Author Topic: How much redressing makes a new knot?  (Read 14351 times)

Mobius

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Re: How much redressing makes a new knot?
« Reply #30 on: May 14, 2015, 11:04:18 PM »
And, as I've said, I'm happy to call this loop by a different name, after all I cannot keep calling it "this loop", my vote, and it can be neither right nor wrong no matter how close to a Zen master one thinks they have become, is that it would contain butterfly as its middle name, but that is just my "vote" (maybe better to say it's what I'll call it for now since I don't need to take a vote about that anyway).

Let's just use 'Mobius Loop' for now. A simple name for a simple loop, and reading several posts I see that name coming up.

Cheers,

mobius

Tex

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Re: How much redressing makes a new knot?
« Reply #31 on: May 15, 2015, 01:52:50 AM »

? ? ?
I can't help you.  You will find the light when you are ready.

Quote
Read again my trash !  :) Dumb and naive people may be more correct than you think ( or you can imagine...)  :)
If the loop is loaded by, say, 2 units of force ( that is, 1 unit and 1 unit on each eyeleg ), and the angle between the ends is 120 degrees, each end is loaded by 2 units of force.
However, if the same loop is loaded by the same load ( 2 units of force ), and the ends are parallel, each end will be loaded as much as each eyeleg, that is, by 1 units of force, 2 ( = two ) times less than previously !
What "part" of that you do not understand ?  :) :)

but I will try anyway although I know that you must find the light for yourself.  Your post is far to imprecise to clearly describe something such as vector addition.  I think pictures suit your communication style better than words when it comes to technical detail.

I was not arguing about the values of the forces, but the angles.  120 degrees is a huge angle for a loop (at least a couple of adjustable loops will slip FAR before that) and I will assume you were only using that to demonstrate a point.  That's fine.  I cannot clearly decipher your words but if you have three legs tensioned at 120 degrees to each other all three will have the same force (unless the knot part is accelerating).  If one of those is doubled (two standing ends) then obviously each half of the doubled line will have half that force.    If that agrees with what you said, then great.  Of course if two legs are at 120 but unequally tensioned, the third leg then will not be at 120. Let's restrict ourselves though for the moment to cases where the two eye legs are equally loaded.

But this was not my point.  My point is that if two equally loaded eye legs are at 120 degrees the one tensioned standing end must point straight between them.  If two eye legs are at 10 degrees and equally tensioned, the one tensioned standing end must still point straight between them, now only 5 degrees off of each from parallel, and in either case (10 or 120) the standing end at least is at the same angle relative to the knot structure.  As for the eye legs being at various angles, well small angles are not uncommon at all, but large angles on the mobius correspond to a non-straight parent line on the alpine. So, as I said, the important difference is not the angle of loading so much as it is which line is not loaded, and even that can be reconciled by situations for either which would be outside their idyllic knot tyers view of their use, but not outside of realistic expectations.  Ropes are quite often improvisational tools. 

The difference in the end, comes down to not even angle or loadings that are possible or even will certainly happen, but that for different configurations different angles and loading are more convenient or likely.
It is the relationship between the possible loadings and angles to the manipulation of our attached  object and rope that has changed.   We have to do different things with our things to create the same loadings and angles for the two configurations and so the configurations are in that way different, but do not change  names simply as/when or because the angles and loadings change, well they could I guess, but...

(added:)
What this loop's knot surely shares with its twin loop's identical knot, is that both can tolerate a wide range of abusive loadings BEYOND their ideal use in a particular configuration while still holding.  THIS is maybe the most important property of this knot beyond it's TIB nature, and anyway, both of those properties are the same exactly BECAUSE the knot part is identical.  Differences in these LOOPS will bring some differences in behavior, but the identicalness of these KNOTS (parts) will bring the most important properties especially in a and even because of situations where the knot part loadings become indistinguishable too.  The same cannot be said of the eskimo bowline.




« Last Edit: May 15, 2015, 02:17:55 AM by Tex »

Tex

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Re: How much redressing makes a new knot?
« Reply #32 on: May 15, 2015, 04:05:14 AM »
The community should straighten out its grammar if there is to be any consensus on such things:

From wikipedia, butterfly loop entry:
Quote
The butterfly loop, also known as lineman's loop, butterfly knot, alpine butterfly knot and lineman's rider, is a knot used to form a fixed loop in the middle of a rope.

