Author Topic: The "Bourdon's Slide & Grip Loop"  (Read 9870 times)

Dan.Bourdon

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The "Bourdon's Slide & Grip Loop"
« on: October 10, 2014, 09:04:54 AM »
̰ ̃   ҈ ֹˌ  ⁀·⁀ Greetings, ̊٩̷ֹ̢̊ ̗(Ӧֹ̮Ӧ)̢ ̗۶
I am glad to have found this valuable forum.

⊱ๆ̮⎰ֹ̐̈́ The "Bourdon's Slide & Grip loop"  ̐̈́⎱ጋ̊̈́⊰

  • A loop that can slide and grip on a rope or a pipe.
  • It can be used as comfortable handgrips to carry any form of objects.
  • It is easy to untie as all the good knots.
   

The motive of my knew knot:

I wanted to repair a broom, the kind for driveway that looks like a mustache with a stick. The problem was that the wooden screw of the handle could not hold the broom anymore. So I decided to glue them together. Oops! A collage of wood needs to be squeeze tightly with clamps during the drying period. But how can I force a stick in a hole with a great mechanical advantage for at least 24 hours, when clamps are made for parallel edges?

Can a few twines and knots achieve that challenge?

YES! I did it with three categories of knots:
  • A knot that can anchor the twines to the stick. Many climbing hitches can be use, like the Schwabisch, Distel, Klemheist and Blake, as well as other kind of hitches such as the Icicle, Pipe, Prusik and Dropper loop.
  • A mechanical advantage from a compound or a complex system of pulleys made of inline loops. Many knots can suit that purpose, like the Alpine Butterfly, Perfection, Karash Double, Inline Fig. 8, Double Dragon, Spanish Bowline, the Farmer's loop and the Square Knot or ABOK #1032 (the real one that is square).
  • But a knot that can behave like a movable pulley is an absolute requirement for those systems due to the huge mechanical advantage obtained with just a few pulleys (the advantage is multiplied, while it is just added in a simple system.) See why in my second comment below "The necessity of my new knot in a pulley system".
Can you imagine how next to impossible it was to dress and tighten a climbing hitch with and to a general purpose twine of about 0.025 inch tick... and to extend it into an inline loopโ̢ ̗(͠❂ֹ̰̃ ̰͠❂ֹ̃)̢ ̗۶‼? Those two knots in series produced pretty long pulleys for a compact system! ̒८̯ ̒ ˀʅ

Usages:
  • To "Capture the Progress" in a compound and a complex pulley systems when you need to "reset" the last pulleys. The rope passes through the knot, then enters the first pulley at the anchor near you when you pull at the end of the system. But my knot grabs the rope when you release it to free your hands to reset the movable pulleys. Just wrap the loop behind that pulley with a simple clove hitch while making the knot around the rope just before it enters that pulley. See how it works (with a prusik) in my Knots playlist on YouTube from 0:00 to 3:17.
  • A "Movable Anchor" in a compound and a complex pulley systems when you need to "reset" the pulley hooked to it. See its principle in my playlist on YouTube (without the simplicity of my loop instead of a bulky prusik attached to the pulley with another knot).
  • A "Movable Pulley" in a system where you need more mechanical advantage, but you ran out of mechanical pulleys. I recommend my multi-loops variation below, because the ticker the loop, the lesser the friction.
  • A "Extra Movable Pulley Made With The End of The Rope" that is increasingly sitting there while you pull. Why not double (less the friction) your entire mechanical advantage with it?
  • A "Post or Rope Hanger" to hook something, like your luggage, tools, even yourself in a climbing situation.
  • A "Extractor Hook" to pull up a post or a pipe stuck in the ground, a peg squeezed in the wood... Slide it farther down to grab some more. See its principle with the Pipe hitch (without the advantage of my loop) in my playlist on YouTube.
  • Very good "Handgrips" to carry something heavy like a big jar, a barrel, a five litter bottle of water, etc. If you are two persons of different heights, just slide one handle up or down accordingly. (See also a major improvement in the variations below)
  • There are many other applications. Please, list yours here and post them on my Wall or privately in my e-mail box on Facebook.

Variations:

I came up with many useful variations that I will disclosed later once the drawings and the text are done. I will post them here or in another topic, such as:
  • The "Bourdon's Slide & Grip Double loops" that do not cross each other and once it is dressed and tightened, a load on one loop will not shrink the other. Useful to hang many objects at different heights (with uneven loops) around a post (one loop on each side) made of only one knot that can move up and down easily and stay there even if the post is slippery...
  • Why stop at two loops when we can make three, even four totally independent loops? The knot will grab regardless of which loop⒮ you are pulling and it will not affect the other loops.
  • The "Bourdon's Slide & Grip Wrapped Multiple loops" that makes the "Handgrips" much more comfortable for the hands. As a movable pulley, that also reduces greatly the friction of the rope going through this ticker and smoother loop.

Coming up next:

 ⊱ๆ̮⎰ֹ̐̈́ How to make the "Bourdon's Slide & Grip loop"  ̐̈́⎱ጋ̊̈́⊰

  Regards,
« Last Edit: November 02, 2014, 11:58:14 AM by Dan.Bourdon »
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

xarax

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Re: The "Bourdon's Slide & Grip Loop"
« Reply #1 on: October 10, 2014, 12:03:23 PM »
   Please, show it with the minimum number of wraps / turns around the object it can be tied, so the reader can see clearly the how it works. Then, he can add as more wraps / turns he/she wishes, to achieve a harder or a softer grip - depending on the purpose of the hitch, the load, the friction characteristics of the rope and the object, etc.
This is not a knot.

