Author Topic: Constriction cam-action knot for sleeping bags, compression, camping  (Read 16973 times)

Tex

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #45 on: April 27, 2015, 12:58:45 PM »
xarax you're not telling me anything I didn't already cover in my post.

Zig zag is zig zag and I don't think at this point you can really think I that I don't get zig zag advantage just because I used a label, for expedience of description, that you don't love.  The reason I called out versa tackle by name is to distinguish from other false trucker's hitch-like binding geometries that have only a mild relationship to a true trucker's hitch-like advantage, like the lasso configuration (zigging around one side of a sleeping bag, and back up the other side doesn't count, EVERY binding knot does that.  No advantage).  Versa tackle is zig zag, and zig zag is versa tackle.  Versa tackle just uses two loops to make the zig and zag through.  You can create open turns to do it instead just as you can use all different knots for a trucker's hitch, but it doesn't change what it is, a double turn 3-leg pulley advantage (which really is 2:1 not 3:1 for the purpose of binding.  Tug-of wars with a binding knot in the middle are a different story.).  The knot I talked about inventing/discovering, is not truly versa tackle either, but it's a 2-turn pulley closure system.  I haven't shown it and I probably won't.  For binding it's better than much stuff shown here, but it's still worse than a three turns and a slipped square knot, and as a hitch it's useless, so who cares?

The point you are missing xarax is that three turns around the object has the same advantage MINUS the extra LARGE friction in the 180 turns. People are missing the most obvious simple advantage right in front of them and are messing it up with all kinds of friction, thus destroying it. 

Like I said, actually try it.  I stand by my statements.   I spent a bit of time trying junk around my sleeping bag and leg before I posted it and at best I can find solutions that come close to 3 turns and a slipped square knot.
 
« Last Edit: April 27, 2015, 01:41:26 PM by Tex »

Tex

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #46 on: April 27, 2015, 01:31:01 PM »
By the way, my 3 wrap zigging (along the surface) is similar in effect and look to your locked cow hitch (which I knew about when I made it) as far how it binds, except it doesn't have any nipping lock, which means it hitches worse, locks worse,  but you can pull it tighter.  Yet it still binds worse than 3 unimpeded turns because it still has far more friction. 


In the end there is a VERY simple principle at play here.  EVERY frictionless three wrap bind (3 wraps everywhere, backhand reversals acceptable) will have a 3 to one advantage because if you pull out 3 inches of rope it will get one inch smaller in diameter.    If anyone doesn't get why this equates to a 3x force advantage, brush up on simple machines and Newton's laws.  Yes versa tackle like arrangements can take you from 1 wrap most of the way around to still having 2:1 advantage without 2 full wraps, but it just doesn't work as well.

It doesn't matter how many zigs and zags went into forming those three wraps full.  If the total rope is 3 pi d and some number of wraps everywhere, then that's what its advantage will be.

« Last Edit: April 27, 2015, 01:39:08 PM by Tex »

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #47 on: April 27, 2015, 01:44:13 PM »
xarax you're not telling me anything I didn't already cover in my post.

  OK. I am used to tell everybody what he already knows for quite a long time now. Do not read my posts... ( You would nt be the first one, you know... :) )

  You are the one who used the term Zig Zag for the first time in your first post on the Trucker s hitch, Ashley had used it, too, so I was trying to use this nomenclature because it is descriptive, and it is understood by anybody, even if he is not a knot tyer. On the contrary, VersaTackle is relatively recent name given to a particular configuration, when we have the Standing Part passing through the SAME two bights many times... The knot tyer who used this name, although I believe he did not understood the essence of the "opposed bights" locking mechanism (1)(2), felt he should had referred to the block and tackle mechanism, for good reason. He used the word "tackle" of the name of a 2000-2300 years old simple machine, to describe a recently described knot mechanism, not the other way around.
   The point you miss is that I am talking about the general case, about tight hitches and binders, in general - I am not talking about sleeping bags, in general, and about your sleeping bag, in particular !  :) :)  I am talking about the knots which can serve as very tight hitches, able to withstand a lengthwise pull, or as self-locking binders ( think about the term "self-locking", and compare this feature with the features of the solution you propose ).
   Of course, three-four round turns and three-four overhand knots or half hitches, the one after the other, will solve all your particular/special problems - the burden of reading my posts included !  :)  :)

If anyone doesn't get why this equates to a 3x force advantage, brush up on simple machines and Newton's laws.

