Author Topic: Figure 8 bends  (Read 19553 times)

xarax

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Figure 8 bends
« on: June 16, 2011, 01:55:51 AM »
   The interested reader would probably have noticed an apparent omission on the thread about interlocking overhand knots (1). Starting from the "knot base" of the two interlinked bights, we have enumerated, and labelled, the 7 "black holes" formed. If so, counting the over-the-Standing-End paths of the working end (oSE) , we should have had 7 x 2 =14 different combinations. Yet, we have mentioned only 8. What happened with the rest ?
   The simple answer is that those omitted combinations do not lead to interlinked-overhand-knots ( the theme of the thread), but to interlinked fig. 8 knot bends - or to no interlinked-knots bends at all. So, I decided to have a look to bends made by interlinked fig. 8 knots. ( Some people in this forum would be too quick to characterize such reasoning as "random", probably claiming that they are the only that have been blessed, right from above, with the ability for systematic, rational "thinking"... :) I do not wish to "bother" them, and so disturb, in any way, their deep "thoughts".)
   There are many ways to connect two fig. 8 knots to form a bend ( a "bend", you know, this tangle of ropes that has no known "function" or "use"... :)) The well known fig . 8 bend is only one of them. ( Actually, it is only one of the 17 possible fig. 8 bends, made by retracing one fig. 8 knot.)
    I have tried to interlink the two fig. 8 knots in a way that, presumably, would  be beneficial for the bend s strength, i.e, a way that leads to the widest curves possible. To do this, we have to encircle, with the main, first bight of each fig. 8 knot, as many rope strands as we can. Two quite straightforward implementations of this idea are shown in the attached pictures. The interested reader is advised to try his own hand on this : Try to connect two fig. 8 knots in a way that leads to the widest possible curves on the final bend. It is not difficult, and it yields many interesting good looking bends. The fact that the rope strands in each knot are convoluted so much, is assuring of the good holding power of all those bends.

1) http://igkt.net/sm/index.php?topic=3086.msg18717#msg18717
   
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xarax

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Re: Figure 8 bends
« Reply #1 on: June 16, 2011, 01:58:19 AM »
   A second interesting variation of a two-interlinked-fig. 8-knots bend.
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xarax

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Re: Figure 8 bends
« Reply #2 on: June 16, 2011, 09:26:19 AM »
   Another variation on the same theme .
   Notice the particular way the tails are crossing each other, while going through the main fig. 8 shapes bights - both of them.
   Is it a "complex" knot ? I do not thing so. It may look like such, but, at the end of the day,  it is nothing than two interlinked fig. 8 bends. Due to the fact that we are accustomed of following the lines, and recognizing a properly tied fig. 8 knot, I believe that the bends presented in this thread, are, in fact, simpler than other similar bends ( like the Vice Versa and the Simple Simon bends, for example). All these fig. 8 bends are easily inspected, and if it happens to be tied incorrectly, the mistake is quickly and easily recognized from the first sight, even by a not-so-experienced knot tyer.
« Last Edit: June 16, 2011, 09:27:36 AM by xarax »
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xarax

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Re: Figure 8 bends
« Reply #3 on: June 16, 2011, 05:44:27 PM »
   Now I have examined various fig.8 bends, I see that the C - C bend, shown at (1), can be described as a two-interlocked-fig. 8 knots-bend more accurately than as a two-interlocked-overhand-knots bend. I post here some more pictures of this bend, for an easy comparison with the other previously posted fig.8 bends at this thread.

1) http://igkt.net/sm/index.php?topic=3086.msg18725#msg18725
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SS369

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Re: Figure 8 bends
« Reply #4 on: June 16, 2011, 06:12:50 PM »
I like these knots where the working end is tucked or re-tucked so that the tightening force is around a bulkier section. In my experience with bends, towing, climbing and in use for wood work (construction included), I have yet found to be unable to untie the ones I have used with this feature.

SS

xarax

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Re: Figure 8 bends
« Reply #5 on: June 16, 2011, 06:46:58 PM »
   Thank you, SS369,

   Yes, when we re-tuck the tails of the fig.8 ends posted here once more, through both central bights of the two interlinked fig.8 knots, we get even wider first curves ( so we get even stronger bends). ( The central bights are encircling even more rope diameters) However, I have received complains that the parent beds are already very "complex", so people do not have "the time or the motivation" to tie them...I guess that, when confronted with the less simpe, or more complex, re-tucked siblings of those bends, most of the less interested knot tyers will lose any chance of having learnt something new... However, these re-tucked bends retain the smooth paths into the knot nubs followed by the rope strands of their parent bends, and this is very good : We can inspect the knots easily, and their maximum strength are even higher. I am glad you have brought this issue here : Re-tucking those bends through the two central openings, result in bulkier secure knots with even wider smooth curves.
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knot4u

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Re: Figure 8 bends
« Reply #6 on: June 16, 2011, 06:54:00 PM »
I like these knots where the working end is tucked or re-tucked so that the tightening force is around a bulkier section. In my experience with bends, towing, climbing and in use for wood work (construction included), I have yet found to be unable to untie the ones I have used with this feature.

For example...

knot4u

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Re: Figure 8 bends
« Reply #7 on: June 16, 2011, 06:58:45 PM »
...However, these re-tucked bends retain the smooth paths into the knot nubs followed by the rope strands of their parent bends, and this is very good : We can inspect the knots easily, and their maximum strength are even higher...

