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Cutaway cable cleaning mistake

 

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sundevil777  (D License)

Apr 24, 2013, 6:46 AM
Post #26 of 43 (1278 views)
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Re: [JeffCa] Cutaway cable cleaning mistake [In reply to] Can't Post

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I avoid a good part of this issue by continuing to be old school and using large 3 rings. Less tension on the loop, less deflection of the cable, more tolerance on the construction of the riser.

Can somebody please elaborate on this? Is it correct that large 3 rings reduce cutaway pull forces?

I believe this chart came from UPT/Booth many years ago in a thread here. I don't know if it is just the pull force for one cable, or if there is any housing friction present, or if anything had been lubed. Even with the control variables unknown, it is a useful comparison.


Attachments: pull_force_comparison.JPG (45.3 KB)


sundevil777  (D License)

Apr 24, 2013, 6:54 AM
Post #27 of 43 (1266 views)
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Re: [JohnSherman] Cutaway cable cleaning mistake [In reply to] Can't Post

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The rigidity of the cable depends on the inner core and the outer layer. Is it possible that the yellow coating is more rigid than the red? Perhaps my memory is wrong about this aspect of claimed rigidity difference.
Durometer is the term used to describe the hardness of the coating. Booth stuck his fingernail in it and declaired it to soft. I had it tested and found that the durometer varies for both within the same range. It has been is service now for maybe 20 years and other than a cracking problem from a former vendor many years (1996+/-) ago have had no problem. There is probably 20,000 units in service.

Did you measure the hardness of the coating on a cable, or a large thick chunk of the material. I would expect there to be a difference. Hardness measurements of plastics are not like those of metals. Hardness measured on a cable doesn't necessarily equate to the coating's contribution to rigidity. None of that is important though, as what matters is much more easily evaluated - are the red cables easier to bend than a yellow cable?


(This post was edited by sundevil777 on Apr 24, 2013, 7:05 AM)


dpreguy  (D 835)

Apr 24, 2013, 7:40 AM
Post #28 of 43 (1243 views)
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Re: [JohnSherman] Cutaway cable cleaning mistake [In reply to] Can't Post

Oh. Here we go again with the red Teflon cutaway cable discussion.

I would caution anyone who reads a DZ.com post and changes a component on their rig, based only on this source. An article in Skydiving magazine came out about 10 15 years ago about this. One customer came in with his rig and it was so equipped. It had dents where the loop had pulled in, and the coating was butter soft compared to a yellow nylon cutaway cable. The coating had dents in some places. Once again, in my opinion - just by handling it - it seemed considerably less rigid.

Put the customer on the phone with the mfg of the rig and he was told to put the original equipment yellow cutaway cable back in. I refused to reassemble the rig with the red
cable and ordered a brand new yellow nylon cutaway from the mfg.. Put my own rig's cutaway cable on while it was being shipped. Threw the red cable in the trash. Have seen this rig since: no dents in coating and no bending.

This is simply my experience, and my suggestion to anyone who is contemplating a change - to call the mfg and listen to what they have to say.

And yes, the yellow cable does need to be lubricated. Once again, call the mfg for this advice, or go to the Poynter manual, vol II.


JohnSherman  (D 2105)

Apr 24, 2013, 1:04 PM
Post #29 of 43 (1178 views)
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Re: [JeffCa] Cutaway cable cleaning mistake [In reply to] Can't Post

In reply to:
Can somebody please elaborate on this? Is it correct that large 3 rings reduce cutaway pull forces?

You will find your answer here.

http://www.jumpshack.com/...NG&SortBy=DATE_D


JeffCa  (B License)

Apr 24, 2013, 2:16 PM
Post #30 of 43 (1148 views)
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Re: [JohnSherman] Cutaway cable cleaning mistake [In reply to] Can't Post

Thanks very much, John! And thanks Sundevil for the graph! John, that's better than the Wikipedia article on the 3-ring. I've never seen it on any other manufacturer's site.


evan85  (C 41367)

Apr 24, 2013, 2:45 PM
Post #31 of 43 (1131 views)
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Re: [JohnSherman] Cutaway cable cleaning mistake [In reply to] Can't Post

I have a Mirage G4, and happened to take a look at the user manual. Mirage recommends silicone spray, not 3-in-1 oil. Could you elaborate on the advantages/disadvantages here? Why do they recommend silicone while you recommend 3-in-1 oil?


Premier skydiverek  (C 41769)

Apr 25, 2013, 2:12 AM
Post #32 of 43 (1041 views)
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Re: [evan85] Cutaway cable cleaning mistake [In reply to] Can't Post

Oil lasts one month, silicon lasts one week (as per John Sherman).


