jamming and collars in untying knots

Knotting Concepts & Explorations
1

I have been examining jamming mechanisms for different knots in an effort to show what exactly determines how easy a knot is to untie. Most of this work is with bends, as they are easy to observe load on. So far, the jamming mechanisms i have isolated are as follows:
1: knots that try to bend one or more strands opposite directions at points right next to each other. some examples include the zepplin knot, the surgons knot, and a fisheman’s bend
2: knots that twist two strands opposite directions, to the point where they can’t twist anymore. The best example of this is the whatknot, where it will bind only when this condition is met, although an augmented thief’s knot, that one overhand bend with both collars on opposite sides and both tails on the same side, who’s name i am forgetting, and a blood knot in fishing
3: knots that attempt to kink a loaded strand, or attempt to kink two strands. Probably the best known example of this is a sheet bend, although others include a carrick bend, or a figure 8 bend, or a glumpir knot
4: knots that simply pinch a strand really really tight. These knots are so worthless i won’t even try to list them

I suspect there are many more than listed here. Each one has unique properties, and yields different types of knots. I have also noticed that in many cases, knots that are easy to untie feature a collar that may be manipulated to give slack, and a binding mechanism in the middle. I figure if we could find such a correlation, it would benefit our ability to see verify if a knot is easy to untie or not.

Here, i have attached a knot that well demonstrates this property but i can’t identify exactly how to say the binding mechanism works. Regardless, it seems to be a handy little knot, and seems to demonstrate this point well as the collars are not under tension, but are crucial to the structure of the knot.

121115-225541.jpg

2

In short, a loose collar is only a consequence of a loose knot, an effect, not a reason , a cause that results in a not-jamming, easy to untie knot. Also, a loose collar can serve to untie a knot, but it cannot transform a jamming knot to a non-jamming one. A collar is but one bight of the knot. There may be other bights that are jammed, being entangled together in a compact, tight configuration, able to accumulate any tension that is induced into the knot s nub by the pulling of the standing ends.
You jump to conclusions too fast, so you are lead to wrong conclusions… but this proves that you can jump, and you wish to conclude, which are very good things ! :slight_smile:
I know next to nothing about the reasons behind the fact that a knot will probably jam, and/or will jam early, and another will not. I suspect that jamming is something quantitative, not qualitative - and it depends upon the material too much to allow us to make general statements.
I will attempt to make the following rough distinction ;
When the nipping mechanism of the one link of a bend forces the other s to enhance its own nipping action, the knot will probably jam, or it will jam early. Jumping into an analogy, we can say that the two nipping mechanisms work in a series.
When the nipping mechanism of the one link of a bend do not force the other s to enhance its own nipping action, and both mechanisms work independently of each other, the knot will not jam, or it will not jam early. Jumping into the same analogy, we can say that the two nipping mechanisms work in parallel.
So, when I see the one nipping structure to encircle the other, and the one tail to twist around the other inside this double nipping embracing cocoon, I suspect that the knot will probably jam, or will jam early. When I see the two nipping structures side-by-side, and the tails to run parallel to each other inside those two nipping mechanisms, I hope that the knot will not jam, or will not jam early.
Two extreme examples are the Oyster bend ( M. B5 ),(See (3)), and the Zeppelin bend. The first is the most jamming bend I have encountered, and the second one of the least ones.
Now, on the very interesting, very nice bend you show, that I was not aware of - I had never tied it, although I had tied many similar bends, using the same nipping mechanism. It can be tied in two variations, the one you show here, and an even more symmetric one, that is known. When I had tied this second variation, I had called it “twisted collars” Zeppelin bend - but for the time being, I call both variations as ZB bends ( ZB bend (A) and (B). The (B) is the one you show here. See the attached pictures ). Both are, of course, variations of the Zeppelin bend, but one can also say that they are interlocked bowline-like structures ! I think I should relate them with the bowlines and B bends shown at (1). Why is that so ? Because, although we have not “proper” bowline collars, we have “proper” bowline nipping loops - and, in a bowline, the nipping loop is more important than the collar.
The ZB bends are similar to the Double Zeppelin bend (B2), shown at (2). However, I think that the Double Zeppelin (B2) would be a more stable knot, because the segments of the standing parts before the first curves are more aligned, i.e., they reach the pair of the tails closer to the axis of the bend and to each other. So the collars are not pulled out of their tight positions, and they are less loose than at the ZB bends.
Their apparent disadvantage of the ZSB bends is that the collars, through the standing ends they turn around of, can be pulled out of the two side-by-side ( in parallel ) nipping structures, and get loose. However, that does not jeopardise the integrity of the knot, nor does it diminish the gripping force on the tails. The bends are genuine Zeppelin-like rope-made hinges, so the tails serve mainly as pivots - they can well be unloaded from both their sides !

1 http://igkt.net/sm/index.php?topic=2871
2. http://igkt.net/sm/index.php?topic=1980.0
3. http://igkt.net/sm/index.php?topic=1919.msg16217#msg16217
http://igkt.net/sm/index.php?topic=1919.msg18926#msg18926

P.S. Nice focused pictures. However, I think that the color pattern of your cord is a little confusing. A one-color cord - better, two cords, each of a different color - would make the paths of the lines more easy to read. Also, if you use ropes of a larger diameter, say, 1/2’ inch, the knots may be more difficult for you to tie, but more easy for us to see.

3

As i saw it, i found these knots to be closely related to a fisheman’s bend, in that they are simply an overhand tied around the other rope, but with the tails both facing inwards and then passed through the other knot. From that prospective, there are a few knots derivative of this bend, the obvious being the case with the tails not tucked through the other overhand, but they may also be tucked through the part of the overhand containing the standing part. This produced a similar binding structure, but the tails were each separate, creating a unique knot. Also, the tails may be wound together with a half knot, i guess mostly for asthetics, though i could see some functional value in it.

Also, I did not find the original bend to be a rope made hinge, as the end of the tails connected to the knot is under tension, as the collar is stretched while the knot twists.

In the pictures are these other bends.

121116-232436.jpg

4

I see that you have managed to post 100MB focused pictures, but you have failed on anything else ! :slight_smile:
There is no point to use the 100KB file space, if the knot occupies the 1/100 only of the area within the frame - the rest being occupied by the knot-tyer.. A 1KB picture can not be magnified to a degree that will enable us to examine the knot in detail.
Could you, please, take new pictures, where the knots would be on a larger scale ?
Also, it would be better if the knots are placed on a background of a neutral colour - so the outlines of the rope segments will not be confused with lines of shapes behind the knot.

( P.S. Why do you post those pictures here ? I thought that thread was meant to be a thread about the subject described at its title. If you wish to explore the structures of knots, or to present new knots, please start new threads at the appropriate sections of the Forum.)