I'd make the same guess.  However, unless I've tested strength with a suitable machine, I won't make any assertions there.
« Last Edit: June 16, 2011, 09:46:50 PM by knot4u »

SS369

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Re: Figure 8 bends
« Reply #8 on: June 16, 2011, 07:50:03 PM »
I like these knots where the working end is tucked or re-tucked so that the tightening force is around a bulkier section. In my experience with bends, towing, climbing and in use for wood work (construction included), I have yet found to be unable to untie the ones I have used with this feature.

For example...

For example: I recently constructed a foot bridge (16ft. x 6ft. with handrails, etc.) at my shop, transported it to the site and then had to get it installed over the creek. Using a re-tucked Zeppelin bend to construct a sling and some webbing (around a tree to fix the sling stationary) I then dragged it off my trailer (driving out from under it) to partially cross the creek. I took my truck to the other side and using the sling over the truck hitch finished pulling across. Though the bend saw maybe half the weight (approx. half ton) of the effort it took no effort to untie it.
The re-tuck was added security and gave the bend internal cushioning.

I use this bend (re-tucked) when hoisting trusses to tops of walls, pulling large stones and vehicles, sometimes stuck in mud, etc. Not always in sling form.

Many more examples in the wood shop where standard clamping methods just will not work. I don't know the tensile measurements of strain exerted, but I do know that the clamp blocks get severely crushed under the cord. And a high note can be strummed on the cord. ;-)
Haven't had to cut a cord yet.

And I use re-tucked bends when rock climbing every time.

The added bulk bothers me not and if the additional use of material were a hold back then I would consider myself ill prepared.

SS

knot4u

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Re: Figure 8 bends
« Reply #9 on: June 16, 2011, 09:36:41 PM »
SS, by retucking the Zeppelin Bend, do you mean simply doubling the last turn at the working end?

Or are you retucking the working end somewhere else (in which case I'd call that a different knot)?
« Last Edit: June 16, 2011, 09:38:02 PM by knot4u »

SS369

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Re: Figure 8 bends
« Reply #10 on: June 16, 2011, 09:46:14 PM »
What I mean knot4u, is that I re-tuck the working ends in through the central area following the original working ends' path and direction.
Hope that made it clearer.

SS

roo

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Re: Figure 8 bends
« Reply #11 on: June 16, 2011, 09:52:01 PM »
What I mean knot4u, is that I re-tuck the working ends in through the central area following the original working ends' path and direction.
Hope that made it clearer.

SS
That sounds like what I have pictured as a Double Zeppelin Bend here:
http://notableknotindex.webs.com/Zeppelin.html

The ease of untying may be more related to the nature of the parent bend.
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SS369

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Re: Figure 8 bends
« Reply #12 on: June 16, 2011, 10:59:17 PM »
Yes roo, it is as you have pictured, but, I take a different view of the name your page calls it. I don't think of it as the parent knot doubled, just the working ends re-tucked.

Yes, I think the parent bend lends itself to an easy untying. My cases of usage adds more curvature to the central nipping area and makes it more unlikely that the working ends could work out under jerking loads. (which happens in towing/construction use.)
Totally unscientific reasoning.

I cited the Zeppelin bend here, but the re-tucking is something I personally think helps almost any knot.

SS

xarax

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Re: Figure 8 bends
« Reply #13 on: June 17, 2011, 01:17:10 AM »
The re-tuck ... gave the bend internal cushioning.
 
  Despite my limited knotting experience, I, too, have sensed the presence of this quality in a number of more complex or/and re-tucked simpler knots. In those cases, I think it is reasonable to expect a stronger and more secure bend, especially when this bend is subject to dynamic loadings. Internal cushioning is something we should pay more attention to.
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Dan_Lehman

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Re: Figure 8 bends
« Reply #14 on: June 17, 2011, 03:57:19 PM »
  Now I have examined various fig.8 bends, I see that the C - C bend, shown at (1), can be described as a two-interlocked-fig. 8 knots-bend more accurately than as a two-interlocked-overhand-knots bend. I post here some more pictures of this bend, for an easy comparison with the other previously posted fig.8 bends at this thread.

1) http://igkt.net/sm/index.php?topic=3086.msg18725#msg18725

"1)"  Xarax, I find it a PITA to follow LINKS to get to what is
simply got by scrolling up the page of the current thread?
Why not just say "to the fig.8 bends above (post #x)" ?
Yes, it could be the case that a post gets deleted and the
re-numbered remainders then indicate an adjustment to
the reference; but deletions should really be a non-issue.


 ???
I canNOT make the "D"-2nd image be the same knot as the others:
it shows the orange tail CLEARLY crossing IN FRONT OF the
white; but the slight & 90deg rotations, respectively, of preceding
& succeeding images clearly show the tails in opposite place!?
 ::)

Whatever, here and in some other of these knots, I think it might
be best to orient the tails such that the draw of the SParts pulls
them tighter, unlike the present cases where there is some potential
for an opposite, loosening action. [2nd edit to add : here, but for
this 2nd image, the tails ARE so oriented; in the 2nd image & others,
they are not.]

AND, although they are indeed fig.8 components, one can see
these knots as securings of the Thief knot --taking the tails
into a simple wrap & tuck.  And THIS should suggest that the
knots will be amenable to untying, esp. the one with the big
bowline-like collars (knot-C).

--dl*
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« Last Edit: June 17, 2011, 05:04:19 PM by Dan_Lehman »