International Guild of Knot Tyers Forum

General => New Knot Investigations => Topic started by: bushrag on January 29, 2014, 08:21:03 AM

Title: Constriction cam-action knot for sleeping bags, compression, camping
Post by: bushrag on January 29, 2014, 08:21:03 AM
Hello guys, I hope you find my submission to be intriguing. It is a knot that must be used with a fixed loop, as far as I can tell. Maybe it shouldn't be called a knot.

Uses:

-Bind a sleeping bag
-Secure rolled up blankets
-Compress a duffel bag
-Tie a bed roll
-Bundle sticks
-Secure bundled items to a backpack
-give 2-1 pull advantage
-easy release

To date the knot works with paracord, slightly larger sailing cord, nylon catfish line, and thin lace-style guy lines, all of which are handy for camping to set tarps, tent guy lines, etc. You should have plenty on hand.

I think this knot is a handy and practical knot when compared to others, for the intended applications. Here are some similar knots, and the pro-con comparison.

Constrictor knot: requires 2x the circumference length of cordage. Tricky to set up. Hard to release the constriction.
This knot: only requires one circumference of cord, easy to set, easy to release.

Trucker's hitch: better applied to freestanding loads. Useful as a constrictor knot for the 2-1 pull advantage. Time consuming to set. Clumsy to untie.
This knot: requires no practice, gives 2-1 pull, releases easily and quickly

The images shown below use an angler's loop. At the loop, form the shape of a ring hitch (pic 1), and proceed by laying the right loop on top of the left (pic 2). Pass the tag end around your bundle and up through the center of both loops. Pull the slack through while the knot is loose. Pull the tag end back toward itself and the knot will grab as it tightens. As the loop around the bundle constricts, the knot will lock it tight. The soccer ball in pic 3 shows the knot in its set form.

To release, push in the shear direction indicated below (pic 4) and the knot will immediately release.

Its so simple, 'i'd be surprised if it hasn't been done before. However, I was not able to find it in Ashley. Let me know what you think.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Sweeney on January 29, 2014, 06:35:28 PM
Hi bushrag and welcome to the forum.

What you suggest was the subject  of a discussion a few years ago which resulted in the name "Gleipnir" - the forum name of the original poster (taken from Norse mythology). The thread started here: http://igkt.net/sm/index.php?topic=1449.0 (http://igkt.net/sm/index.php?topic=1449.0) and went on for some time (using a fixed loop was suggested by Dan Lehman during the discussion).

Nonetheless what you have discovered for yourself is the essence of a knot which has yet to become widely known outside of here. A search for "Gleipnir" on this forum will show numerous references to the knot since the original post but unless you know the name you would be very lucky to find it on a web search.

Barry
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Festy on January 30, 2014, 06:53:47 PM
nice knot, easier than the Gleipnir

F
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Dan_Lehman on January 31, 2014, 06:30:22 AM
It is a knot that must be used with a fixed loop, as far as I can tell.
Maybe it shouldn't be called a knot.
Not so, and it probably works better when used
with a hitch vice eye knot --more stable (and such
knotted structures are in ABOK).

Yes, I'd not call it a "knot" but a "knotted structure"
(which includes a knot (if not two)).

Quote
..., for the intended applications. Here are some similar knots, and the pro-con comparison.

Constrictor knot: ... Hard to release the constriction.
No, quite the contrary, and this is why it
fails in your applications : its security depends
on firm, convex surfaces, not compressibly soft
ones (bed roll) or broken ones (collection of sticks)!

Quote
Useful as a constrictor knot for the 2-1 pull advantage.
You're actually close on this, but given your apparent
counting of theoretical MA, no, the trucker's hitch
has 3:1 ; after friction is accounted for, the actual MA
is more like 1.6:1 --YMMV.

Quote
the knot will grab as it tightens.
Which grabbing further reduces MA, NB!

Quote
I'd be surprised if it hasn't been done before.
I've tried it, and didn't like the instability of
the nipping turn.  Somewhere in the lonnnng
Gleipnir thread is a post of mine in which
I present a like structure in which a line runs
through the nipping turn to keep it from capsizing,
and so another eye is employed to enable the
haul line to be returned through the nipping eye.
Which, yes, is more complicated to set up.


Thanks,
--dl*
====
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: bushrag on February 20, 2014, 03:37:36 AM
Thanks for the input Dan.

After reading the gleipnir thread, I have a few more ideas to add.

The first is a variation of the above structure. Use it in the same capacity for compression or bundling. Reuse the same fixed loop. Pass the tag end around the bundle and feed all the slack through the fixed loop. Form a ring hitch in the fixed loop by bringing the bight on top. Now send the tag end through the ring hitch and pull the slack out. Keep the nipping turn from capsizing as the knot is snugged tight.

The bulk of the ring hitch gives a tighter U-shaped angle to the nipping turn and is still quick to form. However, it is harder to release (need to capsize it on purpose). much more friction as well.

The second idea is a variation of the gleipnir itself. If I understand what you are saying Dan, this knot might just be a visual rehash. Reuse the same fixed loop. Pass the tag end around the bundle and feed all the slack through the fixed loop. Form the gleipnir's nip somewhere back along the bundle, and send the tag end through the nipping turn. Protect the nipping turn from rolling toward the fixed loop as you snug the knot.

