Author Topic: Figure 8 bends  (Read 19119 times)

xarax

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Re: Figure 8 bends
« Reply #15 on: June 17, 2011, 04:49:59 PM »
   Thank you, Dan Lehman,

I find it a PITA to follow LINKS to get to what is simply got by scrolling up the page of the current thread? Why not just say "to the fig.8 bends above (post #x)" ?

  You are right, sometimes my references might be regarded as redundant, and sometimes they are, indeed. I do not have a good memory, so, sometimes, I repeat things just to be sure that they are documented there again, so, when later I will go back to that specific post, I will remember what I was referring to...I will try to avoid it in the future...I understand it might be annoying for the reader, who is already annoyed by having to tie all those "new" knots that has been tossed out !  :)

 I can NOT make the "D"-2nd image be the same knot as the others:it shows the orange tail CLEARLY crossing IN FRONT OF the white; but the slight & 90deg rotations, respectively, of preceding& succeeding images clearly show the tails in opposite place!?

   You are right again, obviously. I have just inserted the same front view picture of the C-C bend used in the interlocking-overhand-knot bends thread, to show that this same knot can better be described as a two interlinked fig.8 knots bend. But the difference is not essential at all. One can dress the bend the one or the other way. What is more important, is the relative position/ crossing of the two tails along the axis of the bend. I believe it is better if we place the tails in such a way, so that the "rope volume" encircled by the two main fig.8 knot bights is as large as possible, and the first curves of the two standing parts are as wide as possible. I think that this purpose is better served if the "orange" tail exit the knot s nub near the "white" standing end, and vice versa.( See the other three pictures, and the attached picture) If the "orange" tail do cross the "white "one, it is of no importance if it passes "in front"/from the "left" side, or "in back"/from the "right" side of it.

Whatever, here and in some other of these knots, I think it might be best to orient the tails such that the draw of the SParts pulls them tighter, unlike the present cases where there is some.

   My main concern was the radii of the first curves of the standing parts around the central "rope volume", not the orientation of the tails. Because I have found that the fig.8 bends, ( especially the A, B, and C variations), are so convoluted, that the tails are not pulled by the standing ends very hard... I would say that, after we dress and tighten the bend, pulling the standing ends by hand,  the tails will not be pulled again by the standing parts at all ! This might be considered as a drawback of those bends...The additional tuck and consumption of rope length is used, mainly and almost exclusively, for the augmentation of the "rope volume" of the central core, to force the bights that go around it following wider curves - not for the security of the tails themselves.

« Last Edit: June 17, 2011, 05:29:13 PM by xarax »
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xarax

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Re: Figure 8 bends
« Reply #16 on: June 17, 2011, 05:47:04 PM »
  AND, although they are indeed fig.8 components, one can see these knots as securings of the Thief knot --taking the tailsinto a simple wrap & tuck.
As was remarked elsewhere (by Sweeny, IIRC), the Fig.8 bend can be seen as a securing of the Thief.

   True. I have tied/tried some re-tucking on the Reef family-of-knots, at (1). I post the pictures of this old thread again here, for an easy comparison with the fig.8 bends.

1) http://igkt.net/sm/index.php?topic=2085.0

« Last Edit: June 17, 2011, 05:49:39 PM by xarax »
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Dan_Lehman

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Re: Figure 8 bends
« Reply #17 on: June 18, 2011, 07:39:17 AM »
   Now I have examined various fig.8 bends, I see that the C - C bend, shown at (1),
can be described as a two-interlocked-fig. 8 knots-bend more accurately than
 as a two-interlocked-overhand-knots bend.
???

No, as it IS the latter, and not the former.


 ;)

xarax

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Re: Figure 8 bends
« Reply #18 on: June 18, 2011, 10:20:02 AM »
No, as it IS the latter, and not the former.

