Author Topic: Omnidirectional-loaded loop with omnidirectional tails?  (Read 1733 times)

bushrag

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Omnidirectional-loaded loop with omnidirectional tails?
« on: March 21, 2020, 12:22:53 AM »
Is there a knot to make a loop that can be loaded in all directions with tails that can be loaded in all directions?

Groundline

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #1 on: March 21, 2020, 01:57:47 AM »
Don't look at the Sun.

roo

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #2 on: March 21, 2020, 05:18:23 PM »
Is there a knot to make a loop that can be loaded in all directions with tails that can be loaded in all directions?

What's your application?

 I think we've had some members experience flipping of the Butterfly Loop when the loop legs are pulled in different directions during special tests.  Maybe they could chime in.  I experienced such a capsizing with a quick and dirty bungee test just now.
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agent_smith

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #3 on: April 15, 2020, 03:01:24 AM »
per bushrag:
Quote
Is there a knot to make a loop that can be loaded in all directions with tails that can be loaded in all directions?
The answer is yes.
However... as was hinted at in a previous post, there might be certain performance characteristics which you deem to be crucial (of which we are unaware).

For example, consider these metrics:
[ ] jam resistance
[ ] stability

And possible applications:
[ ] life critical (eg climbing)
[ ] yachting
[ ] fishing
[ ] camping

#1053 Butterfly is vulnerable to jamming when eye loaded.
When through loaded from SPart to SPart, it is jam resistant.

If you don't mind a composite knot, #1763 Prusik hitch actually provides an omni-directional attachment point (which can be adjusted up/down a line).
Another interesting composite I have been experimenting with is dual #1074 Bowlines (tied in opposition). Bring the 2 eyes together and you have an omni directional attachment point.

If you state that the knot is for life critical applications, it casts everything in a different light.

KC

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #4 on: April 15, 2020, 11:31:02 AM »
i think angle of pull on Butterfly and tension ratio change things some.
Best if eye is loaded less/if at all; and best if angle of pull is perpendicular.
>>this will pull more evenly to both sides of mainline than lengthwise pull
>>and maintain 'dominance' to both sides of eye from the mainline proper.
.
At lengthwise pull, pull on eye is to 1 unbalanced tension side of mainline axis
>>i think this imbalance gives distortion that dominoes to problems.
Prussik as mentioned also good as sited, can get some slip on lengthwise per loading and materials
>>unless sits on B'Fly as shelf, that is found to be a different matter.
.
i like knowing the pull direction on prussiks to set by pulling outwards 90degrees to tighten
>>then in anti-travel direction and groom, then fold down to user position.
Prussiks to me are dual legged, sharing load to 1 full load line of greater tension thus rigidity
>>lesser half tensioned/'softer' prussik legs should then be formed in smaller/tighter diameter
>>who's rigidity would more match or exceed the double loaded (from prussik perspective) mainline .
Friction Hitches like Taut Line, Blake's etc. that have single input leg of pull are more likely to work without being smaller than mainline.
>>prefer prussiks for this app if friction hitch used, and if can't get smaller/tighter, B'Fly shelf makes more usable
.
Never done that bi-directional tho, but w/o making 2nd B'Fly shelf , should be able to reeve prussik leg thru eye as 2nd restrictor to prussik drift.
« Last Edit: April 15, 2020, 11:43:05 AM by KC »
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SS369

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #5 on: April 15, 2020, 02:38:02 PM »
When I tie the #1053 Butterfly I use the three coils on my hand method.
I suggest trying four coils using the same method (or any method with the same result.), passing the coils over three times and then through them all.
Using climbing rated rope and cords I have not been able to jam the loop after loading in any direction.
I haven't tried itty bitty strings of soft materials.
It seems that the additional turn within the nub adds sufficient bulk to offset jamming.

SS

jimmyh

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #6 on: May 02, 2020, 11:45:37 PM »
It gets a bit bulky, but for omnidirectional loading I've had good luck with this one tied in a bight.

agent_smith

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #7 on: May 03, 2020, 12:53:53 AM »
per jimmyh:
Quote
It gets a bit bulky, but for omnidirectional loading I've had good luck with this one tied in a bight.
Hello jimmyh, strictly speaking - and going directly off the knot image you offered... this is not helpful to the original poster.
The specific knot image you posted isn't TIB and it isn't in the form of an eye knot (ie loop knot).
Its actually a rotated variant of #551 from 'ABoK'.