It seems to hold like a vice but can explode/capsize if the bundle applied a sharp asymmetric expansion force to the structure. But given the nature of sleeping bags, tarps, blanket rolls, etc. these work pretty good as quick-set knots.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on February 20, 2014, 01:31:35 PM
  I will tell it right from the beginning, and I will tell it once more at the end of my post :
  Do NOT use a fixed loop ! Replace the fixed loop with some other structure - simplify the mechanism !

  The issue discussed in this thread is NOT resolved, and one reason for this is that oftentimes people mix many purposes, and arrive at no end.
  It will lead us nowhere if we describe knots, by their application to particular problems ! It is a common mistake most knot tyers do, because of years of brain-washing by the popular books about knots - which, most of the time, are books about recipes on how to tie certain knots, not books about the knots themselves - and they are addressed to people like they were parrots, soldier-like boy scouts, housekeepers, etc. We have to describe the knots themselves, as mechanisms based on some structures. And to start doing it, we have to start from the first thing the knots are : 3D objects - i.e., we have to start from their geometry.
    I believe that the geometry of the many different knots discussed and the many more hinted in this thread has not been clarified - and, instead of this, the only categories we have, are the categories of the various functional characteristics the knots are meant to incoropate : A quick and dirty enumeration of those functions would one be like this :

   1. Adjustable nooses / loops.
   2. Lockable sliding loops.
   3. Tight hitches, on the surface of the object.   
   4. Tight hitches, away from the surface of the object (mid-air).
   5. One wrap binders.
   6. Two wrap binders.
   7. Adjustable grip bends.
   8. Localized or spread along the line knots ( like the Sheepshank, or the Capt. Mullins knot )
   9. Knot mechanisms that utilize a block-and-tackle like mechanical advantage.
 10. Post eye tiable (PET), or ante eye tiable (AET) knots.

   and so on...  :)
   
  Even if we restrict ourselves to study the function, and not the geometry, the structure or the mechanism, as we should, the knots described in this thread belong to many different categories - so I believe we can not compare them.
   The usual pitfall we fall into, is to try achieve too many goals, and excel on each and every one of them - this pitfall goes straight to the abyssal dead end of the KnotLand, called "complexity". The exact opposite of complexity is simplicity - we know it is a good thing for us, although we do not know what it is per se - and, of course we can not define what it is !  :) (1) 
   If we are ready to accept a fixed loop at the one end of the line, we can simply tie the most easy knot mechanism that utilizes a mechanical advantage, the "trucker s hitch" - or tie a symmetric binder, a Double Trucker s hitch, like the ones shown in (2), or the asymmetric ones shown at (3) or at the first attached picture, for example. However, the interesting and challenging thing is to figure out simpler knots, easier to tie than the trucker s hitch.
   One other, simpler way to go, is to the start from a decent adjustable loop, and reverse the direction of the returning eye leg, as it enters into the nipping structure tied on the Standing Part. Sometimes this simple trick works, because the additional U-turn of the line, just before it enters into the neck of the loop, is sufficient to alleviate the tension the nipping structure has to absorb. Of course, this nipping structure/trap has to remain oriented as before, and not flip and release its pray ! I find it very hard to predict if a nipping structure is stable, after it is penetrated and loaded the other way, or it flips - I just try and see. The nipping structures of the Constrictor and the Serpent nooses / hitches (4), for example, do not flip. See also simple symmetric binders, utilizing a mechanical advantage, at (5).
   What is the angle between the two loaded ends of the tensioned loop ? That is a question of geometry, and it matters ! If the angle is not very wide, we may use many Eskimo-like adjustable loops, like the ones based on the very tight, and sometimes even jamming, Glove, Girth or Pretzel nipping structures ( 6), (7).
   In an effort to use a as simple locking mechanism as possible, I have thought of the Blackwell hitch, where, in place of the hook we have a properly positioned bight. See the two mid-air binders shown in the attached pictures ( which, obviously, are too simple to be able to incorporate the doubled lines of a rope-made block-and-tackle mechanism ). They are the most simple such binders I could think of.
   Even if those or similar knots do not seem tight and secure enough, I believe that the middle ground should be explored, before we need to use a fixed loop. There is ample of space in the KnotLand that has never been explored- and that is why I had made the comment I made at the start of my post :

   Do NOT use a fixed loop ! Replace the fixed loop with some other structure - simplify the mechanism !
   
1. http://igkt.net/sm/index.php?topic=3740.0
2. http://igkt.net/sm/index.php?topic=1870.msg17414#msg17414
3. http://igkt.net/sm/index.php?topic=3012.msg17902#msg17902
4. http://igkt.net/sm/index.php?topic=4454
5. http://igkt.net/sm/index.php?topic=1870.msg21229#msg21229
6. http://igkt.net/sm/index.php?topic=4347
7. http://igkt.net/sm/index.php?topic=4464.msg28352#msg28352
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Bjoern_Hee on February 24, 2014, 08:19:03 PM
Hi bushrag, I like your nipping loop, the one in your first post (what do you call it?). It is not strong, but it is simple and works nicely for those non-demanding tasks.

There are two simple variations that you may find interesting.

