Author Topic: Non slipping bend in Dyneema  (Read 68392 times)

Dan_Lehman

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Re: Non slipping bend in Dyneema
« Reply #150 on: February 07, 2014, 09:56:57 PM »
you claim that it slip less and/or it is stronger... Why
Let's start this way.  I have proposed two knots.
One can be untied and one cannot.
One is slightly stronger than the other.
They are both stronger than the industry standard triple fisherman's knot which cannot be untied.

If you can propose a knot that is stronger and simpler than the knot I presented,
I will test it.  THEN you can propose a simpler one that might be stronger ...

Allen, I liked your description of what you saw as making
your end-2-end knot work (which words I didn't find just
now, but in a lonnnnng thread) : the rather mild initial
bending of the line and the later sure clamp to secure them.

As you know, I've looked at the mechanism in the mirrored bowline
--the incompleted version which was tested by Toss-- where the
bowlinesque "nipping turn" (aka "turNip") is repeated as giving
some guidance on how to solve this problem.  And, yes, I
was amazed that a re-tucked Ashley's bend #1452/1408 ...
would slip --quite!!  But, still, along this line of re-tucking
through a central nipping area, I want to try a knot in which
the S.Parts make a full turn --they make U-turns when forming
the interlocked overhands of Ashley's--, in hopes that
in that there is better concentration of pressure for the
nip (and maybe some less holding open of it got where
the overhands' collars are held out?!).

To this end, I've just illustrated one such knot.  It won't
win Brion's seal of Easily Tied (but then he had trouble
understanding my extended bowlilnes --and left the
intended mirrored b. w/o final tuck, alas),
but maybe it will show us something further in the
behavior of HMPE; and maybe with all the diameters
tucked it will bump strength?  (Untying is sometimes
not an important feature.)

I think that I'll post it all under a new thread, later.

BTW, have you tried any OTHER MATERIALS to HMPE?
When Brion sent out a warning about knots not working
well, in his Sail article some years ago, he was finding
troubles with all "hi-mod" ropes at the time --HMPE,
Vectran, Technora, Kevlar (IIRC).  While these might
be less slick, they are equally static and of high strength.


Cheers,
--dl*
====
« Last Edit: February 15, 2014, 05:34:57 AM by Dan_Lehman »

allene

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Re: Non slipping bend in Dyneema
« Reply #151 on: February 07, 2014, 10:13:31 PM »
I have only tried Amsteel, which is Dyneema.

allene

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Re: Non slipping bend in Dyneema
« Reply #152 on: February 07, 2014, 11:52:46 PM »
Where is the new thread?

Dan_Lehman

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Re: Non slipping bend in Dyneema
« Reply #153 on: February 08, 2014, 05:18:02 AM »
Where is the new thread?
It's "later" !   ???

Which is now, and voici : http://igkt.net/sm/index.php?topic=4777.0
"Ashley Bowled Over #1452 & re-tucked"


 ;)

Ruby

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Re: Non slipping bend in Dyneema
« Reply #154 on: August 07, 2015, 03:13:30 PM »
interesting simple knot。 what's the size of that dyneema rope? seems 3mm? 6mm string?

seems the instruction on how to tie it is wrong. why not correct it in the first post?

Dan_Lehman

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Re: Non slipping bend in Dyneema
« Reply #155 on: August 07, 2015, 05:04:30 PM »
interesting simple knot。 what's the size of that dyneema rope? seems 3mm? 6mm string?

seems the instruction on how to tie it is wrong. why not correct it in the first post?
?!
I don't understand what you're referring to;
please give a quote of what you find to be a problem.

--dl*
====

Ruby

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Re: Non slipping bend in Dyneema
« Reply #156 on: August 07, 2015, 09:43:26 PM »
interesting simple knot。 what's the size of that dyneema rope? seems 3mm? 6mm string?

seems the instruction on how to tie it is wrong. why not correct it in the first post?
?!
I don't understand what you're referring to;
please give a quote of what you find to be a problem.

--dl*
====





what Allen presented at reply 2 and later in reply 85 is different, and he later realized it.

i think he can include the correct one in first place. so no need to read all those reply to find it out.




? Reply #2 on: January 22, 2014, 05:58:32 PM ?
Estar posted how to tie the knot

http://www.bethandevans.com/pdf/modified%20Carrick.pdf


? Reply #85 on: January 28, 2014, 09:23:29 PM ?


http://l-36.com/no_slip_knot.php
That is a step by step tutorial of how to tie the knot.


79


Re: Non slipping bend in Dyneema
? Reply #130 on: January 30, 2014, 06:46:25 AM ?
oops.  I did not catch that Estar had it wrong.  Makes me wonder if that is why it slipped for him and not for me.  Throws into doubt the data as well.  I wish I had a calibrated setup... 