   I would LOVE to return to high school - I had left many opportunities I had nt got when I could, there... :) :) :)

1. http://igkt.net/sm/index.php?topic=4906.0
2. http://igkt.net/sm/index.php?topic=4906.msg33365#msg33365
« Last Edit: April 27, 2015, 02:01:52 PM by xarax »
This is not a knot.

xarax

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #48 on: April 27, 2015, 02:14:05 PM »
   On a more serious discussion, we should always try to separate the issue of the efficiency of the mechanical advantage, from the issue of the efficiency of the locking mechanism - two different things which are often confused - especially in the case of the Trucker s hitch - but also when we are talking about other tight hitches / binders.
   To my view, the simplest starting post of incorporating a mechanical advantage into a tight hitch / binder, is the humble Cow hitch, with its Zig Zag, U-turning path of the Standing Part on the surface of the hitched/bound object(s). And the most secure, and minimum material consuming locking mechanism, is not the Gleipnir-like mechanism ( used also by the bowline ), but the opposed bights mechanism, used in the Trucker s hitch and the Versatackle.


« Last Edit: April 27, 2015, 02:15:13 PM by xarax »
This is not a knot.

Tex

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #49 on: April 27, 2015, 02:28:55 PM »
  OK. I am used to tell everybody what he already knows for quite a long time now. Do not read my posts... ( You would nt be the first one, you know... :) )

Don't take any of it wrong.  Arguing about knots (or ropes) is surprising fun.

   The point you miss is that I am talking about the general case, about tight hitches and binders, in general - I am not talking about sleeping bags, in general, and about your sleeping bag, in particular !  :) :)  I am talking about the knots which can serve as very tight hitches, able to withstand a lengthwise pull, or as self-locking binders ( think about the term "self-locking", and compare this feature with the features of the solution you propose ).

Yes yes.. exactly.  This discussion has turned into one about tight hitches, how much tension the can TAKE while tightening up enough to not slip loose, or maybe even around.   That's fine.  That's a great discussion which is why there are so many cool tight hitches.  But it's not the same discussion as how tight can you BIND something using a strictly LIMITED amount of force.   Hitchers are not great binders, but some hitches are pretty good binders.

If everyone is understanding that that is what this discussion has become, then excuse my interruption.  The original question though asked about binding, specifically asked about compression, sleeping bags, and specifically asked about pull advantage and clearly wasn't related to finding out how much hydraulics you can attach to a tight hitch.

I never saw anywhere in here where anyone mentioned simple turns and a double square knot.  If we've moved on from trying to answer the original question, then my suggestion is no longer valid. 


Tex

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #50 on: April 27, 2015, 02:30:36 PM »
... slipped square knot, typo.

JohnC

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #51 on: June 15, 2017, 03:15:19 AM »
Hello guys, I hope you find my submission to be intriguing.

[...]

Its so simple, 'i'd be surprised if it hasn't been done before. However, I was not able to find it in Ashley. Let me know what you think.

I stumbled across this post a couple of weeks back and have been experimenting with the knot for various applications.

At first I was unimpressed - tying it in the hand - as it seemed to slip with the slightest of tension, but that was unfair as it performs much better when actually binding something. The other thing that put me off a bit was the allusion to the constrictor, which doesn't seem to me at all comparable, but that's unimportant.

I've glanced at the various replies but haven't studied them in depth so my comments apply to the original post as presented.

I like this knot very much.

First off I used it in cheap garden twine to compress some rubbish that was in bin liners (polythene shopping bags) and needed to go into the mandated 60L plastic sack used for rubbish collection in my neck of the woods. The problem I had was that I only had one sack left (and they won't pick up anything else) but I had more bin liner bags than would fit, and the truck was due any minute so no time for a dash to the shops. A closed bin liner/shopping bag has a lot of air and compressible stuff in it, but if you squash them up by hand and stuff them in they "reinflate" to a large degree before you can get the outer bag closed.

So I made this loop, put it under one bag, then placed two others on top and gently knelt on the three while I cinched up the knot. Then placed the three in the sack and repeated for another three. Worked brilliantly and I eventually got eight bin liners worth in a sack that I would normally struggle to get six into.

Next up was some empty kitty litter bags that I like to keep for storing or disposing of various things (they are lined with thick/absorbent cardboard and coated with plastic on the outside so they don't leak). The kitty litter bags tend to want to unfold after you've folded them so I was having trouble keeping them together. This loop is excellent because you can just expand it a bit with each new bag you slot in.

Lastly, cardboard paper towel rolls, which make great fire starters mixed in with the kindling (especially filled with tinder), but they are tricky to "wrangle" without a container. This loop makes a great adjustable sling for them.

For reuse/adjustment, it works better with soft, braided cord that it can get a grip on, but having said that, the plastic garden twine worked fine too since I didn't care if it jammed completely (I was discarding it with the rubbish).

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John

bushrag

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Re: Constriction cam-action knot for sleeping bags, compression, camping
« Reply #52 on: June 15, 2017, 04:20:56 AM »
Hi JohnC,

Glad you like it. For your smaller bundling tasks Bjoern_Hee took the original and made a beautifully improved version on page 4 i think. I found his extra turn to be redundant as a single turn is very secure. See the attached pic for the improved. It's superior to the gleipnir. I'm glad I inspired this beautiful knot.