Author Topic: The pattern of the Rectangular bend  (Read 6176 times)

xarax

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The pattern of the Rectangular bend
« on: February 04, 2014, 03:05:35 PM »
  If a known simple bend slips when tied on Dyneema, the most easy to remember ways to enhancing it are :

1. Re-tuck its Tail Ends once more through the same openings they were tucked in the first place.
2. Retuck its Tail Ends through the central opening of the bend.
3. Un-tuck the Tail Ends once, drive them turn around the Standing ends ( so they make a 180+ degrees turn, a collar, around the Standing ends ), and re-tuck them through the same openings they were tucked in the first place.
4. Use the Tail ends to tie half hitches around the Standing ends.

 When the individual links of the bend follow a certain easy to remember and to tie pattern, we can enhance the anti-slippage capabilities of the parent bend by just following this same pattern once more. Even very simple bends, when they are modified this way, can become disproportionally more secure, in comparison to the complexity and/or material such a modification has added on them.
  If we want to cut some corners ( and, instead of following a more systematic step-by-step method of examining the known bends starting from the more simple and proceeding to the more complex ) we can pick up an already not-so-simple bend right from the beginning, and modify it in one ore more of the ways described previously.
  In this thread I show one bend that :

1. It is already convoluted in the way suggested by the properties of Dyneema lines ( which seem to require paths of the Standing parts making sharp U turns, and not constricting wide round turns ).
2. In each link, the Standing parts follow a certain pattern, which can easily be repeated one more before the final closure of the bend. This pattern can be followed once more, so the Standing part of the one link makes another U turn around the Standing part of the other.
 
  One advantage of this bend is that it can be tied by following the easy to remember and inspect "alternating" tying diagram, shown by Miles at p.84.
However, I advise the reader to tie it by following the attached pictures, so he/she will understand the pattern of the 3D path of each link s Standing Part immediately. Then, the way this pattern can be repeated for another time ( before the final closure of the bend, so the Standing Parts of both links follow more 8 shaped, Lissajous curve-like paths ), would be obvious.   
« Last Edit: February 04, 2014, 03:07:33 PM by xarax »
This is not a knot.

xarax

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Re: The pattern of the Rectangular bend
« Reply #1 on: February 04, 2014, 06:17:55 PM »
  Another way we can modify a known simple bend in an easy to remember and to tie way, in order to enhance its security ( as described in (1)), is to move one step up on the ladder of the topology of each link - from the overhand knot to the fig.8 knot, and from fig 8 knot to the one of the three fig.9 knots (2), etc ). At the attached pictures one can see a Fisherman knot s-like bend, where the Standing end of the one link and the Tail end of the other go through the same opening. It is the bend Miles calls "Forty-Five knot" ( M. B23 ), where each link is an overhand knot. ( I show it on a stage just before the one links "kisses" the other). Similar "inter-penetrating" bends are shown at (3),(4). So, we can replace those overhand knots with fig.8 knots, fig.9 knots, etc.. We retain the same pattern of the bend, but we make it more convoluted in the hope that, even if the previous step will be proved insufficient and the knot will slip if is tied on Dyneema, the next will not.

1. http://igkt.net/sm/index.php?topic=4771
2. http://igkt.net/sm/index.php?topic=4764
3. http://igkt.net/sm/index.php?topic=3671
4. http://igkt.net/sm/index.php?topic=4705.msg30503#msg30503
« Last Edit: February 05, 2014, 01:15:36 PM by xarax »
This is not a knot.

xarax

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Re: The pattern of the Rectangular bend
« Reply #2 on: February 05, 2014, 06:06:32 PM »
  Regarding the "interpenetrating-overhand-knots bend" shown in the previous post, I wish to add that there are more ways we can implement this pattern, involving back-to-back , Pretzel-to-Pretzel bends. See, for example the bends shown by Luca (1), or elsewhere (2). When the ends  are adjacent when they leave the nub, we can consider them as variations of the Tweedledum bend, where the "bellies" of the two overhand knots ( i.e., the backs of the interweaved Pretzel-shaped links ) are not crossed. However, I believe that the arrangement of the strands in the Forty-Five knot is preferable : the segments of the ropes that form the "bellies" of the two overhand knots bite each other deeper and harder, because they meet at almost a right angle - when they meet at a more acute angle, as it happens in the bends mentioned in the present post, they can possibly slide on each other, so the bend will run the danger to become less secure.
   How do I know that something like "sliding" this may happen ? Well, actually I do not - I only have some indirect indications about this (3)-(4), and the reasoning itself of the mechanism sounds reasonable to my ears. We can not test complex, very convoluted bends on ordinary material, simply because, on such materials, such bends do not slip at all. Therefore, the only way we can test them is to tie them on Dyneema, and see what happens.
 
Those who can, test, those who can not, tie, and those who can not tie, talk. - and often post some pictures, too, to muddy the waters !   ;)

1. http://igkt.net/sm/index.php?topic=4705.msg30503#msg30503
2. http://igkt.net/sm/index.php?topic=4188 
3. http://igkt.net/sm/index.php?topic=2191.msg25358#msg25358
4. http://igkt.net/sm/index.php?topic=4756.msg30822#msg30822
This is not a knot.

xarax

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Re: The pattern of the Rectangular bend
« Reply #3 on: February 07, 2014, 08:20:48 PM »
   Just an example of another "similar"" interpenetrating-overhand-knots" bend, is the Double "S" ( M. B21 ), shown in the attached picture. One should notice that many of those bends are not perfectly symmetric, and even if the parent tying diagrams look like being so, when we specify which end is the Standing and which the Tail end, the apparent symmetry disappears.
« Last Edit: February 08, 2014, 09:36:55 PM by xarax »
This is not a knot.