Author Topic: The TackleClamp gripping hitch.  (Read 17723 times)

xarax

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The TackleClamp gripping hitch.
« on: March 01, 2012, 08:11:39 PM »
The "TackleClamp" gripping hitch.

There are two ways we can enhance the effectiveness of a multi-wrap friction hitch, tied around a spar/pole, and used to withstand a lengthwise pull

1. Increase the number of wraps.
2. Increase the force with which those wraps nip the spar/pole.

Now, there are two ways we can achieve the 2.

A. Wrap the "under" wraps with other, "over" wraps - i.e. wraps that lie on an outer shell, on a second layer around the central core of the spar/pole.
B1. Increase the tensile force with which the ends of the wraps are being pulled , and,
B2. keep them under constant tension, so they nip the spare/pole at their core more forcefully.
 
B1. To pull the two ends of a rope segment more forcefully/effectively, we may use the "mechanical advantage" offered by a block-and-tackle rope mechanism. In fact, we do not even need the blocks/pulleys, because we can use bights formed on the ends of this segment (i.e, a bight-and-tackle rope mechanism).
B2. To secure the two ends of a rope segment that we want to keep under constant tension, we may drive them in between two interlinked opposed bights that are also kept under constant tension. The friction forces generated in the area in between the two tips of those bights from where ends pass through, are sufficient to not let them slip through.

The "TackleClamp hitch" is a multi-wrap friction hitch that incorporates both mechanisms, B1 and B2, in order to increase the force with which the wraps nip the spar/pole they are tied around. Thus, the total friction forces induced by this hitch on the spar/pole are greater than by the other known friction hitches.

It should be stressed that, in order a segment of rope can accumulate tensile forces and not run the danger to release them with a small displacement of its ends towards each other,
1. The rope segment should be sufficiently long. Most of the times, with commonly used spars/poles and ropes, this requirement means that we should use as many wraps as we can, within the limits imposed by practical considerations. Certainly, one wrap would not probably be enough, most of the times.
2. The material of the rope should be able to be elongated under tension as much as possible. Nylon is a material that can be elongated a lot, yet retain its tensile characteristics, and, moreover, not suffer from creep or fatigue.

   A slight modification that might be helpfull in some applications, is to let the "lower" end to pass through the "upper" bight once more, or vice versa. This is easily done, because those bights remain sufficiently wide open - as they already turn around one rope diameter, and their two legs remain parallel. By doing this, we have both standing ends pass through the same bight as they exit the knot s nub. I do not know which of the two alternatives ( i.e., to have them pass through the "higher" or the "lower" bight, at their last passage through them)  will pull the hitch LESS effectively along the spar/pole.

( I have listened  the song of the seductresses Sirens, and dared to place a name, as a label, for this hitch. ( Actually, this name was proposed by a friend of mine, who have tied the hitch...). I would be glad if there are any other proposals, which might be able to name this hitch even more descriptively.)
( I post here only the already published pictures. I plan to take new, better  pictures with some new material that I will put my hands on in the near future. Here I had tried to repeat, in other words, what was the "ratio" that drove me to this knot, so it does not look something "random", that had suddently fell from the sky...Knots are just rope mechanisms, there is nothing magical in the conception of their structure.)

   P.S. I have just remembered a well known tool that is used on tubes and pipes, and which works in a very similar way the TackleClamp gripping hitch works : Not by increasing the contact area between the rope and the spar/pole ( as it is often done, by increasing the number of the wraps ), but by increasing the tension of the wraped rope segment. It is called "strap wrench", and one can see many variations of it with the help of Google Images. The same tool is used to replace spin-on oil filters in cars, and it is called  "oil filter wrench" (strap type). The TackleClamp hitch is nothing but a rope-made, multi-strap "strap wrench" - where the mechanism to pre-tension the straps is not a lever mechanism, but a bight-and-tackle rope mechanism.
« Last Edit: March 02, 2012, 09:30:54 AM by xarax »
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xarax

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How to tie the TackleClamp gripping hitch. (1)
« Reply #1 on: March 02, 2012, 04:52:27 PM »
  How to tie the TackleClamp gripping hitch.