  In both variations of the C-C bend,( depending upon how exactly each one of the tails go "left" or "right" of each other, before it exits the knot s nub - and one might even, like we did with Ashley s bend, distinguish yet a third one, where the two tails do not cross each other... ), the two interlinked overhand knots are elongated and twisted in their middle : In the final, tightened form of the bend, each one of the two links looks like it is formed by two consecutive bights, each one rotated 90 degrees to each other, a shape resembling a figure 8  ( That was not happening in any other of the 6 interlinked overhand-knot bends presented in the other thread ) That was the meaning of my observation above. Of course, topologically, each link remains an overhand knot, and not a proper fig.8 knot.
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Transminator

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Re: Figure 8 bends
« Reply #19 on: June 18, 2011, 12:26:23 PM »
Without having read the entire thread, I want to throw one in myself. I very simple figure 8 / fishermans bend hybrid.
When tying the fishermen's bend just user figure 8s instead of overhand knots. I have not done extensive testing but
it seems to be secure but is less prone to jamming than the fishermen's. It also slides easily as adjustable bend for decorative knotwork (necklace etc.)

Xarax knots are, though I admire his ability to find and construct new knots and his enthusiasm in his relentless hunt for new knots,
mostly uninteresting for me personally because they are for the most part rather elaborate and often bulky.
I love the beauty of simple and effective knots. Usually there is always a simpler solution for a complicated knot,
which is easier to tie (and remember) and thus less error prone. Those simpler versions are usually as secure. I don't share Xarax' enthusiasm that there
are tons of knots out there to be discovered, at least not new knots that could replace the simpler ones that are already known.
Very few new knots are therefore worth to remember. Xarax' knots disqualify for the most part, in my opinion, because they are to elaborate, bulky and
(as mentioned above) there are simpler knots already availble that are overall better.
Among those few are the Gleipnir, the HFP slippery 8, the Blake hitch and the double-bight bowline (the last two by Prohaska). Those qualify for their simplicity and
effectivesness.
I will have a closer look though at the buntline extinguisher, which seems simple enough. I want to see if its name holds what it promises.

xarax

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Re: Figure 8 bends
« Reply #20 on: June 18, 2011, 01:33:12 PM »
   Thank you, Transminator,

When tying the fishermen's bend just user figure 8s instead of overhand knots.

  There are FOUR holes through which the standing end of the other fig.8 knot can penetrate, to form the bend you describe. AND there is also the possibility , for the standing end of the other link, to pass through 2, 3 or even 4 of them, the one after the other...Which is the one you you are talking about ?

knots... are, for the most part, rather elaborate ...

  That is true for some knots I have presented, but not for some others.  :) One has to tie a knot a number of times, I would say at least a dozen, to get a first feeling of it, and be able to have a first opinion about the knot, if is complex and difficult to tie, or not. People are often tend to judge knots by mere sight, do not fall into this trap !  :)

  Usually there is always a simpler solution for a complicated knot, which is easier to tie (and remember) and thus less error prone. Those simpler versions are usually as secure.

   Unfortunately, this is not always true, especially for the maximum knot strength, which is the main reason we should keep searching further...Security is not the only quality we expect from a knot, otherwise we wouldn't have so many alternatives, and we would nt search for even more !
   I understand the need for a small knot toolbox, that our brain can carry easily, because I myself have a very poor memory. We are not living machines built to remember convoluted rope paths in 3D, and many of us are even less able to remember such things than others...However, if we see the knots as rope mechanisms, there are always many more/other ways to skin a cat... :)

« Last Edit: June 18, 2011, 01:35:12 PM by xarax »
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xarax

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Re: Figure 8 bends
« Reply #21 on: June 18, 2011, 02:15:04 PM »
two consecutive bights, each one rotated 90 degrees to each other, a shape resembling a figure 8 

   Another instance I can remember where the overhand knot has taken such an elongated and twisted "figure 8-resembling-shape", is the Water 8 bend ( hence its name...)((See (1)). Notice the different looks of the two topologically equivalent interlinked overhand knots (See attached pictures) Of course, an overhand knot is an overhand knot is an overhand knot, and a fig.8 knot is a fig.8 knot is a fig.8 knot.  :)

