Author Topic: A tensioner inspired by DL's binder  (Read 13849 times)

roo

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Re: A tensioner inspired by DL's binder
« Reply #15 on: March 31, 2011, 04:36:18 PM »
When pulling the tails in this situation, the tails will actually hold the coils open. You have to pull the tails vertically to have any chance of closening.
The primary factor that I see holding the coil open is the tension on the portion of the rope highlighted in yellow in the attached image.
« Last Edit: March 31, 2011, 05:22:15 PM by roo »
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Dan_Lehman

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Re: A tensioner inspired by DL's binder
« Reply #16 on: March 31, 2011, 05:56:52 PM »
When pulling the tails in this situation, the tails will actually hold the coils open. You have to pull the tails vertically to have any chance of closening.


The primary part that I see holding the coil open is the tension on the portion of the rope highlighted in yellow in the attached image.

Which can be referred to as the "coil-stabilizing strand".

It's possible that some improved behavior attaches to slight changes
in the overall structure, in either of two ways:

Anchor Eye Side : fix the structure w/cow/girth hitch at the left side
(as shown here), so that the eye-knot's strand is fixed, not turning,
around that ring

EyeTail : have the stabilizing strand be from the eye-knot's
tail (and the eye-knot's S.Part is anchored, or runs around some
object to form the opposing eye/ring sheave).

Consider how the forces arise:
1) tail is hauled away from the eye's coil --(1) unit force ;

2) given friction, perhaps only 0.5 applied force obtains
in the continuation of the tail through the coil to the right
ring;

3) so the eye strand has about 1.5 force upon it;

4) of which some lesser portion survives the turn around
the left ring --about 1 unit (0.66 x 1.6),
which is a boost over what would be coming to it from
the right ring (0.66 x 0.5), but that should nearly hold
(the 0.5  vs. 1.0 : friction enables the balance).


Whereas with the first structure, the stabilizing strand gets
no force from the left, so only the 0.6n x 0.6 surviving the
turn 'round the right ring, and thus is more readily deformed,
enabling better turNipping ?!

 - - - - - - - -

Working with structures that involve combinations of these
sorts of "two-to-one" mechanical-advantage structures can
lead to surprises, as some parts don't move as expected and
parts go WAY slack while others shift unexpectedly --and maybe
much is "YMMV" depending upon materials (smooth steel rings
vs. rusty vs. cordage sheaves; smooth flexible vs. firmer rough
cordage; ...).

I just collected on a bike ride some white, hard-ish fibrillated
PP (PE?) white twine --hard-firm as in not wanting to *bend*
so much as *kink/sharply fold".  I played around with some of
these binding structures trying to bind a coil of moderately firm
poly-Dac 3/8" rope (of maybe 18 coils?, x 2 (i.e., binding from
the outer sides the long oval of coiled rope)).  The Gleipnir
performed well, even though showing some slack on tensioning.
The #35 did well, even with both ends slipped --i.e., when
finished with slip-bights (so, 4 diameters through the coil (single).

And ... then came a *new* knot, as I sought to answer the rope
problem How to efficiently bind a collection of branches?
--or so I think, on first impression.  (I was getting concerned that
some need to haul one's stock of binding twine through a coil
would not be all so easy/time-efficient.)


Somewhere, I have some other variation(s) on this theme.--out in some vegetable patch.

   By the time you will finally decide to present them to us mortals, along with your ...

???

Really?  The structure you started this thread with was presented by me
on 2009... --nearly TWO YEARS AGO.  What difference did that make?
Where were your electrons, then?   ::)
That post --no ghost-- can still be found,
and has been referred to above; its electrons yet function.


--dl*
====

dmacdd

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Re: A tensioner inspired by DL's binder
« Reply #17 on: March 31, 2011, 09:48:27 PM »

The primary part that I see holding the coil open is the tension on the portion of the rope highlighted in yellow in the attached image.

Which can be referred to as the "coil-stabilizing strand".

It's possible that some improved behavior attaches to slight changes
in the overall structure, in either of two ways:

Anchor Eye Side : fix the structure w/cow/girth hitch at the left side
(as shown here), so that the eye-knot's strand is fixed, not turning,
around that ring

EyeTail : have the stabilizing strand be from the eye-knot's
tail (and the eye-knot's S.Part is anchored, or runs around some
object to form the opposing eye/ring sheave).


I tried using the tail of the bowline forming the eye as the coil stabilizing strand.
The s.part of the eye passed only once through the coil. I tried having it pass
both ways with respect to the direction through the coil taken by the tail of the eye knot.
I tried these combinations with and without fastening the s.part of the eye to its
support with a cow hitch.

All of the arrangements I tried that included the use of the tail of the eye knot as the coil
stabilizing strand degraded the performance of the tensioner.  I used the same hard stiff
5 mm static accessory cord that I used with the tensioner as pictured at the top of the thread.
When used previously, as pictured there, it performed perfectly, not backing off at
all from the maximum tension I was able to apply. There was significant slippage
with the eye knot tail as the coil stabilizer.