Allen

Re: Non slipping bend in Dyneema
? Reply #131 on: January 30, 2014, 08:24:42 AM ?
^^ Could it be that the same properties of the knot that make it hard to load are what is making it not slip in Amsteel?

By the way, that picture clarifies why I was having so much trouble getting my point across.  If you tie it like that, it does not have the nice properties I kept asserting.  I feel really bad about missing that.  I sent a note to Estar to see if that was the latest drawing and expect to hear tomorrow.

Allen






....



all quotes above

NautiKnots

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Re: Non slipping bend in Dyneema
« Reply #157 on: July 03, 2017, 07:58:44 PM »
Hello everyone.  I'm new to the forum, and apologize in advance if I'm committing a faux pas by resurrecting an old topic.

Anyway, I've been experimenting with bends lately and had some success with Dyneema that I thought I'd share.  Many of the bends I've evolved are in the class of "true lovers' knots" - that is, they consist of two interlocked overhand knots that draw up to form a visually pleasing whole.  One of these (a modification of ABoK 1452 that looked to me like it had better nip and less fiber distortion) seemed a promising candidate for Dyneema.

So, I spliced an eye in a piece of 3mm Amsteel Blue (as an attachment point), and bent the other end to another length of 3mm Amsteel Blue with the aforementioned knot.  I took the assembly to my splicing bench, looped the eye around a table leg, and tensioned up the line on my bench winch.  Much to my dismay, the bend slipped.  The knot rolled off the running ends, leaving two well-ironed and stiff bits of Dyneema.

Then I decided to see how well it compared to other mentioned knots, so I repeated the experiment with two interlocked buntline hitches.  The buntline hitches also slipped, but under noticeably more strain.  That is to say, the drawn-up buntlines worked better than my knot.

Reasoning that I needed a knot with a tighter nip rather than one with more crossings, I went back to the Angler's Loop (ABoK 1017, 1035), which I've also been using as a bend.  I tied Angler's loops in the ends of two pieces of 3mm Amsteel Blue, and eye-to-eye hitched (ABoK 1495) them together.  Back on the winch, I pulled the line until the attached end drew up so tight that it crushed the 2x4 I had looped the terminal eye splice over.  The Dyneema was so taut that it sang when I tapped it, but the bend did not slip at all.  The running ends of the Angler's Loops deformed from the constriction on them, but they held in place.

At that point, I wondered if the central square knot (from the eye-to-eye hitch in the loops) was contributing to the security of the knot, so I tried again without the loops.  I bent the two lines each to the other in the form of an Angler's Loop (except that instead of making a loop, I brought in the running end of the other knot).  This bend also drew up tight without slipping (and without any pre-tensioning).  I pulled a little harder on the winch handle than before, and the line broke at the entry to one of the Angler's Loop knots.

I can't tell how much the knot weakened the 3mm Amsteel Blue, so I don't know how strong the bend is, but I'd definitely have to say that it is quite secure.  There's no untying the knot once it has taken a load, but I think that's par for the course with any knot that holds in Dyneema.

Looking at the remnants of the experiment, it appears as if the two legs of the knots may not have been even, which leads me to wonder if a single bend based on the Angler's Loop may suffice.  I doubt a single bend will hold (I expect the overhand knot to roll), but I'll have to try it to be sure. <edit> I just tried a single "Angler's Bend" (what I call it) and just as I expected, the knot did not hold.  A repeat experiment of the "Double Angler's Bend" (again, what I call it) also held until the line broke. <end edit>

I hope you find my experience useful.  If anybody wants, I can post photos of the knot (either here, or in another thread - whichever is the proper forum etiquette).

Regards,
Eric

« Last Edit: July 03, 2017, 08:28:33 PM by NautiKnots »

JohnC

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Re: Non slipping bend in Dyneema
« Reply #158 on: July 04, 2017, 07:44:02 AM »
Hi Eric

Welcome to the forum.
John

agent_smith

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Re: Non slipping bend in Dyneema
« Reply #159 on: July 04, 2017, 02:03:10 PM »
Hi Eric (NautiKnots),

I would like to see the photos please.

Can you show both loose and tight dressings. Try to photograph against a plain white background (dont have anything in the background because it add clutter and confuses the image.

Thanks,

Mark

NautiKnots

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Re: Non slipping bend in Dyneema
« Reply #160 on: July 04, 2017, 07:03:47 PM »
Here's how to tie what I'm currently referring to as the "Double-Angler Bend", or "Dangler Bend" for short.