So does the knot make the loop or the loop makes the knot?  I don't really care.  I'm happy to just call this loop a Mobius (B.) Loop, but I if people's minds really thought entirely of the loop and the knot as indistinguishable, then the sentence would say "knot WHICH FORMS a loop a in the middle of a rope".  It is not a tool used to make a loop, it itself forms (in the sense of takes on the form of) the loop because the loop is part of the it.  And yet, I'd be surprised if a single person here would have even stumbled in the slightest on that sentence as it is now, if not for this conversation at least.  Why, because the grammar parses fine at a very subconscious level, the way that it is written now.

Tex

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Re: How much redressing makes a new knot?
« Reply #33 on: May 15, 2015, 06:48:59 AM »
Wow xarax ok, so you want to talk about 4 leg loading? That's fine(and I did some). I don't disagree with your "point". If we're talking about 4 leg loading then I think we're already talking about unusual cases and once we go that way it becomes all the more easy to find analogous (I almost said parallel ;))  loading scenarios as I hinted at, especially in improvised versa-tackle like constructions as just one example.

ex here:
http://www.southee.com/Knots/Versatackle3.jpg

If you take the standing end, wrap it back around the bottom door knob and off to somewhere else to load it again, then that bottom loop is loaded by 4 lines in parallel, and it makes little difference at all which way the knot part is oriented.  Does our Mobius B. loop suddenly transform into a Schrodinger loop when this is done?  I say no, because it's not the loading that defines the configuration.  It's still a Mobius B. loop (if it was to start with) (and yet the knot part itself is now indistinguishable in all respects).

As an end loop I think kind of by definition you have 3-line loading, and as a midline loop you often (usually?) do too, but of course you can use either as a mid-line loop too if you want and you can load it from 4 legs if you want.  Anyway, I kind of covered all that pretty well I think.

As I said it's not so much the different loadings and angles that make it a different configuration as it is the potential for how to create those loadings and angles in relation to manipulating our things that makes it a different configuration.  We can with either one, produce most any loadings and angles if we try hard enough, although some are easier to imagine than others. 

Anyway I started this by saying that difference in angles in particular, especially angles, are not the main point and I still certainly stand by that.  Any 3-leg loading with near parallel eye-legs has nearly the same angles, ie 0 and 180 and this is probably the most common loading scenario there is for either form.  You kept talking about loading angles. Yes there are still differences in those 3-leg loadings and I never said otherwise. 



« Last Edit: May 15, 2015, 06:53:06 AM by Tex »

Mobius

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Re: How much redressing makes a new knot?
« Reply #34 on: May 15, 2015, 11:44:41 AM »
Wow xarax ok, so you want to talk about 4 leg loading? That's fine(and I did some). I don't disagree with your "point". If we're talking about 4 leg loading then I think we're already talking about unusual cases and once we go that way it becomes all the more easy to find analogous (I almost said parallel ;))  loading scenarios as I hinted at, especially in improvised versa-tackle like constructions as just one example.

I have no way to conveniently test 4-way loading on my test rig at the moment, so I tested the Mobius Loop (or Mobius B. Loop if you prefer :) ) end-2-end with no load on the loop. As I expected, the knot collapsed to a Butterfly, at around 80kg load.

The Mobius Loop wasn't designed to handle end-2-end loading and it doesn't. That is so if you are not happy about rope parts 'twanging' under load and the knot taking another form even if that form is the Butterfly Loop. You cannot have it both ways, so the Mobius Loop 'fails' under end-2-end loading for me.

Perhaps interestingly, I can untie an end/eye loaded Mobius Loop loaded to near break force (132Kg with a break force ~140Kg), yet the Butterfly Loop I inadvertently ended up with tonight was rock solid after 80Kg and I can't untie it by hand.

Cheers,

mobius.


Mobius

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Re: How much redressing makes a new knot?
« Reply #35 on: May 15, 2015, 01:45:52 PM »
   The test you had performed is interesting, but irrelevant, because the Mobius loop is NOT a "Reversed Butterfly loop" !
   You should start from a Butterfly loop, spread its eyelegs, make the collars of its ends approach each other, so the ends themselves become parallel, and then load this thing ex-eyeleg-to-ex-eyeleg ! I expect that THIS knot is going to capsize to a Butterfly loop - and so it will be proved that the "reverse" of the Butterfly loop is the Butterfly loop itself.
   You should better load the Mobius loop as it is, eyelegs-to-ends ( the one, the other, or both ends ) - but LOAD it heavily ! If it is stable, and does not capsize to anything else, then we have a new stable, nice end-of-line loop ( NOT an in-line loop...), the Mobius loop.