I also tried fixing the s.part of the eye knot as the only modification of the original
configuration, in other words the s.part of the eye knot passed twice through the coil.
This modification seemed to produce no change in the performance of the tensioner,
but I think there might have been improvement I could not observe because of the generally
excellent performance without this modification with the materials available to me.

I believe the failure of the 10 mm climbing rope is due to its extreme unwillingness to bend
to a radius small enough to be effective with this tensioner. It would refuse to work with
many such knots.
« Last Edit: March 31, 2011, 10:00:30 PM by dmacdd »

xarax

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Re: A tensioner inspired by DL's binder
« Reply #18 on: April 02, 2011, 02:42:51 AM »
  I have tried many variations of double nipping coil ( single turn, ABoK#41) Versatackle/Gleipnir binders. They all hold very well, but they are somehow difficult to dress and tighten properly. It seems that the double coil nipping loops are  too effective for this knot ! They often lock too early, and, when this happens, to tighten the binder, one has to pull all the four connecting lines, (not only the tails), the one after the other, to equalize their tensions. (See, at the attached picture, an example of such a binder, witlh double coil bowline loops.)
« Last Edit: April 02, 2011, 03:10:22 AM by xarax »
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xarax

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Re: A tensioner inspired by DL's binder
« Reply #19 on: April 02, 2011, 06:54:28 PM »
  Trying to combine some of the tricks we have learnt till now for the binders - the double nipping coils action, the tucker s and the Versatackle anchor loops, how to secure the tail through two tensioned U s ( 1, 2, 3), I arrived at an interesting tensioner-binder, shown in the attached picture. I believe that there should be many more knots that can achieve the same thing, and some of them might even be simpler and better holding. And some of them might be just under our noses, as was the great Gleipnir.

1.http://igkt.net/sm/index.php?topic=1870.msg17364#msg17364
2.http://igkt.net/sm/index.php?topic=1870.msg17414#msg17414
3.http://igkt.net/sm/index.php?topic=1451.0
« Last Edit: April 02, 2011, 06:56:44 PM by xarax »
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dmacdd

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Re: A tensioner inspired by DL's binder
« Reply #20 on: April 03, 2011, 04:10:21 AM »
 Trying to combine some of the tricks we have learnt till now for the binders - the double nipping coils action, the tucker s and the Versatackle anchor loops, how to secure the tail through two tensioned U s ( 1, 2, 3), I arrived at an interesting tensioner-binder, shown in the attached picture. I believe that there should be many more knots that can achieve the same thing, and some of them might even be simpler and better holding. And some of them might be just under our noses, as was the great Gleipnir.


My first reaction to the pictured one, it having defeated my attempts to figure out how to tie it, is that I have to figure out how to tie the constituent knot in the bight in order to tie the two constituent knots the same way, a necessity for ease of retention in memory, mine at least.  I'm not sure if even this is true, however, not having been able so far, to figure how to tie it.

xarax

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Re: A tensioner inspired by DL's binder
« Reply #21 on: April 03, 2011, 11:48:24 AM »
to figure how to tie it.

   There is not much more there than what I have described as "binder tricks", the one after the other : Follow, 1 : the double nipping loop , 2 : the U through the coil "tube" it is formed by this double nipping loop (so the two U s (*) of the two ends of the rope - the orange and the white - are nipped intside this coil "tube" ), and 3 : the finall exit of the working end through the bight of this U, so the whole knot is tighten when we pull the end(s), and it stays in place as an anchor loop (such as the loops we find at Tucker s and Versatackle knots).
   If you manage to arrange those tricks in another way, you would probably end up with another valid canditate for a tensioner/binder, that might be better and/or simpler. Now, if you succeed to achieve this with a TIB knot, that would be great indeed !  :)  

*. Actually, because the white end does not pass through the white coil "tube" for a second time, the white "U" looks more like a half-U, an inverted L.
« Last Edit: April 03, 2011, 12:40:29 PM by xarax »
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dmacdd

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Re: A tensioner inspired by DL's binder
« Reply #22 on: April 03, 2011, 03:57:59 PM »
to figure how to tie it.
Now, if you succeed to achieve this with a TIB knot, that would be great indeed !  :)  


My point was that you can always tie the first of the two constituent knots with an end, but the second constituent knot has to to be tied in the bight because the ends of the cord in which it must be tied are not, in general, accessible. 

dmacdd

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Re: A tensioner inspired by DL's binder
« Reply #23 on: April 03, 2011, 04:25:40 PM »
to figure how to tie it.
Now, if you succeed to achieve this with a TIB knot, that would be great indeed !  :) 


My point was that you can always tie the first of the two constituent knots with an end, but the second constituent knot has to to be tied in the bight because the ends of the cord in which it must be tied are not, in general, accessible. 

There must some misunderstanding here...There is only one cord, with two accesible ends, with which piece of cord you bind together a number of objects. You can tension this binder pulling the two ends of the binder simultaneously.