Dan.Bourdon

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Re: The "Bourdon's Slide & Grip Loop"
« Reply #2 on: October 10, 2014, 12:44:34 PM »
Thanks xarax to reply so soon. My "How to" is coming up only tomorrow with good images at every step.  It took me longer than expected to post here due to some issues with the BBCode and some characters this site cannot display properly. Now it prints '?' instead of Left.ALT + 0147 and 0148.

 It is all done on my web site in html, but it is not for the public. I will PM you the URL upon request.

Regards,
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

Dan.Bourdon

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How to make the "Bourdon's Slide & Grip Loop"
« Reply #3 on: October 11, 2014, 12:58:15 AM »
̰ ̃   ҈ ֹˌ  ⁀·⁀ Greetings, ̊٩̷ֹ̢̊ ̗(Ӧֹ̮Ӧ)̢ ̗۶

 ⊱ๆ̮⎰ֹ̐̈́ How to make the "Bourdon's Slide & Grip loop"  ̐̈́⎱ጋ̊̈́⊰

I am pretty sure that my knot is safe if it is tied properly. So, pay attention to the important notes and during the dressing, because I am not responsible for any damage or injury caused by a mistake in tying the knot or misuse it.

 For me, a knot is not something to remember, rather, it is the understanding why any knots are done that way, the Physics of the forces of the pressure, friction, tension, slippage of the cords, etc.

Happy knotting!

Step 1:
Tighten the rope on which my knot will be made on (if it is not a solid object).

Step 2:
Start my knot with a stopper from at least one inch of the end.
Important note:

It is capital that the stoppers be big enough and not prone to shake loose, because they are more than just for security, they are at the root of the loop with its great pull.

Beside the 'Ashley (Oysterman's)', the 'Stevedore' and the 'EStar' Stopper knots, I like a very tight 'Blimp' knot for another reason I will explain further down. See how the Blimp knot is made at 3:38 and in my Knots playlist on YouTube.

Note that the 'Figure 8' is too prone to shake loose.

Step 3:

Place the rope parallel to the pipe (that I will call 'the parallel' from now on). Make your loop a bit smaller than what you want, and pinch it during all the wrapping, which is done from under, behind and over the pipe.

 Step 4:

 Wrap at least one time under 'the parallel'. Add more wraps if necessary to increase the gripping power according to the application and the type of cordage or solid object you will use my knot.

 But a minimum of four wraps are required for climbing and rescue operations. You must test/inspect your hitch before using it for your own and other's safety.

Step 5:

I call the fifth wrap 'the oblique', which passes behind the pipe, over 'the parallel' at the first wrap, then inside the loop where you are pinching. Wrap around the bottom part of the loop, change direction, and then under 'the oblique'.

Here you have two options for what I call 'the final wrap':

a) The default is to pass the working end under 'the parallel'.
b) Or pass over it to increase the slippage when it is used for 'Capturing the Progress' in a compound/complex pulley system.

 Step 6:

 Fold 'the parallel' over 'the oblique' and 'the first wrap'...
 ... and twist the stopper to be in the best locking position for the next step.

Step 7:

Wrap 'the final wrap' over 'the folded parallel' between the stopper and 'the oblique' & 'the first wrap', then behind the pipe.

 Step 8:

 Exit through the small loop created by 'the oblique', 'the final wrap' and the bottom of the main loop. And finally, make your second stopper.

Step 9:

Dress my knot and tighten it by starting from the second stopper and work your way back until the loop, which should become wider.

Important note:

Make sure that 'the final wrap' do not cross 'the first wrap' behind the pipe. Otherwise, the first stopper might unfold !



Now enjoy the utilization of my multi-purposes knot, the

"Bourdon's Slide & Grip loop".



How to untie my knot:

Step 1:

Untie the second stopper. For the Blimp, just push the end through it's last loop, then pull on it.
Go to the step two...

Or loosen the rope around it:
  • Push the knot at both ends to gather the wrapping together.
  • Push the two stoppers towards one another, which will loosen the rope around the second stopper.
  • If it is still too tight, twist the wrapping to loosen 'the oblique', then pull it from before it wraps the stopper. Bend the knot if necessary.
Step 2:

Once the stopper is free (or untied), free 'the oblique', then pull it to unwrap the rest of the knot. That's it!



The principle or mechanism of the
"Bourdon's Slide & Grip loop".

 โ̢ ̗(͡ө̮̃ ̮̃͡ө̃)̢̃ ̗۶̑ We remember a knot when we understand why it was created that way. So, in wrapping order after the loop:
  • The 'oblique' that comes back to the front (steps #5 to #8), which wrap locks both stoppers and squeezes the top part of the loop (steps #3) with the 'oblique',
  • The second wrap who applies some pressure on the top part of the loop (steps #3), then starts the gripping power among the
  • Third wrap that is right after the folding position of the first stopper and squeezes it with the second wrap when a load is applied.
  • More wraps are optional to increase the gripping power according to the application, the material in use and the surrounding conditions.
 Ӧֹ̮Ӧ As you can see, if tied properly, the rope of the loop will brake before it unwinds. But wait, I provided some variations for heavier loads as well by making two to four independent loops, i.e., pulling one loop in any direction will not shrink the other.

