Author Topic: A knot that can be tied while the line is taut.  (Read 15179 times)

roo

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Re: A knot that can be tied while the line is taut.
« Reply #15 on: March 07, 2013, 09:34:17 PM »
I would like to move away from the clamps as they add weight, which affects the performance of the arm badly.
If you do use hex head cap screws with a hole drilled down the axis (per my earlier suggestion), you can buy them in plastic to reduce weight.  It'll also be easier to drill.

A standard washer may or may not be needed distribute force over the plastic.
« Last Edit: March 07, 2013, 09:44:38 PM by roo »
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alpineer

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Re: A knot that can be tied while the line is taut.
« Reply #16 on: March 07, 2013, 09:46:40 PM »
I would like to move away from the clamps as they add weight, which affects the performance of the arm badly.
If you do use hex head cap screws with a hole drilled down the axis (per my earlier suggestion), you can buy them in plastic to reduce weight.  It'll also be easier to drill.

The holes must be drilled in the perpendicular axis (per my suggestion). Shims and angles are not allowed. And yes, plastic bolts/nuts are certainly worth a try. Good Luck!

blooop

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Re: A knot that can be tied while the line is taut.
« Reply #17 on: March 07, 2013, 09:51:18 PM »
Stop!

Modify your (HDPE?) cruciforms with threaded holes to accept machine bolts spanning a slotted space which accepts the wire cable. The machine bolts will indirectly pinch the wire cable via the HDPE, and thus avoid cable abrasion. If you find it necessary to apply more pressure to stay the cable, use a nut on the end of the machine bolt. This will remove the stress from  the HDPE threads.

It is 3D printed ABS. 

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

Ideally I'd like to avoid having to rebuild the entire thing from scratch.  I can't do any work on them while they are stuck to the carbon fibre and removing them from the carbon fibre destroys the rod.    That is why I'm looking for knot based solutions.


alpineer

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Re: A knot that can be tied while the line is taut.
« Reply #18 on: March 07, 2013, 09:58:26 PM »
Stop!

Modify your (HDPE?) cruciforms with threaded holes to accept machine bolts spanning a slotted space which accepts the wire cable. The machine bolts will indirectly pinch the wire cable via the HDPE, and thus avoid cable abrasion. If you find it necessary to apply more pressure to stay the cable, use a nut on the end of the machine bolt. This will remove the stress from  the HDPE threads.

It is 3D printed ABS. 

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

Ideally I'd like to avoid having to rebuild the entire thing from scratch.  I can't do any work on them while they are stuck to the carbon fibre and removing them from the carbon fibre destroys the rod.    That is why I'm looking for knot based solutions.
  Well, Sorry then. Knots won't work for your application.

blooop

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Re: A knot that can be tied while the line is taut.
« Reply #19 on: March 07, 2013, 10:17:25 PM »
Well, Sorry then. Knots won't work for your application.

Ok, then I'll go along with this:  http://i.imgur.com/3RrSmYq.png  and glue it (unless someone can suggest a good knot for tying this off).

roo

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Re: A knot that can be tied while the line is taut.
« Reply #20 on: March 07, 2013, 10:27:43 PM »
  Well, Sorry then. Knots won't work for your application.
Why not?
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roo

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Re: A knot that can be tied while the line is taut.
« Reply #21 on: March 07, 2013, 10:31:07 PM »
Ok, then I'll go along with this:  http://i.imgur.com/3RrSmYq.png  and glue it (unless someone can suggest a good knot for tying this off).
Considering the open geometry, this may work, too:

http://notableknotindex.webs.com/Versatackle.html

Especially as shown in the second diagram.

However, you have many other options that will look cleaner when done.
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alpineer

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Re: A knot that can be tied while the line is taut.
« Reply #22 on: March 07, 2013, 11:23:04 PM »
Like this?: http://i.imgur.com/sZVbxlV.png 

No. More like this http://www.parktool.com/uploads/images/blog/repair_help/shm_da_542.jpg just to demonstrate the concept, with some modification necessary for your purposes.

The pinch bolt applies pressure to the crankshaft. The crankshaft would be the analog of your wire running through the end of your cruciform arm structure. 

alpineer

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Re: A knot that can be tied while the line is taut.
« Reply #23 on: March 07, 2013, 11:31:17 PM »
  Well, Sorry then. Knots won't work for your application.
Why not?

unwieldy, unreliable, finicky(requiring too much attention), tendency to go out of tune...

roo

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Re: A knot that can be tied while the line is taut.
« Reply #24 on: March 07, 2013, 11:43:35 PM »
tendency to go out of tune...
If that were the case, you could just use the stopper knot in concert with a tensioning mechanism, as has been discussed.

It may not be the case.  I don't know.
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knot4u

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Re: A knot that can be tied while the line is taut.
« Reply #25 on: March 07, 2013, 11:53:23 PM »
I'd probably borrow from the concept of a guitar string tension on a guitar.  Of course, you'd have to reconfigure your system somehow, adding a few components here and there.

Another possibility is Round Turns and Half Hitches, which is my default tension system before I consider a Trucker.  Can you widen the hole and go around the anchor to make Round Turns?  Try one RT and then two RTs if one doesn't hold the tension long enough to tie the Half Hitches.
« Last Edit: March 08, 2013, 12:24:13 AM by knot4u »

blooop

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Re: A knot that can be tied while the line is taut.
« Reply #26 on: March 07, 2013, 11:55:21 PM »
No. More like this http://www.parktool.com/uploads/images/blog/repair_help/shm_da_542.jpg just to demonstrate the concept, with some modification necessary for your purposes.

The pinch bolt applies pressure to the crankshaft. The crankshaft would be the analog of your wire running through the end of your cruciform arm structure. 

Ah ok.  I don't think that will work because there is no way that I can apply more force with plastic than I am at the moment with the metal.  I'm turning the scews so much the metal is tearing and it still slips. 

blooop

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Re: A knot that can be tied while the line is taut.
« Reply #27 on: March 07, 2013, 11:58:42 PM »
Ok, then I'll go along with this:  http://i.imgur.com/3RrSmYq.png  and glue it (unless someone can suggest a good knot for tying this off).
Considering the open geometry, this may work, too:

http://notableknotindex.webs.com/Versatackle.html

Especially as shown in the second diagram.

However, you have many other options that will look cleaner when done.

That's really cool.  Unfortunatly it probably won't work because the lines are not always completly taut.  When it bends in weird ways some of the lines go slack.  I assume that would not work well with this. 

SS369

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Re: A knot that can be tied while the line is taut.
« Reply #28 on: March 08, 2013, 01:25:26 AM »
Hi Blooop and welcome.

If there is room for the wire rope to pass back through the hole,  then you might be able to thread it through a suitable washer or dowel after it comes through (keeping the loop from pulling through like a toggle), then on the return side of the cross tie a knot after tensioning.
Or use a crimp ferrule.

Hope this generates more ideas.

SS

roo

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Re: A knot that can be tied while the line is taut.
« Reply #29 on: March 08, 2013, 03:56:23 AM »
...some of the lines go slack.   I assume that would not work well with this.
Possibly.  A Slippery 8 Loop would handle that fine and provide tension:
http://notableknotindex.webs.com/slippery8.html
« Last Edit: March 08, 2013, 03:59:52 AM by roo »
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