LOL, just as well I thought the trial I did was relevant, and who knows, someone else might think so too :) I did the test because I was  interested to see just how versatile I could be with the loading of the Mobius Loop. It changed form about 80Kg, so it showed some resilience to collapse. Nothing is perfect and I didn't expect too much.

I have already trialled the knot eye legs-to-ends (I guess we could call that a 3-way loading) several times, all were at break load or near to it. The knot has stayed stable in every trial, however that is only for my material (3mm 'smooth' 16 plait braid).

Cheers,

mobius
« Last Edit: May 15, 2015, 11:28:51 PM by mobius »

Tex

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Re: How much redressing makes a new knot?
« Reply #36 on: May 15, 2015, 04:09:12 PM »
The test is quite interesting.

Apparently the barrier between these states of the system is not so high in some directions.

The test is in particular interesting because it also tells us something about the other knot that uses the same knot.  This capsizing must also occur if a normal Butterfly is ring loaded heavily with no parent loading.  But again that this capsizing does not fail is not some accidental discovery at this point in history.  If it did fail, this knot would not be a knot that gets talked about so much. 

But, we are only allowed to think about what these knots do when they are used according to the 10 ten commandments of The Great One (except he decries that we can consider 4 leg loading), so with that considered, this might not really be so interesting after all ;) 

Tex

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Re: How much redressing makes a new knot?
« Reply #37 on: May 15, 2015, 04:14:27 PM »
... and what is im"proper" about thin cord? 

Sweeney

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Re: How much redressing makes a new knot?
« Reply #38 on: May 15, 2015, 05:39:21 PM »
... and what is im"proper" about thin cord?

Nothing in itself but whether a knot behaves the same way in rope is an open question.  In practice rope is likely to be used so this is potentially important.

Tex

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Re: How much redressing makes a new knot?
« Reply #39 on: May 15, 2015, 11:38:25 PM »
Sure Sweeney, no disagreement from me on that.

I wonder too how much difference pre-tightening the eye legs makes.  It is obvious that SOME pre-tightening is required, to resist capsizing.  The question is, does more help more. Mobius you gave these loops a firm tug of the hand before doing this?

Mobius

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Re: How much redressing makes a new knot?
« Reply #40 on: May 16, 2015, 12:14:25 AM »
... and what is im"proper" about thin cord?

Nothing in itself but whether a knot behaves the same way in rope is an open question.  In practice rope is likely to be used so this is potentially important.

For sure, and I have said as much myself several times in previous posts.

The whole purpose on building a test rig was for me to do a few trials with knots I was interested in and provide some feedback to the forum about whether that knot might show promise in other applications.

The 3mm braid I am using is 'stiff' and getting the nub to dress well is somewhat of a challenge before I even start loading it. I don't know much about ropes and knotting is a new hobby for me, however from what I have read, tying a larger diameter 'static' rope (say 11mm) used in caving/rescue is at least a little bit like my trial rope. I suspect a larger diameter rope would actually be easier to handle than the material I am trialling with. Untying loaded 3mm rope isn't much fun. The rope diameter is small enough that it makes just about any knot a little challenging to tie, dress properly and then untie after load.

 
The knot has stayed stable in every trial

  I do not even think of such a thin "rope" as a rope at all ! It is more "a cord" - and we just do not know yet if knots behave the same, in all scales... I believe you should try your knot on a "proper" modern rope, a climbing / rescue kernmantle one - and when it is loaded with much heavier loads, of course. In my preliminary trials, it seems it is stable - but I have not loaded it as much as I should...

Be a little kind please xarax  :) It seems my photography skills are inadequate and now my testing methods are too. I have already done more testing on this new knot than 99% of other new knots get. And if I report that the knot shows stability and was easy to untie, then rather than negating that maybe consider those findings as sign of promise  ;)

Cheers,

mobius
« Last Edit: May 16, 2015, 03:33:42 AM by mobius »

Mobius

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Re: How much redressing makes a new knot?
« Reply #41 on: May 16, 2015, 12:59:23 AM »
Sure Sweeney, no disagreement from me on that.

I wonder too how much difference pre-tightening the eye legs makes.  It is obvious that SOME pre-tightening is required, to resist capsizing.  The question is, does more help more. Mobius you gave these loops a firm tug of the hand before doing this?