  The important thing to remember, is to pull the two ends and tighten the whole knot in two stages. At the first stage, the two bights should better be at diametrically spaced positions, as shown in picture/step 3. At this first  stage, we do not have to pull the ends very forcefully. At the second stage, shown at step/picture 6, it is better if we pull the ends with all the power the morning breakfast had offered to us - and it pays if we are able to place our feet against the spar/pole, if possible, so we use the whole body power to tighten the knot. ( See picture 6b)( We can do it even if we are not row-men or weight-lifters, of course...)
    Another thing I should perhaps mention, is that the step shown at pictures 7 and 8 might not be necessary. In this, we pass the one, "upper" end through the other,  "lower" bight once more, ( or vice versa), so that both ends exit from the same point of the knot, and are oriented towards the same direction. We can then use the one end that has passed through the same bight twice - or we can use both ends. I believe that it is not necessary to connect them further, with another knot.
   I dare to say that this is the tightest gripping hitch able to withstand a lengthwise pull we know till now. Of course, I am sure that nobody in this forum will accept  this - as it is always the case with knot tyers - for complex reasons, well beyond the simple field of knotting  :). However, I am also sure that it is a good thing this knot has been revealed to us - even with a fifty or a hundred years delay- and it will be presumably there, to common view, the next half century. The next generation of knot tyers will accept it, that is also for sure... :)
« Last Edit: March 02, 2012, 05:14:23 PM by xarax »
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xarax

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How to tie the TackleClamp gripping hitch. (2)
« Reply #2 on: March 02, 2012, 04:54:13 PM »
How to tie the TackleClamp gripping hitch. (2)
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xarax

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How to tie the TackleClamp gripping hitch. (3)
« Reply #3 on: March 02, 2012, 04:56:34 PM »
How to tie the TackleClamp gripping hitch. (3)

(The step shown in the pictures 7 and 8 might not be nessesary. Read the note in the first post of this series.)
« Last Edit: March 02, 2012, 04:58:37 PM by xarax »
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richardpeterson

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Re: The TackleClamp gripping hitch.
« Reply #4 on: March 04, 2012, 03:40:58 AM »
I am able to tighten this down to an absurd degree.

I was tightening this down on a highlighter marker with some small cord (not using the suggested gloves and boots...), and I had to stop for fear of bursting the marker.

This seems to work great as a binding knot in some instances (minus a few wraps, of course). It does impart a twist to whatever it is being tightened around. If it's a pole, that isn't a problem. If it is a bundle of poles, it might be hard to tighten without the poles splaying out and twisting. It doesn't stay tight over a concave surface unless finished with a bend.

It takes a bit of trial and error to know where to start out the bights so that things tighten into place.

It doesn't look much like the kind of structure I generally expect to load lengthwise. However, by keeping the loaded rope so far from the surface of the pole, this knot must impart a good deal of torque, which of course must help.

The first part reminds me a bit of the scaffold board hitch used to sling a plank (ABOK #2159, if I'm not mistaken. Whichever is based on the clove hitch, not the marlinspike hitch).

Thanks for sharing.

xarax

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Re: The TackleClamp gripping hitch.
« Reply #5 on: March 04, 2012, 05:12:28 AM »
  Thank you, Richard,

minus a few wraps
It doesn't stay tight over a concave surface unless finished with a bend.

   This knot is designed to be a hitch able to withstand a lengthwise pull. I have seen that the possibility of pre-tightening/pre-stressing the multiple wraps on any of the known multi-coil friction hitches had a great beneficial impact upon the gripping power of it.  So, the starting point of the design of this knot was there, the multi-coil friction hitches. That was the origin and the purpose of the many wraps. ( I was trying it as a gripping hitch tied around a stainless steel pole, with some olive oil or butter on it... :)) Now, it can also used as a binder of many objects, of course, but this is not a difficult task for a knot...We have many other knots capable to deal with this relatively "easy" problem, in a quite satisfactory way.
   So, if this knot is not loaded, and if it is not loaded lengthwise, it is not supposed to stay tight - unless, as you have noticed, it is secured further with another knot, be it a bend, some half hitches or whatever. The thing I do not yet know is if the final tuck of the one end, shown at pictures 7 and 8, is really necessary...I do not believe that loading it from the one or both ends will really make any significant difference - but I have shown it at the pictures 7 and 8 as loaded from the "lower" end (or from both ends) nevertheless - with the "higher"driven through the lower bight for the second time -, just because this is how most friction hitches are usually loaded.