I deduce from the fact that you are not understanding me that the working ends in the first photo are the pieces extending to the left and right. If the working ends are the pieces extending up and down, as I have been assuming, then one of the constituent knots has to be tied in the bight.  It should a  rigid convention that we do not picture knots without clearly distinguishing working ends from standing parts.

xarax

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Re: A tensioner inspired by DL's binder
« Reply #24 on: April 03, 2011, 04:40:57 PM »
   If we wish to classify all the possible variations of this binder, we can follow the scheme outlined in the next posts ( plural, because of the limit of 4 pictures per post...)

   First, we can classify them in two broad basic classes, let us name them A and B. An example of the A class is the binder presented previously. ( Notice that the "white" knot is mirror symmetric to the "orange" one. This in not obligatory, of course, but I think that many people will inspect easier a pair of knots that are placed face to face to each other, if the one is a mirror symmetric copy to the other - and not a translated copy to the other). In the B class binders, the working end forms first the U inside the coil tube, (through which the other end will pass), and then the double coil tube. ( In the A class, we have seen an example of the opposite.
   We can pass the "white" end, first over the "orange" U and then under it, or vice versa. I denote those variations as (over-under) and (under-over), respectably. We can also have the working end cross with the tail before it enters into the coil tube (to form the U), or after. I denote those variations as (before) and (after), respectably.    
« Last Edit: April 03, 2011, 05:22:07 PM by xarax »
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xarax

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Re: A tensioner inspired by DL's binder
« Reply #25 on: April 03, 2011, 04:51:04 PM »
   We can also have the two coils tied in two different ways, the "normal", where the two ends of the coil leave the coil tube "far" from each other, and the "crossed", when they leave the coil tube "near" each other   I denote those variations as (far) and (near), respectably. Also, we can have a twisted collar around the standing end, or not. I denote those variations as (twisted) and (untwisted), respectably.
« Last Edit: April 03, 2011, 05:41:08 PM by xarax »
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xarax

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Re: A tensioner inspired by DL's binder
« Reply #26 on: April 03, 2011, 04:59:19 PM »
   Can we classify, with those 4 characteristics, all the possible variations of this binder ? Unfortunately, no !  :) See the two examples in the attached pictures, and try to figure out how we could possibly describe them...
   Now, all those variations hold very well, but their problem might well be the exact opposite ! Some of them, hold too well, they nip and gripp the "white" end too early, so it is difficult to tighten the binder even more. Of course, it depends, as always, on the material used.
   I have tied all the possible variations of this quite simple binder, but I have not tested them the one against the other in a quantitative/systematic way. OPT would be much welcomed !  :)
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xarax

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Re: A tensioner inspired by DL's binder
« Reply #27 on: April 05, 2011, 03:16:45 PM »
It seems that the double coil nipping loops are  too effective ... They often lock too early, and, when this happens, to tighten the binder, one has to pull all the...connecting lines, (not only the tails), the one after the other, to equalize their tensions.

  When we use materials that are not slippery enough, or when we need a binder/tensioner where we have to pull one only end to tighten the structure, we can always tie the -simpler - tucker s hitch variation of the binder at (1), or the -more complex- double nipping loop variation of the binder at (2). Although here we have only one double loop nipping the two U s, we might also have to tighten the structure in three steps. ( First, pulling the tail, then pulling any slack connecting cord, and finally pulling the tail again.)( See the attached picture for such a binder/tensioner. I have used a simple bowline here, but we can also use any loop, (ABoK #1050,#1053, #1054,#1058, etc.). The white rope placed "vertically" in the picture s frame, is the free end.)

1). http://igkt.net/sm/index.php?topic=2996.msg17830#msg17830
2). http://igkt.net/sm/index.php?topic=1870.msg17364#msg17364
« Last Edit: April 05, 2011, 03:46:36 PM by xarax »
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Dan_Lehman

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Re: A tensioner inspired by DL's binder
« Reply #28 on: April 08, 2011, 06:20:02 PM »
...
*. Actually, because the white end does not pass through the white coil "tube" for a second time, the white "U" looks more like a half-U, an inverted L.

I should remark that the orange structure shown here,
 [ Xarax's post with nicely loosened / open knot, to show structure ]
 if the inner loop is removed,
is my "symmetric Fig.9" : and I find that IT will adequately nip the white rope
(where that is simply the same line, closing the eye of this adjustable eyeknot),
in common materials (though one would often prefer to tie a stopper, 2 B sure).
The tail is strongly nipped between the turns of the S.Part & other eye-leg.
(But if the tail is pulled in isolation against the S.Part, it most likely will pull out
--the other leg must also be tensioned.)

And this "symmetric fig.9" structure seems to make a good mid-line
stopper, non-jamming (in common materials; really slick ones can jam);
such things are occasionally seen in dock lines, marking the point to which
the line should be set.  The same structure can be used as the hitch (with
various orientations of how it is hitched/entangled to ...) for a noose-hitch.

--dl*
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