Author Topic: A most simple bend .  (Read 12971 times)

xarax

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Re: A most simple bend .
« Reply #15 on: July 09, 2011, 04:30:22 PM »
   The fact that the retucked versions, of ABoK#1406 and ABoK#1490, are so different, is another indication of the difference between their parent bends.
   See the attached pictures for a second variation of the re-tucked ABoK#1490 bend. It is also a fisherman knot - like bend - where we better say that we have two inter-penetrating overhand knots, rather than two inter-locking overhand knots.
 
« Last Edit: July 09, 2011, 04:36:38 PM by xarax »
This is not a knot.

xarax

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Re: A most simple bend .
« Reply #16 on: July 09, 2011, 04:51:45 PM »
... this video of the tying of a grass bend is of the ABOK 1406 http://www.youtube.com/watch?v=-ElzdyZqfrc.

  Precisely !  :) This video shows the tying of the ABoK#1406, and not of the Grass bend ! The Grassbend is not a stable knot on cylindrical ropes, but only on flat straps.
  The way the knot is tied in this video, proves that the tier has not understood the relation between the Whatknot (ABoK#1406), and the Sheet bend. I was driven to this knot by contemplating on and manipulating the Sheet bend, so I tie it differently, like we tie the Sheet bend - and not one bend of the Reef family of knots. Doing this, we do not run the danger to tie the falsely tied Whatknot (the ABoK#1407).

The Grass Bend looks to me to have its ends oriented the same as in ABOK 1406 ...

   Not in the final, tightened, compact form. It is there that we see the functional differences I am talkng about. See how the tails will move, if they get loose from the nipping action of the bights. In AB0K#1406 and in its re-tucked versions, they will move in tandem, towards the same direction, while in the Grass bend (ABoK#1490) and in its re-tuced versions, they will move towards opposite directions.
« Last Edit: July 09, 2011, 05:04:55 PM by xarax »
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alpineer

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Re: A most simple bend .
« Reply #17 on: July 09, 2011, 05:23:01 PM »
The Grass Bend looks to me to have its ends oriented the same as in ABOK 1406 as opposed to ABOK 1407.  That is, ABOK 1490 looks just like 1406 tied using flat material to me.  If using the same material, I do not see how 1406 would differ from 1490 in structure or mechanism.  Granted, flat material or straps would behave somewhat differently.  Not that this is authoritative as far as I know, but, this video of the tying of a grass bend is of the ABOK 1406 http://www.youtube.com/watch?v=-ElzdyZqfrc.  -- DDK

You are right DDK. And once again we have another uninformed and misleading video from selfmadesailor. The knot shown in the video is tied using round cordage, and is therefor called the What Knot ABoK#1406. Only when tied in flat material, is it called the Grass Bend ABoK#1490. Same form structure, flat vs. round material, different name. It's called the Grass Bend to reflect the shape of the material it is tied in.

alpineer
« Last Edit: July 09, 2011, 05:43:36 PM by alpineer »

DDK

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Re: A most simple bend .
« Reply #18 on: July 09, 2011, 05:47:21 PM »
The Grass Bend looks to me to have its ends oriented the same as in ABOK 1406 as opposed to ABOK 1407.  That is, ABOK 1490 looks just like 1406 tied using flat material to me.  If using the same material, I do not see how 1406 would differ from 1490 in structure or mechanism.  Granted, flat material or straps would behave somewhat differently.  Not that this is authoritative as far as I know, but, this video of the tying of a grass bend is of the ABOK 1406 http://www.youtube.com/watch?v=-ElzdyZqfrc.  -- DDK

You are right DDK. And once again we have another uninformed and misleading video from selfmadesailor. The knot shown in the video is tied using round cordage, and is therefor called the What Knot ABoK#1406. Only when tied in flat material, is it called the Grass Bend ABoK#1490. Same structure, round vs. flat material, different name. It's called the Grass Bend to reflect the shape of the material it is tied in. ABoK#1490 is also known as the Stop, or Strap Bend in some countries.

alpineer

Not to get technical nor to be disagreeable, but, I do believe that selfmadesailor is accurate on this video.  That is to say that as the width of a strap becomes closer to its thickness, ABOK 1490 becomes the same as an ABOK 1406 in the same way a rectangle becomes a square.  Technically speaking, calling a square (special case of) a rectangle (general) is completely accurate and is often done for good reason.  ABOK 1406, therefore, is a Grass Bend, albeit, special case thereof.  Sorry to split hairs, but, given your comment about the video and its producer I though it needed saying.  As for selfmadesailor's other videos, I have not seen them nor can I comment on their accuracy.  Sometimes even the blind ...

