A concern about the Arborist Splice

[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

[RonReese]

Originally Posted by 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

I'm interested.

1- What kind of machine will you be performing the tests on?

2- In addition to testing whipped and stitched splices, could I persuade you to test some splices that haven't been stitched or whipped? Or, have you already done that?

3- How much rope do you need per splice?

4- Could you test a splice in each end of a rope? As I think about that though, that would place a heavy load on the rope - twice and the rope may fail superficially.

5- How many could I send you?

Since a splice has a larger cross-sectional area than the rope, it almost makes you wonder if the splice could actually be stronger than the rope????

[Dan Lehman]

Originally Posted by RonReese

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.

Lots of things are claimed, but often those claims are shown to not hold water. IIRC,
a recent arborist posting about a new "Grizzly" stitch-splice (eye) revealed a vendor claim
that it was stronger than a splice in the same material (so obviously that splice wasn't
100%). But I've not said that whipping was supposed to replace the splicing, only that it
seemed a better/surer method to guard against low-load (and otherwise) shifting. Yes, it
IS exposed--precisely my point about its inspectability, and also re use in an application
where the material is readily viewed--, but the adjacent turns of tight whipping resist
abrasion pretty well. Compared with something called "invisible" of much less material,
it seemed preferable.
Yeah, it might be that in a pure one-time break test that the point of whipping becomes
the point of weakness; on cyclical non-break loading, it might be that an unwhipped splice
yields, ultimately, whereas the whipped one endures. And which testing more accurately
models usage? You should be nowhere near the break strength in use!

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.

And partly that's why I sometimes raise a question--to try to learn, to see the rationale/basis.

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.

Again, the tensile machine is one measure of one aspect and not likely the most important
one. The Fisherman's knot is common in commercial-fishing/-marine use; on the tensile
machine, many other bends will test stronger, but after several months of usage, the other
knots might well suffer more damage from being knocked about, run though pot haulers,
whatever, and tested X months later, not fare so well. So, which knot was "stronger"?

----------
Nick, to your testing offer, we need more details:
1) what size specimen, & how constructed (e.g., eyes at each end, 4-7' span)?
2) where to send (etc.) (who's doing the testing?)

I don't expect to splice anything like above, but I might like to see how a seized eye tests.

Thanks,
--dl*
====

[Brion Toss]

Hi Dan,
My apprentices are currently preparing some splices to be destruction-tested. We do that sort of thing fairly frequently. We have also run cyclic loading tests on occasion. I would be happy to send along the results. This next batch will be broken by New England Ropes, but you can likely find several test facilities in any major city. Typically the samples should have at least 5ft. between the ends of the splice tails, to minimize the distorting effects that the two splices might have on the rope. And typically the eye circumference is a bit over 2ft., so they can fit onto the machine's pins. I'll look to see if we have saved any results from past tests. The most recent one was on some 5/8" Vectran, as I recall, and it broke in the high 90's, but I'll have to dig the file out for specifics.
As for the whipping vs, stitching question, experience in the field and on the testing machine confirms that stitching works just fine. You ask how invisible stitching could hold well. Reasonable question. Because the rope has opposing diagonal weaves, there's always a layer under the surface. So if I stitch such that the thread disappears between two sets of surface yarns, it will always pick up the layer beneath, as long as the stitch has any length to it. And I believe you are mistaken in saying that stitching puts less material into the rope; a whipping has 6 or 8 frapping tucks through the rope, and sometimes only 2, whereas one can stitch as many times as one wants -- though I usually say 6 to 8 is fine. Not only that, but those stitches can be made at a wide variety of angles, and can travel linearly and radially, intersecting the core in more places. As for inspectability, again, why would you need to inspect it, any more than you would need to inspect the "invisible" buried rope tails?
And yes, you could say that the splice is stronger than the rope, but then you could say the same thing about a Bowline or any other knot; there's more mass in the knot, plus you have the two parts of the eye, so that's twice as strong as the rope. Unfortunately, the bowline, and to some extent even splices, distort the rope, weakening it. The goal is not to have a strong splice --- that's easy --- but to avoid having a weak rope. Hence tapers, core/cover balance, and a general effort to minimize distortions.
I recently spoke with the developer of the Grizzly stitch splice. It's a wonderful thing, but as even the developer pointed out to me, it does have some significant limitations, including the size and type of rope you can use it on. No magic bullet here.
I do my best to have viable reasons for doing things the way I do, though of course it is always so easy to fall into dogma. For instance, for years I was emphatic about the need to taper any splice. And it almost always does make a significant difference in rope strength, as well as being less likely to chafe than a square-shouldered finish. But destruction tests on 3-strand ropes consistently showed that untapered splices were stronger.
Fair leads,
Brion Toss

[RonReese]

One more question if I may, that has puzzled me for some time. I notice that some ropes are described as spliceable on one end. How is it that a rope can only be spliced on one end, and I guess one shouldn't buy such rope by the foot or something?????

