A concern about the Arborist Splice

[RonReese]

Nick,

Just so there's no misunderstanding, I'm not implying that stitching or whipping are not essential. I just want to be sure that the strength of the splice (not the security of the splice) does not depend on stitching.

I would be horrified to think that the support of my weight ( or more) would be dependent on how well and with what material an eye splice was stitched.

I have tested an unstitched, unwhipped eye splice in Velocity rope at 600# and it didn't budge even a fraction of an inch under repeated loading and release.

What I hope is true is that the strength of a splice is in the splice per se, not the splice plus stitching. I'm hoping that the stitching is there just to keep the splice from being inadvertantly pulled or worked loose at no or low loads.

Ron

[Dan Lehman]

Originally Posted by RonReese

What I hope is true is that the strength of a splice is in the splice per se, not the splice plus stitching. I'm hoping that the stitching is there just to keep the splice from being inadvertantly pulled or worked loose at no or low loads.

If you're concern about the splice strength is for the end of a climbing line,
then I'd think you need little concern (for maximum strength), as that needs only
so much strength (how strong is your body, e.g.?!). What's important is the eye
staying an eye (and not, er, winking or something); and doing so always.

I much prefer stitching ó and invisibly stitching, at that ó to whipping. The purppose of both is to hold the splice together at low loads, when the "Chinese handcuff" effect is weakest. Whippings look emphatic, but they typically engage the interior of the rope minimally. This leaves the support largely to compression from the round turns. This seems less effective, as well as being vulnerable to chafe.

!? I don't see how a few bits of cross-woven (stitched) thread/yarn so much holds
together collections of fibres: afterall, it's not as though one is impaling some solid
object--rather, the stitched lines run through (very small) space, strictly! And being
few and with minimal surface (sheath) contact, they can only generate so much
compression. How (much) does the Chinese finger-trap squeeze effect engage the
interior of the rope?!
Whereas with whipping, considerable compression can be generated (which, remember,
is supposedly only needed at "low" loads--not when considerable tension might so
elongate the material as to effectively reduce compression by reducing the bound
diameter). As for chafe, that depends upon material & usage; in the case of the eye
of a (tree) climbing line, it's readily visible/inspectable (unlike some other applications).
(Some 60-100# monofilament fishline & extended Strangle knots can make for a tough
binding.) How really safe from chafing can stitching be--as it too comes to the rope
surface (in small quantities)? If it's so "invisible", how will you know if it's intact?

--dl*
====

[RonReese]

Originally Posted by Dan Lehman

If you're concern about the splice strength is for the end of a climbing line, then I'd think you need little concern (for maximum strength), as that needs only so much strength (how strong is your body, e.g.?!). What's important is the eye
staying an eye (and not, er, winking or something); and doing so always.

I'm concerned about how to properly perform and terminate an eye splice in a rope. A properly done splice purportedly retains 90% or better of the rope's strength and I want to get every bit of the strength out of my splices I possibly can. We could ask why ANSI sets a minimum strength of 5400 pounds for an arborist rope, when all it's likely going to support is 200 pounds or so, AND that 200 pounds is often supported by two ropes giving a minimum strength of 10,800 pounds of rope strength.

A splice is a lot of trouble to put in a rope, so I might as well maximize the splice if I can. Samson Rope recommends stitching to terminate a splice in double braid and whipping for 16 strand such as the arborist splice. They actually test splices on their tensile machines so I presume they've tested all this. Maybe it doesn't matter a whole lot either way because it's only to hold the splice together rather than to enhance strength. Or maybe stitching is better in double braid and whipping in 16 strand.

From the Samson Rope website (double braid):
Procedure for Lock-Stitching Eye Splices
Stitch locking is advantageous to prevent no-load opening due to mishandling.
Material Required: About one (1) fid length of nylon or polyester whipping twine
approximately the same size as the strands in the rope your are stitch locking.
The same strands cut from the rope you are stitch locking may also be used.

16 strand:
Step 8b - Apply whipping to base of eye for a distance of about 1-inch
or 2 rope diameters.

I just spoke to Sherrilltree. They whip all their splices. They unhesitatingly said that the whipping only adds protection against the splice being inadvertantly pulled apart under no load. They also said that whipping or stitching adds no significant increase in strength to the splice.

11:00am EST - I just spoke to a splicer at Samson Rope. They really prefer stitching. He said that if you whip the splice, be sure it's the whipping method that passes through the rope as well as around it. Also he said, without any reservation that the stitching/whipping is only to keep the splice from coming apart under no load.

I looked at Yale Cordage's splicing instructions. They recommend whipping finished with what looks like two stitches over the whipping.