DDK

P.S.   BTW, Not many parts of the ropes stay round in the final form of a tightened bend.    :)

Edit:  Actually, I think there is an additional very good reason to use the name Grass Bend for ABOK 1406 in that it helps to differentiate the two Whatknots.  One Whatknot shows high levels of positive cogging, the Grief Knot, and the other does not, Grass Bend.  I believe their difference in behavior may have been the reason that Ashley labelled these knots as being of theoretical interest.
 
« Last Edit: July 09, 2011, 06:43:54 PM by DDK »

DDK

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Re: A most simple bend .
« Reply #19 on: July 09, 2011, 06:16:17 PM »
The Grass Bend looks to me to have its ends oriented the same as in ABOK 1406 ...

   Not in the final, tightened, compact form. It is there that we see . . .

Sorry, I don't see the difference you mention. -- DDK
« Last Edit: July 09, 2011, 06:17:08 PM by DDK »

alpineer

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Re: A most simple bend .
« Reply #20 on: July 09, 2011, 07:06:35 PM »
I edited my previous post re Strap/Strop Bend as I'm not certain of my claim, though I do believe I recall this from some source(s) years ago.

DDK, the issue that I have with the video is the material he ties the Grass Bend in. Yes, it is identical in form to ABoK #1406, but only when tied in flat material can it justifiably be called the Grass Bend. Ashley gave it a different number(#1409) for that reason alone.
I understand your statements and the logic behind them. But they don't work for me in this case. If selfmadesailor was accurate he would have described the knot in the video as a WhatKnot(or even a special case orientation of the Grief Knot), or he would simply have used the correct material (i.e. strap, webbing) to tie the "titled" knot. Or he could have tied the knot using fresh wheat stalks and I would then have no call to get my U-know-What in a knot :D.   

DDK

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Re: A most simple bend .
« Reply #21 on: July 09, 2011, 07:16:54 PM »
I edited my previous post re Strap/Strop Bend as I'm not certain of my claim, though I do believe I recall this from some source(s) years ago.

DDK, the issue that I have with the video is the material he ties the Grass Bend in. Yes, it is identical in form to ABoK #1406, but only when tied in flat material can it justifiably be called the Grass Bend. Ashley gave it a different number(#1409) for that reason alone.
I understand your statements and the logic behind them. But they don't work for me in this case. If selfmadesailor was accurate he would have described the knot in the video as a WhatKnot(or even a special case orientation of the Grief Knot), or he would simply have used the correct material (i.e. strap, webbing) to tie the "titled" knot. Or he could have tied the knot using fresh wheat stalks and I would then have no call to get my U-know-What in a knot :D.   

I can see your point.  But like the Bob Newhart Show at one time, there was an acquaintance (sort of a farmer/hillbilly) of the star who had two brothers both named Daryl.  He would introduce them this way, "This is my brother Daryl, and this is my other brother Daryl".  I feel that way about the Whatknots.   :)

DDK

alpineer

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Re: A most simple bend .
« Reply #22 on: July 09, 2011, 07:17:57 PM »

Edit:  Actually, I think there is an additional very good reason to use the name Grass Bend for ABOK 1406 in that it helps to differentiate the two Whatknots.  One Whatknot shows high levels of positive cogging, the Grief Knot, and the other does not, Grass Bend.  I believe their difference in behavior may have been the reason that Ashley labelled these knots as being of theoretical interest.