 More, my "Wrapped Multiple loops" variation provides a smoother loop which reduces greatly the friction. Resulting in a wider circumference, it increases the efficiency of the rope going through my loop, especially if this variation was done with four loops. ใ̮(ಠ̮̃ಠ̃)̢̃ ̗۶



As you can see from these angles, the very tight 'Blimp' knots make it look like a bug with weird eyes and antennas. No wander, the English translation of my name is "Bumble bee"!



  Coming up next:

 ⊱ๆ̮⎰ֹ̐̈́ "The necessity of my new knot in a pulley system:"  ̐̈́⎱ጋ̊̈́⊰

  Thanks for trying my knot and for your response.

  Regards,
« Last Edit: November 02, 2014, 12:04:07 PM by Dan.Bourdon »
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

xarax

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Re: The "Bourdon's Slide & Grip Loop"
« Reply #4 on: October 11, 2014, 03:07:02 AM »
   I had asked you to present the knot with as few wraps as possible, so its working would be more clear than now. However, your presentation is superb, and the working of the knot can be understood, even with some more difficulty than if you had shown it in its elementary, minimum-number-of-wraps form ( I guess you are a professional designer ? If not, become one !  :) )
   I see how this knot can "grip", but not how it can "slide" !  :) With so many wraps, the object should need to have a very smooth, sleek surface, in order to allow it to be transported lengthwise.
   I think that your hitch is sort of a multi-wrap ABoK#200 / ABoK#201, or am I mistaken ?
This is not a knot.

Dan.Bourdon

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Re: The "Bourdon's Slide & Grip Loop"
« Reply #5 on: October 12, 2014, 09:41:23 AM »
̰ ̃   ҈ ֹˌ  ⁀·⁀ Hi xarax, ٩̢ ̗(Ӧ̮Ӧ)̢ ̗۶

Thanks for your replies (to me and to the entire forum).

The number of wraps:

The first three wraps cannot be changed because they are the structure of the loop. The only way to reduce the number of wraps is explained in step #4, which is in the 'grabbing' section.

I used four wraps after the first stopper because it is a standard in the climbing hitches. They have also a fifth wrap that goes back to the front, then wrap around the first wrap. That makes at least five and some have even six. Do you knot any 'slide and grip' climbing hitch that has less than five wraps (beside the Blake)?

The slippage:

I included an option to increase the slippage in step #5b. But we have to keep in mind that all the slide and grip hitches must be balanced regardless of their number of wraps. A hitch too tight will not slide and one that is too loose will not grab, won't it?

As far as I understand, the 'Distel', the 'Klemheist', the 'Schwabisch', the 'Blake', the 'Icicle', the 'Pipe and the 'Sailor's Gripping' hitches are all based on the same principle. A load will stretch out the hitch in three sections:
  • The last three or four wraps take charge of the gripping,
  • The first two or three wraps become the handles,
  • And one or two wraps in the middle bridge both ends that are getting apart.
Then it is only when all those wraps are pushed together that the knot can slide, if it is not too tight, obviously.

The look alike:

My hitch is not a multi-wrap of the ABoK# you mentioned above. Rather, it is in the category of the list I just wrote. But if you want a loop with those slide & grip hitches, then you will have to make one that will end with one or two stoppers, while it is all included in mine.

One of the parents of the "Bourdon's Slide & Grip Loop" is the Icicle hitch, which has six wraps by the way.

  Thanks for your reply and for testing my knot.

  Regards,
« Last Edit: November 02, 2014, 12:22:22 PM by Dan.Bourdon »
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

xarax

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Re: The "Bourdon's Slide & Grip Loop"
« Reply #6 on: October 12, 2014, 10:28:56 AM »
   Do you knot any 'slide and grip' climbing hitch that has less than five wraps (beside the Blake)?

  You had not presented this hitch as a climbing hitch ! - a very technical subject of which I do not know much. However, I do know that Climbing hitches are supposed to do many other things than just "slide" and "grip"... If you intend to propose this hitch as a climbing hitch, you should better present it in specialized sites, where climbers and arborists will scrutinize it more than we do - i.e., they will probably eat you alive ! :)
  If you ask for just a "grip" hitch ( that is, a more or less "permanent" hitch that is able to withstand a lengthwise pull ), then yes, I do know : It is the TackleClamp hitch (1), and the Locked Double Cow hitch (2), to which I had arrived following a similar route as you did. Moreover, those 4-wrap hitches utilize a mechanical advantage due to the zig-zag path of the Standing Part on the surface of the spar, and they work in a way that I think is somewhat similar to the way your hitch works.

   A hitch too tight will not slide and one that is too loose will not grab, won't it ?

   That is exactly what a climbing hitch should do, I believe : be loose enough to slide, but be able to "close" instantly and tightly around the penetrating rope, when pulled by its end(s). Climbing hitches are tied around ropes, that is, around objects of the same or slightly bigger diameter than the ropes they are tied on. That is perhaps the reason for the minimum number of 4 wraps. - it is difficult to grip such a small and flexible object. Around a bigger and solid object, a spar, one can achieve satisfactory results even with 3 or even 2 wraps - especially if the path of the rope can "simulate", in a sense, a block and tackle simple machine, as the 2-wrap Locked Single Cow hitch does (3).
   Another hitch which can slide and grip around a rope, is the Rat Tail Stopper (4), used on board of commercial and naval ships, to immobilize the mooring line(s). I have seen that 4 - 5 wraps on this hitch offer a very tight and secure grip.
   
