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Re: Topband: Ends for older Phillystran

To: Bill Wichers <billw@waveform.net>
Subject: Re: Topband: Ends for older Phillystran
From: Ashton Lee <Ashton.R.Lee@hotmail.com>
Date: Tue, 14 Jan 2014 10:27:26 -0700
List-post: <topband@contesting.com">mailto:topband@contesting.com>
We sailors would wrap a line twice around the eye and then leave a longer tail 
and clamp that with some space between each clamp. The increased friction of 2 
wraps around an eye/block/winch substantially reduces the pull on a knot, 
cleats or (in this case) clamps. It could be that the phillystran needs to be 
wrapped around something with a larger radius than the eye however… not sure of 
the engineering on that point. So you might  need a “thimble” in the set up.



On Jan 14, 2014, at 10:04 AM, Bill Wichers <billw@waveform.net> wrote:

> The bar idea would probably significantly reduce the allowable tension on the 
> cable, similar to what knotting does, due to the force at each "bite point" 
> weakening the cable. I suppose if the cable was sufficiently oversized this 
> wouldn't pose a problem, but I'd certainly expect such a clamping method to 
> effectively reduce the allowable tension significantly below the normal rated 
> load.
> 
> I'm actually a little surprised a dead end / preform isn't supposed to be 
> used with the straight-strand version of the cable. Those grips work by 
> compression of the cable they are "grabbing", and it's a fairly even pressure 
> over the length of the gripped area. If one could be found that was the 
> correct diameter for the cable being used it might be worth a shot, but I 
> completely agree with Tom -- TEST ANYTHING YOU TRY BEFORE USING IT FOR REAL!  
> He's also correct that dynamic loading is much worse than static loading. 
> Wind causes vibration in towers and guys and that can cause your clamps  to 
> loosen over time, especially if they were marginal to begin with.
> 
>   -Bill
> 
> 
>> Has anyone thought of a long rectangular bar with multiple champhered
>> holes, with the Phillystran woven through from side-to-side? With enough
>> weaves, this should self-tension with just a single clamp on the far end.
>> Regardless, I would test pull and see what breaks first at what tension.
>> 
>> 73 Tom
>> 
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