International Guild of Knot Tyers Forum

General => Knotting Concepts & Explorations => Topic started by: Radnor on November 11, 2017, 07:26:12 PM

Title: Reever and Vice Versa bends
Post by: Radnor on November 11, 2017, 07:26:12 PM
I have a question about one of the variations of the Reever bend.  There is a Wikipedia discussion of the bend: https://en.wikipedia.org/wiki/Reever_Knot

One of the "combinations" is not discussed.  As they say, choosing the standing parts as A-B (or equivalently, B-A) results in the Vice Versa bend.  Choosing A-A results in the Reever bend.

But what about choosing B-B?  On page 54 of Harry Asher's book "The Alternative Knot Book" he says of the Simple Simon under bend "At the intersection, the light end (the tail; my comment) passes beneath the standing part; the nip thereby imparted to it considerably increases security..."

Examining the difference between the A-A choice and the B-B choice in the Wikipedia article, it seems to me that the same comment applies to the B-B choice.  When B-B are chosen to be the standing parts, the tails pass beneath the standing parts in the nips.  Wouldn't this be the preferred configuration?

I haven't found any discussion of this difference between the standard Reever bend (the A-A choice) and the B-B configuration on the forums, but I haven't read every post yet.  Can anyone tell me if there has been discussion of this on the forums, and if the B-B configuration has a name of its own?  If it hasn't been named yet, I propose that a name should be invented.

Here are a couple of images of the front and back of the B-B configuration (unnamed top bend in the images) and the A-A (Reever) configuration (bottom in the images).

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22043)

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22045)
Title: Re: Reever and Vice Versa bends
Post by: knotsaver on November 12, 2017, 08:39:36 PM
Hi Radnor,
in KM 85 (cited in the wikipedia article, note 1), the author, Dick Clements, names it the second variant of the Reever knot. He says: "informal testing suggests that both variants are quite secure." His "suspicion is that the first... would be the stronger in the sense of causing the least reduction of strength of the ropes joined".
Hope this helps.
Ciao,
s.
Title: Re: Reever and Vice Versa bends
Post by: Dan_Lehman on November 12, 2017, 09:09:19 PM
...
But what about choosing B-B?
On page 54 of Harry Asher's book The Alternative Knot Book,
he says of the Simple Simon under bend "At the intersection, the light end
[the tail] passes beneath the standing part; the nip thereby
imparted to it considerably increases security..."

Examining the difference between the A-A choice
and the B-B choice in the Wikipedia article, it seems
to me that the same comment applies to the B-B choice.
When B-B are chosen to be the standing parts,
the tails pass beneath the standing parts in the nips.
Wouldn't this be the preferred configuration?

Interesting.  Just from a cursory glance at the images
(thanks for them), I'd say that security looks perhaps
worst in A-A, as the hard-loaded SParts might pull open
the knot slightly AND draw along some tail as it lies
adjacent them and would pull out in the same
direction as loading!?  Whereas in vice versa the
SParts each --in asymmetric paths-- reach to nip the
opposite tail, and as you remark for the B-B loading.
(Btw, in such knot diagrams it should be "A-B" & "1-2"
so to give unique not repeated IDs!  But the mere letters
suffice well here.)


--dl*
====
Title: Re: Reever and Vice Versa bends
Post by: Radnor on November 13, 2017, 01:40:15 AM
Hi, Don_Lehman, thanks for your reply.

I have been reading a lot of forum content since finding the IGKT, and I am learning a lot.  I have read some things by you and others about knot characteristics that give a secure knot, and also characteristics that weaken the rope.

Factors giving secure knots are interlocking and interweaving, among others.  Regarding factors weakening the knot, it makes sense that when the rope makes a turn with a small radius of curvature, this would increase stress in some of the rope fibers, leading to a weakening of the rope.  Having the stressed end enter the knot and remain nearly straight as long as possible is a good thing.

I have also read some posts by a few people who have the hardware to actually test knots under large pull forces, for example NautiKnots.  Someone, perhaps NautiKnots, mentioned that he had tested the Vice Versa in dyneema and that it pulled apart.

