Author Topic: Butterfly bend eye knot  (Read 3005 times)

Harold Kahl

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Butterfly bend eye knot
« on: February 26, 2018, 02:44:40 PM »
I tied the butterfly bend as two interlocking overhand knots. Then using the same method, I made a loop, or eye knot, by treating the tail of the first overhand knot as if it were a second line. Is this eye knot an already known and named knot?
https://youtu.be/cgYfbT_4sIw
https://youtu.be/-ywy0DJQnZM

agent_smith

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Re: Butterfly bend eye knot
« Reply #1 on: February 26, 2018, 03:33:41 PM »
Quote
Is this eye knot an already known and named knot?

Answer = Yes
By whom? Xarax (several years ago)
He also went so far as to conjecture that "if you have tied a bend, you have also by definition tied its corresponding eye knot".

The idea of that 'bends' have corresponding eye knots is a topic that has been explored in some detail by several knot tyers on this forum.
For example:
[ ] Zeppelin bend: Corresponding eye knot = Zeppelin eye knot
[ ] #1415 Double fishermans bend: Corresponding eye knot = Double fishermans eye knot
[ ] #1425A Riggers bend: Corresponding eye knot = Riggers eye knot

and so on...

In the case of #1053 derived Butterfly bend, the corresponding eye knot has the tail inside the 'eye'.
I have not seen or known that it is possible to create the Butterfly eye knot with tail outside the eye.

EDIT NOTE: An interesting exercise is to reverse engineer the Butterfly eye knot.
1. Begin with the #1053 derived Butterfly eye knot (tail inside the eye)
2. Carefully remove the tail (without disturbing the knot core).
3. Re-insert the tail back through the central axis but go in the opposite direction.
4. Congratulations...you have just tied the #1425A derived Riggers eye knot.


Mark G
« Last Edit: February 26, 2018, 03:43:43 PM by agent_smith »

Harold Kahl

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Re: Butterfly bend eye knot
« Reply #2 on: February 26, 2018, 04:14:26 PM »
Thanks for that info. I expected that somebody would have thought of it already. It seems like it would be a useful knot, but I guess it doesn't really do anything that the better known zeppelin loop doesn't.

roo

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Re: Butterfly bend eye knot
« Reply #3 on: February 26, 2018, 04:26:01 PM »
I tied the butterfly bend as two interlocking overhand knots. Then using the same method, I made a loop, or eye knot, by treating the tail of the first overhand knot as if it were a second line. Is this eye knot an already known and named knot?
https://youtu.be/cgYfbT_4sIw
https://youtu.be/-ywy0DJQnZM

David Delaney explored this some time ago:

http://davidmdelaney.com/alpine-butterfly-loop/Alpine-butterfly-bend-loop.html
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agent_smith

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Re: Butterfly bend eye knot
« Reply #4 on: February 27, 2018, 01:57:55 PM »
Here's an image (quality limited by the 100KB file size limit) showing the relationship of #1053 derived Butterfly bend and #1425A Riggers bend.

I had a look at the website roo posted - not really much detail other than (refreshingly) jamming information. Although we know from years of indoor rock climbing gym experience that #1053 Butterfly eye knot (TIB version) jams solid after a week or so of intensive use as part of a dual clip-in system to the climbers harness. Only way to get the darn knot undone is with tools - and even that takes a good deal of effort.  So despite Mr Delaney's assertions - the Butterfly does jam! (Note: In EN892 Dynamic climbing rope - eye loading). Also, it is not conclusive about #1053 resistance to jamming in SPart loading profiles...in EN892 Dynamic rope, tests that I have seen reach a point where the structure was very difficult to untie by hand - with some present who did not have the hand/finger strength to untie the maximally loaded knot.
I note that the image on Delaney's site of the #1053 derived Butterfly eye knot has the tail displaced - in reality - with precision dressing - the tail is actually inside the eye (and not outside the eye as depicted).
He also has odd chosen naming conventions in my view.
For instance - there is a need to distinguish between:
[ ] #1053 (TIB) Butterfly eye knot; and
[ ] #1053 derived Butterfly eye knot (non-TIB version).

Mark G

Edit knot: Clarifications in relation to SPart loading versus eye loading on #1053 Butterfly
« Last Edit: February 28, 2018, 12:53:17 AM by agent_smith »

roo

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Re: Butterfly bend eye knot
« Reply #5 on: February 27, 2018, 07:17:08 PM »
.  So despite Mr Delaney's assertions - the Butterfly does jam!
Where did Delaney state that the Butterfly Loop does not jam?
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agent_smith

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Re: Butterfly bend eye knot
« Reply #6 on: February 28, 2018, 12:28:35 AM »
Quote
Where did Delaney state that the Butterfly Loop does not jam?
Possibly something to do with the intricacies of the English language and your assumptions.
The imputation is that a 'Butterfly' does not jam - as he stated on his website (he wasn't 100% specific in loading profiles for different versions of Butterfly's).
 