1) http://igkt.net/sm/index.php?topic=2893.0
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xarax

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Re: Figure 8 bends
« Reply #22 on: August 06, 2011, 12:52:16 AM »
    There are dozens of interlocked-overhand-knot bends, so one can imagine the plethora of interlocked-fig. 8-knot bends...I have tied many of them, and I present the more interesting nes in this thread.
    See the attached pictures, for another member of this family, a very nice symmetric bend that I call the "88(B) bend", as it resemble the 88 bend ( See (1)).

1) http://igkt.net/sm/index.php?topic=1919.msg16218#msg16218
   
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xarax

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Re: Figure 8 bends
« Reply #23 on: August 06, 2011, 12:54:04 AM »
   Some more pictures of the 88(B) bend.
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Dan_Lehman

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Re: Figure 8 bends
« Reply #24 on: August 06, 2011, 08:44:53 PM »
It is important to reiterate --though it would be better not
to need this reminder-- that these are NOT "fig.8" knots,
but overhands oriented into '8'-like geometries.  This
fact can spare some headaches in trying to figure out
how to tie the knots, lest one go on the presumption
readily got from the (false) name.

.:.  It would be best to re-name these things something
like "8-like overhands" to spare this headache.

(This issue illustrates a problem one can confront in
knots classification : clearly, Xarax wishes to explore
the use of the 2-loops aspect of '8'-like knots (or, in
his perspective, simply THE '8'-shape) ; and to take
one tuck this way, then try one tuck the other way,
and --whoops-- all of a sudden there is some class-rule
alarm going off or whatever, when that  aspect of the
knot is irrelevant to the set, as conceived, and as being
explored, ...
well, seems annoying & unwanted!
Just as making some similar shift in tucking might lose
(or gain) the TIB (Tiable In(the) Bight) quality, or PET
(Post-Eye(forming) Tiable) aspect.

(Now, with my mind reset to understand ... , let me go again
to tie one of these latest discoveries!)


--dl*
====
« Last Edit: August 08, 2011, 04:50:45 AM by Dan_Lehman »

xarax

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Re: Figure 8 bends
« Reply #25 on: August 06, 2011, 11:07:49 PM »
Thank you Dan Lehman,

It is important to reiterate --though it would be better not to need this reminder-- that these are NOT "fig.8" knots, but overhands oriented into '8'-like geometries.

   You are right that, some times. such a distinction seems irrelevant, and so I do not know what to do about it, and how to call those bends...I mean, a bend can initially be an interlocked-fig.8-knot bend, but also can be very easily modified into an interlocked-overhand-bend, just by making some segments of the rope go over, instead of under, some other segments, without changing the general aspect of the knot - and vice versa. In those cases, we have interlocked bends that depend upon the 8 shaped links, but it really does not matter if those links are, topologically, fig. 8 knots, or 8 shaped overhand knots. In this thead I always start from interlocking genuine fig. 8 knots, and, when I succeed to meet some interesting member of this group, I try to simplify it as much as possible, so it can be tied as easily as possible. It seems to be the case that this can be done in many interlocked-fig. 8-knot bends, i.e. these bends can be easily modified into interlocked 8 shaped overhand knots bends, without much alteration of the original knots. If I call them simply by their topological description, as interlocked-overhand-knots bends, I run the danger to confuse the reader more than if I call them interlocked-fig. 8-knot bends...as they can be made, indeed, by a simple modification of some rope segment paths, without changing the general appearance of the knot !
  I think I should call them "interlocked-8 shaped-links bends, without mentioning if, topologically, those links are fig. 8 knots, or twisted, 8 shaped, overhand knots, or even twisted, 8 shaped double nipping loops, equivalent to the unknot ( as the 88 bend ).
   