It takes a bit of trial and error to know where to start out the bights so that things tighten into place.

   Right ! That is why I propose the diametrically placed bights, which turns to be a a good starting point, for the diameters and the number of wraps shown in the pictures - or any other similar combination. The fact that we do not want, is to start tightening the bights when they are too close, so they run the danger to touch each other before the end of the pre-tightening/pre-stressing process. As a rule of thumb, the diametrically opposed bights is something that seems to work in most of the cases I tried, and it is an easily remembered and inspected position. With many more wraps, and nylon ropes, we will need an even greater distance between the bights, so they will be allowed to rreach the end of their route during the pre-tensioning/pre-stressing stage without getting too close and touch each other.

It doesn't look much like the kind of structure I generally expect to load lengthwise.

I know that most people will not believe or accept it, but it is the tightest gripping hitch able to withstand a lengthwise pull we know - far better than any other I have known and tried till now. You will be surprised by its efficiency, believe me !  :)

   Its "secret" is not the distance of the pivot point from the axis of the pole - it is the possibility of the pre-tightening/pre-stressing of the ends of the coil 'tube" - combined with the mechanical advantage that enhances the force we are able to apply to achieve it, and the self-locking mechanism. It is the tightest member of new class of gripping hitches - and I do not doubt that another knot tyer will be able to discover another knot that that uses the same mechanosms - perhaps even simpler and more powerful. 
« Last Edit: March 04, 2012, 05:22:37 AM by xarax »
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Sweeney

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Re: The TackleClamp gripping hitch.
« Reply #6 on: March 04, 2012, 04:03:58 PM »
I know that most people will not believe or accept it, but it is the tightest gripping hitch able to withstand a lengthwise pull we know - far better than any other I have known and tried till now. You will be surprised by its efficiency, believe me !  :)

It may indeed be the tightest gripping hitch and under strain does not elongate at all. I tried it twice in 4mm accessory cord (quite stiff cord) around a plastic pipe about 1.5" in diameter (I can estimate better in inches!) and it does go on very tight and not slip when a moderate load is applied. However it started to move when I bent the ends together and put my weight on it - albeit it moved very slowly.  I tried the same materials with a 3 wrap Klemheist and that elongated but I couldn't move it. This is hardly scientific and until I have tried the TackleClamp hitch a few times I cannot be sure I dressed it as tightly as I might. So for the moment I don't think I would use it as first choice (that may change after some more practice) - mainly because it has 2 free ends which need bending together to be able to attach a separate lifting rope whereas a Klemheist or Prusik can be kept on a hook in the garage ready for use with a carabiner.

The pictures showing how to tie this are very helpful thanks.

Barry

xarax

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Re: The TackleClamp gripping hitch.
« Reply #7 on: March 04, 2012, 09:53:29 PM »
   Thank you Sweeney,

   I am not going to "defend" this hitch, because it does not need me ... :), and because I know very well, from past knowledge and personal experience, that knot tyers - in general - are conservative, and will never accept any "new" knot that is unlucky enough to be presented during their own life time !  This in not something that happens only in our field, of course. It is said that the new theories of physics can be really established only after the previous generation of physicists die, and the physisists of the new generation have nothing to loose if they will accept them . However, I would like to make two comments, one with a question mark and one with an exclamation mark.  :)

I tried it twice in 4mm accessory cord ... around a plastic pipe about 1.5" in diameter

   (Twice is never  enough !  :) :) :) )
   I had used a 8mm kermantle nylon around a 3" plastic pipe - so the relation between the diameters of the rope and the pole in our tests were the same. However, I do not know if we can really scale things like this. It is a very difficult subject, because we use the length of the rope - to be able to pre-tension/pre-stress it-, but the surface of the pole...How hitches around poles are supposed to be scaled ? A question mark here...

mainly because it has 2 free ends which need bending together to be able to attach a separate lifting rope

   No, it does not...because those two ends are not "free", they are not independent - they are already bound together inside the knot ! ( An exclamation mark here). And they are even more tightly bound together by the final tuck of the one of them, shown at pictures 7 or 8 - which I think it might not be always  necessary.
« Last Edit: March 04, 2012, 09:56:23 PM by xarax »
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Sweeney

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Re: The TackleClamp gripping hitch.
« Reply #8 on: March 04, 2012, 10:32:27 PM »

mainly because it has 2 free ends which need bending together to be able to attach a separate lifting rope

   No, it does not...because those two ends are not "free", they are not independent - they are already bound together inside the knot ! ( An exclamation mark here). And they are even more tightly bound together by the final tuck of the one of them, shown at pictures 7 or 8 - which I think it might not be always  necessary.