Yes, I tried my best to dress it well, I tugged on everything and got my glasses out to see if the nub looked reasonable  8) .The material I'm using (quite good quality for what it is I think; blind cord; starter cord) tends to want to spring apart. I actually don't mind this in terms of trialling since if the trial still goes well it gives me even a little more confidence that the knot might be useful in 'real life' applications with larger material.

The other thing I tried to do was cross the legs. To me there was a possibility of setting the legs in a way that would resist end-2-end loading. That was really hard to do in my material, it just wants to spring open. Also, white cord is hard to see when all together in the nub, so seeing the legs were where I wanted them was a bit tricky. Anyway, if the knot still holds after less than optimal dressing, then that is another good sign.

Cheers,

mobius

Mobius

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Re: How much redressing makes a new knot?
« Reply #42 on: May 16, 2015, 02:20:32 PM »
Be a little kind please xarax  :) It seems my photography skills are inadequate and now my testing methods are too.

  I manage to become kind, only if and when I am sincere - and I tell the truth as I see it.
  In my opinion, your photography can be improved very much and very easily, if you only follow the small tricks I had suggested - and your knots can be explored, understood, and possibly improved, if you really test them ( systematically, under laboratory, repeatable conditions - you did not : you had just tried them...) - and, first of all, if you tie them on thicker, stiffer and rounder ( not "compressible" ) ropes.

I am only doing home trials and the rig I designed and built just won't do large diameter ropes. As I said before, perhaps consider my results based on small diameter rope as a promising sign if I say the results  were good. In most cases 'good'  will only mean the knot was stable, or broke at a given percentage of breakload in my material. If that isn't enough for you, please refrain from giving me more negative comments about the results I do give. I am not building a Test Facility that will handle larger ropes safely just because you see fit to criticize what I have already done.

As for photography, I am tying knots as a hobby, not taking photos. As many posters don't go to the trouble of providing images, those that do so need not be chastised by you for not meeting your exacting standards. The advice you gave me more recently is far more helpful than telling me firstly that I "deliberately blurred" my pictures. As it turns out I think I will shortly buy a short length of good rope material and try to improve my photos at least a little.

Sincerity and telling the truth are fine qualities. Though, perhaps if you cannot be kind you can try diplomacy instead? It may achieve wonders  8)

Cheers,

mobius

« Last Edit: May 16, 2015, 02:45:23 PM by mobius »

Tex

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Re: How much redressing makes a new knot?
« Reply #43 on: May 16, 2015, 03:56:54 PM »
I will give xarax some unsolicited advice:  Don't give unsolicited advice and be careful with the word "should".  The first rule can be broken, but only with sufficient understanding first of why it exists.

Xarax's photography tips for that matter seem to be targeted specifically toward smart phone cameras.  Some of it is far from ideal advice for any real camera and applies to conditions where a smart phone isn't going to work amazingly anyway.  However, I was glad he (mobius) took them and they were certainly useful enough to me.
« Last Edit: May 17, 2015, 01:36:47 AM by Tex »

Mobius

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Re: How much redressing makes a new knot?
« Reply #44 on: May 16, 2015, 04:34:32 PM »
   If I were someone else, I would had asked the Moderators to delete this STUPID thing, or LIE / MUD you throw against me, unashamedly  :
   Because THAT is what I wrote ( NOTICE the smileys ! If you do not have glasses, ask me to give you my own ! )
( AND, you blurred the picture as much as you could  :), because it was so much out of focus ! Some better pictures, where you would had pre-load / pre-tighten the loop a little bit, before you take the picture, and its eye legs would not be spread out SOOO much  :), would be much appreciated. )

I should have looked back at your original message, however "you blurred the pictures as much as you could" means pretty much the same thing as if you had actually said I "deliberately blurred" them. The quote might be wrong, however that is not STUPID, that is just a mistake. So instead of admitting that your actions were wrong in the first place (regardless of trying to hide behind the smiley's) you escalate the situation by accusing me of lying.

Somewhere along the line this type of ridiculous behavior has to stop xarax. We are "off topic" and more posts will be deleted. Say whatever you like now I suppose, by the time I get up in morning there will be a bunch more posts missing from this thread, and I won't have to suffer reading more insults from you.

« Last Edit: May 16, 2015, 04:36:43 PM by mobius »