New England seems to think both is best.

Originally Posted by Dan Lehman

!? I don't see how a few bits of cross-woven (stitched) thread/yarn so much holds together collections of fibres: afterall, it's not as though one is impaling some solid object--rather, the stitched lines run through (very small) space, strictly! And being few and with minimal surface (sheath) contact, they can only generate so much compression. How (much) does the Chinese finger-trap squeeze effect engage the interior of the rope?! Whereas with whipping, considerable compression can be generated (which, remember, is supposedly only needed at "low" loads--not when considerable tension might so elongate the material as to effectively reduce compression by reducing the bound diameter).

Harnesses and webbing loops both rely solely on stitching and the stitching approaches the strength of the webbing.

Just to be clear, I'm not asking should a splice be stitched or whipped or nothing at all. I consider it a given that the splice will be secured with either stitching or whipping. What I was asking orginally was the purpose of the whipping and stitching. It seems that the stitching is to prevent the splice from being pulled apart under no load/light load conditions due to miss handling, etc. They actually don't say that whipping 16 strand serves the same purpose as stitching in double braid, but clearly a method of securing the splice is certainly called for. I now wonder if stitching is better for double braid and whipping is better for a 16 strand braid, or if maybe Samson has gone to stitching and just haven't updated their instructions.

[Brion Toss]

Hi again,
Dan, neither stitching nor whipping will add significant compression to add to the handcuff effect. Whipping might apply more, but even if so, whipping can be chafed away. In any event, both methods provide security through shear strength, not compression.
As for how we know if invisible stitching is intact, you may as well ask how we know if the buried tail of the splice is intact; of course they almost certainly are okay, as they can't be chafed externally, or degraded by UV. That leaves chemical corrosion or grit causing internal chafe, and those can be prevented/watched out for.
Whipping 16-strand might seem more attractive than stitching, as the looseness of the weave gives less "bite" to the stitches. Even so, I find that stitching is neater, chafe-proof, and easier done. You just have to be a bit more careful about it.
The strength of arborist rope might seem needlessly high, but there are a couple of compelling reasons for it: shock loads can easily multiply a person's weight (which could easily approach more like 300lbs at times, what with all the gear that arborists take aloft); and the factor of safety had better be at least 10:1, as arborists typically do not use secondary support lines, so must get their redundancy by other means.
Finally, I think Ron is exactly on in saying that it is a given that the splice will be either stitched or whipped. Or both. And by the way, the stitching will also keep your splices from floating apart in a washing machine...
Fair leads,
Brion Toss

[RonReese]

For the life of me, I can't seem to get the slack out of the cover in the eye. The eye looks pretty good, but when I "milk" the cover in the eye from one side of the eye to the other, it bunches up some. Boy that's frustrating! I thought I was keeping tension on the cover and the core as I buried them, but something's happening.

Since I haven't stitched it yet, I presume it's possible to "unbury" and re-bury and try to deal with the tension better??????

[NickfromWI]

Originally Posted by RonReese

For the life of me, I can't seem to get the slack out of the cover in the eye. The eye looks pretty good, but when I "milk" the cover in the eye from one side of the eye to the other, it bunches up some. Boy that's frustrating! I thought I was keeping tension on the cover and the core as I buried them, but something's happening.

Since I haven't stitched it yet, I presume it's possible to "unbury" and re-bury and try to deal with the tension better??????

Ron...you're not talking about the 16 strand splice any more, are you? Sounds like double braid probs to me.

When there's a tiny bit of tension, is there still excess cover? If so, then there's a prob. If it only happens when the eye is slack, that might be normal...I'd have to see it. Just think how rope can be milked when there's no tension on it...is it like that?

love
nick

[RonReese]

Very astute, Nick, of course from your posts that I've read, that's pretty SOP for you.

I'm sorry, I was splicing Velocity again, which is double braid. I "unburied" the splice and re-buried it. I had to use one of Brion's tricks of "skewering" the rope and pulling out the slack. I think I finally got what I wanted.

Originally Posted by NickfromWI

"...Just think how rope can be milked when there's no tension on it...is it like that?..."

Impressive insight Nick, I think that's exactly what's happening - well now anyway. I think before I tightened it, the cover did have a bit of slack in it, but it's better now. I think you're right; it does seem to be a normal milking thing.

[Dan Lehman]

Originally Posted by Brion Toss

Hi again,
Dan, neither stitching nor whipping will add significant compression to add to the handcuff effect. Whipping might apply more, but even if so, whipping can be chafed away. In any event, both methods provide security through shear strength, not compression.