Premier skydiverek  (C 41769)

Apr 25, 2013, 2:14 AM
Post #33 of 43 (1038 views)
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Re: [JohnSherman] Cutaway cable cleaning mistake [In reply to] Can't Post

John,

So, how do you rebuttle the TK Donle's points (posted here on DZ.com in 2002):

"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"


evan85  (C 41367)

Apr 25, 2013, 3:24 AM
Post #34 of 43 (1016 views)
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Re: [skydiverek] Cutaway cable cleaning mistake [In reply to] Can't Post

In reply to:
Oil lasts one month, silicon lasts one week (as per John Sherman).

Yep, I did in fact see that post. I was hoping for a more-detailed explanation--hence my use of the word "elaborate". Wink Also I figure Mirage must have a reason to recommend silicon over 3-in-1, and I was hoping to figure out what that might be.


hillson  (D 33134)

Apr 25, 2013, 5:23 AM
Post #35 of 43 (984 views)
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Re: [evan85] Cutaway cable cleaning mistake [In reply to] Can't Post

In reply to:
In reply to:
Oil lasts one month, silicon lasts one week (as per John Sherman).

Yep, I did in fact see that post. I was hoping for a more-detailed explanation--hence my use of the word "elaborate". Wink Also I figure Mirage must have a reason to recommend silicon over 3-in-1, and I was hoping to figure out what that might be.

IIRC it has something to do with it not being a petroleum distillate (covered earlier). Rigging Innovations, too, recommends silicone.

FWIW, last year in Parachutist they covered basic 3 ring maintenance and mentioned to follow the mfgs instructions / using silicone.

In the photos accompanying the article there is a can of...WD-40. YYMV, I guess...

http://parachutistonline.com/...g-system-maintenance


JerryBaumchen  (D 1543)

Apr 25, 2013, 7:27 AM
Post #36 of 43 (946 views)
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Re: [skydiverek] Cutaway cable cleaning mistake [In reply to] Can't Post

Hi Bartek,

Quote:
Due to its slick nature, Teflon does not stick well to other materials,
including stainless steel cable.

The last that I knew, the cable inside of the yellow 3-ring cable is galvanized, not s/s.

I 'think' that it was mentioned up-thread that the wire cable in the red telflon cable was also galvanized. Hopefully, John Sherman will correct me if this is incorrect.

JerryBaumchen


dpreguy  (D 835)

Apr 25, 2013, 8:18 AM
Post #37 of 43 (925 views)
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Re: [hillson] Cutaway cable cleaning mistake [In reply to] Can't Post

I use silicone (cypress grease) and it lasts and lasts. It loses it sticky in a few minutes and stays with the cable coating a long long time. It is also most mfg recommended lubricant. Even dry, it works. I use the grease because I don't like the spray cans. The spray goes everywhere.

Longevity: It's in your Cypres loop for 6 months and still works there. OK, I admit this isn't scientific-tested.

Note: WD 40 is, in general, not a good lubricating oil substitute. It has other stuff in it. Penetrates bolt threads etc. If you are going to use oil, use oil. I do not use oil as it collects dust and grit, and it dries up too. When it dries up it is gone. When silicone dries up, some of it remains, as it is - as they say a "dry lubricant".


JohnSherman  (D 2105)

Apr 25, 2013, 10:26 AM
Post #38 of 43 (892 views)
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Re: [JerryBaumchen] Cutaway cable cleaning mistake [In reply to] Can't Post

Yes, Jerry it is Galvinized.

I will use this post to answer the issues about the Teflon coated cable revived from some 10-15 years ago. It is always my preference to answer issues on and individual basis. However, it would be fruitless to revisit each issue individually when all may be answered with a single statement. I am not avoiding answering specifics and will respond to specifics at a later time if so requested.

All of the negative comments from the 90’s which have been brought up in this thread have come from competitors and riggers, not users. User comments have been good.

New product development is difficult and fraught with pit falls. It is also expensive. It also takes time to perfect the product for this unique application. Ok, so here we are 10-15 years later and time to count the chickens.

Fact: There has never been a 3 ring failure to release due to the Teflon Coated Cable.
Fact: There have been numerous 3 ring failures to release due to the yellow “Lolon” (Loos, Inc. name for Nylon) and clear coated cable, due to failure to lubricate. I personally had one. I had not lubricated because I was told, in writing via the owners manual, that the Yellow cable was “Teflon impregnated and did not require lubrication”. I later spoken to the chemist at Loos who formulated the Lolon, during my search for a Teflon coating, who told me there was no Teflon in the Lolon coating. They were not interested in supplying the Teflon coating because of the small qualities required but gave me the name of the vendor we began with. This inaccuracy nearly killed me. It’s amazing how we can get motivated.

