Author Topic: Non slipping bend in Dyneema  (Read 68053 times)

NautiKnots

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Re: Non slipping bend in Dyneema
« Reply #165 on: July 09, 2017, 11:54:24 PM »
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?!).
Thanks Dan.  I agree that "twin" might be a better appellation than "double" in this case - especially because "double" often indicates that an additional loop or half-hitch has been added to a knot (ala "double sheet bend" and "double becket bend").  "Twin" would avoid any confusion on that point - and I've already started experimenting with adding a half-hitch to (and thereby "doubling") the angler's loop knots to see if it makes them any stronger.  I've also considered tying the two angler's loop knots in opposite chirality in order to make the bend more symmetric (although I doubt it would make any difference in the strength of the bend).

Would you suggest "Twin Angler's Bend", or perhaps "Twang Bend"? for short (and because the Dyneema "twangs" if you tap it under tension)?

I'll post my variation to "Ashley's Bend" when I get a chance to photograph it.  The knot has some interesting characteristics.

I'll try the other suggested bends when I can - along with some stopper knots and knob knots.

Regards,
Eric

NautiKnots

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Re: Non slipping bend in Dyneema
« Reply #166 on: July 10, 2017, 03:19:36 PM »
How about the vice-versa? How did that fare?
I tied the Vice-Versa and my two angler's loop knots bend inline with each other in Amsteel Blue and put it on my bench winch this morning.  The Vice-Versa slipped at relatively low tension.  The angler's loop knots weren't showing any sign of strain when the Vice-Versa came apart.

NautiKnots, ... 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.

I tied the "Bowled Over and Re-tucked Ashely Bend" in 3mm Amsteel Blue inline with my bend below.  I have to say that your bend is quite attractive.  From the top, it looks like a symmetric diamond-shaped doubled 4-part button.  The underside looks good too.  The bend retained its form as I tightened up the line.  It held pretty well (up until the angler's loop knots began showing signs of strain) and then it rolled off its tails.

I also tried two variations on the Angler's Loop knot.  In one, I took an additional half-hitch through the overhand knot (i.e. I repeated the final half-hitch).  In the other, I took a half-hitch around the standing end before hitching through the overhand knot.  I first tried them against each other to see which was stronger.  The first one broke.  That initially surprised me (I thought it would be stronger if it held), but after examination, the half-hitch around the standing part straightened up the entry to the knot, which I surmise made it stronger.

Then I tried the winner inline against the Angler's Loop knot.  I pulled the line so hard that I was afraid that my winch would pull out of the bench (the benchtop was flexing visibly).  Finally, my first bend broke.  The "doubled" (with the additional half-hitch) knot was just beginning to show signs of strain.  It was only one try, but initially, it looks like this variation may be significantly stronger.

I'll take some pics of the bend and post them soon.

I hope that helps,
Eric

NautiKnots

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Re: Non slipping bend in Dyneema
« Reply #167 on: July 11, 2017, 02:54:38 PM »
NautiKnots, you mention trying something similar
to #1452 : could you show an image of that?
Dan,

The knot I tried (that slipped in Dyneema) was a True Lover's Knot with Interlocked Crowns, which you can see at http://igkt.net/sm/index.php?topic=5921.0.  It starts the same as Ashley's Bend (ABoK 1452) but the final tuck is in a different place.

Regards,
Eric

Dan_Lehman

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Re: Non slipping bend in Dyneema
« Reply #168 on: July 11, 2017, 08:25:13 PM »
How about the vice-versa? How did that fare?
I tied the Vice-Versa and my two angler's loop knots bend inline with each other in Amsteel Blue and put it on my bench winch this morning.  The Vice-Versa slipped at relatively low tension.
I dare say that with HMPE one must be more selective
at what knots to test : why should anyone think that
vice versa would succeed when much more *entangled*
knots have not?!  (Btw, this knot is an asymmetricly loaded
reever bend which was introduced by Wright & Magowan's
1928 Alpine Journal article.)


Quote
NautiKnots, ...
I'd like to see what you find in testing of that.
...
  It held pretty well (up until the angler's loop knots began showing signs of strain) and then it rolled off its tails.
Thanks much, and ... egadz.  Well, it slipped for EStar, too.
But, my, all those tucks & turns ... !! ?!

I have one other ides, aiming for something simpler
--bereft "all those tucks & turns"--, trying to pinpoint
some aspect of security that can endure!

