Author Topic: An easy-to-untie bend.  (Read 6385 times)

xarax

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An easy-to-untie bend.
« on: October 31, 2011, 01:25:53 AM »
   This bend has large collars, which can be easily pushed and pulled wide open, to release the knot s nub tension. In theory, such a bend will be easy to untie, even after heavy loading.. Although the knot shown in the attached pictures is a very simple one and looks familiar - like some variation of a Hunter s or a Shakehands bend -, I have not seen it or tied it till now. It is the reverse of the B 16 bend, named "Orthogonal bend" by Roger E. Miles : Symmetric Bends (How to Join Two Lengths of Cord), 1995, p.91.
« Last Edit: October 31, 2011, 02:06:49 AM by xarax »
This is not a knot.

DDK

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Re: An easy-to-untie bend.
« Reply #1 on: November 13, 2011, 04:35:08 PM »
. . . Although the knot shown in the attached pictures is a very simple one and looks familiar - like some variation of a Hunter s or a Shakehands bend - . . .

This bend can be tied from the same interlocking of "p" and "d" loops that produces the Ashley's Bend, ABOK 1452.  By ABOK 1452, I mean specifically the jamming version, where the working ends have been configured as in the Whatknot/Grief Knot ABOK 1407 (and not configured as in the Whatknot/Grass Bend ABOK 1406/1490).

In the Ashley's, the working ends are tucked through both of the central loops of the "p" and "d" while in this bend, each WE is tucked only through the "p" or "d" loop which its own standing part has produced.  The WEs must be configured as in the Whatknot/Grief Knot ABOK 1407 as mentioned previously.  Otherwise, this bend becomes a very simple and insecure interlocking of overhand knots.

DDK
 

xarax

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Re: An easy-to-untie bend.
« Reply #2 on: November 14, 2011, 12:44:08 AM »
   Thank you DDK,

The WEs must be configured as in the Whatknot/Grief Knot ABOK 1407 as mentioned previously.  Otherwise, this bend becomes a very simple and insecure interlocking of overhand knots.
 
   After tying and trying almost* all  the possible bends based upon interlocking overhand knots -, I have only this to say : Even in the case of those "elementary" bends, we can not predict, in advance, if a "simpler" bend will be more secure than a more complex one - and we can not even define what "simplicity" means in this case... The apparent. pictorial simplicity is, in fact, misleading : the mechanism is more complex than it looks ( probably because we can not "see" and evaluate the contribution of torsion ). We need tests, and we need people able to perform those tests...otherwise all predictions are condemned to remain highly hypothetical and uncertain.
   Anyway, in the above mentioned bend, my aim was to retuck the working ends in a way that would leave the collars as large as possible . So, the original purpose was to tie a Hunter s-like bend that will be difficult to jam and easy to untie - not a more secure interlocked-overhand-knots bend.

* I say "almost", because we do not have a systematic method of enumerating all those bends. Even the "mathematical" approach of Roger E. Miles, based upon the devise of symmetric planar diagrams and the "invention of suitable lattice walks"(p. 143), is in fact heuristic, not exhaustive.

This is not a knot.

DDK

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Re: An easy-to-untie bend.
« Reply #3 on: November 14, 2011, 04:32:30 PM »
   Thank you DDK,

The WEs must be configured as in the Whatknot/Grief Knot ABOK 1407 as mentioned previously.  Otherwise, this bend becomes a very simple and insecure interlocking of overhand knots.
 
   After tying and trying almost* all  the possible bends based upon interlocking overhand knots -, I have only this to say : Even in the case of those "elementary" bends, we can not predict, in advance, if a "simpler" bend will be more secure than a more complex one - and we can not even define what "simplicity" means in this case... The apparent. pictorial simplicity is, in fact, misleading : the mechanism is more complex than it looks ( probably because we can not "see" and evaluate the contribution of torsion ). We need tests, and we need people able to perform those tests...otherwise all predictions are condemned to remain highly hypothetical and uncertain.
   Anyway, in the above mentioned bend, my aim was to retuck the working ends in a way that would leave the collars as large as possible . So, the original purpose was to tie a Hunter s-like bend that will be difficult to jam and easy to untie - not a more secure interlocked-overhand-knots bend.

