Forums: Skydiving: Gear and Rigging:
Cutaway cables

 


petur  (C 74)

Jul 8, 2002, 11:19 AM
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Cutaway cables Can't Post

Hey all! In a thread posted in march I read a very informative reply from Bill Booth himself regarding cutaway cables, housings etc. In his reply he wrote: "Jump shack IS using Teflon, which they color code red. We do not use it for too many reasons to go into here."

Ok, I bought that same type red teflon cable from Jumpshack in april Shocked, simply because of a neater look and color of the pad Unsure. Should I put the original yellow cable from RWS back on my rig... and if so, why?


(This post was edited by petur on Jul 8, 2002, 1:18 PM)


Jimbo  (D License)

Jul 8, 2002, 2:31 PM
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Re: [petur] Cutaway cables [In reply to] Can't Post

 

Hmm. It would be great if Bill would post the downside of the teflon cables. I'm sure a lot of people here are interested in hearing them.

-
Jim


weid14  (D 20292)

Jul 8, 2002, 2:53 PM
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Re: [Jimbo] Cutaway cables [In reply to] Can't Post

teflon is a soft material that "cold flows" over a period of time. Meaning, that if you exert some pressure on it, the tendancy is for the material to "give" and not recover it's original shape (which could be bad if it conforms to the white loop or cut away housing). There are additives that are used to improve it's physical properties in that respect (glass, carbon, etc). That may be one reason he (Bill) doesn't like them. Although John Sherman at Jump Shack will tell you why the teflon (there are like 2 or 3 different major grades of teflon, and many different subgroups off of those) is OK to use, too. I think there is an article at their web site about them. When they first came out there were cracks in some of them, but that problem was rectified. I'm not quite sure why he (John) wanted to make the switch in the first place.


Premier billvon  (D 16479)
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Jul 8, 2002, 8:25 PM
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Re: [weid14] Cutaway cables [In reply to] Can't Post

>I'm not quite sure why he (John) wanted to make the switch in the
> first place.

The stated reason, I believe, was that the teflon cables have less friction and thus make for easier cutaways.


petur  (C 74)

Jul 22, 2002, 8:49 AM
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Re: [billvon] Cutaway cables [In reply to] Can't Post

The following is a reply I received earlier today from T.K. Donle at RWS, posted here with his permission.

Quote:
Hello Petur,

We carefully tested the red Teflon cable when it was introduced in April of
1997. In its current form, it is not approved for use with Relative
Workshop Vector, Micron, or Sigma Systems. Here are the reasons why.

1) Due to its slick nature, Teflon does not stick well to other materials,
including stainless steel cable. One local manufacturer of these new
cutaway handles has already discovered long runs of Teflon separating from
the cable. Can you imagine pulling your cutaway handle, only to find the
Teflon still running through your 3-Ring loop, thereby preventing a cutaway.

2) It's difficult, if not impossible, to melt the Teflon to effectively
cover the sharp, exposed cable ends. Instead of melting into a liquid
state, Teflon tends to evaporate into a gaseous state when heated. (This is
referred to as "sublimation.") We understand the current supplier of these
handles is simply blunt cutting them with no further end preparation. We've
heard a recent report of a sharp cable-end snagging the 3-Ring loop and
damaging it.

3) A local rigger reported that the outer Teflon coating shrunk noticeably
during a 120-day inspection cycle on one of his customer's rigs, exposing
the end of the inner cable. Samples provided to us by the current supplier
also exhibit this problem.

4) Red Teflon can be sucked through the grommet at the end of the cutaway
cable with less force than the standard yellow Lolon-F cable now in use.
This is a major disadvantage when coupled with out-of-spec risers that can
heavily load the 3-Ring loop.

5) Teflon coating is softer than Lolon-F. You can easily create an
impression on the surface with your fingernail. Worse yet, the 3-Ring loop
and the housing grommet will imbed themselves into the Teflon under high
loads, hence the increase in pull forces at 2000 lbs. We know we're getting
2000 lbs.+ loads due to the number of broken risers that we have seen over
the last 6-8 years.

In our estimation, red Teflon cable exhibits far too many problems in its
current form. Teflon coatings are not a cure-all for improperly made 3-Ring
risers. And don't forget Relative Workshop has been producing cutaway
handles with the yellow Lolon-F coating for over 14 years, and we've never
had a reported problem with it when combined with properly constructed
risers.

And if you were to think about improving the qualities of Teflon, you'd want
to make it slightly harder so it wouldn't be so impressionable; You'd make
it slightly less slick, so it sticks to the cable permanently; You'd add
something to it so it wouldn't sublimate when heated so one could form a
bullet-shaped end...........and what you come up with is Lolon-F! And
you've already got it!

Hope that answers your question. Loose the red stuff and go back to your
original RWS yellow Lolon-F handle, and you'll be safer for it!

Best regards,

T.K. DONLE
Tandem Program Director
Quality Assurance Manager
Vice President
The Uninsured Relative Workshop, Inc.
1645 Lexington Avenue
DeLand, FL 32724



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