1. http://igkt.net/sm/index.php?topic=3813.0
    http://igkt.net/sm/index.php?topic=4224.0
2. http://igkt.net/sm/index.php?topic=4035.0
3. http://igkt.net/sm/index.php?topic=4035.msg24785#msg24785
4. http://www.animatedknots.com/rattailstopper/
   

   
« Last Edit: October 12, 2014, 12:42:09 PM by xarax »
This is not a knot.

Dan.Bourdon

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Reply #6: The "Bourdon's Slide & Grip Loop"
« Reply #7 on: October 13, 2014, 03:19:35 PM »
̰ ̃   ҈ ֹˌ  ⁀·⁀ Hi xarax, ٩̢ ̗(Ӧ̮Ӧ)̢ ̗۶

 Thanks for your information and your references. That is exactly why I came here for. I am not a knot tyer. I just made a research to solve the problem of my broom described above in my motive. I have decided to use knots thanks to the guys who raised my interest on YouTube, enough to make a new category of my playlists.

You had not presented this hitch as a climbing hitch ! - a very technical subject of which I do not know much.

 -̀ˁ̺̍̍̍̍ˀ-́ It is while 'McGuyver'-ing a pulley system with different kind of knots that I came up with something worth sharing, i.e., a multi-purpose hitch, which usages include climbing:
? A "Post or Rope Hanger" to hook something, like your luggage, tools, even yourself in a climbing situation.

 But saying that I have not presented my hitch as a climbing hitch, makes me understand your strict request to present a
...minimum number of wraps / turns around the object it can be tied, so the reader can see clearly the how it works.

 Since it would take me weeks to re-draw the entire set of images, which might affect my presentation that you've found "superb" (thanks),  I will update the information in step #4 (if it's not done as reading this.)


If you intend to propose this hitch as a climbing hitch, you should better present it in specialized sites, where climbers and Arborist will scrutinize it more than we do.
 I was and still hoping for my knot to be investigate and debate here for its originality and its usages, and to be technically scrutinize. I welcome estar to do his test bench ̒?̒ ̡ ̃ʅ

 ∫̃̒ ̮̃̃ʼ̃̃ʖ̃̃ Any link to specialized sites of Climbers and Arborists for New Knot Investigations are welcome.



 You are right xarax about all the applications besides the climbing - arborist - rescue ones where security is the priority. In general applications, my knot must have a minimum of three wraps to hold the loop and to grab (and slide too when necessary).

The principle of the '3-wraps minimum' of my knot:

 โ̢ ̗(͡ө̮̃ ̮̃͡ө̃)̢̃ ̗۶̑ In wrapping order after the loop (The steps below refer to the "How To" in reply #3.)
  • The 'oblique' that comes back to the front (steps #5 to #8), which wrap locks both stoppers and squeezes the top part of the loop (steps #3) with the 'oblique',
  • The second wrap who applies some pressure on the top part of the loop (steps #3), then starts the gripping power among the
  • Third wrap that is right after the folding position of the first stopper and squeezes it with the second wrap when a load is applied.
  • More wraps are optional to increase the gripping power according to the application, the material in use and the surrounding conditions.
 Ӧֹ̮Ӧ As you can see, if tied properly, the rope of the loop will brake before it unwinds. But wait, I provided some variations for heavier loads as well by making two to four independent loops, i.e., pulling one loop in any direction will not shrink the other.

 More, my "Wrapped Multiple loops" variation provides a smoother loop which reduces greatly the friction. Resulting in a wider circumference, it increases the efficiency of the rope going through my loop, especially if this variation was done with four loops. ใ̮(ಠ̮̃ಠ̃)̢̃ ̗۶

Regards,

Coming up next:

⊱ๆ̮⎰ֹ̐̈́ Embellish your city in any season with a  ̐̈́⎱ጋ̊̈́⊰
3-wraps "Bourdon's Slide & Grip loop"

 Thanks everybody for investigating my multi-purposes knot‼ ̊٩̷ֹֹֹ̢̗̊(ಠ̮̃ಠ̃)̢̃ ̗۶̑
« Last Edit: November 04, 2014, 08:28:23 AM by Dan.Bourdon »
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

xarax

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This is not a knot.

