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General => Practical Knots => Topic started by: xarax on October 28, 2010, 07:08:53 AM

Title: Best lashing knot for three perpendicular poles.
Post by: xarax on October 28, 2010, 07:08:53 AM
Best lashing knot for three perpendicular poles.
  
Title: Re: Best lashing knot for three perpendicular poles.
Post by: knot4u on October 28, 2010, 09:42:07 PM
I'm no expert, but this tripod lashing (racking turns) works and is easy for me to remember:
http://www.ropeworks.biz/archive/tripod.html
Title: Re: Best lashing knot for three perpendicular poles.
Post by: SS369 on October 28, 2010, 11:58:33 PM
"Bind three poles, in touch and perpendicular to one other, with one piece of rope, as tightly as possible."
This above statement is what you are trying to accomplish?
Perpendicular:  noun:   a straight line at right angles to another line
                adjective:   intersecting at or forming right angles
They are the same size I assume, touching each other (no rope between them) and perpendicular to each other?

What will be the abstract purpose of these three poles?
Do they have to support themselves in this configuration or bear additional weight?
Or is this decorative?

Scott
Title: Re: Best lashing knot for three perpendicular poles.
Post by: SS369 on October 29, 2010, 03:15:34 AM
The sticking point here for me is the need for the poles to be oriented Perpendicular to each other.
To me that means they are to be at right angles, 90 degrees to each other.
And if only the ends are to be joined the I see the need to "waste" cord with frapping turns.
Otherwise a knot is to be tied and then the parts of the affair rotated to induce a tightening twist.
The knot must have sufficient round turns to reduce the load(s) on the cord alleviating the strain on one small area.
If the knot is overtightened before the twist/reorienting is done then all bets are off.
The attached is a fairly simple tripod style lashing that to me reduces the frapping turns.

S
Title: Re: Best lashing knot for three perpendicular poles.
Post by: knot4u on October 29, 2010, 04:01:44 AM
SS, I don't understand what's going in step 3.  Is there a better diagram?
Title: Re: Best lashing knot for three perpendicular poles.
Post by: SS369 on October 29, 2010, 04:17:02 AM
Hi knot4u,
what is happening is the same as in doing the sail-makers whipping.
The cord is being roved between the poles to fill and tighten.
It is just an alternative to "standard" sheer lashing.
No I don't have a better diagram at present, sorry.
Title: Re: Best lashing knot for three perpendicular poles.
Post by: oldpete on October 29, 2010, 06:12:46 AM
i think people are getting confused by the perpendicular part. think of the corner of a table, one pole is one side, one is the other and the third is the leg . i e repeat 4 times to make your table frame. hope this helps
Title: Re: Best lashing knot for three perpendicular poles.
Post by: knot4u on October 29, 2010, 06:29:51 PM
Exactlly ! The poles are put as to be oriented perpendicular from each other right from the begining, before they are bound together, and they stay so till the end...  

While we're looking for a knot solution, I'm also interested in a solution for holding the poles in that position before the rope is applied.

If the practical application is heavy logs, which you mentioned above, then having the poles in the final position before tying the rope is already a difficult thing to do.  For this pre-problem, I'm imagining some kind of support on each leg to hold each leg up at the appropriate angle.  Based on your criteria that I quoted, you may have eliminated the option of tying two legs and then attaching the third.  Or did you not mean to eliminate that option?
Title: Re: Best lashing knot for three perpendicular poles.
Post by: knot4u on October 29, 2010, 08:01:44 PM
You have a nearly impossible problem.  With heavy logs, the rope will have to overcome an extremely high moment of inertia on each leg.  The tripod lashing may consume a lot of rope, but this contraption would consume way more rope to keep the legs stable.

