Author Topic: A knot that can be tied while the line is taut.  (Read 15178 times)


knot4u

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Re: A knot that can be tied while the line is taut.
« Reply #31 on: March 08, 2013, 11:54:11 AM »
I'd try using that center axis somehow. Round turns again...

blooop

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Re: A knot that can be tied while the line is taut.
« Reply #32 on: March 08, 2013, 04:07:43 PM »
http://yumetalhardware.en.alibaba.com/product/599292165-215854581/Flemish_Eye_Steel_Swaging_Sleeves.html

Cool thanks.  I tried crimping a ferrule to the wire before but they were not strong enough.   I just need to find the right one. 

blooop

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Re: A knot that can be tied while the line is taut.
« Reply #33 on: March 08, 2013, 04:13:30 PM »
I'd try using that center axis somehow. Round turns again...

Like this? : http://i.imgur.com/BikGqOo.png

Would a round turn and two half hitches work well in terms of having tension while tying?


knot4u

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Re: A knot that can be tied while the line is taut.
« Reply #34 on: March 08, 2013, 05:01:15 PM »
I'd try using that center axis somehow. Round turns again...

Like this? : http://i.imgur.com/BikGqOo.png

Would a round turn and two half hitches work well in terms of having tension while tying?

Yes! Except that loop is one or more Round Turns, and you secure with Half Hitches.  One modification, if you can't get underneath the wire to tie Half Hitches, then raise the base on that axis by using a thick washer/spacer or something.

By the way, you should experiment with making tension in rope by using RTs. It's a fundamental concept. Knowing about RTs in rope is analogous to knowing how to purify water or make fire in camping. Learn it in and out.
« Last Edit: March 08, 2013, 05:14:00 PM by knot4u »

knot4u

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Re: A knot that can be tied while the line is taut.
« Reply #35 on: March 08, 2013, 05:46:31 PM »
"Round Turn and Two Half Hitches" is the search you want.

alpineer

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Re: A knot that can be tied while the line is taut.
« Reply #36 on: March 08, 2013, 07:06:18 PM »
Some form of appropriately sized  threaded collet would be the most elegant and effective solution. I can envision a hex-head collet  having two nuts to grip the wire.  One of the nuts would do double duty as a fine tension adjustment without having to re-adjust the gripping point on the wire. Sorry, I couldn't find any Google images of exactly what I'm describing.

But thinking about it, Roo's idea of having a threaded bore in the cruciform which accepts a hollow bore threaded hex-head sleeve/bolt (plastic should work here) seems a simple, effective, and more easily executed solution, but requires one added modification . That knot must be glued/epoxied to create a reliable and effective stop against (but not glued to) the hex-head tension adjuster. So, after all,  knots are a perfectly reasonable solution. Now everyone is happy :) Good job Roo. What nice, elegant knot would you use?

P.S. Use clear epoxy so that knot can be seen :) 
       
« Last Edit: March 08, 2013, 07:12:07 PM by alpineer »

James Petersen

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Re: A knot that can be tied while the line is taut.
« Reply #37 on: March 08, 2013, 08:04:38 PM »
You might try a small eyebolt or a hook bolt (a piece of allthread with a hook bent in the end might suffice.) passing through, but not threaded into the plastic (the outside diameter of the threads should be slightly smaller than the hole through the plastic). You could then attach the line to the hook or eyebolt with a loop knot and adjust the tension on the line with a nut on the other end of the bolt. A lock nut could be used in addition.  It might not be pretty, but it should do the job. 

Dan_Lehman

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Re: A knot that can be tied while the line is taut.
« Reply #38 on: March 08, 2013, 08:13:01 PM »
Given the fineness of your environment --the small material and close tolerances, i.e.--,
I can't imagine a knotted solution to be adequate to your needs.  ...
Maybe the simplest knotting solution is to turn the lines around the white plastic *peninsulas*
and then tuck it beneath this turn (perhaps with a 2nd wrap & tuck), sort of sheet bend,
blackwell-hitch-like locking!? (One need be chary of slippage from lack of sure nip of a
semi-flexible cord turning hard out of the hole and over a flat surface (with wrapped tail to nip);
a clamp could be the finish, now needing less pressure for effect.)

