Author Topic: Butterfly bend eye knot  (Read 3014 times)

Dan_Lehman

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Re: Butterfly bend eye knot
« Reply #30 on: March 17, 2018, 09:47:33 PM »
And there is no A versus B in the corrupted sense you are implying.
??
I wrote no "A"/"B" and don't follow your reference
to some such dichotomy loosely so labeled?!

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With reference to eye loading...
Quote
HOW MIGHT THIS BE LOADED IN <what___?> PRACTICE?

This remark demonstrates a surprising lack of knowledge on your behalf.
Eye loading is common!
1. it occurs in anchor systems
2. it occurs within indoor climbing gyms
The "Y-hang" anchoring is something I've heard of,
and here the loading is on all *ends*, with a bias
in direction for the eye (but as both SParts are
loaded, neither collar should collapse).
THAT loading situation isn't one that would see
a loading_1 changed to loading_2 AND BACK
--it would go from all-ends-loaded to either
eye- or through-loading.

"Within climbing gyms" ?!  How/why?
(I've not seen it in the gym I've occasionally
dropped in to see what's what (and come away
once w/sample old gym rope --thick stuff).)

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3. it occurs in top-managed belay systems for abseiling.
???

The use with short 2nd-biner-attached-w/strangle_noose
is a sort of bogus use --a bowline on a bight looks to be
a better fit here, where the knot in the butterfly's position
will be eye-loaded and never (I think not?) *through* loaded.

(It was somewhat amusing to see the CMC Rope Rescue Manual's
test results showing the fig.8 eye knot to be stronger than
the inline directional fig.8 when through loaded, and nearly as
strong as the butterfly --whose raison d'etre is that loading !!
--in "Rhino Rescue rope 12.7mm")

--dl*
====
« Last Edit: March 18, 2018, 06:15:54 PM by Dan_Lehman »

agent_smith

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Re: Butterfly bend eye knot
« Reply #31 on: March 18, 2018, 01:11:00 AM »
All of this is drifting waaaayyyy off topic.
However...

per Dan Lehman:
Quote
The "Y-hang" anchoring is something I've heard of,
and here the loading is on all *ends*, with a bias
in direction for the eye

Nevertheless - it is a form of 'eye' loading - which cant be dismissed.
There is loading on the eye - that is the point.
And, the degree of loading on the eye is dependent on alignment of force through the load focal point. A small shift left or right will cause loading bias to also shift.
Rope access operators commonly and routinely use this type composite anchor system. I perform a lot of rope access work - and use it regularly myself.

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"Within climbing gyms" ?!  How/why?
Dan - you might want to stop here, as it is apparent to me that there are holes nearly as big a black holes in your knowledge and understanding of this subject area.
I could write an entire book on this subject area alone.
I will throw you a bone though - one of the many reasons why indoor climbing gyms use dual clip-in systems is to reduce human error (and related to that is risk of litigation in a court).
Think about it...in a commercial climbing gym, you get all kinds of experience levels - from absolute novice, to very experienced and all shades in-between. You also get a w-i-d-e variance in age levels, which means you get widely varying levels of maturity and appreciation of risk.
Allowing inexperienced customers to tie-in to their harness with a knot is inviting risk (and I would have thought that you would understand this?).

Now - some proprietors (ie owners) of climbing gyms are business people first - and climbers a distant last. They typically dont understand the subtle yet ever present risks of the various methods of attaching  climbing rope to a climbing harness (at a workplace - remember that a climbing gym IS a workplace). I spend a lot of time giving advice and consultancy to business owners of climbing gyms. Many of the accidents that have occurred in climbing gyms relate to rope attachment/connective issues. The other risk area is with 'human belay' related incidents. That is why 'auto-belay' units such as the 'TruBlue' are becoming more popular (you eliminate the human from the belay chain). Although, for lead climbing, you still need a human belayer.

A pre-configured dual clip-in system removes the need to tie-in with a knot (you eliminate that area of risk).
The reasons go on and on and on... here is another: Think of staff who work in a climbing gym. They have to patrol/roam the floor always being vigilant and observant for human error. Mistakes can and do happen regularly. This puts pressure on staff to always be alert and on their game. And staff cant be everywhere, all of the time. Dual clip-in systems reduce the burden of this pressure on staff. Also, carabiners that employ triple-action self-locking gates further eliminate human error (screw-gate carabiners invite risk).

A further benefit of this loooonnnnng list is that it also eliminates the tedious, repetitive and time consuming need for staff to teach a customer how to tie-in with a knot. Think about it...with dual clip-in systems, it makes the job of the staff easier because they dont have to invest large chunks of time repetitively teaching customers how to tie-in (when indeed some of those customers have short memories and 'forget' what they were taught - or worse, some customers simply dont care or dont appreciate risk).