Unless... You first carve out pegs and recipient holes in each leg.  Fit the legs together so that they form the right angles as described.  Then, apply the rope around the vertex such that the rope provides support to the pegs and holes.  The pre-fitting will take strain off the rope.  Even then, I think you'll need additional support beams to support the three legs, like the cross beams at the top of this structure:

(http://i56.tinypic.com/4qfyn4.jpg)

By the way, rope is not the best solution to this problem, but we're all playing along because that's the parameters.
Title: Re: Best lashing knot for three perpendicular poles.
Post by: knot4u on October 29, 2010, 10:47:34 PM
You have a nearly impossible problem.  With heavy logs, the rope will have to overcome an extremely high moment of inertia on each leg.  The tripod lashing may consume a lot of rope, but this contraption would consume way more rope to keep the legs stable.

No!  :) The weather beaten, standard solution of engineers, when they have an orthogonal frame with joints of beams and it is hard to keep them together at right angles, is to put diagonals that keep the corners at a constant distance, so that the whole frame is stabilized. The diagonal cables/ropes connecting the opposite corners do what is called "triangulation", and take off most, or even all, the strain of the joints, so the angles do not become oblique - i.e, the shape of the frame remains an orthogonal parallelogram, it is not transfigured to an oblique one. Bind the three poles at each corner for me as tightly as you can, so that they do not slip, and I will manage to prevent our parallelogram decay into a rhomboid.  :)

Well, yeah, but you just added more material.  I thought the only material we had were the three legs and rope.

If we can add other materials, then your problem becomes trivial.  You bind two legs on the ground at a right angle by using a cross beam and nails/bolts.  Then, bind the third leg by using two more cross beams.  You can add the rope, but it would be unnecessary.  I have made this type of construction before.  If you remove the crossbeams and have just rope at the vertex, then the structure becomes unstable.  I wouldn't use if for anything other than art.
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DerekSmith on October 30, 2010, 01:17:52 PM
Have you considered the Chinese bamboo scaffold solution?

(http://darkwing.uoregon.edu/~struct/courseware/hk1/hk1_bamboo/bamboo_connection2.jpeg)

Derek
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DDK on October 30, 2010, 07:48:30 PM
Many "tripod" junctions by knots are known, but I think they are not satisfactory, ... Notice also that the first and the third of the poles are not tied to each other, ...

A cloverleaf lashing (slightly adapted for non-parallel poles) would connect each pole to the other and maintain the symmetry of the joint.  Tightening will need to be addressed for any method where the poles are to remain stationary during the entire process.  Tourniquet methods may be of use for tightening?  This topic falls under the category of "Pioneering" for those of us that are/have been involved in scouting.

DDK
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DDK on October 31, 2010, 02:15:46 AM
This topic falls under the category of "Pioneering" for those of us that are/have been involved in scouting.
... Yes, it could be useful in scouting, and, in fact, it is , but its general character makes it an interesting knot problem for all of us, I believe.  

You may have read more into my comment than I had intended.  I certainly was not implying that this was only of interest to scouts nor was I suggesting that this knot problem would only arise for those engaged in Pioneering.  As it happens, this problem has been addressed by several involved in Pioneering and their solution may be worth a look.

The cloverleaf lashing was developed to address the multiple attachment of poles at (or near) a single point.  I have seen examples of 4, 5 and 8 pole attachments.  For 3 poles, the attachment would be at a single joint (that is, each pole is intimately connected to the other two with the use of in total a single lashing).

DDK
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DDK on October 31, 2010, 07:25:49 AM
...  For 3 poles, the attachment would be at a single joint (that is, each pole is intimately connected to the other two with the use of in total a single lashing).
   So you would have three two-poles lashings, not a one three poles binding knot ! :)

No.  You would have one (single) three pole binding knot (lashing).  If one googles cloverleaf lashing, the first link to be listed has a description of this lashing

http://ropesandpoles.blogspot.com/2007/06/clover-leaf-lashing.html (http://ropesandpoles.blogspot.com/2007/06/clover-leaf-lashing.html)

DDK
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DDK on October 31, 2010, 08:51:44 PM
... The fact that the same piece of rope can go around the 4 or n number of poles, the one after the other, does not makes such lashings one integrated knot, I believe -  but exactly a compound knot made by the addition of more and more lashings, that I  have talked about in my previous post. ...

Indeed, when the number of poles is 4 or more, I would also describe the cloverleaf lashing as a compound knot or multiple joint as it is clear that each pole is not directly connected to all the others.  When the number of poles is 2 or 3, however, this is not the case and it is clearly not a compound knot, but a single binding.  For the problem you posed, the number of poles is 3.