I like the sound of this but without the clamps.  ...
Here is a diagram of what I think you have suggested:  http://i.imgur.com/3RrSmYq.png

What would be a good knot to tie up the loose end to minimise slippage over time?

There are various ideas of securing this, the simplest being
an extension to what I said --which entailed tucking that
first completed pass beneath the start of the wrapping
(so, the tensioned line clamps down upon itself against
the flat --and this is an issue(!)-- surface).  One might
continue with a 2nd wrap, trying with it to pass over
the tensioned line (which needs to be secured for when
it loses tension) and then under itself (half-hitch)
to make a 2nd lock; and some 3rd pass & lock is likely
needed for better security, given the material & surface.
One can conceive of working in a Gleipnir nipping here,
in order to become immune to the surface-geometry issue
(because the G. will do nipping of material against material
and be independent of the shape & contact w/surface).

Quote
I've just realized that the fact that the underside is sloped may effect things.

And so affect them.  It can effect some assured positioning
via its slope, making a wrap press against the tensioned line,
e.g..  It should also ameliorate the sharpness of the turns
around this side of the object, much as I suggest doing with
an added cylinder, below.  ...>>

Now, again, considering the relatively sharp (right-angle)
edges of the hitched-to object, I might favor using some
small cylinder to effect the locking while also easing
the abuse on turning around the object.  Here's what I'm
thinking of:

with a small cylinder, able to fit between the hole & side,
wrap the line over this ("O1") and around,
and then come back over ("O2") and tuck under the cylinder ("O3"),
and around ("O4") and back under again ("O5"), to secure the lock.

And re exact orientation of these wrap-&-tucks of the
cylinder:
start on the center-side of the turned-over... line,
but tuck at angle to pass on the away side of the
hole;
then wrap around and cross over both the starting-out
and returning-to-lock lines (top of cylinder),
and go between the first tuck and the hole, to finish.

 = = ====O1O2O4 ===.......||B
 = = = == = = = = ===.......||A
 = =O3 O5 Hole= == ==.......||R

Pressure/tension of the wraps should press the cylinder
against the cross piece w/hole, trapping the tucked ends
to lock.  Working the tie-off into proper tension will need
to come after getting the wraps & tucks into place.


---dl*
====

roo

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Re: A knot that can be tied while the line is taut.
« Reply #39 on: March 08, 2013, 08:49:49 PM »
But thinking about it, Roo's idea of having a threaded bore in the cruciform which accepts a hollow bore threaded hex-head sleeve/bolt (plastic should work here) seems a simple, effective, and more easily executed solution, but requires one added modification . That knot must be glued/epoxied to create a reliable and effective stop against (but not glued to) the hex-head tension adjuster. So, after all,  knots are a perfectly reasonable solution. Now everyone is happy :) Good job Roo. What nice, elegant knot would you use?     
I haven't played with the line that blooop has, so I have no idea if glue is needed on an overhand knot.  Earlier, I suggested a Slippery 8 Loop as a tensioner (which works for rope and monofilament), but I wonder how any complex knot will perform in a line that has a metal core.  I have to accept blooop's word that it is knottable, but to what extent?

So, all we can do is throw out ideas, and let blooop see what happens.
« Last Edit: March 08, 2013, 08:52:40 PM by roo »
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blooop

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Re: A knot that can be tied while the line is taut.
« Reply #40 on: March 11, 2013, 12:49:41 PM »
There are various ideas of securing this, the simplest being
an extension to what I said --which entailed tucking that
first completed pass beneath the start of the wrapping
(so, the tensioned line clamps down upon itself against
the flat --and this is an issue(!)-- surface).  One might
continue with a 2nd wrap, trying with it to pass over
the tensioned line (which needs to be secured for when
it loses tension) and then under itself (half-hitch)
to make a 2nd lock; and some 3rd pass & lock is likely
needed for better security, given the material & surface.
One can conceive of working in a Gleipnir nipping here,
in order to become immune to the surface-geometry issue
(because the G. will do nipping of material against material
and be independent of the shape & contact w/surface).