Thanks,
Ron

[NickfromWI]

Ron, are you still talking about arborist rope? The rope IS spliceable on both ends. There is a risk, though. If you think about how the friction hitch reacts on the rope, if you were to descend 60' out of a tree on a 120' rope, when you got to the end, your friction hitch would have milked 120' worth of slack and sent it into the splice on the tail end. You know that splice is a delicately balanced act of tension, and now you messing with all that, risking loosening the splice, and you can figure out what happens next.

love
nick

[RonReese]

Originally Posted by NickfromWI

Ron, are you still talking about arborist rope?...

Well this thing has kinda "moved" from the orginal inquiry, but I've learned a lot and hope it hasn't been too much of a drift.

Nick, I think the answer to your question is yes, but there is arborist rope and then there is arborist rope. To wit: Arbormaster is a 16 strand with a unique splice for that type of rope construction. Velocity is a 24 strand double braid construction arborist rope but it uses a different splice than ArborMaster type ropes.

But, both of these ropes are advertised as simply spliceable. Other arborist ropes, such as ArborPlex, and some others, are listed as not spliceable at all. Yet other arborist ropes, such as New England's Fly, Samson's Yellow Jacket, Yale's XTC series, Wall Rope's Pro Stripe and Pro Spec are listed as, and I quote from SherrillTree's catalog, "Spliceable (eye, 1 end)"

So I was wondering why some ropes are spliceable, period, and some are listed as, "Spliceable (eye, 1 end)"?

Are the ends different somehow?

Does "Spliceable (eye, 1 end)" imply that if you cut off 4 -5 feet of the rope from the spliceable end, it now becomes unspliceable?

Originally Posted by NickfromWI

...if you were to descend 60' out of a tree on a 120' rope, when you got to the end, your friction hitch would have milked 120' worth of slack and sent it into the splice on the tail end. You know that splice is a delicately balanced act of tension, and now you messing with all that, risking loosening the splice, and you can figure out what happens next.

IF the splice is properly secured with stitching or whipping, the milking should stop at the stitching or whipping. I think that is the quintessence of the importance of a properly secured (stitched or whipped) splice. I.e. it protects the splice during no loads and adverse handling conditions such as milking.

However, in a double braid splice even if the splice had not been stitched, while it wouldn't be a desireable condition, I don't see that the milking issue would necessarily lead to a catastrophe since the final step of the splice is to bury the cross-over via milking. Certainly the eye would become smaller IF the milking was forceful enough to force the cover over more of the splice. But when force was applied to the eye, it seems like the rope would simply adjust to a smaller eye, or back to near it's original size. But that's just an opinion, that is not backed by experience.

But, it is somewhat of a moot point, since I think the one thing we all agreed on from the start, is that all splices should be secured by stitching or whipping.

And Nick, I saw where you posted this on another forum.

Originally Posted by NickfromWI

."Ron, we're on the same page. Stitching DOESN'T make the splice stronger. It makes it more secure. In some of the break tests I've seen, the whipping is the first to go, when the rope is really pushed to the max, because sometimes the splice "adjusts" so that the cover/core are holding the load equally.

Will some one get me a rope-breaking machine for christmas?"

I thought that was very enlightening and took the liberty of quoting you here. If you have any objection to that, I will remove it immediately. But I thought it was very mcuh worth sharing.

And I'd like to have rope testing machine too. But maybe I do. We actually have a 20,000 pound tensile machine here at school. We're waiting on a repair and it should be good to go, but, there is some question if the machine will have enough "stroke" to accomdate the length of a splice. And, of course I'll have to come up with an anchor for the other end.