I think there is a misunderstanding here. What I meant is that you have a hitch which has 2 ends either or both of which can be used but I would use this hitch separately from a line I was using to exert a force on the hitch - in other words I would not seek to place this hitch at the end of a long line which I then used to exert a force. That would be clumsy to tie. It would be far easier to attach a separate line by bending the 2 ends together.  The ends are "free" only in the sense that they are available to be used.

Barry


DerekSmith

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Re: The TackleClamp gripping hitch.
« Reply #9 on: March 05, 2012, 02:06:20 PM »
Hi Xarax,

Thanks for giving me a 'heads up' on this evolution of a hybridisation between the Versatackle and Dan Lehman's 'S Hitch',  As Dan mentioned back in his post in 2009 http://igkt.net/sm/index.php?topic=1451.msg10074#msg10074 we often need a binding that can be significantly pretensioned when it is made and the Tackle Clamp certainly gives us this.

Of interest, when I made it in garden twine or baler twine it was harder to pull it up but gripped itself very effectively, becoming essentially permanent.  But when I made it in smooth surfaced braid, I was able to get a much greater MA through the Versatackle component and so a much tighter binding, but the ends were then prone to slipping back out as, due to the substantial positive cogging of the Versatackle, its self locking ability is limited.

For strength as a binding it is exceptional.  The tension imparted by the Versatackle component puts load into the multiple coils which then do all the work in taking the load of the binding, with very little of the binding load being fed into the tensioning component.  [Note : anything more than ca 5 turns is a waste as the tension is effectively lost over the first two turns from each end see http://notableknotindex.webs.com/friction.html ]

As a hitch, i.e. to give a facility to apply a load along the hitched object, yes it works, but I would not use it for two reasons a) because other hitches are more effective (the Tackle Clamp has virtually no grip under load amplification system) and b) most other hitches are far easier to make (and remove).

Thank you for bringing a very useful tool to my knotting toolkit

Derek

X1

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Re: The TackleClamp gripping hitch.
« Reply #10 on: August 29, 2012, 03:16:25 PM »
   I was thinking that we can utilize one or more of the intermediate riding turns, as a means to squeeze the (twisted) pair of the working ends (prior-to-the-tails) in between this(those) riding turn(s) and the surface of the pole, a la Strange/Constrictor. This way we might "lock" the tails even more securely, so we would probably not need to pass them through the bights for a second time ( as was shown at Replies#2-3, pictures 7-8). We can have a tighten-and-forget hitch, that will remain locked without the need of additional brute-force measures, like the tying of the tails together with overhand knots upon overhand knots and half hitches upon half hitches...
   A disadvantage of this variation is that the bulk of the twisted-pairs-under-the-riding-turn(s) tangle would prevent the two bights from approaching each other beyond a certain point. The course that the two opposing parts/bights of the tackle would now be free to follow, as we tighten the hitch from the pre-tensioned initial position to the tensioned, final one, would now be shorter, so this would probably diminish its maximum gripping power. Of course, we can anticipate this, and start tightening the hitch with the two parts/bights being even further apart of what it is already shown at the previously posted pictures, so they will have enough room to move while they are approachng each other, without being hindered by the bulk of the twisted tails at the space between them.
   (See the attached pictures .)
« Last Edit: August 29, 2012, 07:41:24 PM by X1 »

X1

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Re: The TackleClamp gripping hitch.
« Reply #11 on: October 09, 2012, 08:39:53 AM »
  I have always posted pictures of the TackleClamp with 4 (at least) wraps - although it is obvious that it can be tied with 3, and 3 wraps only. The reason for this was the following : this is a most tight gripping hitch, designed to withstand heavy lengthwise loadings, by the accumulation - inside its multiple turns - of strong tensile forces, during a pre-stressing phase. Provided we use elastic materials that can be elongated quite a bid, ( like nylon, for example ), more turns can store more energy along a longer segment of the rope, that will remain in action even if the free ends slip through the opposing U s "locks" a little bid. The two-turns middle section was used for this purpose.
  However, there might be cases where this longer, two wraps middle section would not be more efficient, because we would not be able to pull the free ends and tension those two wraps efficiently in the first place - due to the greater friction forces induced on them by the surface of the pole. So, the minimum or optimum number of wraps is a matter that depends upon the elongation of the material and the friction coefficient of the pole - among other things !  :) .
   (See at the attached pictures the 3-wraps TackleClamp hitch, and compare it with other, "simpler", 3 and 4 wraps hitches :
http://igkt.net/sm/index.php?topic=4035.0
« Last Edit: October 09, 2012, 08:42:24 AM by X1 »