...  Moreover, trying to tighten this type of lashings without the use of other tools and tricks is impossible, because the poles are not in touch with each other in the first place. ...
A cloverleaf lashing (slightly adapted for non-parallel poles) would connect each pole to the other and maintain the symmetry of the joint.

As I have mentioned in a previous post, the cloverleaf lashing would need adapted to non-parallel poles.  One of these adaptations could be to have the poles in contact.  To point out what may be obvious, one way to reverse-engineer the lashing for non-parallel poles would be to:

(1) Apply the round turns but not the fraps to 3 parallel poles.
(2) Spread the tripod to the orthogonal condition desired (there is a clockwise spread and an anti-clockwise spread - one will tend to tighten the lashing and the other will tend to loosen the lashing).  I would speculate that the spread that loosens the lashing will be preferred in that the applications of fraps will be more effective at tightening the lashing.
(3) Observe the wrapping of the round turns.
(4) Develop a method for the application of the fraps and the tightening of the lashing.

I would assume that all of this has been accomplished a number of times by those that commonly use the cloverleaf lashing, however, I have not seen it reported.

To summarize what I believe to be true about the use of the cloverleaf lashing on 3 poles is this:

(1) The poles can be in contact, orthogonal and stationary prior to their binding.
(2) It will be a single binding.
(3) The lashing will have the same three-fold axial symmetry as the arrangement of the poles. This "cube-corner" symmetry is the same as found in the Monkey Fist, for example.
(4) The application of fraps for the purpose of tightening will be as effective as in most lashings.

DDK
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DDK on October 31, 2010, 11:24:05 PM
...Apply the round turns but not the fraps to 3 parallel poles.
...The poles can be ...stationary prior to their binding.

   So you are telling me that the application of the round turns is not part of the binding process, and the subsequent rotation of the poles - from the parallel to the orthogonal position- does not mean that the poles are not stationary at the phase of their binding, because "binding" refers only to the application of the fraps, not the application of the round turns or the rotation of the poles ?  :)
   Instead of defending this far fetched view, we could better try to improve the "Japanese scaffold lashing" and adapt it in the case of the 3 perpendicular poles, and see what happens.

My mistake - I thought the term reverse-engineering was fairly common and would be understood.  It describes a process by which one may develop understanding and/or a new process from an existing process, for example.   In this case, once one has easily discerned how the round turns are to be wrapped on stationary and orthogonal poles by spreading the tripod in the conventionally wrapped lashing of parallel poles, one forever knows how to apply the round turns from scratch to any set of stationary and orthogonal poles. So, in this "newly" developed process with this "new" information, the poles are in contact, orthogonal and stationary prior to the wrapping of any round turns or fraps.  There is nothing at all farfetched about it.  

DDK

Title: Re: Best lashing knot for three perpendicular poles.
Post by: SS369 on November 01, 2010, 01:51:26 AM
I have been experimenting with this one a bit and besides the want of the poles to go everywhere except where I need them here's the best method I've come up with to date.


However you can secure the three perpendicular poles in the correct orientation, do so.

Cut a suitable piece of accordingly sized cord/rope to length.

Starting with the "vertical" pole tie a double constrictor knot at location and tighten with the leads going around to the backside of the knot. Cross the leads back there. That should be the outside of the corner.
I originally tried Prusik, clove and Klemheist hitches and they work, just not as well.

Now position the additional poles to their respective perpendicular places above the dbl constrictor.

Take the two now crossed leads and go around the outside of the two crossed and touching poles guiding one cord into the each "V". Now do one or two frappings around the V's with both lines in opposite directions. This is all happening outside the vertical pole.

Finally take the leads under both horizontal poles and cross them while going up inside to the final position of over and outside the horizontal poles to be tied off with any number of binding knots. Though continuing to go around the unoccupied V (back) and then to tie off around the vertical pole will add some more spreading stability. to the whole thing.