Dan.Bourdon

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The necessity of my new knot in a pulley system
« Reply #9 on: October 14, 2014, 09:02:46 AM »
̰ ̃   ҈ ֹˌ  ⁀·⁀ Greetings, ̊٩̷ֹ̢̊ ̗(Ӧֹ̮Ӧ)̢ ̗۶

⊱ๆ̮⎰ֹ̐̈́ The necessity of my new knot in a pulley system  ̐̈́⎱ጋ̊̈́⊰

 There are three types of system that produces a mechanical advantage, i.e., with a ratio greater than one to one (1:1) : simple, compound and complex.
  • Simple :
      All the pulleys move in one direction at the same rate of speed and cover the same distance. If the last pulley is hooked to the anchor, it doesn't produce any mechanical advantage. It is just a change of direction. Therefore, if you have only one pulley, fix your rope to the anchor, then attach the pulley to the load. That will give you a 2:1 mechanical advantage. See What Is a 'Simple' Pulley System? (from 3:26)
      The ideal mechanical advantage of a 'simple' system is the number of lines minus one if the last pulley is hooked at the anchor, which is just a change of direction.
  • Compound :
      Many simple systems in series moving in the same direction, but the speed and the distances traveled are greater. Therefore, the last pulleys need to be reset* to their original position due to the mechanical advantage. A 20:1 (20 to 1) means you travel 20 times the distance of the load, e.g., 20 feet of rope to move the load one foot, or 20 meters to move the load one meter. But the load is 20 times (less the friction) easier to move though.
      Say you do not have that extra length of rope or do not want to walk that distance, then a reset* is your solution.
      The ideal mechanical advantage of a 'Compound' system is the number of lines of each simple system in the series, then to multiply those results.
  • Complex :
      Same as 'Compound' but some pulleys move in opposite directions, towards one another. You have no choice but to reset* those when they 'kiss'...
      The ideal mechanical advantage of a 'Complex' system is to calculate the effect of each pulley starting from the last one of the system.

* To Reset a pulley means to slide it back to its original position without moving the rope, because it is anchored to that portion of the rope, not to the fixed anchor as usual. See it as yourself when you extend your harms to grab the rope farther for another pull. The following reset demo (from 5:14 min.) uses a prusik (which tend to loosen without a load, contrarily to my knot that is permanently tied, but easy to untie.)

 The Bourdon's Slide & Grip loop with its stable and strong independent loops is the ideal knot for:
  • Capturing the Progress during a 'reset' by simply tying the loop behind the first pulley anchored near you.  See how it works (with a prusik) in my Knots playlist on YouTube from 0:00 to 3:17.
  • Anchoring a pulley to the rope that will slide and grip strongly at its original position.
  • Making an extra movable pulley with the end of the rope that is increasingly sitting there while you pull, and therefore, double (less the friction) your entire mechanical advantage with that 'left over'.
 Thank you to report your experiences with my knot and your questions here, and/or to post them on my Wall or privately in my e-mail box on Facebook.

Sincerely,

Coming up next:
⊱ๆ̮⎰ֹ̐̈́ Embellish your city during every seasons with a ̐̈́⎱ጋ̊̈́⊰
3-wraps "Bourdon's Slide & Grip loop"
« Last Edit: November 02, 2014, 12:24:11 PM by Dan.Bourdon »
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

xarax

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Re: The "Bourdon's Slide & Grip Loop"
« Reply #10 on: October 14, 2014, 10:56:04 AM »
   I have watched the video you refer to, and it is great : you are a natural teacher of those things  :) - I only wish you learn some knots, and teach knots, too ! We have some good knot tyers in our site, but most of them are lousy teachers - some are even worse than me !  :)
   Now, perhaps you do not know the best ( simplest and more efficient = secure ) method to "capture" progress we have in knots : it is based on the "opposed bights mechanism", where an End, after it is pulled and tensioned as much as possible, it is immobilized and "locked" by passing in between two opposed, tensioned bights. See :
   
   http://igkt.net/sm/index.php?topic=4906

   You have to tie the initial version of the TackleClamp hitch a number of times ( I believe that 12 times is the minimum number that assures one has got the 'feeling" of any new to him knot ), to see how the mechanical advantage of the 2 Cow hitches work ( you may not agree right from the first sight that they work as two joined rope-made block and tackle simple machines, but, believe me, they do ! ( * )), and how the two opposed bights at their ends "collapse" towards each other.
   
   http://igkt.net/sm/index.php?topic=3813.0
 
    In fact, the mechanical advantage is so effective, and it enables us to pull so much ropelength out of the nub when we pull its ends ( simultaneously at the beginning, the one after the other at the end ), that the opposing bights may approach too much, and they may even "kiss" each other, preventing any further tightening ( we can not 'reset" those mechanisms ) - and that is the main reason I had tied the second version of the TackleClamp hitch shown at :
 
    http://igkt.net/sm/index.php?topic=4224.0
   
   There, the "collapse" happens in a way that make the two "opposing bights" to move apart from each other : in fact, they still approach each other, but only if we measure their distance by the length of the path around the hitched object, along the arc of the path that engulfs the object.

   I tell you all those things because I believe you would had understood how those "tight" hitches implement the same mechanisms you describe so clearly, the only difference being that the ropes do not pass around pulleys, but through bights. Although we have the addition of some residual friction forces, the essence of the mechanisms do not change, because the leverage principle remains the same. However, I know from past experience that a person who has tied a "new" knot, never ties a 'new" knot tied by anybody else  :) , and, of course, he does nt tie it the minimum number he should, in order to be able to understand how it works. So my hope that you will tie a TackleClamp hitch and realize how forcefully it grips and how securely it locks the free ends, is rather remote ... :)

   Inside any knot s nub, there are simple machines, rope-made "levers" and "pulleys", which are multiplying the tensile forces induced into the nub by its ends, and that is why some knots are more tightly woven than we would had expected, judging from the tensile forces with which we had pulled their ends in the first place. Moreover, there are rope-made "ratchets" and "locking" mechanisms ( which "capture the progress" of the approaching of the parts while the whole of the nub becomes compact ) by which any tension induced into the nub can not be released. A knot is a very complex mechanism, and the fact that its mechanical parts are interwoven within each other does not make their analysis simpler !