First one is a mix between a timber hitch and your nipping loop. This does away with the fixed loop. But it requires the twisted part (the timber hitch part) to be held firmly to the surface of whatever you tie around. So if that has concave parts or space between different parts, this variant may not be suitable. If the object has a very large diameter it can be a problem as well. But for the tasks you list, save the bundle of sticks, it should work just as well as your original fixed loop version.

Second one is to simply double the string. Yes, you need twice as much string, but you don't have to mess around with the fixed loop. In my unrigorous testing it appeared to be a little stronger than your original version.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on February 24, 2014, 09:09:36 PM
   For binders based on a double nipping loop, as the binders shown in the previous post, tied at the one end of the rope, in the case of a 1-wrap binder, or at middle of the rope, in the case of a 2-wrap binder, see :
   
binder #34 : http://igkt.net/sm/index.php?topic=2981.msg17780#msg17780
binder #35 : http://igkt.net/sm/index.php?topic=2981.msg17782#msg17782
 
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Bjoern_Hee on February 26, 2014, 09:26:10 PM
It occured to me, that the "Timber Hitched Nipping Loop" variant, just as well can be viewed as a variant of a timber hitch. The "Nipped Timber Hitch"...

The timber hitch is a heavy duty knot, but strangely loose. Ashley wrote (and exaggerated) that the timber hitch falls apart when the tension is removed. In the "Nipped Timber Hitch" the nipping prevents that. It adds security to the knot.

So if you would like to use the timber hitch when the loading shifts around and is jerky, you could try out the nipped variant.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Sweeney on March 03, 2014, 10:09:06 PM
It occured to me, that the "Timber Hitched Nipping Loop" variant, just as well can be viewed as a variant of a timber hitch. The "Nipped Timber Hitch"...

The timber hitch is a heavy duty knot, but strangely loose. Ashley wrote (and exaggerated) that the timber hitch falls apart when the tension is removed. In the "Nipped Timber Hitch" the nipping prevents that. It adds security to the knot.

So if you would like to use the timber hitch when the loading shifts around and is jerky, you could try out the nipped variant.

I have now tried this in a few different materials from 2mm nylon via 550 paracord to 8mm braided polyester. It is a handy variation when the Timber hitch might otherwise be too loose and fall off - it has the advantage that the Timber hitch is well known and this is but a simple addition, easy to remember. I probably wouldn't use it for its constriction action as such but it holds the hitch in place nicely and is really no more difficult to undo than the original hitch.

Barry
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith on March 05, 2014, 02:03:28 PM
Hi Bushrag,

Thanks for bringing us this lovely sliding grip hitch and starting off this thread of further innovation.  I so enjoy it when open minded knotters pick up on an idea and expand the theme from their different perspectives.  The Timber hitch variant for example is a lovely enhancement.

I don't know whether you realise it or not, but the twist you are using is in effect a single turn KC hitch (or if you prefer, the KC hitch is a multi turn nipping loop), which although it grips well, is not the most stable of gripping structures for rope or cordage.  By contrast, the other principle gripping structure, the Prussik is far more stable on rope, and you might consider using the 'Single turn Prussik' in this application.  Of course, the single turn Prussik also goes by the more common name of Larks Foot or Cow hitch

(http://igkt.net/sm/index.php?action=dlattach;topic=4763.0;attach=13576;image)

Instead of in your diagram putting the rhs loop over the lhs loop, simply fold the rhs loop under the lhs loop.  This single turn Prussik or Larks foot, is a much more stable gripping component, yet just as easy to make.  In fact, you can make the Timber hitch / Larks foot combo with one hand and just a few rotational wrist movements.

I am a total fan of the Gleipner, but this single strand variation has just become my favourite bundle binder with the timber hitch method of making the loop and the Larks Foot nip.

Keep 'em coming.

Derek
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on March 05, 2014, 02:52:10 PM
The Timber hitch variant for example is a lovely enhancement.

   A not-encyclopaedic mind  :) sees the ABoK#1669 in the knot described at Reply#8 - is it wrong ?
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: SS369 on March 05, 2014, 03:08:29 PM
   A not-encyclopaedic mind  :) sees the ABoK#1669 in the knot described at Reply#8 - is it wrong ?

I concur. Looks like ABOK# 1669 in reply #8

SS
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith on March 05, 2014, 07:14:57 PM
Agreed, #1669 or at least #1665 with a round turn.

NB I think it is more of a case of a knot-encyclopaedic mind...

Derek
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Luca on March 06, 2014, 12:59:05 AM
Hi,

I tried this mid-air(knot4u,please,if sometimes you're here,please,made us ​​to feel you!)/zip-tie behaviour-binder that uses the Locked Cow hitch shown by xarax( http://igkt.net/sm/index.php?topic=4441.msg28170#msg28170 / http://igkt.net/sm/index.php?topic=4814.msg31328#msg31328 ) as shown below(one can build the Locked Cow hitch oriented in the opposite way in relation to the standing part and experience what is the best version,because I do not know!),seems to "squeeze" the wrapped object pretty tight!

