Author Topic: Constriction cam-action knot for sleeping bags, compression, camping  (Read 24665 times)

DerekSmith

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #30 on: April 24, 2015, 09:20:45 AM »

   If you are still interested in "overcomplicated knots:) :) :),


Hi Constant, I hope you had your tongue in cheek as you wrote that, You know I hate overcomplicated knots lol.

I thought that your dismissal of my comment was made without giving any substantiation, so I took the OP image into Photoshop and lightened it a little so as to be able to peek into the shadowed area - adjusted image attached.

I hope that even you can agree that this is in fact NOT a Gleipnir because the coil is a turn in the end of a bight and the tensioning ends both come from the same side instead of from opposite directions.

This is made all the clearer by the OP tying the OH crossing of the ends to the side of the nipping coil, so you can see the appearances are not as misleading as you suggested.

Do you not agree?

Derek

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #31 on: April 24, 2015, 09:44:27 AM »
  I am talking about the PENETRATING the "nipping tube" ends, not about the ends of the nipping tube !  :) I am talking about the Tail Ends, the ends that are secured inside the mid-air nipping structure, not the ends which are joined with the ends of the nipping structure itself. It is the way THOSE ends, the ends which enter into / exit from the "nipping tube", which should come there from opposite sides = opposite sides of the "nipping tube" ( the 0  to -1, and the 3 to 4, NOT the 1 to 2, in the picture ) - and so travel inside this nipping tube pointing towards different directions. That is what matters, and what is the reason of the success of the Gleipnir, because it makes the whole mechanism well-balanced, and stable. Of course, as I said, if the nipping tube is too long it risks the danger of being rotated, turn towards one side, and release the end which enters into it by this side.
   So, the appearances ARE misleading, indeed, for yet another reason !
   You believe that what matters in a Gleipnir is the orientation of the ends of the coil/"nipping tube", while the truth is that what matters is the orientation of the Tail Ends after they enter into / before they exit from this coil/"nipping tube", the orientation the travel inside the nipping tube, and are secured there.
   They should enter into / exit from the "coil" = "niping tube" = nipping structure, in general, from its opposite sides, and travel inside it pointing towards different directions.
   Read again
http://igkt.net/sm/index.php?topic=5014.0
the most characteristic feature of a Gleipnir-like binder is that the ends of the encircling the object(s) lines enter into the nipping nub through opposite openings. This is paramount in achieving a "balance" of the nipping loop, and not allowing it to revolve around itself, and release its content, the penetrating ends.

P.S. Your picture shows a two-coil Gleipnir-like binder, not the three-coil ( three turns ) one I had posted, and you had asked me to comment on, at :
http://igkt.net/sm/index.php?topic=2981.msg17791#msg17791
As I said, it remains to be proven if three coils are better ( or worse ! ) than two - and they make the nipping tube very long. That is a good thing, because it offers more length, so more inner space to the nipping tube, so the one Tail end can be twisted around the other, but it may also be a bad thing, because a too-long nipping tube may be unstable.
http://igkt.net/sm/index.php?topic=4821.msg31429#msg31429
« Last Edit: April 27, 2015, 12:10:30 AM by xarax »
This is not a knot.

DerekSmith

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #32 on: April 24, 2015, 01:40:49 PM »


Indeed, you have not shown the original Gleipnir.

The Gleipnir is a cord passed twice around the object to be constrained, then where the ends meet, a twist is put into the middle of the circumventing cord, and the ends coming to that twist from opposite directions, are passed through that twist from opposite sides.

The key advantage of the Gleipnir is that when the ends are hauled, the applied tension travels in opposite directions around the circumventing cord, tightening the tension evenly.

In the knot we see here, when tension is applied to -1 and 4, it is transferred to 0 and 3 and so travels in one direction around the object to be bound.  Irrespective of the number of turns in the nipping coils and the presence or not of an OH in the bound ends, this is not a Gleipnir.