Interesting argument DDK.

xarax

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Re: A most simple bend .
« Reply #23 on: July 09, 2011, 07:22:17 PM »
 ABOK 1406, therefore, is a Grass Bend, albeit, special case thereof.

  The exact opposite, is true !  :)
  DDK, each time we disagree, I have to take new pictures, of "new'"  knots !  :) That is a good thing, provided we speak abut those knots and not knot names, and the "new" knots themselves, and not the parent knots theywere derived from...
   You don t see the differences I mentioned, because you see the Ashley s scketch. I have tied the ABoM#1490 with flat straps, and it was not possible to reproduce the aspect of that scketch, because the really flat straps can only be bent in their longitudinal or an oblique direction, and not in their transverse direction (1). They can not even revolve around their longitudinal axes inside the bights/hollow conical surfaces by themselves, but only if we force them to do so, i.e. if we tie the ABoK#1406 instead of the ABoK#1490... :)
   Have a look at the two re-tucked ABoK#1490 bends, and tell me if they resemble the re-tucked ABoK#1406 bend.

1) The straps are already tightened, and the bend locked, before the tails approach each other more. (See the first picture) The most that the Ashley s sketch can resemble a real situation. The tails do not touch each other more than in the previous stage.(See the second picture). But how then would the tensioned standing ends be aligned ? Only a severe deformation of the flat straps, and their bending along their transverse direction, would make this possible. And even then, the tails would not be squeezed by the standing parts, as it happens in the Whatknot (ABoK#1406) A very different mechanism secures the tails there... Notice that in an ideal, thin, flexible, flat material (like two straps of paper, for example), the final tightened form would be of a regular pentagon. (ABoK#2588)
« Last Edit: July 09, 2011, 11:54:08 PM by xarax »
This is not a knot.

alpineer

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Re: A most simple bend .
« Reply #24 on: July 09, 2011, 07:43:44 PM »
Doing this, we do not run the danger to tie the falsely tied Whatknot (the ABoK#1407).

I don't see any danger here. If tied wrong, when the opposing ends are pulled to tighten the knot, we know what happens. The danger is the tails' potential to re-orient themselves after the knot has been correctly tied. And this of course is the problem you are solving with your re-tucks.
alpineer

 
« Last Edit: July 09, 2011, 08:50:20 PM by alpineer »

xarax

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Re: A most simple bend .
« Reply #25 on: July 09, 2011, 09:08:01 PM »
If tied wrong, when the opposing ends are pulled to tighten the knot, we know what happens. The danger is the tails' potential to re-orient themselves after the knot has been correctly tied.

  You are right, I just used a figure of speech, as Ashley did, for the opposite fact : "There is little danger of anyone ever tying this knot by mistake: the method is too unhandy." 
This is not a knot.

DDK

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Re: A most simple bend .
« Reply #26 on: July 09, 2011, 10:09:17 PM »
  . . . You dont see the differences I mentioned, because you see the Ashley s scketch. I have tied the ABoM#1490 with flat straps, and it was not possible to reproduce the aspect of that scketch, because the really flat straps can only be bent in their longitudinal or an oblique direction, and not in their transverse direction. . . . They can not even revolve around their longitudinal axes inside the bights/hollow conical surfaces by themselves, but only if we force them to do so, i.e. if we tie the ABoK#1406 instead of the ABoK#1490... :)

I have tied the ABOK 1490 with straps in loose "flat" form forcing the working ends to point in opposite directions and tightening as tightly as I can and then, while maintaining tension, have removed my hand which was restraining the knot in flat form and tightened.  Immediately the working ends come together, point toward the same side of the bend and the bend forms the tightened form as depicted quite accurately by the sketch that Ashley provided and which is identical to ABOK 1406 except that I am using straps and not round cordage.  Simply put, Ashley's sketches are a very accurate representation of what I observe and I have not been able to reproduce anything similar to your experiences.  [edit - after posting of new pictures by xarax]  I have been able to produce a bend similar to your second picture upon tightening.  I consider this to have more than enough similarity to Ashley's sketch.  The distortion you mention is expected and is a function of the aspect ratio and flexibility of your strap.

