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Screw Rope

tightening via flexible split bolt + nut
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Two semi-flexible plastic shapes are molded in fixed position around separate ropes in such a way that when the shapes are laid together, they resemble the spiral-grooved pattern of a large bolt.

A metal ring connects one end, where a large plastic nut is looped around the ropes. The opposing ends of each rope are left loose, and able to attach to various anchors.

[SEE IMAGE]

In use, this arrangement allows for triangular fastening of objects using two anchors and a single connection point, such as you might attach a canoe to the top of a car.

Thus fastened, the nut is turned around the bolt-halves, shortening the triangle and increasing tension between the three points.

Your thoughts?

napoleonbag, Jul 23 2008

(?) Proposed Image http://www.brianhauge.com/bolt_rope.gif
[napoleonbag, Jul 23 2008]

[link]






       Nice picture. However, if I imagine it with no green plastic, the canoe is still connected. How does it improve the connection to bring the two ropes together? It would seem to just put tremendous stresses on the plastic.   

       That said, I like the idea of a bivalve screw. It is hard for me to think of a good application. Maybe for a zipperlike closure for a jacket? The problem is that the screw can only be attached at the ends, not in the middle or the nut action will not work.
bungston, Jul 23 2008
  

       The device puts the rope under tension.   

       I think a "comealong" strap would work better because you'd have to worry about the nut loosening with this design. On the other hand, a comealong strap has a minimum practial length.   

       If you can find some way to lock the nut in place - with a pin or something - you might have a winner.
phoenix, Jul 23 2008
  

       Two nuts, one with opposed thread to lock .   

       Could one of the rope threads be held so that when the nut turned the other thread moved - abit like the adjustible cresent mechanism .
wjt, Jul 23 2008
  

       Nice image. Interesting idea.   

       The device would also serve as a way to keep the two halves of the rope from sliding relative to each other. You could make a loop, pull on one end, and keep it in place by screwing the nut down.   

       For my tying canoe on, I find it much better to use two separate ropes in a triangle. That keeps the end of the boat from wiggling side-to-side.   

       (I once tried to secure a load by making a rope triangle like the illustration, and wrapping a coil of rope around the junction where the nut is. I kept winding it up, and bent the bed of my pickup.)
baconbrain, Jul 23 2008
  

       This is a very nice idea! I suspect there's a market for this, especially since it should be pretty cheap to make. Go patent!
MaxwellBuchanan, Jul 24 2008
  

       The thread wouldn't have to be molded onto the rope. Something that clipped over, with a rough textured inner surface (or just a tight fitting opening) would also work.
MechE, Jul 24 2008
  

       One of you smart people tell me, would this be a good way to distribute the weight of the secured object? Would it be better than using two ropes without screwing them together?   

       I'm thing of some kind of situation where you might have a fairly heavy object and you only have some lightish rope. Is this going to help out? I've already bunned the idea, I'm just curious to hear from the engineers.
Noexit, Jul 24 2008
  

       Mechanics ain't my bag, baby, but as far as I know, it doesn't matter (give or take some assumptions about the geometry) whether you have 1 strong rope or n ropes of strength 1/n.   

       That's only taking into account the strength of the suspending rope though. Their may be other reasons like pressure (not the right term) on a single point of attachment to distribute load.
Jinbish, Jul 25 2008
  
      
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