Consider the venerable fisherman's knot ("single"),
as show here:
https://outdoors.stackexchange.com/questions/7342/which-is-better-a-single-fishermans-knot-or-a-double/16556#16556

CONTINUE from the finished/3rd state shown in the top image
of 3 stages of the knot by
(well, firstly, loosening each overhand enough
 to open a bit of space in each SPart's turn,
 anticipating the tuck ...
taking the left/green tail around back & diagonally upwards
--and red tail going opposite, also around back, diagonally
downwards-- to tuck out in those anticipating gaps of each
SPart's initial turn.
(The olive & red pass each other adjacent, olive above, red below.)

The point of this is to put what ought to be the greated
nipping force --of the SPart's initial turn (in this knot, anyway!)--
against the tail,
and then still there is the other nipping done by the overhand
components being pressed together and all.
The tail is alone in being crunched --no parallel part to shield
it from forces (in contrast to my doubly tucked tails in that
like-#1452 knot).
Does it help?
(It's hard to get a grip on what bedeviling behavior comes
from (thin?) HMPE !!  Though I must remind myself that I'd
5 eye knots tested in 5/32" 12-strand Dyneema (coated, IIRC),
and all held to rupture, not slipping.

(Hmmm, looking at the knot in hand, I see that were one
to load it in reverse (i.e., load tails) it would be
a bowlinesque structure doing similar concentrated nipping;
though its turns look shaper and so ... weaker?)

Cheers, and good wishes for your test bed (maybe looking
for reinforcement!)
--dl*
====

Mobius

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Re: Non slipping bend in Dyneema
« Reply #169 on: August 26, 2018, 11:00:51 AM »
 An old thread, however,  I am investigating bends that 'work' in dynemma. Please show me the Carrick Bend variation + tuck that allene had in mind and promotes. Old links here do not work for me. I have given up searching through dated pages looking for a valid image. Thank you in advance.




DerekSmith

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Re: Non slipping bend in Dyneema
« Reply #170 on: August 26, 2018, 11:52:33 AM »
Hi, I regularly fly stunt kites on Spectra.

The standard way of securing, is to sheath the Spectra with a Polyester braid, then any knot will hold, even a simple OH on the bight.

The forces are quite light (only 100lb ish), but then the Spectra braid is only 0.8mm and without the sheath, nothing seems to hold for long.

Derek

Mobius

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Re: Non slipping bend in Dyneema
« Reply #171 on: August 31, 2018, 10:13:16 AM »
Thank you for your response, Derek. I assume you were not just telling me to 'go fly a kite'  ;)

The images in Allene's first post are now showing for me, go figure!? I will work out how to tie it from those images.

The reason for my query is that I have found a bend that appears not to slip and can be untied in 3mm SK75 Dyneema at high loads very close to breaking. I have trialled the knot in question a number of times, though I have yet to set up a test of it and report on it.

Allene's bend was just part of my background research on the topic of a "Non slipping bend in Dyneema".






Rogoshin

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Re: Non slipping bend in Dyneema
« Reply #172 on: August 31, 2018, 09:45:09 PM »
Hey Mobius,

There are two videos about how to tie the bends on Youtube:


Regards
Stefan

Mobius

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Re: Non slipping bend in Dyneema
« Reply #173 on: September 01, 2018, 05:24:16 AM »
Rogoshin, thank you for the YouTube links, that saved me quite some effort working out the tying method.

I ran a single trial of Allene's First bend in 3mm SK75 Dyneema. The First Bend held up until one of the Loop knots broke. The First Bend was first hand snugged and then tensioned to around 40kg, the tails were then marked to help me see any slippage. The knot I trialled did not slip and could not be untied after heavy loading.
« Last Edit: September 01, 2018, 07:26:57 AM by Mobius »

Dan_Lehman

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Re: Non slipping bend in Dyneema
« Reply #174 on: September 04, 2018, 09:25:51 PM »
Hi, I regularly fly stunt kites on Spectra.

The standard way of securing, is to sheath the Spectra with a Polyester braid,
then any knot will hold, even a simple OH on the bight.

The forces are quite light (only 100lb ish),
but then the Spectra braid is only 0.8mm and without the sheath, nothing seems to hold for long.

Derek

It must be noted that in ropes (>=5mm), such sheathing
isn't a guarantee of redress to HMPE's slipping in knots
--it slips within the sheath, which then bears the load
and breaks, leaving a slipped HMPE core to continue to
slip, or the test device stops pulling.

.:.  puzzling material!

 :-\