   (*). See the attached picture, for a quick and dirty sketch : the two axes, with the pair of pulleys on each of them ( 1 and 2 ), are pushed towards each other ( meaning, they encircle and squeeze anything that is located in between them = they squeeze the hitched object ) by the pulling of the free end, shown with the arrow. ( The other end of the rope is anchored on the surface of the encircled object ). The third axis ( 3 ), with the pair of pulleys on it, which is free-floating on the surface of the object, represents the zigzag part of the Standing Part, with the continuation of the Standing End going through this bight. We see that the magnitude of the force applied on the free-floating part is two times the one applied on the Standing End. The same with the force that pushes the two axes towards each other. Of course, on a rope-made such mechanism, there are no pulleys : the rope just slides on the outer surface of the object and on the inner surface of the tip of the free-floating bight, pulled by the Standing End. However, the principle remains the same : the encircled object is squeezed by the shrinking wrap much more forcefully than if it would had, had the pulling force was applied directly on the wrap, without the presence of the intermediate free-floating bight.
   
« Last Edit: November 05, 2014, 12:10:17 PM by xarax »
This is not a knot.

Dan.Bourdon

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Let's stay focus on the thread
« Reply #11 on: October 17, 2014, 06:17:36 AM »
̰ ̃   ҈ ֹˌ  ⁀·⁀ Greetings, ٩̢ ̗(Ӧ̮Ӧ)̢ ̗۶

 Thanks xarax for keeping this thread alive. I appreciate your kind words and your information.

 Dear members, I came to this forum to share my knot with you and to have your feedbacks about its features and originality.
  • Does anyone have tried my knot?
  • Was it too difficult to tie and/or to untie?
  • What type of rope/twine have you used, and on which type of rope/solid object?
  • What application(s) have you tried it for, did it work?
  • Did anyone made some bench tests?


Mechanical advantage with knots:

 There are many ways to put together a system of ropes that will give you a mechanical advantage. But it all boils down to the same principle:

 To multiply by two the force applied to the rope at a certain point.

 The only way to achieve that is with a pulley, be it a body with a rolling part or a knot having a loop. The force of the rope that enters and exits the pulley/loop is multiplied by two at its anchor, whether it is hooked to a fixed object or to the rope itself.

 But a pulley does not always give you a mechanical advantage. It is also just a change of direction of the rope. In order to find out which is which, we must know where are the load and the anchor(s) in the system, and if the load is hooked by the rope or by a pulley which makes a big difference.

 xarax, your drawing and description are not clear enough for my comprehension to picture where those are and therefore, to calculate the mechanical advantage.

Did you tried my knot?


٩̢ ̗(Ӧ̮Ӧ)̢ ̗۶ Knot Tyers,

Keep checking the How-To (reply#3), because I update it as this thread raises questions, like the optional number of wraps in step #4,  the addition of the new section:
The principle or mechanism of the
"Bourdon's Slide & Grip loop".

  Thanks for trying my knot and for your responses.


Off topic:
To xarax (and to the readers as well),

We have some good knot tyers in our site, but most of them are lousy teachers - some are even worse than me !  :)

ใ̮(ಠ̮̃ಠ̃)̢̃ ̗۶ People, nobody is lousy at something, only that he/she could improve. The way we think about someone (good or bad) feeds his/her state of mind. By corroborating in our mind the way that person seams to be, or worse/better spreading it to others, attracts the events accordingly that will amplify that state, not only to that person, but to ourselves as well. We have a control/responsibility of the way we think about others that can help or aggravate them, which includes ourselves in the process.

By examples:
  • If we keep saying "it is dark in the room", it will stay that way, won't it? But as soon as we think that the room could be more illuminated, the mean(s) to light it up comes to mind.
  • "Is my glass half empty or half full?" The real question is:
     "Do I want my glass to be empty or full?"
  • What will append if you keep thinking:
    a) I want to stop smoking... and keep smoking?
    b) I enjoy being a non-smoker... and keep smoking?

    a) No change.
    b) One day your vision will kick in and you will just forget to smoke.
 In light of those inner experiences (not from books), I have decided one day that instead of ending a sad song on a sad note, to write the music to gradually and naturally (without pushing it) initiate an inner path to a more joyful state.

Regards,
« Last Edit: November 02, 2014, 12:27:53 PM by Dan.Bourdon »
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

xarax

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Re: Let's stay focus on the thread
« Reply #12 on: October 17, 2014, 08:35:18 AM »
...your drawing and description are not clear enough for my comprehension to picture where those are and therefore, to calculate the mechanical advantage.