                                                                                                           Bye!
(http://)
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on March 06, 2014, 06:41:20 AM
   Hi Luca,
   I had never thought to use the Locked Cow hitch as a mid-air binder !   :)  When I saw your knot, I grasped the first rope that was near me and ran to my laboratory ( the two central heating pipes in my living room, where I test the binders... :)). I am sorry to report that it was a great disappointment - compared to the rock-solid hitch on a pole, the same hitch around two rope diameters was... soft, to say the least !  :)  The mechanical advantage does not seem to work, and the Tail End, without the support of a solid surface underneath it, can not be squeezed enough, so, in its turn, can not push and block the slippage of the Standing End - which blockage of the Standing End, I should stress, in this case it is not even required most of the times - because binders are supposed to always remain under some minimum tension. Noope, definitely this hitch, marvellous when tied around poles, is just mediocre when tied around a pair of ropes segments.
   The golden standard remains the Gleipnir - nowadays I use the Gleipnir with a Clove hitch instead of a single or a double nipping loop, because, once tensioned enough, the Clove hitch accumulates the induced tension and remains tight - so it provides a more stable basis for the Gleipnir arrangement, even during a possible temporary release of the loading. In other words, I have learned to use the jamming characteristics of the Clove hitch, and I have implemented this trick in the Gleipnir just as in the recently presented Bull / Clove hitch. (1)
  it is very difficult to nip a tensioned straight rope segment - the only thing we can do is to insert the Tail end into the nipping structure only after it has just made an L-shaped deflexion, a "hook" that can more easily be attached to a corresponding "handle" provided by the Standing Part.
  The most effective nipping structure I have met is the double/crossed nipping loop of the Pretzel adjustable loop (2) - because it is very tight AND very well balanced, in relation to the axis of the loading. It will not rotate, so the L-shaped deflexion of the Tail End before it enters into the nipping structure will not run the danger to be straightened out. However, I have not yet figured out how to combine, and merge two such nipping structures into one, as a possible alternative to the Gleipnir / Clove. 

1. http://igkt.net/sm/index.php?topic=4748.0
2. http://igkt.net/sm/index.php?topic=4464.msg28357#msg28357
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Luca on March 07, 2014, 04:57:50 PM
Hi xarax,

  ...compared to the rock-solid hitch on a pole, the same hitch around two rope diameters was... soft, to say the least !  :)  The mechanical advantage does not seem to work, and the Tail End, without the support of a solid surface underneath it, can not be squeezed enough, so, in its turn, can not push and block the slippage of the Standing End - which blockage of the Standing End, I should stress, in this case it is not even required most of the times...

Surely there are mid-air binders better than this, and just as surely  you have in mind quality standards better than what I have in mind(in other words: beware my little gifts ;D!), but, given the very nearly absolute faultiness of good results described by you,I have led to the hypothesis that there is some misunderstanding regarding the direction in which you pull  on the standing end in order to tighten the binder, because to me it happens exactly the opposite of what you describe! If you pull on the standing end in the direction suggested (perhaps not so clearly) in the diagram, so that form a U-turn passing through the Cow hitch component, you will notice the effectiveness of the mechanical advantage (which of course also depends on the shape and the surface type of the wrapped object .) You will also notice that, especially with strings of small diameter, the risk that the Cow hitch component jams squeezing rock solid against the two diameters of rope that wraps around, is quite high: if one does not want to run a slipped version (which however will increase to three the diameters of rope wrapped), I suggest to leave slack the U-turn that  the tail end forms before finally returning through the Cow hitch component...
Pulling the standing end in the opposite direction (ie to the left in my diagram)instead I see that it is exactly what you describe!(:))

                                                                                                             Bye!
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on March 07, 2014, 06:35:02 PM
  Soft ! :) :) :)

  First, see the binders ( and read the, fortunately, not-long texts !  :) ), shown at :
  http://igkt.net/sm/index.php?topic=2996.msg17831#msg17831
  http://igkt.net/sm/index.php?topic=2996.msg17841#msg17841
  and the next posts. You could possibly test them, and report your results to us.
   Second : The angle between the axis of the knot / loading, and the Tail End, should be close to the right angle, or even a little bid less ( more acute ) - not obtuse. If it is very obtuse, the L-shaped deflexion we need will not be adequate, so the Tail End will tend to be aligned to the Stranding End, and it will slis through the nub - any nub, however tight it is... If it is very acute, we would not be able to pull the end and re-adjust / tighten the binder.
   In a correctly balanced nipping / constricting nub ( as nub of the Pretzel adjustable loop ), which does not rotate to the wrong direction, ready to release its grip, the Tail End forms this right angle "hook", corresponding to the nub s "handle", so the nipping / constricting action becomes enough to secure it.
   Third : See those two parallel and adjacent segments into the nub s core ? They tend to slide on each other, like the skis on the surface of the snow !  :) In order to block the slippage of a tensioned segment, you have to bite it hard and deep, with segments at a right angle to it.

Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Luca on March 07, 2014, 11:55:02 PM
OK, but then we have to throw in the sea the whole concept of this type of zip-tie-knots behavior, as it seem to me that in essence are the binders  shown by bushrag and Bjoern_Hee?You have recommended to bushrag  the use of a hitch,and well,OK,now I wonder which is that, in the case of this type of binder, permanently bends the standing part to 90 degrees...
I believe that this 90 degrees bending aids, and the Pretzel loop it is a sure proof of this, but it is not only this that keeps the tension: I saw that building the binder with the Locked Cow hitch positioned in the opposite direction with respect to the standing end,in this way the standing end is a little more bent, but the compression of the two diameters of rope wrapped by the Cow hitch component and the general tension of the binder seem inferior.
At the end, to keep a sleeping bag rolled up and similar tasks, this binder still does not seem to me a so bad solution...and anyway ...  now I go to play my mid-air/single string and note lyre,aware that you will think that I have just a very poor thing to amuse me...and maybe you are right!