   P.S. ( 2013-11-02 )
   Pictures of a symmetric interlocked 8-shaped-links bend, where the links are topologically equivalent to the overhand knot, but the first curves are as wide as in the other, geometrically similar but topologically more complex bends presented in this thread. It can also be considered as a "twice-twisted Hunter s bend".
« Last Edit: November 02, 2013, 12:12:08 AM by xarax »
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xarax

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A side-by-side fig.8 bend
« Reply #26 on: February 19, 2012, 09:32:21 AM »
   Three variations of a side-by-side fig.8 bend. Rotating the pair of tails with our right hand counter-clockwise, we can go from A to B to C.
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xarax

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Re: Figure 8 bends
« Reply #27 on: January 23, 2014, 07:33:09 PM »
   A non-symmetric bend where the one link is topologically equivalent to the unknot ( while, geometrically, is "8"-shaped ) and the other to a fig.8 knot has been proposed by allene (1). The author of the knot describes it as a re-tucked ( through the central opening ) Carrick s bend - or a modified "diamond bend" (2). It is claimed that it holds very well, even when tied on a very slippery Dyneema line. I re-post a picture of it here, so the interested reader, and the knot s creator, will have the opportunity to compare it with pictures of the similar symmetric bends - and I do not overload the very interesting and active thread where this asymmetric bend is presented, with more pictures of many other bends that might hold as well as this. Neither the form nor the tying method of this bend differ much from the bends presented in this thread ( especially the bends formed by side-by-side interweaved-shape"8" links, shown at the previous post ), and so one would expect that their security, regarding slippage, would be comparable - however, to have a more accurate picture of the behaviour of those bends under heavy loading, when tied on such slippery material, we would need more tests.   
  I have expressed my preference for symmetric bends many times. I believe that they distribute the tensile forces inside the knot s nub more evenly and on larger areas - also, I have claimed that they can be inspected by the knot tyer more easily : in a symmetric bend, any mistake will "brake the symmetry" and manifest itself immediately, just like a fly in the ointment ! :)
  I enclose a KnotMaker file of two fig.8 knots, placed on-top, and side-by-side, of each other. The first (blue) link is placed on layer 3, and at the self-crossing at layers 1 and 5. The second, (red ) link, is placed on layer 8, and at the self-crossings at layers 6 and 10. So, one can move the layer of each tile up or down, and design any such bend he wishes - either a non-symmetric one, as the bend presented by allene, or a symmetric - as the three symmetric bends presented earlier. I have not enumerated the distinct possibilities - to offer an interesting pass-time game to the reader !  :)
 
 P.S. Another bend presented by the same author is a side-by-side Pretzel-link bend, shown at (3) and as an the attached picture. It is also a non-symmetric bend, as the two links are not topologically equivalent. A more symmetric / quasi symmetric ( but not perfectly symmetric, because, although the topology of the two links is the same, the geometry still different ), is shown at (3) and as an attached picture.

1. http://igkt.net/sm/index.php?topic=4756.0
2. http://igkt.net/sm/index.php?topic=4756.msg30853#msg3085
3. http://igkt.net/sm/index.php?topic=4756.msg30811#msg30811

« Last Edit: January 28, 2014, 01:08:10 PM by xarax »
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enhaut

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Re: Figure 8 bends
« Reply #28 on: July 16, 2014, 09:24:02 PM »
The immense family of Figure 8 bends just present a new baby ::)

enhaut

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Re: Figure 8 bends
« Reply #29 on: July 17, 2014, 12:30:17 AM »
@ Xarax
Are you being soft?
Just look in the middle of the bend, the two side by side threads are almost 60 degre angled (or 45 depending on the softness of the rope)
The standing ends being 0 degre. Not the case in your attached picture.
Each tags ends exits from its own figure 8 and alongside the standing parts.
So it is the second time you serve me the "looks like" argument, one would to think twice before posting such assertions.
A new baby ? Yes it is ;D