Author Topic: knotting rubber strands together  (Read 4972 times)

RSK

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knotting rubber strands together
« on: April 05, 2006, 04:24:22 AM »
I'm working on something where two strands of 0.7mm diameter rubber meet and am trying to figure out what the best knot would be for tying them together as securely as possible.  The knot is subject to pulling and stretching and I am hoping there's a knot out there I could use which would get tighter when pulled on and one where the clipped ends would not be likely to slide through the knot causing it to come undone.  Any ideas???

squarerigger

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Re: knotting rubber strands together
« Reply #1 on: April 05, 2006, 08:06:36 AM »
Hi!

I think a tucked Perfection Loop should do the job if you want to tie two loops together, or you can modify the knot by making the loop a bight and incorporating the other line around it.  Let us know how you get along with this method and, if it doesn't work, let me know.

Lindsey

Fairlead

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Re: knotting rubber strands together
« Reply #2 on: April 05, 2006, 10:20:20 AM »
No doubt in my mind - The Ashley Bend, but like all knots that are going to be hauled around you need to leave fairly long ends.

Gordon

Dan_Lehman

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Re: knotting rubber strands together
« Reply #3 on: April 10, 2006, 08:27:46 AM »
Quote
I'm working on something where two strands of 0.7mm diameter rubber meet and am trying to figure out what the best knot would be for tying them together as securely as possible.  ...

Are there any other constraints?
E.g., how long/accessible are the strands?
How will this knot need to be tied--i.e., will you have to join the ends
in some sort of limiting situation, using a minimal amount of end,
or will you tie the knot away from its ultimate placement, with great
freedom in tying?

0.7mm (!!) is tiny, quite fiddly, IMHO!

I quite disagree with Fairleads:  while Ashley's bend (any of 'em: #1452, or
1408, 1453, 1425) should hold under tension w/o slippage,
they will be hard to set tight, and be prone to loosening
(well, not 1425 re that, but ...).
Okay, 1452 has the question of versions, but that's hardly worth
the bother to try to communicate, I've learned.

The Water knot aka "Ring Bend" should work best, as one can
set it well by loading BOTH the standing parts & free ends,
drawing the whole knot tight (esp. given the tiny material),
and it should stay tight, I'd think, in a frictive material like rubber.
As for which pair of ends to load in the Ring Bend, well, maybe
you should do some A-v-B testing in the material and see.

With such frictive & elastic material, it's unlikely that any knot with
much to it will work as expected, for the nature of the material will
keep tension from being delivered to the parts of the knot that
normally get it, and other parts will deform much more than usual,
given the elasticity.
(For rubberbands, e.g., the Square/Reef knot works well for precisely
these reasons--the setting and the limited dist. of tension.
And I think that a Blood knot would work quite poorly, again
for same reasons.)

--dl*
====

KnotNow!

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Re: knotting rubber strands together
« Reply #4 on: April 11, 2006, 09:01:32 AM »
Hi, Sorry to be so slow in posting my opinion.  When I got G. Budworth's "Knots and Ropework" (the beautifully photo illustrated book) I worked through all the knots that were new to me.  He shows Harry Asher's 1989 "Vice Versa" on page 62 and says it will even work with "Bungee".  Always a doubter I played with it in "rubber bands" (USA speak.. maybe called "elastics" in other places).  They are often about .7mm I think.  It does work.  It also works on the miserable bungee cord.  Years ago I had some 3/8" "rubber rope" that was solid and had no overmantle.  It had a 1000# breaking rating and was the finest "tie down" for canoes and cartop boats.  I used metal hooks from the supplier as I could not find a knot that was reliable (even in ABOK) but could later be untied.  I wish I'd had "Vice Versa".  Of course now I can't find the rubber rope for sale.  I still tie down canoes and I haven't lost one yet... but that rubber rope was so fast and so easy.... miss it.  I am pretty sure if you try Vice Versa it will work for you.  In case your ".7mm" was intended to be "7mm" I am darn sure Vice Versa will work... since I was dreaming of 3/8 rubber rope as I tested the knot at home.  
ROY S. CHAPMAN, IGKT-PAB BOARD.

DerekSmith

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Re: knotting rubber strands together
« Reply #5 on: April 14, 2006, 08:09:11 PM »
Another variant would be to tie a Constrictor Knot or ABOK #1189  around one part, then another Constrictor knot using the other end around the first part.

Draw the two knots together before dressing them.

Warning - Do not expect to be able to untie the result once it has been set.

Jimbo_The_Kinky

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Re: knotting rubber strands together
« Reply #6 on: April 17, 2006, 10:45:26 PM »
Quote
I'm working on something where two strands of 0.7mm diameter rubber meet


How's your search coming?

It would be easier if you'd be more specific, to wit:

How, exactly, will the strands meet?  End-to-end?  End-to-middle?  Middle-to-middle?

Quote
The knot is subject to pulling and stretching

Questions:  "Pulling & stretching" how?  Hanging in air?  Dragging over rocks?  Deflected from the side (at or not at the knot)?  Pulled lengthwise or laterally?  Further, will it ever be completely slack?

Quote
get tighter when pulled on and one where the clipped ends would not be likely to slide through the knot causing it to come undone


The "0.7mm" puts severe constraints on just how effectively you'll be able to meet these requirements.  If it's really the size of medium mechanical-pencil lead, not "7mm" as PABPRES suggested, then just about any jamming knot will outlast the rubber itself, especially if you pull the ends (to tighten it) so hard they break off on their own.

So...

Have you tried a Zeppelin Bend?  If so, what happened?  Are you willing to put stopper knots in the tips to prevent the "slide through" trick?  Is there any adhesive available in your area which might serve better (begging the IGKT's pardon for a no-knot solution)?  Have you tried any of the earlier suggestions?  What happened?