Is this what you meant?  http://i.imgur.com/tqEbC1A.png
The numbers indicate the turn number, so the black line turns into the brown line underneath the cruciform.

Here is a template image http://i.imgur.com/7TViXSj.png  if I misunderstood you. 

Thanks.




Dan_Lehman

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Re: A knot that can be tied while the line is taut.
« Reply #41 on: March 11, 2013, 08:18:12 PM »
Bloop, you're on the right track.  And, you'll need to try
various locks with the particular conditions you have
--cord & object surface.  But note that in the image
you give (numbered 1-2-3 with black-orange-green-blue)
the black line (would be #0 :o) is UNsecured, and so
this doesn't meet your need for security when slack.

What I described was to have #2 cross over #0 (black)
and under #1 after 1 crossed under 0, as a means to
secure #0.   It's a little tricky given the way in which
#0 arrives at the knotting surface, and with the flat
surface itself.

Another idea is to take #1 away from its crossing at
the top surface to pass over #0 in turning around the
near side face and going back around, to come at the
position of "3" (well, snugly against itself on that side)
and then be tucked over-&-beneath itself (where it has
just crossed over #0, and so might secure it).  This would
make an overhand (binder) knot in the orange part.
How well this works will depend on the materials.

Note that it's nice in that each successive step doesn't
require some prior anticipation of the step --what's done
is done, and added to, not needing to anticipate the later
step.

It might be that a quick & effective securing could be made
by first wrapping #1 twice OVER #0 (so, well securing that,
and the friction of the wraps, held in hand, holding the desired
tension as you go to lock by ...) --and the slope of the underside
ridge should help wraps press towards the tensioned line's entry
there--
... THEN tucking the 3rd wrap under itself (but going from left
to right, opposite to the tucks you show)
and then back around and under as for #3 under #2.
(And hoping that the coating of the cable is relatively frictive
and gripping vs. slipping!)
Not sure where it might be best to PLACE the tucks;
you can try the top or the side (and maybe first one
then finish at the other place).  If the overwraps done
first have decent effect at securing the line out of the
hole, the first tuck might be best done on the side,
so as not to threaten the pressure of these wraps?!


--dl*
====

alpineer

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Re: A knot that can be tied while the line is taut.
« Reply #42 on: March 11, 2013, 08:50:19 PM »
   You can modify roo's idea and avoid threading the cruciform bores. It would consist of a length adjustable 2-part threaded sleeve affair placed between the cruciform and your knot. The adjustable sleeves would not grip but simply float on the cable. You would adjust the sleeves to their shortest length setting, tie your knot, and then adjust the sleeves to the desired length for proper tension. This method eliminates the finicky nature of tying the knot under tension and allows for precision adjustment at any time due to knot slippage or other. If the knot tended to slip (requiring too frequent re-adjustment) this problem could be solved if the finished knot sat in a well of appropriate size - whose walls would need to constrict the knot to some degree - and preclude having to glue knot as a last resort. If gluing the knot was found to be necessary, the well would act as container to glue the knot into.
« Last Edit: March 11, 2013, 08:55:39 PM by alpineer »

alpineer

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Re: A knot that can be tied while the line is taut.
« Reply #43 on: March 11, 2013, 09:39:45 PM »
Maybe simpler yet: slip a small open coil compression spring - of appropriate size and strength - over the end of your cable and then a washer (preferably welled) with a hole just large enough for your cable to pass through. Then, when you tighten the knot, the spring will keep the desired tension on the cable.
« Last Edit: March 12, 2013, 01:34:56 AM by alpineer »

blooop

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Re: A knot that can be tied while the line is taut.
« Reply #44 on: March 14, 2013, 04:12:00 PM »

Another idea is to take #1 away from its crossing at
the top surface to pass over #0 in turning around the
near side face and going back around, to come at the
position of "3" (well, snugly against itself on that side)
and then be tucked over-&-beneath itself (where it has
just crossed over #0, and so might secure it).  This would
make an overhand (binder) knot in the orange part.
How well this works will depend on the materials.

Thanks, I'll see how these combinations work.