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The use with short 2nd-biner-attached-w/strangle_noose
is a sort of bogus use
Oh dear, you might want to stop here Dan---seriously, this is getting a little embarrassing.
There is another loooonnnnggg list of reasons why you use a #409 noose structure to secure the safety belay carabiner on top-managed belay systems to safeguard novice abseilers (eg school children).
I normally charge out my consultancy services, but, I'll give you some free advice:
Think novice abseiler. Think children (for example).
When a school child abseils down and reaches the safety of the ground, they need to unclip the safety belay carabiner from their harness. You definitely dont want them to fiddle around and try to untie the knot that secures the rope to the carabiner.
So you cinch a #409 noose hard up against the carabiner to make it virtually impossible for a novice abseiler to untie/remove the safety belay rope from the carabiner. You have to make it easy for novice abseilers at a workplace...you need your safety systems to be near foolproof as possible.

Using a #409 noose to attach a safety belay rope to a carabiner also prevents risk of misalignment/cross-loading - because the rope is held captive against the carabiner, everything stays in the correct alignment (so if you dont have a carabiner with a captive pin or captive eye, the noose still holds the carabiner in the correct alignment).
#409 noose attachment also prevent 'gate fold-over' - a risk where a person can inadvertently miss-clip a carabiner - on captive pin style carabiners - causing the rope to realign on the pin only - resulting in catastrophic failure (which has happened).


Hmmmmm
« Last Edit: March 18, 2018, 01:13:21 AM by agent_smith »

Dan_Lehman

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Re: Butterfly bend eye knot
« Reply #32 on: March 18, 2018, 06:34:57 PM »
Quote
The use with short 2nd-biner-attached-w/strangle_noose
is a sort of bogus use
Oh dear, you might want to stop here Dan---seriously, this is getting a little embarrassing.
Not to me.  And note that :: I questioned the use of
the butterfly --our topic-- and not the noose;
I questioned the need for the knot in the B's place
to endure "through" loading --and absent that,
there are better knots to be eye knots.

And ditto for the other case where vice the noose'd 'biner
is a fig.8 eye knot.

And in all of this, wondering about whether the butterfly
--or substitute-- will be loaded back'n'forth in direction,
unlike what is tested (just a set knot and one way).

--dl*
====

agent_smith

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Re: Butterfly bend eye knot
« Reply #33 on: March 19, 2018, 08:52:41 AM »
Lets see, where were we?

I think with all the 'a' versus 'the' and 'eye-loading' versus 'through-loading' (ie bi-axial SPart loading), claims of non eye loading, and further claims of bogus use of the secondary dual attachment for indoor climbing gyms (for top rope climbing applications) and claims to restrain the definition of loading on the eye of the composite knot anchor system using Butterfly and F8...I'm lost.

1. In terms of the word 'a' versus the word 'the' - ok, on this social forum, how much scrutiny must a poster give to grammar errors - is there a minimum grammatical standard that must be achieved by forum posters? Its hard to catch all typos and grammar errors. Indeed, on many social media sites, errors abound.

2. In terms of eye loading issues - well, all I can say is that eye loading on Butterfly knots does occur - and depending on industry and application - it is reasonably common. So eye loading occurs - as opposed to not occurring.

3. Bogus use of second attachment point to harness...obviously in the event of primary connector failure, 100% load will transfer to the secondary (downstream) connector. 'Through loading' (bi-axial SPart loading) will occur on the Butterfly knot so that is why it is configured in this way. An eye loaded Butterfly knot isn't the only method - there are several alternative connective options available.

4. Constrained definition of what constitutes 'eye loading' on the composite anchor system built from a Butterfly knot and an F8 knot. No matter what constraint is placed on the definition, there is definitely load transferring through the eye. The degree of loading on the eye is significantly affected by the alignment of load. A small shift left or right of axis causes changes in % loading to each termination anchor point.

Mark G

Dan_Lehman

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Re: Butterfly bend eye knot
« Reply #34 on: March 19, 2018, 10:57:40 PM »
Perhaps you have your own Trump of a mess Down Under?

'the' and 'eye-loading' versus 'through-loading' (ie bi-axial SPart loading),
You'll need to explain your invention with "bi-axial",
for the net doesn't help.  There is one axis of tension
in what I point to via "through" loading --just the SParts,
not the eye.  "Biaxial" (that's Google's not my preference
--I believe in hyphens!) makes sense if eye AND BOTH
SParts are loaded, I guess; but that's contrary your
equating it w/"through" per my use.