It would helpful if you could post an actual 'TIB' eye knot based on your posted image.

Original Posters question:
Quote
Is there a knot to make a loop that can be loaded in all directions with tails that can be loaded in all directions?

KC

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #8 on: May 03, 2020, 11:42:57 AM »
i think it is ok if a thread is free ranging, not locked to focus of single question, as grab wider scope.
Especially if it then helps explain bigger picture, to perhaps allow to show original question's placement in this bigger sea ;
to then give target some definition.
.
Then too, many times it is the thread's journey, not destination target that get most out of.
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jimmyh

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #9 on: May 04, 2020, 07:31:35 PM »
Simply take a bight and tie the same knot. You will end up with every part of the knot doubled over and a loop on one end. Think figure eight stopper knot:figure 8 loop::this knot:______

agent_smith

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #10 on: May 04, 2020, 11:28:43 PM »
per KC:
Quote
i think it is ok if a thread is free ranging, not locked to focus of single question
????
I would suggest to you that the moderators may hold a different view.
If someone asks a question - you should make a reasonable effort to answer the question (and I would have thought such a concept to be obvious).

Politicians are notorious for evading the crux of a question.
They are masters at answering a question with actually answering the question!

Be that as it may, it might be acceptable to explore and add some related concepts and insight - BUT, you should first make a reasonable effort to answer the question.

per jimmyh:
Quote
Simply take a bight and tie the same knot.
Yes - but... your posted photo is not so (and thats my point).
In any case, when it is through loaded (axially from SPart to SPart) - that knot core and eye are offset (ie offset from the axis of tension).
In experimenting with this structure in offset loading profile, it appears to resist capsizing (which is good).
When eye loaded, it is also stable and secure.
As for resistance to jamming, I cant comment because I didn't investigate it.
In terms of the amount of rope consumed to create the knot, it is not insignificant (which is not so good).
Complexity of tying is more so than in comparison to #1053 Butterfly.

I think Groundline's earlier suggestion of #1053 Butterfly neatly and succinctly answers the original posters question.

KC

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #11 on: May 04, 2020, 11:54:04 PM »
I apologize, it is up to the moderators to say; fair point.
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jimmyh

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #12 on: May 05, 2020, 01:49:39 AM »
Quote
Yes - but... your posted photo is not so (and thats my point).

Right... Which is why I specified that it must be tied with a bight instead of as pictured. I'm not sure why you're speaking as if I don't know what I posted?

It's just easier to see what's going on when there are less strands everywhere.

Quote
I think Groundline's earlier suggestion of #1053 Butterfly neatly and succinctly answers the original posters question.

Except that the butterfly loop jams when eye loaded, as a wise poster noted upthread ;)

SS369's solution to that is neat, and perhaps one of the better solutions. I haven't seen it before and will have to play with it.

Quote
Complexity of tying is more so than in comparison to #1053 Butterfly.

I find it actually quite simple to tie. Fold your rope in half and tie a slip knot with the doubled over rope, then pass the end through the loop formed. If you want to get the symmetric and pretty version, you have to make sure do a half twist before passing through the loop, but it doesn't really seem to matter all that much.

agent_smith

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #13 on: May 05, 2020, 03:24:00 AM »
jimmyh:

Here is your original post in relation to OP's question:
Quote
It gets a bit bulky, but for omnidirectional loading I've had good luck with this one tied in a bight.

In reply to your new propositions...
Tied-in-the-bight has a different meaning to tied with a bight.
Refer to #1074 Bowline with a bight for background info.
Another good example is a bend (ie end-to-end joining knot).
It is possible to tie most bends 'with a bight'.
Just to be clear, that's not the same as stating that the bend is 'TIB'.
TIB in its purest definition simply refers to condition where the knot can be tied without access to either end.

Yes - the knot as you propose is 'TIB' - by that definition.
And, it can also be tied with a bight! (which is also good!).
However, when through loaded from SPart to SPart the knot core and eye are offset.
Whilst an offset knot by itself isn't a show stopper, it does require further investigation to assess the ability of the knot to remain stable and secure in the offset loading profile.

Your comment re jamming of #1053 Butterfly is misplaced.
Yes - #1053 jams when eye loaded BUT - only when the load goes beyond a certain threshold.
Mere body weight is not sufficient to induce jamming. Were you aware of this fact?