Maybe I'm thinking of a different whipping than is commonly employed?
Tying extended Strangle or perhaps (Dbl.) Constrictor knots in strong material enables
a good deal of tightening to be done (a man can easily pull with 60-100+ # force on the
ends). This I'd think would give good assurance against low-load shifting.

As for how we know if invisible stitching is intact, you may as well ask how we know if the buried tail of the splice is intact; of course they almost certainly are okay, as they can't be chafed externally, or degraded by UV.

What is "invisible stitching"? Don't you have to bring the thread to the rope surface both
as a methodological necessity but also in order to bind the sheath--the point of it?! And
if so, then that thread's vulnerable. (As for knowing about the bury, well, what possibly
can happen to it?)

We might as well ask why ANSI requires ...

Indeed! And the answer might be something like learning how sausage is made, not
terribly attractive. I think that Tom Dunlap (arborist) and some others have some insights
to some of the motivations behind some rules, and IIRC, they don't all seem so compelling.

The strength of arborist rope might seem needlessly high, but there are a couple of compelling reasons for it: shock loads can easily multiply a person's weight (which could easily approach more like 300lbs at times, what with all the gear that arborists take aloft);

Ah, not with diet, then.
Or maybe durability was part of the formula. (Paolo Bavaresco found some interesting
diffferences in residual strengths of various lines--some seemed to lose a lot, others not
so much.)

--dl*
====

ps: I seem to be queried for re-logging in a many steps en route to making a post,
even though I logged in once or twice (or ...) previously and got the jolly "Hello, Dan Lehman"
greeting!? Homeland Security in on the operation?

[RonReese]

Originally Posted by Dan Lehman

Maybe I'm thinking of a different whipping than is commonly employed?
Tying extended Strangle or perhaps (Dbl.) Constrictor knots in strong material enables
a good deal of tightening to be done (a man can easily pull with 60-100+ # force on the
ends). This I'd think would give good assurance against low-load shifting.

It is claimed that splices retain up to 100% of the rope's strength. That kind of strength retention, as explained by Brion, SherrillTree, Samson Rope, One Rope 1, comes from the integrity of the splice rather than the whipping or stitching method. Most seem to readily admit that whipping/stitching only serves to keep the splice from slipping at very low or no loads or from mishandling.

If the splice itself maintains nearly 100% of the rope's strength then a good, strong, tight whipping or the best stitching isn't going to make it 110%.

In fact, such tight whipping could diminsh the strength of the splice by creating stress concentration at the whipping. This is a commonly known phenomenon in structural materials and design.

Originally Posted by Dan Lehman

What is "invisible stitching"? Don't you have to bring the thread to the rope surface both as a methodological necessity but also in order to bind the sheath--the point of it?! And if so, then that thread's vulnerable. (As for knowing about the bury, well, what possibly can happen to it?)

I would think that stitching does expose a small portion of the thread to abrasion, but whipping is totally exposed, 360? around the splice. But it's a bit of a moot point since the stitching/whipping does not add strength to the splice.

Originally Posted by Dan Lehman

Indeed! And the answer might be something like learning how sausage is made, not terribly attractive. I think that Tom Dunlap (arborist) and some others have some insights to some of the motivations behind some rules, and IIRC, they don't all seem so compelling.

LOL! Well maybe. But I like sausage, and whether the means is attractive or not, doesn't change the palatability of sausage.

But really, we're just expressing opinions and I'm not sure what those opinions are based on. In my field, engineering, I commonly see things being done a certain way because they've always been done that way and nobody knows any other reason for doing it that way.

Sometimes that approach is successful, but in some cases it breaks down because it's been a bad practice all along, and nobody knew it until it showed up one day.

FOR EXAMPLE - I was hired to interface a computer to a fire test laboratory. They test the flammability properties of all kinds of materials. The idea was to computerize the data collection and calculations which I did. Well, except for one calculus based calculation which I had worked on for hours and couldn't get the same answer they got. Finally, with the "top dogs" and technical staff present, I asked them to show me how they calculate this one parameter. As soon as they showed me, I took a deep breath and said, "You know that's not correct don't you?" They didn't even hesitate to admit that they knew it was inaccurate, but that's the way they had always done it. I asked what they wanted me to do and they said make the computer calculate it the way we do. I was done in five minutes and they were happy.

So until we put our splices and stitching and whipping opinions and/or practices to a real test on a tensile machine, we're just doing what we think makes sense to us with little support other than our experiences in the field that may not ever approach critical loads like a tensile machine would.

[NickfromWI]

Would you guys splice some things, then whip and stitch in a variety of ways to have them sent to me and broke tested?

love
nick