I've been practicing tying the Reever variations, and while staring at the knot, I decided to find a way to add additional interweaving.  Here is the result of adding an additional layer of interweaving to the Reever variation B-B.  The extra internal friction in the knot increases enough to make dressing the knot difficult.  The knot becomes a little longer, but does not become any fatter.

These images show the front and back of the enhanced Reever variation:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22047)
(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22049)

The Wikipedia article on the Reever knot: https://en.wikipedia.org/wiki/Reever_Knot

says at the end of the article: "The additional step of passing the ends through the outer loops to complete the knot results in each line entering and exiting the knot being clamped at two points within the knot."

This variation I've shown above clamps the lines at three points within the knot.  Because of this, I propose calling the B-B variation of the Reever knot, the "Doublenip knot", and the variation shown in this post, the "Triplenip knot".  Please, if someone thinks of another possible name, don't keep it a secret.

It's possible to add one more layer of interweaving obtaining a longer yet variation that might be called the "Quadnip knot".

Here's a image showing the B-B variation of the Reever (the Doublenip), followed by the Triplenip, followed by the Quadnip:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22051)

Title: Re: Reever and Vice Versa bends
Post by: Radnor on November 15, 2017, 09:50:43 AM
Here are some images showing how I tie the Reever variant I've called the Doublenip bend.

Start with a double overhand in the two ropes to be joined.  Be sure to tie it such that the rope coming from the left (red) passes over the rope from the right.
Image1:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22054)

Pass each working end down and between itself and the other rope.
Image2:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22056)

Pass the blue tail from the left over the red tail from the right as shown.
Image3:
(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22058)

Pass each tail through the appropriate loop as shown.
Image4:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22060)

Tighten and you have the Doublenip bend, which is the previously discussed variant of the Reever bend.
Title: Re: Reever and Vice Versa bends
Post by: Radnor on November 15, 2017, 10:02:45 AM
To tie the Triplenip bend, start with Image2 from the previous post.
Image2:
(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22062)

This time, pass both tails up through the "hole" between the two ropes, but with the blue tail under the red tail, rather than over as for the Doublenip.
Image6:
(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22064)

Pass the tails through the appropriate loops at the ends of the whole thing.  This provides the extra nip and lengthens the knot.
Image7:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22066)

Tighten the knot and you have the Triplenip bend.
Image8:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22068)

It sure would be nice if someone like NautiKnots would tie one if these in Dyneema and pull on it real hard!
Title: Re: Reever and Vice Versa bends
Post by: Dan_Lehman on November 15, 2017, 05:20:46 PM
It sure would be nice if someone like NautiKnots would tie one if these in Dyneema and pull on it real hard!
So you can watch --if given a video of ...-- the knots
slip apart?  That's the result we can almost certainly
predict, given what has already been seen in HMPE
cordage knotted.

Btw, how hard have YOU pulled on them, and in what
materials?  (The cordage you use in these images looks
to be fairly compressible vs. firm, flexible vs. stiff.)

--dl*
====
Title: Re: Reever and Vice Versa bends
Post by: Radnor on November 15, 2017, 06:44:24 PM
The cordage I used for these pictures is cheap paracord I bought at Home Depot.  It makes for nice pictures, but isn't very slippery.  I was just checking last night to see if I could find any dyneema locally.  West Marine has it available online and they will ship to a local store, but I'm going to give them a phone call today to see if they have any at all in stock.

As to how hard I've pulled on these bends?  I don't have any hardware to do that sort of thing, so my testing has been limited to what I can do with body strength. What does a person do without specialized hardware?  Perhaps I could tie some tie some to the tow bar on a truck and pull my wife's car.

It does seem that the extra interweaving should help keep the bend together.  Do you have a feel for how much improvement might be expected (if any) in going from the Doublenip to the Triplenip?