Step 1:  Loosely tie an overhand knot in the working end of each line.
Step 2:  Pass the working end of each line through the overhand knot of the other, on the same side that the other working end exits the overhand knot.
Step 3:  Pass the working end of one line around behind the standing part of the other.
Step 4:  Pass the working end up through the crown of the other line's overhand knot.
Step 5:  Tuck the working end under itself, forming a half-hitch.
Step 6:  Repeat steps 3-5 with the other working end.

To dress the knot, simply pull on the opposing standing parts.  In stiff line, pulling the working ends may be necessary to snug the knot and one may need to balance the two middle legs.  In Dyneema line, however, pulling on the standing parts is usually all that's necessary to balance the legs and snug it up.

NautiKnots

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Re: Non slipping bend in Dyneema
« Reply #161 on: July 04, 2017, 07:48:37 PM »
Here are some more pictures, of the "Dangler Bend" tied in Dyneema SK-75 (3mm Amsteel Blue).  Below are front and back side photos of the bend, and one showing where (in my previous experiment) the line broke under strain.

If you look closely at the third picture, you'll notice that the line broke at the entry to the knot (which is typical), and you can also see deformation in the working ends right where they exit the knots.  That indicates to me that the strain is distributed throughout the knot.

I didn't pre-tighten the bend beyond regular dressing.  Any imbalance between the two middle legs was taken up when the lines were tensioned, but the working ends did not get pulled into the knot.  That is, it did not noticeably slip at all.

I have since tied an Angler's Loop and a Bowline together (using an eye-to-eye hitch) and pulled it to the breaking point.  I expected the Bowline to slip, but it didn't.  I suspect that a Bowline Bend (ABoK 1455) might also work reasonably well in Dyneema, especially if the two loops were eye-to-eye hitched.  ABoK 1454 could be another alternative.  In my test, however, the line broke at the entry to the Bowline, so my "Dangler Bend" might still be stronger.

I also tied both the "Dangler Bend" and allene's "Last Bend" (very carefully so I made sure the form and chirality matched his photos) in 3mm Amsteel Blue and pulled them until the line broke.  It broke at the entry to the Last Bend.
 
Has anybody seen the Angler's Loop (a.k.a. "Perfection Loop) tied as a bend before?  I haven't, but it seems as though someone must have tried it already.  Likewise, tying it as a back-to-back bend (as Ashley did to the Bowline in ABoK 1454) seems rather obvious.

Regards,
Eric

NautiKnots

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Re: Non slipping bend in Dyneema
« Reply #162 on: July 04, 2017, 10:21:47 PM »
Ok, I just went out and tried allene's "First Bend".  I tied it inline with the "Dangler Bend" in 3mm Amsteel Blue.  On the winch, I got the tension up very high, and then the "First Bend" rolled off it's tails.

I tried the "variation" against the "Dangler Bend" twice.  The first time, when the tension got close to the breaking point, the variation slipped.  The second time, I partially loaded the knot and pulled really hard on the tails with pliers to set the knot as firmly as possible.  That time it held, and the line broke at the "Dangler Bend". 

Watching the knots constrict under extreme tension, it appeared as if the "Dangler Bend" was showing more sign of strain than the "First Bend Variation".  This leads me to suspect that the 'First Bend" and its variation (when they hold) are stronger than the "Dangler Bend", which (given the structures of the two knots) is what I would expect.  The "Dangler Bend", on the other hand, seems to be more reliable.  It doesn't need pre-tensioning nor a pause in loading to be secure.

I also think the "Dangler Bend" is simpler than allene's "First Bend", and easier to verify visually (but that may be just me).  I am a fan of the Carrick Bend though, and appreciate using its form on slick stuff.

Practically speaking, I believe that either bend will suffice for typical working loads.  How often do you load up Dyneema as tight as piano wire?  Both bends held to the point that the line was actually melting under the compressive force.

Regards,
Eric

Dan_Lehman

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Re: Non slipping bend in Dyneema
« Reply #163 on: July 07, 2017, 01:58:38 AM »
NautiKnots, you mention trying something similar
to #1452 : could you show an image of that?
It caught my interest, as you'll see in msg.#153 above
a URLink to a #1452 *improvement* (so I hoped!   ;) )
which I presented as a hopeful knot for HMPE.

I'd like to see what you find in testing of that.

As for the angler's loops, I go with Ashley's (?) naming
convention of calling such knots "twin <whatever>"
--though we can see that the eye knots used could
be different (for whatever reason : different ropes, maybe?!).

I might have some newer ideas.
HMPE sure is a demanding material!

Thanks,
--dl*
====

JohnC

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Re: Non slipping bend in Dyneema
« Reply #164 on: July 07, 2017, 03:31:16 AM »

We are looking for a bend that does not slip in Dyneema and I welcome links to any candidates.  I will test them and any that do not slip in my setup will go to Estar

How about the vice-versa? How did that fare?
John