The main thing is to have a dependable support knot on the main pole and then frapping turns that will cinch the two other poles snug to the main.
Looks like hell but it will freely hold the three poles.

Hope it makes sense. I see it so...... muddily.
:-)


Title: Re: Best lashing knot for three perpendicular poles.
Post by: SS369 on November 01, 2010, 02:20:20 PM
Oh yes, I agree wholeheartedly that the affair I have tangled lacks symmetry.
The first thought was to get the job done.
Next it was to minimize the amount of cord used without diminishing security.
Third is relative ease of tying. Which I don't think I did either.

I believe the basic concept-design elements of what I did would be enhanced by additional round turns on each of the members and even then around all of them.
But that will use an awful amount of cord.
As for a "knot" doing this and doing it well, I think not.

Maybe you could do some kind of super duper go everywhere Pile hitch twisting,and yanking as she went.

What have you got?
Title: Re: Best lashing knot for three perpendicular poles.
Post by: Dan_Lehman on November 04, 2010, 05:51:33 PM
Have you considered the Chinese bamboo scaffold solution?

A nice picture for the "Knots in the Wild" thread, perhaps.  :)
I have also considered Mongolian yurts, but they are circular structures, no relation to western Cartesianism there too, I am affraid.. :)

???
If this photo does not show the general relationships of the
"Bind three poles, in touch and perpendicular to one other"
problem you're exploring, please explain why not, and what does.

To me, an essential element of reality is missing from the problem
statement --to wit, gravity : what bears load, in what direction!?
E.g., in Derek's presented image, the vertical pole supports the
others bound to it, and one might bind the lower of these very
securely essentially just *attach* the 3rd one stop this support,
or one might bind the upper and essentially support the lower
via friction-hitch mechanics.

--dl*
====
Title: Re: Best lashing knot for three perpendicular poles.
Post by: Tha on November 16, 2010, 09:03:19 AM
Hi, I just joined the forum and made my first post. By coincidence it is a solution to the problem posted in this thread. Xarax pointed this out. See http://igkt.net/sm/index.php?topic=2078.0 (http://igkt.net/sm/index.php?topic=2078.0)
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DerekSmith on November 19, 2010, 12:43:03 AM
Lovely symmetry, but virtually zero ability to transfer vertical force on the horizontal poles into the vertical pole (or any other combination), and no mechanism to leverage cord tension.

Was your challenge intended to be functional or simply decorative?

Derek
Title: Re: Best lashing knot for three perpendicular poles.
Post by: squarerigger on November 19, 2010, 08:35:13 PM
Just a thought or perhaps a question:

If you have three poles of circular cross-section at an x,y,z locus, then perhaps the joining material/fiber should be ribbon-like in cross-section to obtain the greatest frictive resistance?  It could be a flat ribbon (woven) or a sennit covered with pine tar (I love pine tar) to help increase the friction.  Otherwise it seems that one should alter the shape of the meeting point(s) of the poles to allow/encourage some mechanical attachment or resistance to movement, one to the other?  FWIW   ???

SR
Title: Re: Best lashing knot for three perpendicular poles.
Post by: knot4u on November 19, 2010, 09:29:12 PM
You're trying to defy the laws of physics if this contraption is for practical use and you're NOT using multiple wraps of rope.  No further explanation, I would be repeating myself.
Title: Re: Best lashing knot for three perpendicular poles.
Post by: squarerigger on November 20, 2010, 01:22:37 AM
Quote
I had never thought of adding a third material, solid or liquid,  that could help increase the friction between the rope and the pole ! Is the addition - of pine tar or whatever - a known knotting practice that I was not aware of ?
   