Title: Re: Reever and Vice Versa bends
Post by: KC on November 16, 2017, 11:51:20 AM
car or truck FRAME (or tow hook) pull against tree with 550 paracord
>>route flow thru cord so no fancy plastics bent on vehicle.
should be able to test slip/stretch/jam/break.
Title: Re: Reever and Vice Versa bends
Post by: Dan_Lehman on November 16, 2017, 09:59:45 PM
... if I could find any dyneema locally.\
IMO, a waste of time, as you have noted that you've
nothing to generate much force with.  I've put my
5:1 pulley (noting : lousy pulley w/much friction)
to pulling 5/16" ? Spectra w/o seeing anything of
the known slippage at higher forces.  (I'm coming
to believe that what might transpire is a melting
and slippage of semi-liquid fibres! --150deg.F is
NOT hard to reach!)

What I do have that seems to defy friction is a
monofilament PP marine cord which I've found with parallel
PP monofil. fibres core or a very slightly twisted 3-strand
core of like material (which latter stuff is well fuller/firmer
than the former); and ORANGE is what I've seen around
the commercial-fishing places of South Jersey (USA).
Now, I don't know that this stuff misbehaves when push
comes to shove, only that manual setting seems to not
impress it much.   :P

As for force, you should be able to rig up some sort of a
pulley --a real one will go far in giving good force (vs.
say using carabiners, for which the coefficient of friction
is around 60-66% (!).  (And if so, you'll want to have a
reasonable idea of what knots will jam and test those
only carefully, lest you make a permanent knot.)
((I once had to use my 5:1 pulley, just getting a hook's
bill tip into some jammed knot (large-ish rope) so to
then be able to pull it open.))


--dl*
====
Title: Re: Reever and Vice Versa bends
Post by: Radnor on November 17, 2017, 07:53:16 AM
I found that West Marine has quite a bit of dyneema and Vectran locally, so I bought some 7/64" (approx 3mm) dyneema in red and silver-gray.  Here is a picture of the Triplenip in that dyneema:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22072)

I also used some rather stiff yellow polypropylene to tie a Triplenip:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22074)

I will probably be able to try to pull down a tree with the dyneema this weekend.  :)
Title: Re: Reever and Vice Versa bends
Post by: Radnor on December 09, 2017, 10:34:47 PM
I have discovered a much better way to test the knot.  Rather than trying to use my auto I have discovered an item available at local hardware stores called a farm jack:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22096)

This little beauty has a load limit of 7000 pounds.  I bought one on sale for $60.  I discovered right away that the main problem with using it is to find a way to attach the ends of the rope to the jack.  I got a couple of grade 5 bolts, 1/2 inch in diameter with a large portion without threads.  They are attached to the jack and the length of 3 mm Dyneema with a triple nip bend in the middle is strung between the bolts like this:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22098)

I applied tension to the arrangement and pulled until the rope began to break near the points where the rope enters the knot.  The rope didn't break suddenly, but began to exhibit breakage in strands of the braid.  The knot didn't pull apart until the strand breakage began.  The knot was hot to the touch as the rope was breaking.  I took video of the process and I'll find a way to post it later.

This bend appears to be suitable for use with slippery modern ropes.  I think I'll start a new thread and test some other bends.  I would like to compare the triple nip (as I've been calling it) to the double nip (my name for the variation on the Reever discussed earlier in this thread).

Title: Re: Reever and Vice Versa bends
Post by: Radnor on December 09, 2017, 10:42:37 PM
Here are a couple of pictures of the remains of the pull test:

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22100)


(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22102)
Title: Re: Reever and Vice Versa bends
Post by: Radnor on December 30, 2017, 10:25:49 AM
I haven't yet edited the video of the triplenip test, but in the meantime I tested the doublenip, which is the variation on the Reever bend discussed earlier in this thread.  The video for this test is so short that I don't need to edit it, so here it is.

The doublenip bend was tied in 3mm Dyneema and just pulled apart as can be seen in the video.  There was no breaking of the rope evident.

https://emailhosting.wistia.com/medias/vb4h7rzzv7

Here is a picture of the ends of the rope after the doublenip which had been tied there was pulled apart on the jack.  There is no apparent breakage of the rope, unlike as in the previous post where can be seen the breaking of rope strands when the triplenip was stressed to failure.

