01:22:50 AM »
I prefer to call it my first bend.  I do not think this bend was anticipated by Ashley and it has no similarity to a Carrick bend when tied.  The Carrick bend is just an intermediate step in the tying of the knot.



« Last Edit: January 31, 2014, 01:24:56 AM by allene »

xarax

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Re: Non slipping bend in Dyneema
« Reply #141 on: January 31, 2014, 01:31:57 AM »
It has no similarity to a Carrick bend when tied.

  Is a not-capsized Carrick mat a Carrick bend ? Does the Carrick bend, especially when it is tied on big ropes, as it often happens, capsize always ? The first seems only a matter of nomenclature, and nomenclature is not exactly the point where knot tyers agree most...I do not know the answer to the second question.
« Last Edit: January 31, 2014, 01:41:41 AM by xarax »
This is not a knot.

Dan_Lehman

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Re: Non slipping bend in Dyneema
« Reply #142 on: January 31, 2014, 06:56:34 AM »
Does the Carrick bend, especially when it is tied on big ropes,]
as it often happens, capsize always ? ...
I do not know the answer to the [] question.
Do you know that it "often happens" --and if so,
how do you not know the answer ... ?!

Except in knots books, I've not seen any such
joining of big ropes --one way or another.
I've read that sometimes the lattice form of
the knot is made with tails seized to S.Parts so
to keep it open and easily untied (after cutting
the seizings); but I do not know whether this
knots-book assertion has any basis in fact, or
in any recent fact!  (And I have trouble seeing
how the *knot* part is much needed, as the
seizings should be doing all of the work!  Brion
Toss & I had some back'n'forth over this, and
other aspects of seizings.)


--dl*
====

McKnottee

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Re: Non slipping bend in Dyneema
« Reply #143 on: January 31, 2014, 09:26:02 AM »
   Pictures of a simpler but somehow similar bend - because we had enough of all those complex bends that had filled the thread without any reason ! :)
   It is the Snug bend ( M. B11 ), which can also be seen as a modification of the falsely tied Hunter s bend :
   http://igkt.net/sm/index.php?topic=3204.msg19167#msg19167

   If the Snug bend is a good-looking bend - and I believe it is, indeed -,  I do not see why the retucked alt. Carrick bend of Allen will be not ! :)

I have been playing around with the Snug bend lately, and the more I do, the more I like it. It seems a very under appreciated bend, simple, elegant, and secure. Flat on one side, with tails coming out as a pair from the top of the bend (as opposed to from the opposite sides), and it is thin (axially), all together which mean it can slip through many narrow crevice type spaces. Also not that hard to undo, just grab the tails and tug a few times in opposite directions should loosen it enough to pull apart with modest effort.

In particular I have been investigating different extra tucks, like these, which could make it suitable for secure bends in Dyneema:

« Last Edit: January 31, 2014, 11:35:32 AM by McKnottee »

McKnottee

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Re: Non slipping bend in Dyneema
« Reply #144 on: January 31, 2014, 09:27:24 AM »
Third tuck version:

McKnottee

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Re: Non slipping bend in Dyneema
« Reply #145 on: January 31, 2014, 09:28:17 AM »
Fourth tuck version:

xarax

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Re: Non slipping bend in Dyneema
« Reply #146 on: January 31, 2014, 10:09:08 AM »
Do you know that it "often happens" ?
Except in knots books, I've not seen...

  I do not say what "happens" only for things that I have actually seen with my own eyes ! I say that there was a man on the moon, but I have not seen this event myself !  :) I say that there is a Dan Lehman who knows how to ride a bicycle, but I have not seen this - and I do not doubt that a bicycle, yes, he does know to ride... :)
   However, I think that I have even seen pictures of such arrangements, entangled on marine and wire ropes- in books about boating / sailing. Now, sailors should not be trusted more than knot tyers, of course, but I do not see the motive that could lead to a fake picture. I hope you will search about this a little more - in books, I mean, not in the wild, riding your bicycle (1).  :)

1. http://weburbanist.com/2009/03/03/futuristic-strange-concept-bicycles-designs/
« Last Edit: January 31, 2014, 10:11:47 AM by xarax »
This is not a knot.