Fact: We did have a cracking problem which occurred in the field after the units left the factory. It was expensive, but we replaced them at no charge. This problem occurred in random batches and we never found a way to identify the potential cause. About 8 years ago we changed vendors. The color of the cable changed from deep red to more of an orange color. We did this for control purposes. Since the vendor change we have had no complaints of any kind.

I do want to specifically address the “Suck Through” issue. This is in reference to the force required to cause the cable to bend in half and pull through the grommet. The test quoted was performed with un-lubricated cables of both kinds. Of course the yellow cable was more resistant to pulling through. It was not lubricated. When the test was repeated with lubricated yellow cable they performed the same.

Skydivers want things easy and maintenance free. This product gives that yet because of the power of the marketing megaphone it is unknown. So maybe it is a good thing to bring it up again. We have just been sitting quietly here in the corner doing our thing and having no trouble. Come join us.
Wink


(This post was edited by JohnSherman on Apr 25, 2013, 1:03 PM)


sundevil777  (D License)

Apr 25, 2013, 11:34 AM
Post #39 of 43 (867 views)
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Re: [JohnSherman] Cutaway cable cleaning mistake [In reply to] Can't Post

In reply to:
Of course the yellow cable was more resistant to pulling through it was not lubricated.

I don't understand this. Do you mean the yellow was harder to pull/release, or that it was more resistant to being pulled through the grommet, or what?

Is there a difference in the rigidity of the cables?


pchapman  (D 1014)

Apr 25, 2013, 12:00 PM
Post #40 of 43 (856 views)
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Re: [sundevil777] Cutaway cable cleaning mistake [In reply to] Can't Post

I guess John is saying that a cable's susceptibility to pulling through a grommet is not just a function of the stiffness of the cable core and coating, but also how slippery the cable is -- a less slippery cable won't "drag around the corners" as easily, when folding it in half to drag through the grommet.


sundevil777  (D License)

Apr 25, 2013, 12:06 PM
Post #41 of 43 (854 views)
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Re: [pchapman] Cutaway cable cleaning mistake [In reply to] Can't Post

In reply to:
I guess John is saying that a cable's susceptibility to pulling through a grommet is not just a function of the stiffness of the cable core and coating, but also how slippery the cable is -- a less slippery cable won't "drag around the corners" as easily, when folding it in half to drag through the grommet.

I see, thanks.

Still, I would think that a large increase in pull force would result from a small amount of deflection, so that the lubrication issue would be less important than the inherent rigidity. Do any others have anything to say about the relative rigidity of the cables?


Divalent  (C 40494)

Apr 26, 2013, 6:32 AM
Post #42 of 43 (759 views)
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Re: [JohnSherman] Cutaway cable cleaning mistake [In reply to] Can't Post

So just thinking randomly here: if one purpose of lubricating the cable is to ensure that it can slip by the loop with as little friction as possible (right?), then what about putting a drop of lubricant on the loop as well?

I suppose part of the friction that is of concern is that between the cable mashed against the grommet, so a lubricated loop wouldn't directly help there, except perhaps by keeping the cable somewhat lubricated in that area (due to normal everyday movement of the cable up and down as the rig is worn and jumped).

Any downside to putting lubricant on the loop?


JohnSherman  (D 2105)

Apr 26, 2013, 2:43 PM
Post #43 of 43 (692 views)
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Re: [Divalent] Cutaway cable cleaning mistake [In reply to] Can't Post

In reply to:
So just thinking randomly here: if one purpose of lubricating the cable is to ensure that it can slip by the loop with as little friction as possible (right?), then what about putting a drop of lubricant on the loop as well?

I suppose part of the friction that is of concern is that between the cable mashed against the grommet, so a lubricated loop wouldn't directly help there, except perhaps by keeping the cable somewhat lubricated in that area (due to normal everyday movement of the cable up and down as the rig is worn and jumped).

Any downside to putting lubricant on the loop?

How about the sleves in the risers for the ends of the cable. They get tight when twisted so the lube would help there as well. All surfaces contacted can produce friction however the loop is the biggest contributor
The cable is what moves and if you lube the entire cable you lube the entire moving surface. No harm at the loop as it will get oil 2nd hand anyway.


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