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claims of bogus use of the secondary dual attachment for indoor climbing gyms
My "bogus" was not for the 2nd attachment
but for the nature of the knot in 1st, esp. thinking
of those uses where the 2nd is a short lanyard to
clip while unclipping & repositioning the main one.

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1. In terms of the word 'a' versus the word 'the' - ok, on this social forum,
how much scrutiny must a poster give to grammar errors -
But IS it a diction error or intended?
THAT is what was questioned --that there is THIS,
"THE" way (which excludes an alternative).

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well, all I can say is that eye loading on Butterfly knots does occur - and depending on industry and application - it is reasonably common. So eye loading occurs - as opposed to not occurring.
Again, my question was in what cases might loading
change BACK from one to another,
such that the later loading confronts a knot already
seriously *set* via the first loading that isn't what
a knot tester would likely have tested :: i.p., if loaded
on the eye vs. one SPart such that the collar tightens
around the unloaded SPart and collapses,
AND THEN might there be a later through loading
which would encounter this *deformed* butterfly
(one wing broken) ?!


--dl*
====

agent_smith

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Re: Butterfly bend eye knot
« Reply #35 on: March 20, 2018, 12:47:55 AM »
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You'll need to explain your invention with "bi-axial",
for the net doesn't help

Are you opposed to new thought or originality?
Maybe its because I spelled it bi-axial instead of biaxial?
I threw a hyphen in there in case the word was too foreign or unknown - to make it clear that there was a 'Bi' (as in dual or 2 directions at once).

Lets run with 'biaxial' if that assists in your understanding.

I used the term 'Biaxial SPart loading' to be clear and distinct from eye loading.
So yes - biaxial SPart loading (in this case) means the same thing as your preferred use of the term 'through loading'. Although 'through loading' could potentially be misunderstood by some - so that's why I tried to be explicitly clear that i meant loading on both SParts simultaneously along the axis of tension...such that the 'eye' is isolated and experiences no load.

Phheew...!

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My "bogus" was not for the 2nd attachment
but for the nature of the knot in 1st, esp. thinking
of those uses where the 2nd is a short lanyard to
clip while unclipping & repositioning the main one

You like to use bogus and other such terms when it conflicts with your understanding - in an attempt to dismiss the alternative view.
The short lanyard you refer to is predominantly used on 'auto-belay' systems which are self-retracting (eg the 'TruBlue' unit).

The dual attachment system I showed was not for use on an 'auto-belay' system.

The dual clip-in /attachment system is required in some jurisdictions in Australia (due to court cases setting a legal precedent).
If the primary connector fails or accidentally disengages from the users harness (via a failure mode known known as 'roll-out') - all load will shift to the secondary 'downstream' connector. This will result in the Butterfly knot being subjected to a biaxial SPart loading event. There's that word 'biaxial' again :)

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THAT is what was questioned --that there is THIS,
"THE" way (which excludes an alternative)
...other than to say that there is no intention to imply that a depiction of the form of a Butterfly knot is 'The' only correct form - the Butterfly can take on several different forms - which is related to chirality and also crossing the eye legs in the 'X' form. So it isn't so much a case of 'The' Butterfly...rather 'A' Butterfly. I'm closing out on this area of discussion as it is bordering on tedium.

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Again, my question was in what cases might loading
change BACK from one to another,
such that the later loading confronts a knot already
seriously *set* via the first loading that isn't what
a knot tester would likely have tested

Its hard to glean (at times) from the construction of your sentences what your real underlying intent is.
If testing is the primary thrust of your entire monologue - than all I can say is that knot testing done on #1053 Butterfly knot is not conclusive and many questions are yet to be answered.
In my view, its nearly the same as the situation with #1410 Offset overhand bend. Testing appears to be limited to the default 'lets just pull it till it fails' mentality. Gather some MBS yield (break) numbers and then pop the champagne cork.

I would go so far as to say that the entire subject area of knot testing (around the world) - is generally abysmal. This may be interpreted quite negatively but, that is my personal view. It is not directed at any individual - rather the state-of-the-art in knot testing is primitive compared to other engineering disciplines. I wish I could do better myself - but I don't have a test facility.

Richard Delaney (rope test lab) has done some testing of the Butterfly (TIB mid-line)... and there is this lengthy thread too: https://igkt.net/sm/index.php?topic=5290.30 which bogs down on statistics and measurement accuracy.
« Last Edit: March 20, 2018, 01:08:21 AM by agent_smith »