When he uses the term 'loop' - I take it to mean 'eye'.
When a Butterfly is loaded from its eye - it jams.


roo

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Re: Butterfly bend eye knot
« Reply #7 on: February 28, 2018, 04:00:46 AM »
Quote
Where did Delaney state that the Butterfly Loop does not jam?
Possibly something to do with the intricacies of the English language and your assumptions.
The imputation is that a 'Butterfly' does not jam - as he stated on his website (he wasn't 100% specific in loading profiles for different versions of Butterfly's).
 
When he uses the term 'loop' - I take it to mean 'eye'.
When a Butterfly is loaded from its eye - it jams.
Again; where?  What URL?  Were you looking at his jam testing of bends?
« Last Edit: February 28, 2018, 04:03:18 AM by roo »
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agent_smith

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Re: Butterfly bend eye knot
« Reply #8 on: February 28, 2018, 04:03:38 AM »
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Again, where?  Were you looking at his jam testing of bends?
2 questions roo:
1. Where are you going with this line of questioning?
2. What do you hope to achieve?

I'm bored.

roo

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Re: Butterfly bend eye knot
« Reply #9 on: February 28, 2018, 04:06:04 AM »
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Again, where?  Were you looking at his jam testing of bends?
2 questions roo:
1. Where are you going with this line of questioning?
2. What do you hope to achieve?

I'm bored.
I'm just not finding where he stated that the Butterfly Loop (eye) does not jam.  Maybe I'm missing it.
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agent_smith

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Re: Butterfly bend eye knot
« Reply #10 on: February 28, 2018, 04:07:55 AM »
Quote
I'm just not finding where he stated that the Butterfly Loop (eye) does not jam.  Maybe I'm missing it.
Why?
What are you hoping to prove?

roo

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Re: Butterfly bend eye knot
« Reply #11 on: February 28, 2018, 04:10:02 AM »
Quote
I'm just not finding where he stated that the Butterfly Loop (eye) does not jam.  Maybe I'm missing it.
Why?
What are you hoping to prove?
At this point, I'm guessing that you must have just misread something on his website.  It's really not a big deal.

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agent_smith

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Re: Butterfly bend eye knot
« Reply #12 on: February 28, 2018, 04:12:44 AM »
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At this point, I'm guessing that you must have just misread something on his website.  It's really not a big deal.
Ah ha...and we come to the real reason.
You wish to uncover an error or point out a failing.
Hmmm

Maybe you misread something roo?
Which part did you misunderstand?

roo

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Re: Butterfly bend eye knot
« Reply #13 on: February 28, 2018, 04:17:22 AM »
Quote
At this point, I'm guessing that you must have just misread something on his website.  It's really not a big deal.
Ah ha...and we come to the real reason.
You wish to uncover an error or point out a failing.
Hmmm

Maybe you misread something roo?
Which part did you misunderstand?
I'm not trying to rub your face in a simple error.  Your impression of his page didn't match mine, and I was trying to see where you were reading.

Have a pleasant evening, Mark.
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agent_smith

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Re: Butterfly bend eye knot
« Reply #14 on: February 28, 2018, 04:48:44 AM »
roo,

Your misunderstanding probably is related to the differing loading profiles and naming conventions for the various forms and derivatives of #1053.
#1053 Butterfly eye knot has different loading profiles.

In SPart loading - it makes no difference whether it is tied in 'bend' form using 2 united ropes or whether it is tied in 'TIB' form using one rope (provided the eye is sufficiently large for the load test so as not to skew results).

In eye loading, it definitely jams.
In SPart loading - the matter is not sufficiently resolved.

I was involved with SPart loading of dual #1053 knots in series a few years back in a facility in NSW Australia.
The knots were maximally loaded to failure (2 Butterfly knots tied in series in the one sample length of test rope).
We did MBS yield (pull to failure) using old/worn EN982 and EN1891 ropes.
There were some in the witnessing group who struggled to untie the surviving knot specimen. They did not have sufficient finger/hand strength to untie the surviving knot.
I was able to untie the surviving specimen but only after considerable effort.
What does this mean?

Delaney suggests that he could not get #1053 derived Butterfly bend to jam.
It is implied that he meant SPart loading and that he meant the end-to-end joining knot and not the eye knot (end of line) that you referred to earlier?
Recall that it is possible to confuse the eye knot version and the end-to-end version of #1053 - given his naming conventions.

My point is that it is not 100% clear-cut that #1053 in SPart loading is totally jam resistant.
I would agree that the Zeppelin bend in SPart loading is totally jam resistant (but not so clear cut with the eye knot version - need to see maximally loaded test samples to confirm or deny).
I have carried out MBS yield tests of the Zeppelin bend (ie maximally loaded - 2 knots tied in series along the one length of rope) - and the surviving knot specimen did not jam.

We would need peer reviewed testing to either confirm or reject that #1053 in SPart loading profile is 100% jam resistant (in human life support ropes).

Mark G