To use your numerated diagram.  The Gleipnir would start with end at -1, enter the nipping coils and exit at 0.  Then travel around the bound object, returning at 1 where it would then form the nipping coil(s), exiting at 3 to return at 2, pass through the coils and exit as the second end at 4.

Hauling on -1 and 4 would applly load out onto 0 and 2 - i.e. in opposite directions around the bundle.

Derek

DerekSmith

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #33 on: April 24, 2015, 07:45:48 PM »

The key advantage of the Gleipnir is that when the ends are hauled, the applied tension travels in opposite directions around the circumventing cord, tightening the tension evenly.

  No, this is only a secondary feature. The key advantage is the mid-air stability of the whole rope mechanism, which is due to the fact that the two ends travel inside the nipping tube towards opposite directions.


This is, I feel, a matter of opinion based on perspective.

To a regular user of the Gleipnir (to which group I include myself), there are two aspects of the knot which are considerably more important and advantageous than the mid-air stability function.

The most important, as I have already stated, is that as tension is applied to the two ends, this is transmitted around the bound object in opposite directions.  When you are drawing up a bundle of irregular objects (such as twigs or canes or poles), you need the forces to wrap around the bundle and bring its components closer together.

The second, and almost equally important aspect, is that as the ends are tensioned, the nipping loop turns and allows the tensioned cords to flow through it unhindered in a straight line.  This means a) that all the force is going into tensioning the bunch and is not wasted on friction within the knot and b) it means that the cord is not being subjected to abrasion through repeated use and turning tight corners under tension, tightening / release etc.

The fact that on release of end tension, the Gleipnir nip rotates, immediately gripping the ends, is of course critical (it is after all - a knot...), but its ability to do this in free air is almost irrelevant.  There are after all, a number of grip after tension knots which hold in free air (eg packers knot), but they do not have the two most valuable attributes discussed above.

Derek

DerekSmith

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #34 on: April 24, 2015, 10:10:41 PM »

   
  Irrespective of the... the presence or not of an OH in the bound ends.

  You should be climbing at a quite high altitude right now, because you "see" things that do not exist 1!  :) :) :)
  I have NEVER use stoppers, OH or others, at the ends of any knot ! There is NO OH knot here. I had tried to use an OH knot as a nipping structure ( so, NOT in the bound ends ! )

Here the problem is caused by you jumping to a wrong conclusion.

You presumed that I was referring to OH stoppers in the cord ends - outside of the knot - I was not.

I was referring to the OH component created within the nipping coil(s), which the OP kindly demonstrated by moving the OH 'wraps' slightly above the coils for, I presume, the sake of clarity.

Irrespective of the presence or not of the OH component, the knot under consideration is not as you claimed a Gleipnir.

As to your use of the term 'Gleipnir type'.  I feel that defining a knot containing a 'free air' nipping coil as being a 'Gleipnir type' is too generalist to be of any meaningful value.  After all, the Myrtle has two single turn enmeshed nipping coils and is 'free air' stable, but it has none of the important attributes of the Gleipnir, so it would be without value to call this a 'Gleipnir type'.

This new group of knots we are discussing, certainly have an advantage over the Gleipnir, in that they can be produced simply by passing a bight around the bundle, forming a nipping loop and passing both ends through it.

It is a valuable knot, so surely it deserves a name of its own.   Suggestions?

Derek

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #35 on: April 24, 2015, 11:00:12 PM »
You presumed that I was referring to OH stoppers in the cord ends - outside of the knot - I was not.

You mean, outside the nub of the knot, of course, because stoppers are parts of a knot.
OK, I have learned something, at last !  :)

I was referring to the OH component created within the nipping coil(s), which the OP kindly demonstrated by moving the OH 'wraps' slightly above the coils for, I presume, the sake of clarity.