                                                                                                       Bye!
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on March 08, 2014, 02:27:27 AM
I wonder which is that, in the case of this type of binder, permanently bends the standing part to 90 degrees...

  Me too !  :)
  I only imagine something similar to the two nubs of the Pretzel adjustable loops I have been referred to, combined and merged into one, where the one, now, nipping / constricting knot tied on the middle of the Stranding part can swallow, and keep firmly it its dents, two Tail Ends, coming from two eyes, at the end of the line.

the compression... seem inferior.

  Compression does not matter so much ! It is what is how one line is compressed on another. If the two lines are at a right angle, they bite each other, so each one is more able to inhibit the movement of the other. If they are at an acute angle, or parallel to each other, they tend to slide on each other - even a greater force and surface friction can not make the one line to sink deep in the other, and generate those saddle-like surfaces on the area of mutual contact which play the role of obstacles to any translational relative motion.

   Tie the one-returning-eye-leg binders I haver shown in this old post, and compare them.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Dan_Lehman on March 08, 2014, 08:53:28 AM
Quote
I will tell it right from the beginning, and I will tell it once more at the end of my post :
  Do NOT use a fixed loop ! Replace the fixed loop with some other structure - simplify the mechanism !
With such an absolute, strong assertion such as this, ::)
one must consider the source, and it can be a good
guide : .:. a fixed eyeknot is just the simple answer
(or part of it) !!    ;)

An overhand eyeknot is one that pretty reliably
stays (simply) tied in common materials.  Make its
eye long enough to tie a 2nd, short-eye'd such knot
or perhaps the bulkier Ashley's stopper --for it will
be qua stopper that this knot will serve, to secure
some simply formed gripping hitch around the
binding tail.

One might, e.g., bring the tail around the object,
then turn the stopper-tipped eyeknot's eye around
this tail with a turn or two and then tuck the
stopper up through the eye legs, to lock it
!
Draw the tail through this gripping hitch, as desired.
One might then turn the tail around the stopper,
jamming it between knot and pinching eye legs.
[#20140308a00:11 series]

QED

(Sorta similar, mid-line-stopper-mechanics thinking
had me implementing a cleat in cordage w/two
stoppers --and this got "too clever by half" quickly,
but it was fun!   ;D )


--dl*
====
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Bjoern_Hee on March 12, 2014, 08:54:59 PM
DerekSmith, that larks foot version is very nice indeed, and a lot stronger. On the other hand the nipping loop has that satisfying pop-open gimmick, so I'm not prepared to give it up.

Looking back over the thread, I think there is a whole set of fine knots. And they have now gone into my "knotting toolbox".

xarax, that ABoK 1669 was a nice find. It is interesting that knots, that are there in plain sight, can be so hard to find. The knotting world needs a set of systematic naming rules in the vein of the naming of molecules.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on March 12, 2014, 09:44:59 PM
The knotting world needs a set of systematic naming rules in the vein of the naming of molecules.

+1 !
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith on March 12, 2014, 11:58:36 PM
The knotting world needs a set of systematic naming rules in the vein of the naming of molecules.

+1 !

+2 !
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Bjoern_Hee on March 15, 2014, 05:48:35 PM
Still another variant. This one has in my opinion a nice combination of strength and simplicity. It is still a cam-action bender, but not so readily untied. The knot will hold in mid-air.

This is what you do: Prepare the doubled string nipping loop. Let the two working ends enter the loop from each side, and tie them into a half knot. Tighten.

This is a knot I wouldn't teach to children.

The half knot part is essential for high strength. The mechanism is not so much nipping, but more like that of the lazy dog knot. Turns that immobilize a component of the knot, that would otherwise be weak or unstable.

In twisted rope it can be tied in four different ways. In non-twisted rope it can be tied in essentially two ways. I have just started experimenting, so I am still undecided about the best way. Though for twisted rope the half knot should probably follow the twisting. It seems that going against the twists introduces some roughness that interferes with tightening and loosening. The "nipping loop" turns should probably go against the half knot twists.

Adding an extra turn in the "nipping loop" makes the knot even stronger. The larks foot can be used instead of the "nipping loop". But in my testing it didn't improve strength in this knot, which I think is due to the change in the mechanism.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on March 15, 2014, 08:21:18 PM
   Evidently, you do not read the posts suggested to you as references, neither you just spear a quick glance at the pictures shown there. To abstain from too much reading of what has already be done may be beneficial for a novice knot tyer, indeed, because our imagination needs freedom to make its first steps - this novice knot tyer, for one, has read a handful only of books on knots, and he was even postponing the reading of Ashley s BoK for as long as he could. However, in this Forum, when one member presents a particular knot, I believe that it is always useful to read what other people have said about it, or about other, "similar" knots, because, even in the vast KnotLand, around a particular point / knot, and within the limited, by the requirement of "similarity", range, there is always a limited area...