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22141)
Title: Re: Reever and Vice Versa bends
Post by: Radnor on December 20, 2020, 12:45:23 PM
I found the video of the pull test of the triplenip in dyneema that I did using the farm jack; I thought it had been lost.  After looking at it, I decided not to edit it.

If I were to do this sort of thing often, I would permanently mount the farm jack on something unmovable.

https://vimeo.com/492117912
Title: Re: Reever and Vice Versa bends
Post by: Groundline on December 20, 2020, 06:15:09 PM
If I were to do this sort of thing often, I would permanently mount the farm jack on something unmovable.

I would do that sooner than later if you plan on pursuing this testing method. Farm jacks are notorious for accidents to person and property when used inappropriately.
Title: Re: Reever and Vice Versa bends
Post by: DerekSmith on May 03, 2021, 11:01:39 PM
Nice work RADNOR, particularly the attention to detail of anchoring the cords by multiple turns around a round bar.

My own test rig used a ten ton hydraulic jack and two 1" round bars. It allowd me to test two knots one against the other and build a ranked table of knot strength.  However, Dan quickly disillusioned me over the absolute strength of a knot as an important factor.  Of much greater concern was knot stability of which slippage in modern cordage is becoming an increasingly important factor in knot design.

You are quite correct in your assertion that the more load a cord can shed on its passage into the knot before it reached a weakening hard turn, the stronger the knot in terms of MBS.  However, there is a contradiction to this position with regards to knot stability of fastness.  To make a knot grip, it must have maximum positive feedback and this is generally achieved by applying the full load directly to the tail end in some form of clamp of nipping loop.  The VV sheds a lot of its input load before it comes to bear upon the opposing (or its own) tail end, so its positive feedback is limited - hence it is prone to slip.

Another aspect of knot stability is cogging.  See the Thief Knot for an example of a structure which in one configuration locks up with negative cogging, yet in its 'trick' configuration, positive cogging has the knot roll itself to nothing.

Derek
Title: Re: Reever and Vice Versa bends
Post by: NYtarzan on August 30, 2021, 03:48:25 AM
I have a question about one of the variations of the Reever bend.  There is a Wikipedia discussion of the bend: https://en.wikipedia.org/wiki/Reever_Knot

One of the "combinations" is not discussed.  As they say, choosing the standing parts as A-B (or equivalently, B-A) results in the Vice Versa bend.  Choosing A-A results in the Reever bend.

But what about choosing B-B?  On page 54 of Harry Asher's book "The Alternative Knot Book" he says of the Simple Simon under bend "At the intersection, the light end (the tail; my comment) passes beneath the standing part; the nip thereby imparted to it considerably increases security..."

Examining the difference between the A-A choice and the B-B choice in the Wikipedia article, it seems to me that the same comment applies to the B-B choice.  When B-B are chosen to be the standing parts, the tails pass beneath the standing parts in the nips.  Wouldn't this be the preferred configuration?

I haven't found any discussion of this difference between the standard Reever bend (the A-A choice) and the B-B configuration on the forums, but I haven't read every post yet.  Can anyone tell me if there has been discussion of this on the forums, and if the B-B configuration has a name of its own?  If it hasn't been named yet, I propose that a name should be invented.

Here are a couple of images of the front and back of the B-B configuration (unnamed top bend in the images) and the A-A (Reever) configuration (bottom in the images).

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22043)

(http://igkt.net/sm/index.php?action=dlattach;topic=6026.0;attach=22045)
How do you tie Quadnip knot? Could you upload some pictures, it looks sick and strong!!
Title: Re: Reever and Vice Versa bends
Post by: agent_smith on August 30, 2021, 04:16:01 PM
Hello 'NYtarzan' (nice name by the way),

'Radnor' does not appear to have been active in recent times...
But he did post an image in reply #3 and the basic concept is derived from his reply #5.

Some commentary: (not directed at 'NYtarzan')
The discussion re the various loading profiles came at a time when some concepts were still evolving and a work-in-progress.
Harry Asher broke some new ground with his discussions on loop chirality and also the fact that all 'bends' have corresponding eye knots (4 in fact - within a chiral domain).
However, Asher did not fully explore and flesh out his ideas... but he steered the ship on the right heading.