  There is NO OH knot there, either !  :)
  The two ends are simply twisted around each other. No OH, in its topological or geometrical sense, is formed. Put on your glasses !  :) :) ::) ::)
« Last Edit: April 24, 2015, 11:00:49 PM by xarax »
This is not a knot.

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #36 on: April 24, 2015, 11:16:53 PM »
  1. I feel that defining a knot containing a 'free air' nipping coil as being a 'Gleipnir type' is too generalist to be of any meaningful value.
  2. certainly have an advantage over the Gleipnir, in that they can be produced simply by passing a bight around the bundle, forming a nipping loop and passing both ends through it.

   1. and 2. are contradictory...
   I have NOT defined a Gleipnir-like knot the way you say...
   I had defined such a knot as having a mid-air nipping structure ( be it a single nipping turn, like in the original Gleipnir, all the way to the more and most tight nipping structures I had showed ), and as having its Tail Ends passing through it, entering into and exiting from opposite sides of it, and traveling towards opposite directions inside it.
   Mind you that the orientation of the ends of this nipping structure, if they leave the nub towards the same direction, or towards different directions, is irrelevant ! They will make wraps around the hitched/bound object(s), the one clockwise and the other counter-clockwise, or both clockwise, or both counter-clockwise - it does not matter. Since they are tensioned, they keep the nipping structure tightly wrapped around the penetrating Tail Ends, gripping and immobilizing them - that is all we require from it - besides, of course, to be stable in its mid-air position, and not rotate and so straightening the L-shape of the one end, and releasing it.
   What matters is the orientation of the Tail Ends, in the sense I had explained many times, and in the previous paragraph.
   The Prusik-based Gleipnir-like binder shown in :
   http://igkt.net/sm/index.php?topic=4821.msg31447#msg31447
   and in the attached picture, or all the other similar binders tied by dan Lehman, SS369, Luca and me, are such knots.
« Last Edit: May 18, 2015, 01:21:25 AM by xarax »
This is not a knot.

alpineer

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #37 on: April 25, 2015, 12:48:15 AM »

There is NO OH knot there, either !  :)
 

I call it OH - like! ;D ;D ;D

DerekSmith

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #38 on: April 25, 2015, 10:13:22 AM »
The most important [ aspect of the Gleipnir knot ] is that as tension is applied to the two ends, this is transmitted around the bound object in opposite directions. When you are drawing up a bundle of irregular objects (such as twigs or canes or poles), you need the forces to wrap around the bundle and bring its components closer together.

   I do not understand anything in this sentence !  :)
   What are the "ends" where "tension is applied" ? The "ends" of the "coil"/nipping tube ( which, of course, are tensioned, otherwise the "coil"/nipping tube would had opened up, and would had released the Tail Ends which penetrate it ), or the "ends" of the rope ( which, of course, they are not ) ?


Hi Constant,  it is not like you not to be able to understand what I have written.

This aspect, which I consider (as a user of the Gleipnir) to be its most valuable attribute, is probably worth my time explaining in greater detail, just in case other readers were also confused by my words.  However, I would hope that you do not misconstrue a more detailed (and therefore simplistic) explanation to be in any way an attempt at sarcasm - that is not my intention and I would ask you to treat my response accordingly.

When I use the Gleipnir, I typically use a 1m to 2m length of cord.  This piece of cord has two 'ends'.  These are the 'ends' I haul on to apply tension to the bundle I am compressing.  I take hold of an end in each hand and pull the ends apart so the ends are in line with the cord travelling around the bundle, that is, I am pulling across the bundle.

As I do this, the Gleipnir nip rotates slightly so that the cords under tension by my hands pass through the nip in straight lines.  They slide through the nip coil unmolested because my tensioned cords have all my applied force within them, but the nipping loop has very little tension in it because my applied force has largely been shed in the passage of the cord in its turn around the bundle.