Hi xarax,
The use of pine tar as a preservative of natural fiber line acts also to form an adhesion to underlying surfaces.  In particular note the use of the selvagee (SEL-vah-jee) from ABOK #3521, that was found to adhere with much improved force when made with spun-yarn or marline that had been well-soaked in tar, a practice I use to this day (well, tomorrow, at my weekly volunteer rigging) to obtain a purchase on a shroud prior to adjusting the tension in the lanyard through the dead-eye.  As for the use of tar with other knots - it may well be that tar was used as a preservative that was also found to have side benefits, not the least of which is the adorable smell!  Another practice that is used aboard ship is the parcelling of the shroud prior to applying the serving or service.  A similar layer is added under wire seizings made on shrouds and stays.  There may be more in other fields, such as rosin on pulling cable for electrical wiring or cabling and the use of chalk on climbing ropes.  Specifically are they designed to help a knot?  That depends on what one would term a knot, doesn't it?  If a knot is any confusion for some specific purpose or otherwise in a line then - maybe; but if a knot is simply a deliberate tangle in a line then perhaps not!  Maybe that is a discussion for another topic?

SR
Title: Re: Best lashing knot for three perpendicular poles.
Post by: DerekSmith on November 21, 2010, 09:58:22 AM
"  I believe/hope that this can be achieved by hard tensioning of the two riding turns per pole, and/or by more than two riding turns per pole, so that these turns function like they do in friction hitches."

Yes, we can always turn to 'More Rope' for a feel good or partial solution

(http://knotbox1.pbworks.com/w/file/fetch/8097439/JobKnot.jpg)

But I hope you are seeking an intelligent solution rather than 'saturation knotting'.  This little example would have been so much better tied with a Gleipnir or the more recent 'Xarax Knot with no name a la Gleipnir'.

So, back to the tripoles.

For nothing more than artistic bondage, the delightful manifold you have given us or the basic manifold used by the scouts in another thread are ideal.  But for a 'real' application, the nature of the materials and the nature, magnitude and direction of the forces involved are critical aspects.  Surely the binding chosen must accommodate the requirements of the(a) 'real' application.

If it is a table, then not only must the binding handle the vertical forces, but it must also resist the horizontal force of being leaned against and so resist parallelogram style deformation (presumably we are not allowed the luxury of diagonal spars or spoke ties?).

The use of Tar soaked cord raises a significant question - might I presume that this challenge must achieve the desired goal without adhesive?  Tar soaked cord today, Superglue or Araldite soaked cord tomorrow and resin soaked carbon fibre for the final solution?

Derek
Title: Re: Best lashing knot for three perpendicular poles.
Post by: SaltyCracker on December 05, 2010, 02:46:48 PM
xarax,
Thanks for the invitation to post to this subject. I'm afraid that I'd take the traditional process of applying two, adjacent square lashings. One between the vertical (with the vertical spar perpendicular to support surface) and bottom most horizontal spar; the other between the bottom most horizontal and 2nd horizontal spar with the 2nd spar positioned (supported) on top of the bottom horizontal spar. Can be done with one piece of line and there remains sufficient room between the spars for frapping the 2nd lashing.

The above assumes that additional supporting structure will provide lateral support to the vertical spar.

That said, where slick spars, heavy traffic, working due to wind (from experience), etc. are involved the lashing between the bottom-most horizontal spar and vertical spar tends to slip. One solution, when the vertical spar extends sufficiently beyond & above the two horizontal spar, is to provide suspension support to the bottom most horizontal spar by applying an Icicle Hitch to the vertical spar with the "load" end secured and tensioned to the bottom-most horizontal spar. A taut-line hitch can be used to provide adjustable tension.

The idea of using a constrictor knot, as suggested by one poster, around one of the spars instead of a clove hitch to start a lashing is a good one. In the above it would be the starting "knot" applied to the vertical spar, just below the bottom-most horizontal spar.

SaltyCracker
(formerly KnotInGuild... felt that name a bit glib.)
Title: Correction... Re: Best lashing knot for three perpendicular poles.
Post by: SaltyCracker on December 05, 2010, 02:49:31 PM
... intended to reference a Wagoner's Hitch to provide adjustable tension rather than a Tautline Hitch.
Title: Re: Best lashing knot for three perpendicular poles.
Post by: JohnC on December 18, 2017, 07:03:39 AM
Best lashing knot for three perpendicular poles.

Hi, can you advise how this lashing is done?

Thanks.
Title: Re: Best lashing knot for three perpendicular poles.
Post by: eric94110 on May 29, 2019, 12:41:02 AM
Your photos are cool but I cannot figure out how to actually make this lashing... and video?