   You have only to count:)
   In a mechanical system in equilibrium ( and iff we suppose that friction forces are negligible ) the tensile forces "running" along the segments of the rope are equal. So, let us count the blue lines and the total forces that are applied on each of the three parts of the shown system : the three axes with the pairs of pulleys on them :
   Axis#1, with the first pair of pulleys on it, is pulled by 4 lines towards axis#2, so let us say that the first part is pulled by a force of magnitude 4F towards the second part. Same thing for axis#2, with the second pair of pulleys, which is pulled towards axis#1 by a force 4F, too. The third part, with the axis#3 and the third pair of pulleys, is free-floating, and is located in between the two others. By pulling the Standing End ( shown by the arrow ), we pull it by a force F, that is, by the one quarter of the force with which the first and the second part are pulled towards each other. That is the mechanical advantage. Pulling by a force F, we force the two halves of the object to be squeezed on each other by a force 4F.
   Of course, friction forces are NOT negligible, because in the real system we have no free-revolving pulleys : the segments of the rope just slide on the outer surface of the two parts / halves of the hitched object ( which are represented by the first and the second part of the system ), or through the tip of the free-floating bight ( which is represented by the third part of the system ) . So, the mechanical advantage is diminished, depending on the friction coefficients of the surface of the object and the rope. However, it does NOT disappear, as one can see at once when he ties the TackleClamp hitch, for instance.
   This is the simplest way I can think of, in order to describe the mechanical advantage of the zig-zag path of the Standing Part on a Cow hitch. I am sure you can describe it in a much better way, using the standard terminology.
   When you will tie and tighten a hitch which uses a mechanical advantage like this, you will start to "feel" the effect of the mechanical advantage, without having to calculate it !  :) Tied around a hollow metal object, a pipe, for instance, the tight grip of the TackleClamp hitch can almost be heard : if you hit the squeezed cylinder or the tensioned rope with something, you will notice the change in the pitch of sound - and by measuring this you can, in principle, calculate the tensile forces ...
   I believe that you have not yet understood the rope-made mechanism by which we increase the tension by which the wraps are encircling and gripping the hitched object, or the way we " capture the progress" of the pulled ends, by the opposed bights locking mechanism. This is quite normal : few knot tyers have realized how those mechanisms really work, although they are much simpler than the ones they had studied in high school ! Now, it should expected that a teacher can not learn the same things with another way, so the only thing I suggest to you, is to tie the TackleClamp hitch over and over again  :), until the whole thing I try to describe becomes absolutely clear to you. Then, I am sure you would be able to present it in a much more comprehensible way than me... 

    P.S.1. Of course I had tied your knot - MANY times, as I always have to do, and I do ! I can not learn other people s knots, and I can not tie "new" knots, by just looking at them !  :) If you do the same, the same sufficiently large number of times, my drawing and description will become crystal clear !  :)
    P.S 2. Have a look et the attached pictures. I had included two "locked" Cow hitches, and a picture of the same mechanism shown my previous drawing, in flesh and blood  :).  I have placed a third, "red", thinner pole in place of the third axis ( axis#3), to facilitate the understanding of the correspondence, where the only thing that really exists is the free-floating bight of the Cow hitch, and the Standing End going through it : they work in tandem, just like two pulleys on a common axis. The two other parts are the two squeezed on each other, so bound together, "white" thicker poles, with the arced segments of the rope sliding on their surface, instead of going through freely revolving pulleys. 
   
     
« Last Edit: October 17, 2014, 08:42:09 AM by xarax »
This is not a knot.

Dan.Bourdon

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Re: Let's stay focus on the thread
« Reply #13 on: October 18, 2014, 05:51:54 AM »
̰ ̃   ҈ ֹˌ  ⁀·⁀ Greetings knot tyers, ٩̢ ̗(Ӧ̮Ӧ)̢ ̗۶

   I am still looking for specialized organizations/sites where climbers, arborists and rescuers will scrutinize my hitch and have the authority to corroborate officially its virtues. All your links are welcome.

   Don't be afraid to criticize my knot. That is why I'm here for.

P.S.1. Of course I had tied your knot - MANY times, as I always have to do, and I do ! I can not learn other people s knots, and I can not tie "new" knots, by just looking at them !  :)
And...?
  • What do you think about my knot?
  • What type of rope/twine have you used, and on which type of rope/solid object?
  • What application(s) have you tried it for, did it work?
  • Do you have any questions, recommendations?

Off topic.
...your drawing and description are not clear enough for my comprehension to picture where those are and therefore, to calculate the mechanical advantage.
("those" = the load and the anchor(s) in the system.)

   You have only to count:)

 There are three methods to calculate the Mechanical Advantage in a pulley system, which depend on the type of system, i.e., 'simple', 'compound' or 'complex'. It is only in the 'simple' system that we count the lines (except the one that exits the last pulley if it is at the anchor.) I wrote a section about how to identify each type:
"The necessity of my new knot in a pulley system" (reply #9)

 But it is impossible to choose which method to use without knowing the location of the anchor(s) and how the load is hooked to the system. It will be much easier to grasp how the whole system works once they are established.

 Have you tried my knot in a pulley system?

Regards,

P.S.1: I have added the Tackle Clamp hitch to my bar of 'slide & grip' hitches.

P.S.2: Keep in mind that I am not a knot tyer. It don't have the free time necessary to try so many knots just to know them. I have learned a few knots on a 'need to know bases'. You see, when I need a knot for a particular application, I look on my bars to choose the appropriate one. If I don't have any, then I search for a better knot, look at the images while trying them on my bars. I keep the useful ones on those, then I use the new appropriate knot (or I make a variation of it) to my application.
« Last Edit: November 02, 2014, 12:28:55 PM by Dan.Bourdon »
  Daniel  ⌢ ◦ ⌢  ≈ֹ̰ ̃(ړײ ) ֹ̰̃〰͠

xarax

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Re: Let's stay focus on the thread
« Reply #14 on: October 18, 2014, 10:49:08 AM »
  • What do you think about my knot?