X1

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Re: The TackleClamp gripping hitch.
« Reply #12 on: October 23, 2012, 01:57:56 PM »
   During the pre-tightening of a multi-wraps TackleClamp hitch, it is better to pull the one free end after the other - so the multiple middle wraps coil is tensioned through both ends. Otherwise, the friction forces between the multiple wraps and the surface of the pole could prevent a very tight grip of the hitch on the pole.
   With a 3-wraps TackeClamp hitch, tied around a slippery enough pole, this is not required. Just place the one end at the right location, between the two opposed bights, leave it there, and pull the other against the pole - as hard as you can !  :) A word of caution : the impulse generated by the great potential of the tackle mechanism is almost irresistible : The knot tyer should remember that he, himself, is but a fragile mechanism. He should be aware of the danger to harm his spinal chord. (Human : Kingdom: Animalia . Phylum: Chordata...). Pulling the one end of the rope by both hands against the pole, while, simultaneously, pushing the pole by both feet, can tighten the hitch to un unbelievable degree, -but it can also harm the back of the careless knot tyer / would-be Oxbridge-rower...
   Now, something else : When the hitch would be tightened, it may be difficult to pass the tail in between the last bight and the surface of the pole, in order to untie the knot, as I have said earlier in this thread. So, It is better to do it in advance : I would nt call this knot a slipped TackleClamp hitch ( it is nt, because the second/last leg of the tail is not nipped there, as the first,  it is just squeezed a little bid ), but it looks like a slipped knot nevertheless. The moment we pull the bight, the Tackle Clamp hitch is released in a glimpse, independently of the degree it has been tightened. Because the pulling of this bight does not pull a niped segment of a rope along its axis, it just re-locates the perpendicular to the axis position of the tail, so the "lock" does not work anymore, it is unlocked, and the knot is untied instantly. ( See the attached picture).
   The reader who have read (1) - where I have mentioned that the TackleClamp hitch is topologically equivalent to the overhand knot ( while the Double Cow hitch, presented there, is topologically equivalent to the unknot, so it is TIB ( tiable in the bight )) - would notice the useful change : the "slipped" TackleClamp hitch is TIB, too !!-- bonus, that, eh?!  :)

1. http://igkt.net/sm/index.php?topic=4035.msg24345#msg24345
« Last Edit: October 23, 2012, 08:51:11 PM by X1 »

xarax

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Re: The TackleClamp gripping hitch.
« Reply #13 on: January 20, 2014, 01:31:27 PM »
  I have seen some interest for the simple tight hitches recently  :) - although I do not know what exactly stirred it, the mechanism of the knots, or the colour of the ropes on which those knot were tied  :). Anyway, see more pictures of the tightest three-wrap hitch / binder we have - which, due to its symmetry, was characterized by somebody as " half clever" - probably because he has not understood, yet, that it is more than twice as tight - so, compared to other hitches, the net outcome can not but be positive  :).   
« Last Edit: January 20, 2014, 01:32:02 PM by xarax »
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Dan_Lehman

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Re: The TackleClamp gripping hitch.
« Reply #14 on: January 21, 2014, 06:39:48 AM »
Anyway, see more pictures of the tightest three-wrap hitch / binder we have
?!
By what method have you confirmed this bold
assertion (not just starry-eyed gazing for glory,
but some empirical method that others might
employ to see for themselves)?  "twice as tight"!!

Quote
--which, due to its symmetry, was characterized by somebody as " half clever" - probably because he has not understood, yet, that it is more than twice as tight - so, compared to other hitches, the net outcome can not but be positive  :).   

What has symmetry to do with "half clever"-ness?
Was some asymmetric binder claimed to be more clever?


--dl*
====