DDK  
« Last Edit: July 09, 2011, 11:08:46 PM by DDK »

xarax

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Re: A most simple bend .
« Reply #27 on: July 09, 2011, 10:29:47 PM »
I have tied the ABOK 1490 with straps

   Me too !  :) :)

Simply put, Ashley's sketches are a very accurate representation of what I observe and I have not been able to reproduce anything similar to your experiences.

   No, they are not, as it happens very often with Ashley s sketches ! I have tied hundreds of Ashley's bends, and taken pictures of them, and compared them with those sketches...The sketches are good, but as artistically, not scientifically sound representations. In this occasion, the standing parts, "simply put"  :), can not be aligned, if the material is not severely deformed ! And the tails can not be brought in a position that they squeeze each other, as it happens in ABoK#1406, unless you turn the flat straps into round cylinders by alchemy...In other words :
 a)  if you pull the standing ends, and get them tensioned and aligned, you should have a view where the standing parts are in line to each other, and not in some angle, i.e. you should have something resembling more the first Ashley sketch - the supposedly un-tightened form -  than the second - the supposedly tightened form ! At the first sketch, the standing ends are as aligned as they could ever be, although this stage is meant to represent the loose, un-tightened knot .
  b)  if you pull the tails, and get the knot to be as compact as it can ever be, and the knot s nub approach the ideal form, that of a regular pentagon, you have standing ends that are not aligned, and so the second Ashley sketch, that, supposedly, represents the final tightened phase, is not accurate.
 
   As I have suggested in our previous similar disagreement, it is better if we speak about knots, and not knot names, and if we present our pictures of the knots that we, by ourselves, have tied, and not reproduce icons of various bibles...  :) (See my pictures at reply#23.)
« Last Edit: July 09, 2011, 11:56:31 PM by xarax »
This is not a knot.

xarax

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Re: A most simple bend .
« Reply #28 on: July 09, 2011, 11:46:36 PM »
The distortion you mention is expected and is a function of the aspect ratio and flexibility of your strap.

  I am afraid that you have not understood my reasoning. Ashley s second sketch is un-realistic, not my pictures of my strap !  :) ( a photographic image is a "realistic" representation of what we see, by definition...) Ashley s second sketch is un-realistic, unless its material was very flexible in the transverse direction, and of low aspect ratio ( thick, and not very wide ). By the way, in those pictures I used the straps of my first camera - that was also the best I ever had...- but you are probably too young to recognize them...  :)
   Let me try again :
   If you have no distortion, ideal, flexible - only along the longitudinal and not across the transverse direction - high aspect, thin, wide straps, you get a shape of a regular pentagon (ABoK#2588)( that I still try to figure out how on earth it has "more than enough similarity" with the Ashley s second sketch !  :))
   If you have distortion, real, flexible along the longitudinal as well as the transverse direction, low aspect, thick, narrow straps, you get a shape resembling that of Ashley s second sketch. But then, my dear DDK, you have not tied an ABoK#1490 knot with flat straps, but an ABoK#1406 knot with almost round ropes...It is geometrically impossible to have tightened, aligned standing parts, unless we are in a dressing and tightening stage closer to the first Ashley s sketch, the one that supposedly represents the loose, un-tightened knot - than to the second, the one that supposedly represents the tightened, most compact knot.
  
« Last Edit: July 10, 2011, 12:06:11 AM by xarax »
This is not a knot.

DerekSmith

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Re: A most simple bend .
« Reply #29 on: July 10, 2011, 01:12:12 PM »
The Grass Bend looks to me to have its ends oriented the same as in ABOK 1406 as opposed to ABOK 1407.  That is, ABOK 1490 looks just like 1406 tied using flat material to me.  If using the same material, I do not see how 1406 would differ from 1490 in structure or mechanism.  Granted, flat material or straps would behave somewhat differently.  Not that this is authoritative as far as I know, but, this video of the tying of a grass bend is of the ABOK 1406 http://www.youtube.com/watch?v=-ElzdyZqfrc.  -- DDK