   Now, this knot you have tied is a two-coil Gleipnir binder, with crossed tails - a common trick we use to increase the entanglement of the Tail Ends before they exit the knot s nub. We do not know the optimum number of coils the nipping tube of this knot should have : two coils seem better than one, because, although the total nipping force is spread over a larger area ( so the two rims of the double nipping loop can not 'bite" the Tail ends as hard and deep as in the case of the one rim of a single nipping loop ), the segment of the double helix those Tail Ends form, as they are twisted around each other, clearly needs this longer nipping tube. However, a very long nipping tube may be unstable, and, if it is pulled from the "wrong" end a little more, it can rotate, and release its grip. I have tried the two- and the three- coils, but I have not been able to decide which is the better solution... The recently tied Gleipnir-like hitch and binder with a Prussic knot as its nipping tube, go as far as to use four coils - it becomes rock-solid as a hitch, but it may be too unstable as a binder.

    http://igkt.net/sm/index.php?topic=2981.msg17791#msg17791   
   
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Tex on April 19, 2015, 03:19:53 PM
Hi Bushrag,

Thanks for bringing us this lovely sliding grip hitch and starting off this thread of further innovation.  I so enjoy it when open minded knotters pick up on an idea and expand the theme from their different perspectives.  The Timber hitch variant for example is a lovely enhancement.

I don't know whether you realise it or not, but the twist you are using is in effect a single turn KC hitch (or if you prefer, the KC hitch is a multi turn nipping loop), which although it grips well, is not the most stable of gripping structures for rope or cordage.  By contrast, the other principle gripping structure, the Prussik is far more stable on rope, and you might consider using the 'Single turn Prussik' in this application.  Of course, the single turn Prussik also goes by the more common name of Larks Foot or Cow hitch

(http://igkt.net/sm/index.php?action=dlattach;topic=4763.0;attach=13576;image)

Instead of in your diagram putting the rhs loop over the lhs loop, simply fold the rhs loop under the lhs loop.  This single turn Prussik or Larks foot, is a much more stable gripping component, yet just as easy to make.  In fact, you can make the Timber hitch / Larks foot combo with one hand and just a few rotational wrist movements.

I am a total fan of the Gleipner, but this single strand variation has just become my favourite bundle binder with the timber hitch method of making the loop and the Larks Foot nip.

Keep 'em coming.

Derek


I ran into this old post and had to reply to this because I noticed something that's just too funny.  I don't know if DerekSmith is still around, but anyway...

If you put a lark's foot midline, run the working end around a structure and through the lark's foot can anyone guess what you get???

take 5 seconds to think about it..













... and the answer is... a square knot (sort of, well topologically at least it is a square knot).

So if you have a fixed loop and put a larks foot "nip" in it and bring the rope back around "like a trucker's hitch" you have.. a square knot with a backing knot on one side (whatever knot you used for the loop).  Of course tying it this way let's you use two hands to pull and even more importantly to secure the remaining free end, and this is mostly the real advantage that a trucker's hitch buys over a square knot actually.  If you tie it right you can get a similar mechanical advantage on the square knot, but only with one hand (and no feet) and it's hard to lock it in.

I should say though, that it's only sort of a square knot.  Tightened in this manner you will usually end up with something which behaves much more like a taut line hitch than a square knot (well it's a single/half prusik).  As such, even without the backing knot/loop, it can be tightened down well, but even with the backing knot, it is also less secure than a properly dressed square knot. 

So the question is, is a square knot still a square knot when it's a cow hitch tied around the other end of the rope (but still used as a binding knot)?




Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Tex on April 19, 2015, 04:30:21 PM
oh and there's a quick and dirty way to bypass tying the loop, just bring both ends of what would be the loop back around the object together and through the hitch.  Then you have a double ring hitch used as a binder.  You gain back ability to use two hands without tying a loop, but anyway, the cow hitch eats up all the mechanical advantage.  As far I can tell you just get an intentionally insecure binding knot that's pretty easy to tie and doesn't get that tight, which is the same as a shoelace "bow" except the shoelace bow is pretty secure. 



Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith on April 23, 2015, 06:42:23 PM

   Now, this knot you have tied is a two-coil Gleipnir binder, with crossed tails - a common trick we use to increase the entanglement of the Tail Ends before they exit the knot s nub.

    http://igkt.net/sm/index.php?topic=2981.msg17791#msg17791   
   

Hi Xarax,

Are you sure that this is a Gleipnir?

It is a bit of a job telling from the top photo, but to me it does not look as though the ends approach from opposite directions as they would in hte Gleipnir.

Rather, they seem to come from the same side.

Have a closer look and see what you think.

Derek
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on April 23, 2015, 11:15:42 PM
...it does not look as though the ends approach from opposite directions as they would in the Gleipnir.

  Appearances are deceptive !  :) :)
  No, they do - as you point out, in a Gleipnir, we have a mid-air nipping structure ( be it a single, double or even triple nipping turn - as here (*)-, but also a single or double overhand knot (1), or even a Clove or a Constrictor hitch, or a Prusik (2) )(*)
   AND we have two penetrating this structure Tail Ends, entering/exiting to/from it, from opposite directions (0).

   I tend to believe that the most characteristic feature of a Gleipnir-like binder is that the ends ... 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

0. http://igkt.net/sm/index.php?topic=5014.0
1. http://igkt.net/sm/index.php?topic=4818.0   
2. http://igkt.net/sm/index.php?topic=4821.msg31447#msg31447

   numbers, and see which end is connected with which, and where it goes.