* I say "almost", because we do not have a systematic method of enumerating all those bends. Even the "mathematical" approach of Roger E. Miles, based upon the devise of symmetric planar diagrams and the "invention of suitable lattice walks"(p. 143), is in fact heuristic, not exhaustive.

The primary content of my post was directed at the relationship between structures and not performance.  However, any comments I made regarding performance were given after my testing.  I have made no predictions.  Also, I sense you believe I have said that your OP "easy-to-untie bend" is insecure or simplistic.  This is not true as I have made no comments regarding the simplicity or security of the OP bend.  My comments about performance were concerning a related bend.

The relationship between the structure of three different bends were discussed in my post;
     (1) the Ashley's Bend ABOK 1452, jamming version - WEs configured as in the Whatknot/Grief Knot ABOK 1407
     (2) the OP "easy-to-untie bend" - which like (1), has the WEs configured as in the Whatknot/Grief Knot ABOK 1407 and
     (3) a modified "easy-to-untie bend" - modify the tuck of the WEs of (2) and configure as in the Whatknot/Grass Bend ABOK 1406/1490

My comments about simplicity and insecurity where in regard to (3) after having tested the knot.  To be more specific, my testing indicates the security of (3) as being similar to a Thief Knot, YMMV.  The qualitative assessment of the simplicity of (3) was determined by inspection.  My testing of the OP knot, (2), indicate it to be "secure at low levels of loading" (defined as no signs of capsizing or slipping @ 200 pounds, 7/16" braided poly-p) and easy to untie, again, YMMV.

DDK

xarax

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Re: An easy-to-untie bend.
« Reply #4 on: November 14, 2011, 08:57:05 PM »
  I see. However, your attempt to group the interlocked-overhand-knots based bends according to the way their WEs are retucked, have one serious problem, namely, the Zeppelin bend... How can we explain the security of the Zeppelin bend - where the working ends are used only as parts of a rope-made axis in a rope-made hinge ? Why the quite similar "falsely tied Hunter s bend" does not behave the same way ?  I can not explain those differences, so I am driven to the conclusion that all I can do - at least for the time being - is try to capture the interest of another knot tier...in short, patiently wait for OPT*.
  * OPT : Other People s Tests. :)

   P.S. I think that your load, for this rope diameter, is not enough to help us arrive at any conclusions... It is claimed that the Hunter s bend can jam, so the interesting question is this : will the above mentioned bend remain easy-to- untie, when tied with the same material and loaded with the same load that would jam a Hunter s bend ?

 
« Last Edit: November 14, 2011, 09:17:40 PM by xarax »
This is not a knot.

DDK

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Re: An easy-to-untie bend.
« Reply #5 on: November 14, 2011, 10:54:01 PM »
Yes, I would agree that the way the WEs are retucked does not appear to be a useful characteristic for the grouping of interlocked overhand knots.  I never intended to suggest that it was.  Much more fundamental to my way of thinking is the fact that, for example, your OP knot and the Ashley's Bend share exactly the same interlocking of "p" and "d" loops.

It was for the purposes of clarity that I included the fact that the jamming version of the Ashley's Bend is more closely related structurally to your OP knot than the non-jamming version. In other words, if I take the jamming version of the Ashley's Bend, I can partially untuck eack WE and directly produce your OP "easy-to-untie bend".  This is not true for the non-jamming version of Ashley's Bend.

I did mention that I considered my testing of your "easy-to-untie bend" to be at a low level of loading.  However, in the same rope and loading, the Hunter's Bend nearly jams and proves difficult to untie without tools (more than a minute of effort).  The "easy-to-untie bend" is undone in seconds.  I dressed the "easy-to-untie bend" so that it reduced the size of its collars.  This can be done by tightening the WE of the bend.  It is yet to be seen if a higher load can expand and slide the collars to the point where they might become jammed.

DDK

akhollland88

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Re: An easy-to-untie bend.
« Reply #6 on: November 30, 2011, 02:09:52 PM »
I had these subjects when I attended a Boyscout Summer Camp when I was still in grade school. I can still recall on how to do a square-knot. I think the knots you shared are for very tight applications but still, it is easy to untie. Nice share!