  1.  I do not like the way you immobilize and secure the ends - that is, to inhibit motion by using the volume, the bulk of a knot, of a stopper, as an obstacle : The line does not move, because the wide cross section of this stopper can not pass through a narrow opening. We seldom use this way in practical knots, and for good reasons. It consumes way too much material, the stoppers can jam, it needs time to be tied in the first place and then dressed, it is not elegant or clever, there is always the danger the opening will accidentally open up and the stopper will slip through, and the knots it generates are often bulky and ugly. 
   That is the reason I had shown you the best method we have in practical knots - elegant, clever, and of zero bulk : the opposing bights locking mechanism. I have referred to the recent thread where there are clear drawings and pictures of that mechanism, and to some knots where it is used, with great success. Evidently you thought that my references were "off topic", and that I should "stay focus on the thread", because you had not understood the direct relation of what I was saying with what you have shown !  :)
   2. The way you implement, using rope, elements of a mechanical system using pulleys and the mechanical advantage they offer, in general, and of the simple "block and tackle" machine, in particular, is, to my view, ad hoc : You have first imagined / thought of the mechanism, and then you have tried to "simulate" its working using a piece of rope and knots tied on it - but one can still see the "seams" of your effort to "simulate' the working of a mechanism by a compound knot : the end result is not homogenous, at least it is not yet : perhaps you may simplify it further in the future.
   See, for example, another rope-made mechanism we have in knots : a "rope-made hinge", the Zeppelin bend. The idea could had its origin in the somewhat complex mechanical system of a hinge ( actually, it had not, but that is irrelevant here ) : how to use the stiff rope segments of the Tail Ends as hinge pins, as toggles, which can hold the two parallel bights of the two links of the bend together, as a hinge pin holds together the two knuckles of the hinge, attached to its two leaves. However, in the end result you only see a most simple, tiny knot, where all the elements of this "initial"  mechanism have been integrated into a whole : a compact, small, elegant, clever knot, where nothing is redundant - in short, a marvellous object ! All the separate parts of the "initial" system have been fused into this simple object, and one can not see the seams between their junctions any more. The "initial"  mechanism is there, you can always analyse it to see how it works, but is not just a mechanical system redrawn with the help of rope !  :)  If you see a Cow hitch, you will not see the complex diagram I had drawn to represent how it is working - the rope-made system, the knot, is a much more integrated and simple object than the pulley-made system which corresponds to it. You see how much simpler is the Cow hitch itself from the diagram of the mechanism. That is exactly what a good mechanism of a knot should be : look simpler than the diagram of the corresponding mechanism ! In Zeppelin bend, the knot went further than the mechanism : it achieved the same purpose, with just two pieces of rope and a few deflexions of the straight path of their segments. In the case of the Cow hitch-based Locked Cow hitches, as pulleys, the knots use the surface itself of the hitched objects, on which the Standing Parts slide, or the inner surface of the tip of the bights, through which the ends slide. In your compound knot, I do not see the "distance" I would had wished between the original purpose, the mechanism made with mechanical parts which serves that purpose, and the final result, where the flesh and the blood of the mechanism are rope-made, the knot.
   3.  I had not referred to ABoK#200 - #201 for no reason ! If you analyse the way this well-known and practical knot works, you will find elements of the your knot in a much more straightforward, simple form. Starting from this knot, you can arrive at your knot, and vice versa. However, your knot lacks it symmetry ( so it can not be tied and inspected as easily...) and  incorporates those ugly stoppers, which, as I had said, are the last thing one should have think of, if he wants to finish a knot.
     
  • What type of rope/twine have you used, and on which type of rope/solid object?

  Oh, knot tyers use more kinds of rope you could had imagined ! They suffer from other diseases, but they prefer to starve rather than to be left with a few only ropes ! Beautiful, straight, unknotted ropes are at the very heart of our love for knots, and see what we are doing to them !  :) I have MANY different ropes, although I prefer to buy ropes with no colour patterns on them, so I can enjoy better the play of shadows on their gentle, curved surfaces, and such ropes have became more rare nowadays... I did nt tie your knot on all of them, but I tied it on plenty of them ! Climbing ropes, mainly, and some "softer", more compressible marine ropes as well.

  • What application(s) have you tried it for, did it work?

   Personally, I am not interested in applications of knots, I study the knots themselves. Imagine a person who studies geometry : he is not interested of how farmers will use geometry to measure the areas of their fields before and after the flooding !  :)
   If a knot is good, it will find applications by itself ! However, I can tell that your knot is not destined to become a climbing hitch - but you should better ask experienced climbers about it. I have only climbed some stairs in my life - and not many ! I prefer the elevators...  :)

knowing the location of the anchor(s) and how the load is hooked to the system. It will be much easier to grasp how the whole system works once they are established.

  I have shown to you CLEAR pictures of simple, good knots, based on the Cow hitch, which use a mechanical advantage - I believe you should be able to tie them and analyse them ! In a hitch or a binder, there is no "anchor", for KnotGod s sake !  :) We do immobilize and secure the ends, but we do not attach them somewhere !
« Last Edit: October 18, 2014, 11:53:38 PM by xarax »
This is not a knot.