  I have marked the ends of the lines shown in the picture of the loose knot with numbers, so it will be easy to follow the
(*) More than three turns make the nipping "tube" too long - and the knot unstable :
    http://igkt.net/sm/index.php?topic=4821.msg31429#msg31429

(*) Perhaps the root of the misunderstanding was this word, "approaching". It does not matter how the ends travel outside the nipping structure ( which in this case, is a three turn coil ), and from which direction they "approach" it. The only thing that matters is how they travel inside it. If they travel pointing towards opposite directions, the binder is Gleipnir-like.
In the picture of the binder you had cited, the Tail ends which penetrate the nipping structure and they are locked, and immobilized, by its gripping, travel inside the nub towards opposite directions.   
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith 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
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax 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
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith on April 24, 2015, 01:40:49 PM
(http://igkt.net/sm/index.php?action=dlattach;topic=4763.0;attach=17370;image)

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
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith 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
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith 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
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax 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 !  :) :) ::) ::)
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax 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.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: alpineer on April 25, 2015, 12:48:15 AM

There is NO OH knot there, either !  :)
 

I call it OH - like! ;D ;D ;D
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith 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
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax 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 !  :) :))
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: alpineer on April 25, 2015, 05:22:57 PM
THE INTERNET!!!
This communication fail could have been resolved in seconds around a campfire.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: DerekSmith 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.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax 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
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Tex 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.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax 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.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Tex on April 27, 2015, 12:58:45 PM
xarax you're not telling me anything I didn't already cover in my post.

Zig zag is zig zag and I don't think at this point you can really think I that I don't get zig zag advantage just because I used a label, for expedience of description, that you don't love.  The reason I called out versa tackle by name is to distinguish from other false trucker's hitch-like binding geometries that have only a mild relationship to a true trucker's hitch-like advantage, like the lasso configuration (zigging around one side of a sleeping bag, and back up the other side doesn't count, EVERY binding knot does that.  No advantage).  Versa tackle is zig zag, and zig zag is versa tackle.  Versa tackle just uses two loops to make the zig and zag through.  You can create open turns to do it instead just as you can use all different knots for a trucker's hitch, but it doesn't change what it is, a double turn 3-leg pulley advantage (which really is 2:1 not 3:1 for the purpose of binding.  Tug-of wars with a binding knot in the middle are a different story.).  The knot I talked about inventing/discovering, is not truly versa tackle either, but it's a 2-turn pulley closure system.  I haven't shown it and I probably won't.  For binding it's better than much stuff shown here, but it's still worse than a three turns and a slipped square knot, and as a hitch it's useless, so who cares?

The point you are missing xarax is that three turns around the object has the same advantage MINUS the extra LARGE friction in the 180 turns. People are missing the most obvious simple advantage right in front of them and are messing it up with all kinds of friction, thus destroying it. 

Like I said, actually try it.  I stand by my statements.   I spent a bit of time trying junk around my sleeping bag and leg before I posted it and at best I can find solutions that come close to 3 turns and a slipped square knot.
 
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Tex on April 27, 2015, 01:31:01 PM
By the way, my 3 wrap zigging (along the surface) is similar in effect and look to your locked cow hitch (which I knew about when I made it) as far how it binds, except it doesn't have any nipping lock, which means it hitches worse, locks worse,  but you can pull it tighter.  Yet it still binds worse than 3 unimpeded turns because it still has far more friction. 


In the end there is a VERY simple principle at play here.  EVERY frictionless three wrap bind (3 wraps everywhere, backhand reversals acceptable) will have a 3 to one advantage because if you pull out 3 inches of rope it will get one inch smaller in diameter.    If anyone doesn't get why this equates to a 3x force advantage, brush up on simple machines and Newton's laws.  Yes versa tackle like arrangements can take you from 1 wrap most of the way around to still having 2:1 advantage without 2 full wraps, but it just doesn't work as well.

It doesn't matter how many zigs and zags went into forming those three wraps full.  If the total rope is 3 pi d and some number of wraps everywhere, then that's what its advantage will be.

Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on April 27, 2015, 01:44:13 PM
xarax you're not telling me anything I didn't already cover in my post.

  OK. I am used to tell everybody what he already knows for quite a long time now. Do not read my posts... ( You would nt be the first one, you know... :) )

  You are the one who used the term Zig Zag for the first time in your first post on the Trucker s hitch, Ashley had used it, too, so I was trying to use this nomenclature because it is descriptive, and it is understood by anybody, even if he is not a knot tyer. On the contrary, VersaTackle is relatively recent name given to a particular configuration, when we have the Standing Part passing through the SAME two bights many times... The knot tyer who used this name, although I believe he did not understood the essence of the "opposed bights" locking mechanism (1)(2), felt he should had referred to the block and tackle mechanism, for good reason. He used the word "tackle" of the name of a 2000-2300 years old simple machine, to describe a recently described knot mechanism, not the other way around.
   The point you miss is that I am talking about the general case, about tight hitches and binders, in general - I am not talking about sleeping bags, in general, and about your sleeping bag, in particular !  :) :)  I am talking about the knots which can serve as very tight hitches, able to withstand a lengthwise pull, or as self-locking binders ( think about the term "self-locking", and compare this feature with the features of the solution you propose ).
   Of course, three-four round turns and three-four overhand knots or half hitches, the one after the other, will solve all your particular/special problems - the burden of reading my posts included !  :)  :)

If anyone doesn't get why this equates to a 3x force advantage, brush up on simple machines and Newton's laws.