You are right DDK. And once again we have another uninformed and misleading video from selfmadesailor. The knot shown in the video is tied using round cordage, and is therefor called the What Knot ABoK#1406. Only when tied in flat material, is it called the Grass Bend ABoK#1490. Same structure, round vs. flat material, different name. It's called the Grass Bend to reflect the shape of the material it is tied in. ABoK#1490 is also known as the Stop, or Strap Bend in some countries.

alpineer

Not to get technical nor to be disagreeable, but, I do believe that selfmadesailor is accurate on this video.  That is to say that as the width of a strap becomes closer to its thickness, ABOK 1490 becomes the same as an ABOK 1406 in the same way a rectangle becomes a square.  Technically speaking, calling a square (special case of) a rectangle (general) is completely accurate and is often done for good reason.  ABOK 1406, therefore, is a Grass Bend, albeit, special case thereof.  Sorry to split hairs, but, given your comment about the video and its producer I though it needed saying.  As for selfmadesailor's other videos, I have not seen them nor can I comment on their accuracy.  Sometimes even the blind ...

DDK

P.S.   BTW, Not many parts of the ropes stay round in the final form of a tightened bend.    :)

Edit:  Actually, I think there is an additional very good reason to use the name Grass Bend for ABOK 1406 in that it helps to differentiate the two Whatknots.  One Whatknot shows high levels of positive cogging, the Grief Knot, and the other does not, Grass Bend.  I believe their difference in behavior may have been the reason that Ashley labelled these knots as being of theoretical interest.
 

@ DDK,  I must agree totally with your post.

It is a sad reflection of the sloppy (or should I say organic) 'history' of knots that puts us in the position of having knots named by numerous aspects that have nothing to do with the form and function of those knots.  Our history dictates that what a knot is tied in, how it is made, even what it is to be used for (or by what trade), will define its name.  In hindsight, chemistry has a similar background - if I take Sodium metal and burn it is Chlorine gas, I make a white dust - If I take 'Spirits of salt' and mix it with soda ash, I get clear crystals - If I take 'Sea Brine' and evaporate it to dryness, I get 'Table Salt'.

It took the clear minded thinking of Chemistry to come to the understanding that these were simply three ways of making the same thing.

Personally, I find it quite exciting that today we are standing at the very junction between 'Knot Alchemy' and 'Knot Science' and 1406, 1407 and 1490 are exquisite examples to utilise in deminstrating this transition.

As we have discussed before, 'Cogging' is one of the fundamental elements of knot functionality and in this one delightful knot, 1407, we have probably the best example of a knot exhibiting as near 100% +ve cogging as we will ever witness.  Then in 1406, by shifting the cogging to opposing rather than reinforcing, we have what we might consider to be 100% -ve cogging - i.e. possibly the perfect 'knot' with respect to this aspect of knot functionality.

Take some 10mm flexible braid, preferably with notable surface patterning, and make 1407.  Then load the SP's gently and note that as the tension goes on, the SP's apply a rotational torsion to the opposing cord's collar at the same time as generating a linear frictional pull on the opposing cord's end.  Both cords exhibit identical forces and flows, and nothing in this knot steps in to block any of these movements.  Interestingly, the knot is symmetrical with respect to this flow - load the ends instead of the SP's, and the cord flows back through the knot the way it just came out.

Now make 1406 (1490) and load it - the collars are rotated as in 1407, but there the similarity ends, immediately, flow and rotation of the ends is opposed by frictional contact with the opposing flow and rotation of the other end.  As cord flows out of the collars, the knot tightens creating greater lateral pressure on the adjacent ends, reinforcing the ability of each to block the flow and rotation of the other.  1406 / 1490 has a -ve cogging component that is reinforced with positive feed back as the knot is loaded.  Of note, every knot I have studied that auto dresses itself without through feed of the ends, has a positive feedback -ve cogging component at or near its ends...

It is a shame that Ashley called them both the Whatknot, because although the difference in topology is only tiny, the difference in functional structure is massive, and there is no way we should be countenancing calling them the same.  As DDK suggests, we should be striking out 1406 and calling it 1490, and it really does not matter what material it is tied in.

Derek