[Dan Lehman]

Originally Posted by Brion Toss

The most recent one was on some 5/8" Vectran, as I recall, and it broke in the high 90's

Actually, this raises another issue: Cordage Institute standards required that conforming
vendors use splice strength AS the material's tensile strength; they made some bit of noise
about this in contrast with methods of calculation used internationally. Naturally, this begs
the question as to real rope strength, what with some particular splice being as it were
defined to be 100%!
(This is mentioned e.g. in that Practical Sailor Sept 2001 issue carrying their purported
re-testing of your Sail article's alarm about knots being so weak in hi-mod cordage.
--that great testing with Aramid Rigging, seemingly somewhat associated w/Yale, who "knew
a trick or two" about dealing with the new-fangled ropes, but whose eye splice(s) in Yale
Light pulled out before a Bowline broke !! And then they reported THAT value in the table!)
So one question is whether vendors are following the CI recommendations on advertised
strength.

You ask how invisible stitching could hold well.

Rather, I asked how such simple back'n'forth few strands of stitching such as I've seen
recommended could hold well. Re "invisible", I simply asked What's that? The Grizzly
stitch splice I think has many bindings of a braided core, and is somewhat more of a
seizing between two rope parts. I don't see a single yarn going through cordage
as finding much purchase with which to hold.

And I believe you are mistaken in saying that stitching puts less material into the rope; a whipping has 6 or 8 frapping tucks through the rope, and sometimes only 2, whereas one can stitch as many times as one wants -- though I usually say 6 to 8 is fine. Not only that, but those stitches can be made at a wide variety of angles, and can travel linearly and radially, intersecting the core in more places.

Actually, I don't see a whipping putting ANY material through the rope, but as tightly
compressing it. Again, I mostly whip small stuff (3-12mm), and prefer to haul tight an
Extended Strangle, or French (and was just playing around with a sort of doubled
half-hitch in that--a structure presented by Geoffrey as a decorative hitch, but which
has some appeal qua whipping). This ExtStrangle has an extra crossing of its ends, and
enough wraps to cover, and usually a finish of one end with a sort of Common Whipping
or Blood Knot binding (the end being a tucked bight, initially done to not have to size and
waste the whipping thread!). Give a few squeezes with pliers during tightening, which my
belief (hope?) is helps distribute tension at the hauled-tight ends into inner wraps.
And, again, all this for a low-load squeeze when finger-trap sheath squeeze hasn't risen
to the task.

As for inspectability, again, why would you need to inspect it, any more than you would need to inspect the "invisible" buried rope tails?

Because this stitching is only a few bits, and breaking it somewhere makes for a big loss,
percentage-wise. Assuming that the splice gets beat up enough there, you might not so
readily see that the stitching took a hit; no way can something be happening to the core,
and if whipping suffers greatly, that will be obvious. Again, for use by arborists where the
splice is in plain, frequent view.

And yes, you could say that the splice is stronger than the rope, but then you could say the same thing about a Bowline or any other knot

And this could be tested by ... ?! The claim has been made; e.g., On Rope 1st ed.
carried some caver's claim for the Triple Fisherman's Knot. But this surely resulted from
a naive testing & interpretation of results. You have to transfer load from the rope to the
additional parts of a knot or splice, and that takes friction and isn't going to multiply the
load bearing.
Sometimes angler's knots are given high claims; this comes from using rated vs. actual
tensile strength (of which there can be a huge discrepancy in esp. gel-spun lines!!)

For instance, for years I was emphatic about the need to taper any splice. And it almost always does make a significant difference in rope strength, as well as being less likely to chafe than a square-shouldered finish. But destruction tests on 3-strand ropes consistently showed that untapered splices were stronger.

I'm interested in exactly how the competing splices were made. E.g., if it's the case that
the taper began at a point where the untapered splice simply ended, one might speculate
that the tapering simply aggravates a build up of torsion in the strands. As opposed to an
engineering principle of If it breaks, take some material away from it (well, that's a bit
of the rule in swaging bicycle spokes.) So one might thus back out one strand 1, another
2, tucks, and yield a by-strand aka West Coast/California taper!? (some of the eyes on the
Cape May - Lewes ferries have 3-4-5 tucks in this way, with a common start; using that
Pro-Splice start I think puts one 1 tuck ahead in one strand and you'd have 3-3-4, etc.)

Thanks,
(-;
[now to see if the system wants to ID me yet again (yep)]