   I would LOVE to return to high school - I had left many opportunities I had nt got when I could, there... :) :) :)

1. http://igkt.net/sm/index.php?topic=4906.0
2. http://igkt.net/sm/index.php?topic=4906.msg33365#msg33365
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: xarax on April 27, 2015, 02:14:05 PM
   On a more serious discussion, we should always try to separate the issue of the efficiency of the mechanical advantage, from the issue of the efficiency of the locking mechanism - two different things which are often confused - especially in the case of the Trucker s hitch - but also when we are talking about other tight hitches / binders.
   To my view, the simplest starting post of incorporating a mechanical advantage into a tight hitch / binder, is the humble Cow hitch, with its Zig Zag, U-turning path of the Standing Part on the surface of the hitched/bound object(s). And the most secure, and minimum material consuming locking mechanism, is not the Gleipnir-like mechanism ( used also by the bowline ), but the opposed bights mechanism, used in the Trucker s hitch and the Versatackle.


Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Tex on April 27, 2015, 02:28:55 PM
  OK. I am used to tell everybody what he already knows for quite a long time now. Do not read my posts... ( You would nt be the first one, you know... :) )

Don't take any of it wrong.  Arguing about knots (or ropes) is surprising fun.

   The point you miss is that I am talking about the general case, about tight hitches and binders, in general - I am not talking about sleeping bags, in general, and about your sleeping bag, in particular !  :) :)  I am talking about the knots which can serve as very tight hitches, able to withstand a lengthwise pull, or as self-locking binders ( think about the term "self-locking", and compare this feature with the features of the solution you propose ).

Yes yes.. exactly.  This discussion has turned into one about tight hitches, how much tension the can TAKE while tightening up enough to not slip loose, or maybe even around.   That's fine.  That's a great discussion which is why there are so many cool tight hitches.  But it's not the same discussion as how tight can you BIND something using a strictly LIMITED amount of force.   Hitchers are not great binders, but some hitches are pretty good binders.

If everyone is understanding that that is what this discussion has become, then excuse my interruption.  The original question though asked about binding, specifically asked about compression, sleeping bags, and specifically asked about pull advantage and clearly wasn't related to finding out how much hydraulics you can attach to a tight hitch.

I never saw anywhere in here where anyone mentioned simple turns and a double square knot.  If we've moved on from trying to answer the original question, then my suggestion is no longer valid. 

Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: Tex on April 27, 2015, 02:30:36 PM
... slipped square knot, typo.
Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: JohnC on June 15, 2017, 03:15:19 AM
Hello guys, I hope you find my submission to be intriguing.

[...]

Its so simple, 'i'd be surprised if it hasn't been done before. However, I was not able to find it in Ashley. Let me know what you think.

I stumbled across this post a couple of weeks back and have been experimenting with the knot for various applications.

At first I was unimpressed - tying it in the hand - as it seemed to slip with the slightest of tension, but that was unfair as it performs much better when actually binding something. The other thing that put me off a bit was the allusion to the constrictor, which doesn't seem to me at all comparable, but that's unimportant.

I've glanced at the various replies but haven't studied them in depth so my comments apply to the original post as presented.

I like this knot very much.

First off I used it in cheap garden twine to compress some rubbish that was in bin liners (polythene shopping bags) and needed to go into the mandated 60L plastic sack used for rubbish collection in my neck of the woods. The problem I had was that I only had one sack left (and they won't pick up anything else) but I had more bin liner bags than would fit, and the truck was due any minute so no time for a dash to the shops. A closed bin liner/shopping bag has a lot of air and compressible stuff in it, but if you squash them up by hand and stuff them in they "reinflate" to a large degree before you can get the outer bag closed.

So I made this loop, put it under one bag, then placed two others on top and gently knelt on the three while I cinched up the knot. Then placed the three in the sack and repeated for another three. Worked brilliantly and I eventually got eight bin liners worth in a sack that I would normally struggle to get six into.

Next up was some empty kitty litter bags that I like to keep for storing or disposing of various things (they are lined with thick/absorbent cardboard and coated with plastic on the outside so they don't leak). The kitty litter bags tend to want to unfold after you've folded them so I was having trouble keeping them together. This loop is excellent because you can just expand it a bit with each new bag you slot in.

Lastly, cardboard paper towel rolls, which make great fire starters mixed in with the kindling (especially filled with tinder), but they are tricky to "wrangle" without a container. This loop makes a great adjustable sling for them.

For reuse/adjustment, it works better with soft, braided cord that it can get a grip on, but having said that, the plastic garden twine worked fine too since I didn't care if it jammed completely (I was discarding it with the rubbish).

Title: Re: Constriction cam-action knot for sleeping bags, compression, camping
Post by: bushrag on June 15, 2017, 04:20:56 AM
Hi JohnC,

Glad you like it. For your smaller bundling tasks Bjoern_Hee took the original and made a beautifully improved version on page 4 i think. I found his extra turn to be redundant as a single turn is very secure. See the attached pic for the improved. It's superior to the gleipnir. I'm glad I inspired this beautiful knot.

(http://i66.tinypic.com/358yk9d.png)