As the bundle tightens, some force reaches the nipping loop, attempting to twist it (and my end lines) to 90 degrees across the binding cords.  But of course, as the bundle tightens, so does the force I apply to continue to compress the bundle, so the tension in my 'end lines' is much greater than the nipping loop torsion, so keeps them straight as they pass through the nip coil.

This means that as I apply tension to the 'ends', it flows in a linear and unobstructed manner into the wraps around the bundle without having to fight its way through contortions within the knot.

Is this a clear enough explanation?  Perhaps if I concentrate on each of the points you have contention with individually, untill they are resolved, then maybe I can work my way back to the rather simple statement I made at the beginning, that the knot in the image I reposted is not a Gleipnir as you had claimed.

Derek

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #39 on: April 25, 2015, 12:41:11 PM »
   OK, communication extablished - at last !
   Now, go back to my ( edited ) replies, as I did to yours.
   Re-phrase your question and comments in the context we are talking.
   The knot shown in the pictures, a three-coil binder#35, IS a Gleipnir-like binder !
   Ask dan Lehman about that ( since I had already expressed my view, "we" can be sure what "His" will be ! The exact opposite of mine!  :) ( Good for you !  :) :))
« Last Edit: April 27, 2015, 12:16:24 AM by xarax »
This is not a knot.

alpineer

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #40 on: April 25, 2015, 05:22:57 PM »
THE INTERNET!!!
This communication fail could have been resolved in seconds around a campfire.

DerekSmith

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #41 on: April 25, 2015, 07:12:01 PM »

There is NO OH knot there, either !  :)
 

I call it OH - like! ;D ;D ;D

LOL, I call it an OH component...  you know I am not a great favourite of  '- like', because you also need to define when -like is in fact not-alike, and then it can all get a  bit silly  -  Ho Hum.

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #42 on: April 25, 2015, 08:21:09 PM »
I call it an OH component... 

  There is nothing OH-component-like there !  :)
  There is only a twist around the two ends, ABoK#35-like, or ABoK#36-like...
  This is a way to enhance the gripping power of any sufficiently long nipping tube - I had use it in the simple-hitch-a-la-Gleipnir, with very satisfactory results.
   The two-turn nipping tube of dan Lehman s binder#35 is a little longer than the single nipping turn of the classic Gleipnir, but it can not surround a ABoK#36 configuration. To do this, we need a three-turn nipping tube ( as shown in the third/bottom picture of Reply#24 (1), and in the top picture of Reply#38 of the thread about the Gleipnir three years ago (2) - but then we may run into the problems of instability of this very long structure suspended in mid-air from four lines...

http://igkt.net/sm/index.php?topic=4763.msg31498#msg31498
http://igkt.net/sm/index.php?topic=2981.msg17791#msg17791
This is not a knot.

Tex

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #43 on: April 26, 2015, 02:29:42 PM »
This is a rope use problem more than a knot problem.

I don't think you're going to find a configuration that has much more mechanical advantage or is simpler to tie and untie than three turns around the sleeping bag and a slipped square knot, (other than four turns and a square knot).  That has a 3:1 advantage over 1 turn and I'd say reality gets closer to the ideal with that than it does for a trucker's hitch, even one being used as a trucker's hitch. The reason is because 1 turn has friction, but three turns has 3 times less tension and pressure per line so total friction doesn't go up as much as you might think for a given tightness (this depends on how the wraps interact with each other though as a deep groove in your sleeping bag does pull them together some).

Talk is all fine, but try actually tying these things around your sleeping bag (or calf if you want to feel how it works). I'm trying with mason line which is what I use for such tasks. 

Ok in principle, a true versa tackle can get you 2x (*) and this does save a little rope relative to three full turns, but as far as I can tell it doesn't actually work better.  You lose a bunch on friction in those two turns through the loops.  It probably depends on how you space your loops.  I invented (re?-discovered) a three wrap knot that produces a versa tackle mechanism without tying any loops, but that CLEARLY adds more friction compared to just three wraps and it shows. 