The original poster did not state precisely how much load his knot would need to withstand.
If its body weight only (and indeed up to around 2kN), Butterfly works fine (when eye loaded).

Quote
It's just easier to see what's going on when there are less strands everywhere.
The idea behind posting your initial image would have been excellent had it been also accompanied with the 'TIB' version!
Also, not all readers/visitors to IGKT are fully savvy with all the concepts - so it makes sense to provide them with all the information they need to understand (not isolated pieces).

By the way, have you also experimented with #551 tied with a bight? It would be based on #1425A (Riggers bend).
Also, your presentation and #551 (tied with a bight) have not been fully investigated to determine jamming threshold.

jimmyh

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Re: Omnidirectional-loaded loop with omnidirectional tails?
« Reply #14 on: May 05, 2020, 08:05:39 PM »
Quote
Tied-in-the-bight has a different meaning to tied with a bight.
Refer to #1074 Bowline with a bight for background info.
[...]
Just to be clear, that's not the same as stating that the bend is 'TIB'.

I'm familiar with the difference between a "bowline with a bight" and a "bowline on a bight", as well as the acronym "TIB" for "tieable in the bight". Yes, I suppose "with" would have been the better choice of word here, but I figured that the meaning would be clear given that the knot pictured is clearly neither TIB nor an eye knot, and that the method of tying can't be relevant unless you're actually forming a different structure.

Out of curiosity, was this a genuine misunderstanding, or a roundabout way of reminding me of the proper nomenclature?


Quote
Your comment re jamming of #1053 Butterfly is misplaced.
Yes - #1053 jams when eye loaded BUT - only when the load goes beyond a certain threshold.
Mere body weight is not sufficient to induce jamming. Were you aware of this fact?

The original poster did not state precisely how much load his knot would need to withstand.

Sorta seems that last line there sorta invalidates your point here, don't you think? If OP had specified conditions under which the butterfly loop doesn't jam then the jamming wouldn't be relevant. Since it wasn't specified, it sorta seems like the topic remains omnidirectional-loaded loops in general, where jamming of 1053 is a relevant drawback.

Certainly you seemed to think so upthread.


Quote
If its body weight only (and indeed up to around 2kN), Butterfly works fine (when eye loaded).

Depends on what you're tying it with. Try loading paracord that way with body weight and then untying it. No knot jams if you load it lightly enough in thick enough line.

Doesn't make 1053 a good knot for general purpose omnidirectional loading. I learned that one the hard way.

Quote
By the way, have you also experimented with #551 tied with a bight? It would be based on #1425A (Riggers bend).

I don't believe I have. This is actually really interesting, since "connecting the tails of a bend and tying with a bight in order to form an eye knot" is the exact process I was trying to achieve when I found this knot, only I don't think I ever found this particular (and quite aesthetically pleasing) knot partially because I wasn't actually familiar with the riggers bend. I was *aware* of it, but never looked at it in any detail because of it's reported tendency to jam, and it seems like the zepplin bend is a strictly superior knot. The thing that makes it interesting though, is that the same thing that kept me from learning more about the riggers bend is the same thing that steered me away from discovering "#551 tied with a bight".

As a general rule, overhands with something passing through them are more more prone to jamming when both the incoming and outgoing lines are on the same side of the thing passing through the center. As far as I can tell, there are two reasons for this. One is that the line has to bend around a larger angle before getting to the part where it binds and the capstan equation says that more angle means less tension, and less tension means less jamming. The other is that there is a bit of a "collar" formed, and there's always that space under there that doesn't get cinched down with tension. This allows loosening in the same way one would loosen a bowline.

For example, in the butterfly loop there are two interlocking overhands. There's one of each type, and the one that jams more is the one that doesn't have the incoming and outgoing lines separated. In comparison, Ashley's bend two of the less jam prone type, and in my experience doesn't jam so much when you pull on the tails (e.g. when making a loop in the same fashion one makes a "zeppelin loop" from a zepplin bend (hope I'm not opening a can of worms here)). Too bad there's no TIB Ashley's bend equivalent of the butterfly loop.

Since #551 has both knots of the more jam prone variety, and riggers bend is known to jam, I would bet fairly confidently that it would retain that greater propensity to jam than the knot I presented above.

Quote
Also, your presentation and #551 (tied with a bight) have not been fully investigated to determine jamming threshold.

You mean "by you"? Or are you claiming to know that no one else has ever investigated it either? The latter seems like quite a bold claim :p