The attempts to assign different names to the 'Reever' based on choice of SParts reminds me of #1411 F8 bend (refer image below).
The same concept applies - in that there is a choice of loading profiles.
But does that choice disturb the title of the 'bend'?
Topologically, they are all the same knot.

In my view, regardless of which combination of SParts are chosen - it is still a #1411 F8 bend (the title of the knot does not change).
Does that analogy also apply to the 'Reever bend'? That is, do we set aside the Reever as being 'special' in some way - and that choice of SParts does disturb the title?
In my view, this line of thinking has historical roots - where Asher was likely first to bring it to peoples attention - and in more recent times, knot tyers may still be influenced by past thinking?

All knots have mirror versions - should we assign different names to the mirror versions?
That is, take any knot and hold it adjacent to a plane mirror.
The reflected image will be the inverse - but it is still the same knot.

I would also comment that there is no peer reviewed testing using the scientific method (with a 'control') of the various loading profiles of either the 'Reever' or #1411 F8 bend.
And the discussion re 'dyneema' always appears to invoke cord of an extremely slippery nature.
And yet, I can go into my local boating hardware and purchase 'dyneema' cord - which has a core + sheath design and does not slip.
Probably need to properly specify exactly what type/model of 'dyneema' is being imagined - instead of just saying 'dyneema'.

I would also comment that testing a knots MBS yield strength is mostly irrelevant.
Unless the t4ester is specifically investigating a geometric change in a knot relative to a 'control'.
In life critical applications, the properties of security, stability and jam resistance are of greater importance.
Title: Re: Reever and Vice Versa bends
Post by: NYtarzan on August 30, 2021, 07:32:51 PM
Hello 'NYtarzan' (nice name by the way),

'Radnor' does not appear to have been active in recent times...
But he did post an image in reply #3 and the basic concept is derived from his reply #5.

Some commentary: (not directed at 'NYtarzan')
The discussion re the various loading profiles came at a time when some concepts were still evolving and a work-in-progress.
Harry Asher broke some new ground with his discussions on loop chirality and also the fact that all 'bends' have corresponding eye knots (4 in fact - within a chiral domain).
However, Asher did not fully explore and flesh out his ideas... but he steered the ship on the right heading.

The attempts to assign different names to the 'Reever' based on choice of SParts reminds me of #1411 F8 bend (refer image below).
The same concept applies - in that there is a choice of loading profiles.
But does that choice disturb the title of the 'bend'?
Topologically, they are all the same knot.

In my view, regardless of which combination of SParts are chosen - it is still a #1411 F8 bend (the title of the knot does not change).
Does that analogy also apply to the 'Reever bend'? That is, do we set aside the Reever as being 'special' in some way - and that choice of SParts does disturb the title?
In my view, this line of thinking has historical roots - where Asher was likely first to bring it to peoples attention - and in more recent times, knot tyers may still be influenced by past thinking?

All knots have mirror versions - should we assign different names to the mirror versions?
That is, take any knot and hold it adjacent to a plane mirror.
The reflected image will be the inverse - but it is still the same knot.

I would also comment that there is no peer reviewed testing using the scientific method (with a 'control') of the various loading profiles of either the 'Reever' or #1411 F8 bend.
And the discussion re 'dyneema' always appears to invoke cord of an extremely slippery nature.
And yet, I can go into my local boating hardware and purchase 'dyneema' cord - which has a core + sheath design and does not slip.
Probably need to properly specify exactly what type/model of 'dyneema' is being imagined - instead of just saying 'dyneema'.

I would also comment that testing a knots MBS yield strength is mostly irrelevant.
Unless the t4ester is specifically investigating a geometric change in a knot relative to a 'control'.
In life critical applications, the properties of security, stability and jam resistance are of greater importance.
That's why i'm concerned, i know there's nothing better than splicing dyneema/technora/aramid cord
but still the last version of this specific knot looks promising!!