xarax

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Re: Non slipping bend in Dyneema
« Reply #147 on: January 31, 2014, 11:17:58 AM »
  Beautiful complex symmetric bends ! - as it should perhaps be expected, for symmetric retuckings of beautiful simpler bends.
  Nobody has ever tied any of them, I believe - because nobody had ever searched for so convoluted bends - we used to think that the simpler bends were already too many, even for the experienced knot tyer s mind, and convoluted more than enough for the job, so any further retucking of them could offer very little, and it would not worth the trouble - and the added material. Now with the Dyneema revolution, we are back to the square one - or , for that matter, to the square zero, as shown with a picture at the previous post.
   However, I am not yet convinced that all the simpler bends we already know are inadequately convoluted - nobody has ever tied and tested more than a handful of the 60 bends presented at Miles, for example, and Miles book is 20 years old... People seem to be ready to jump into conclusions and make general statement, indeed, they almost feel compelled to do so, especially regarding knots that have tied, but they do not feel obliged to see what other knot tyers have already tied before them. That is often a good thing, because it offers them the power of a fresh look, but I believe that, at this stage, we need more tests, not more ties. Of course, people that can not test, tie, and people that can not tie, only talk about knots - I know this because I have actually seen this, with my own eyes, in my case !  :)
   To my eyes, the tuck B style looks more promising - as I have also tried to explain (1)(2), a few sharp turns and/or right angle crossings can do a better job then many constricting=nipping round turns/loops. I have thought that the fig.9 stopper, which has such properties, can be more effective than the almost equally complex double fisherman s knot, for example - so I tried to incorporate it in a fisherman s knot, and see what happens.(3)
  I think we should not high-jack allene s thread any more, showing more and more "new" bends that should possibly be as efficient as the retucked alt. Carrick bend - or even more efficient. I suggest the previous posts be moved to a new thread, and we continue talking about those particular retucked Snug bends there.
 
  "When the one line is squeezed on an other, their surfaces are deformed - the saddle-like shapes that are generated play the role of obstacles, of "dents", which increase the amount of forces required for any lengthwise motion predicted by the theory of friction of solid, non-deformable bodies.
  We can actually see this by measuring the friction between two lines when they meet each other at different angles. When the angle is more acute, so the area of mutual contact is more extended, the lines can slide along each other easier, because the deformations / obstacles on their surface are less pronounced - they are more extended, but less deep. When the angle approaches the right angle, the contact area is smaller, so the same perpendicular force can allow the lines to bite each other harder and deeper - so they can not move lengthwise as easily as it would had been predicted by a theory of friction which does not take account the local deformation on the surfaces of the bodies."(1)
 "Why does the Twedledee bend slips "easily", while the 88 bend does not ? I believe that this is due to the fact that the oblique elements of the two 8-shaped links meet each other at an almost right angle, so the surface of the one bites hard and deep into the body of the other - a condition that deforms the two lines, and prevents their mutual lengthwise displacement more effectively than the increase of the pressure they are hold together. So, just constricting two lines is a less efficient mechanism than preventing them to slide on each other, by paying attention to the angle they follow as they reach to their contact point."(2)

1. http://igkt.net/sm/index.php?topic=4756.msg30822#msg30822
2. http://igkt.net/sm/index.php?topic=4756.msg30894#msg30894
3. http://igkt.net/sm/index.php?topic=4764.0

P.S.
As you can see, the Snug bend ( M. B 11 , p 89 ) can be represented as a tying diagram on a 5 x 5 square grid. I suggest we label the openings of the tying diagram with their position in the matrix - for example, the central opening is the ( 3, 3 ). Then, we can label the variations by denoting through which openings we have driven the ex-Tails, in order to retuck the "base" bend once more. We can use the + or - symbol to denote that the ex-Tail penetrates the tying diagram going from the one half-space to the other : + if it penetrates it moving "downwards", relatively to the diagram laying on a horizontal plane, and - if it penetrates it moving "upwards". This way we can avoid the "first", second", etc labels, and provide the adequate information so one can tie the knot, without having to look at a picture of it.
« Last Edit: January 31, 2014, 11:56:13 AM by xarax »
This is not a knot.

McKnottee

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Re: Non slipping bend in Dyneema
« Reply #148 on: January 31, 2014, 11:54:59 AM »
If it is deemed appropriate by the mods, I am happy for my posts to be split off into a new thread. 

If so, I will respond to Xarax's thought provoking post there.

allene

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Re: Non slipping bend in Dyneema
« Reply #149 on: February 01, 2014, 03:53:31 AM »
I thought you all might be interested in a comment I got from Brion Toss as his name was mentioned in this post.

"Allen, nice bend video. Sounds like an untieable version is the new Grail."

Allen