Yes these things help hold the gains while you tie down, but you start so far behind, and you CAN hold a square knot while you tie it, it just isn't easy. With three turns though a little slippage is 3x less damaging than with one turn, and with 3x less tension you can finish it with less slippage anyway, so you win a bunch over one turn.

All these constrictor knots are great at locking in tightness but most do only a little to try to actually create gains in the first place.  I mean 4 wrap constrictor style knots with a ton of nefarious twists producing friction?  That's going to get you pulling power?  This is supposedly THE construct to beat?  I don't buy it for a second.  That's not the pedigree of these types of knots.  It's not what they're for, and I don't think they're so good at this.  This is a binding, not a hitch.
 
It seems to me there are three ways to beat 3 wraps  and a shoelace bend. 
1) easier to lock in pretty tight but ultimately not as good, ok, many things can do this.
2) Use less rope try to get similar gains =-> must have a versa-tackle-like mechanism there is NO OTHER WAY.  Some constrictor type-knots have some of that aspect.
3) Have better force lock-in while tying off.  Unless this can produce better end results, it relates back to 1.
4) 4 wraps and a shoelace bend.

Surprisingly, I'm finding the 3 wraps gets the best advantage and least resistance and STILL has just enough friction at the end, to mostly lock itself out just enough to tie it. I haven't tested a ton though.

I think a simple lariat (lasso) (where this thread started) does provide one of the easiest solutions in terms of effort of tying and probably gets good enough for many sleeping bag squishing purposes, and I use it often.  So it comes down to what you are trying to accomplish.  I think you have to define that, and then you can engineer an answer.

Of course the tightness result can be measured pretty easily.  One just has to try the knots, then take an extra rope and use it to measure the circumference.  Which ever one gets smallest wins.  You cannot generalize the results to other objects like hard poles though because the sleeping bag does interact differently and even pushes the ropes into each other differently.

(*) 3x against one hand but 2 against the other, ok if there's no friction, let's just not even start agin on the details of the frictional effects because it's complicated, making it better and worse at the same time in ways that are much harder to consider than a normal truck hitch use and ultimately have to be just measured

edit: I removed "round turn" terminology because counting "round turns" could be ambiguous.
« Last Edit: April 27, 2015, 12:25:46 AM by Tex »

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #44 on: April 27, 2015, 12:38:15 AM »
   I don't think you're going to find a configuration that has much more mechanical advantage or is simpler to tie and untie than three turns around the sleeping bag and a slipped square knot, (other than four turns and a square knot).

  You have to think it over, I am afraid...  :)
  If you make the Standing Part follow a Zig Zag path on the surface of the object(s), you can then utilize the offered mechanical advantage.
   Examine the simple case of a Cow/Girth hitch, tied around a cylindrical object, where the one end is attached somehow to the tip of the Zig Zag ( the U-turn of the Standing Part ), and you pull the other end in a direction tangent to the surface of the cylinder.

must have a versa-tackle-like mechanism there is NO OTHER WAY.  Some constrictor type-knots have some of that aspect.

  There is no "Versa-tackle mechanism" !  :) There is simply the almost primordial block and tackle mechanism of the simple machine studied by Archimedes 2300 years ago, and explicitly described by Hero, 2000 years ago.  :)
  The apple pie is made from apples, not the other way around !  :)

  Of course, if by this you mean the Zig Zags of the Standing Part on the surface of the objects, and the segments pulling the tips of them, I agree.
   If you are interested in tight hitches/binders, have a look at the 4-wrap Locked Double Cow hitch, and the tightest 3/4 wraps hitch/binder we have, the TackleClamp hitch. You can make a metal pipe sing, literally, if you wrap and squeeze it with a TackleClamp hitch - no comparison to the double Constrictor whatsoever.
« Last Edit: April 27, 2015, 12:55:20 AM by xarax »
This is not a knot.