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ja1484
Jul 9, 2008, 11:48 PM
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jeremy11 wrote: ja1484 wrote: My personal thoughts: Why bother with real strength when rated strength is already more than enough? We are overly curious, unashamed nerds in our element 
I prefer to think of it as wasting time that could be used for useful, needed research.
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adatesman
Jul 10, 2008, 1:43 AM
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jt512
Jul 10, 2008, 1:52 AM
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ja1484 wrote: My personal thoughts: Why bother with real strength when rated strength is already more than enough?
I'm rated for 5.14a, and all this training kinda sucks. Maybe I should just go for it!
Jay
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ja1484
Jul 10, 2008, 2:34 AM
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jt512 wrote: ja1484 wrote: My personal thoughts: Why bother with real strength when rated strength is already more than enough? I'm rated for 5.14a, and all this training kinda sucks. Maybe I should just go for it! Jay
That's more like it.
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d0nk3yk0n9
Jan 24, 2009, 7:13 PM
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If you ever get back to testing these, try the Beer Knot as well. I've heard that it's stronger than a water knot, so this seems like a good way to test that theory.
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phil.nomad
Mar 6, 2009, 12:58 AM
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16stfd16 wrote: d0nk3yk0n9 wrote: If you ever get back to testing these, try the Beer Knot as well. I've heard that it's stronger than a water knot, so this seems like a good way to test that theory. Id be interested to see how the beer knot sizes up as well (d0nk3yk0n9 you beat me to it!) ..and I think I'll buy red tubular webbing from now on, just incase. 
Hear, Hear - beer knots too!! - I would love to see how those break and if they are any stronger than water knots
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rschap
Mar 7, 2009, 3:22 AM
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Back in the day before I could afford real slings I tied my own, I used a figure 8 with a follow through because I figured it was stronger. Any chance I can talk you in to testing it?
Edit for spelling
(This post was edited by rschap on Mar 7, 2009, 3:24 AM)
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adatesman
Mar 7, 2009, 3:49 AM
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knudenoggin
Mar 8, 2009, 8:56 PM
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adatesman wrote: Just in case Knudenoggin sees this- have you seen any data on Flemish bends in webbing? I don't recall seeing any, but you're more up on these things than I am..... I'm curious if they'd be less prone to creep than ring bends. That said your asymmetric ring bend for webbing looks promising and I apologize for not getting back to it. 
1) Who cares? -meaning, given the dubious slack-security
of the Fig.8 bend, who would risk using it, regardless of strength
(well, okay, there are those who believe StrongerIsBetter)?
We're not getting reports of broken slings, are we?
2) The Fig.8 knot in tape has now two orientations: loaded
part on outside, or on inside (w/Overhand, it's both;
except with my Symmetric Overhand).
3) I've seen results showing it to be stronger, a little.
And I do have another tape bend up my sleeve!
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bandycoot
Mar 31, 2009, 2:40 AM
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Cool test, but it seems to me that your results are skewed low. If you used two knots on each loop, and only one failed, then you're only reporting the lowest failure out of two weak points in each test. So, in essence, you tested 3 pairs of knots so 6 knots total and reported the weakest failure point of each pair. If you were testing the knots one at a time, you'd have a higher average because the other three knots would, obviously, held a higher force. Just a random thought.
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adatesman
Mar 31, 2009, 5:34 PM
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bandycoot
Apr 1, 2009, 3:16 PM
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Wow, never would have thought that was an issue but it makes sense. The side with out the knot is more static so it stretches less, and since it is run over a carabiner the friction takes a percentage of the forces since it can't slip so there's actually less force in the deforming knot side... Learn something new every day. Thanks!
Josh
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knudenoggin
Apr 2, 2009, 7:38 PM
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adatesman wrote: Not necessarily....
There was a test done by another fellow using the 2-knots-in-loop
format in which the Grapevine, on three such tests, rated about
72%. He then tested single knots in-line and got 78% avg.,
which seems a surprisingly higher result. But there could be
all sorts of things going on, such as the particular calibration
and state of the test apparatus (home-brew, too).
In any case, as precise "strengths" got by this slow-pull way
are really not the sort of terribly meaningful values to make
much of, having two knots feel the pain, and having one survive
(though not in one tape test BOTH knots saw damage, fraying!),
seems worthwhile. And, certainly, having strength values that
might be skewed conservatively isn't all bad to make judgements
with.
It is interesting to think that the arguably naive calculation
of the strength of a loop-sling as the sum of both *sides'* strengths
(say, 100% (unknotted) + 75% (Grapevined) = 175%)
might actually be nearer the true sling strength given this
knot-compression-material-feed factor than figuring twice the
weaker side ( ... = 150%) !
One might e.g. wonder if the difference in material feed/compression
between the Water Knot (small) & Grapevine (more) accounts for
the supposed difference in sling strength often quoted?
--i.e., that the knots could be even reverse the indicated
relative strengths, but if the weaker puts off its breakpoint
by feeding material and letting the unknotted side take the
increasing load, it can hang on to a higher force and look
stronger!
*kN*
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snoboy
Sep 4, 2009, 10:56 PM
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adatesman wrote: ... it would probably be easier to just ask one of the manufacturers whether they've seen a difference in strength by color. Given that they don't rate them differently, I suspect that there isn't one. -a.
Actually... I did the Rigging for Rescue seminar this Spring with Kirk Mauthner, and he related a similar story of noticing a disparity in test results between two sets where the rope was identical other than colour. He did ask the manufacturer, and indeed the answer was that the colours do affect strength to a small degree.
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cintune
Sep 5, 2009, 12:52 AM
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Any interest in testing the beer knot? It's been documented to preserve 80% of the webbing tensile strength and show no slippage of the tails. People tend to raise the objection that it is bad because "you can't check the length of the tails," but that's not really true. You can see one and you can feel the other. Once they're weighted a couple of times they weld down into a very compact mass. I have some slings tied with 'em and could send them, but the webbing is six years old or so and so might not represent the purest sample.
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knudenoggin
Sep 7, 2009, 7:13 PM
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snoboy wrote: adatesman wrote: ... it would probably be easier to just ask one of the manufacturers whether they've seen a difference in strength by color. Given that they don't rate them differently, I suspect that there isn't one. -a. ... and indeed the answer was that the colours do affect strength to a small degree.
In fact, in the case of some arborist ropes, the WHITE rope IS rated with
a higher strength than one with color.
-- that's a colored vs. non-colored difference, though,
not between colors. (IIRC, the diff. was a couple hundred #s of 6,000ish).
*kN*
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knudenoggin
Sep 7, 2009, 7:22 PM
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cintune wrote: Any interest in testing the beer knot? It's been documented to preserve 80% of the webbing tensile strength and show no slippage of the tails.
Note that this will have some bias of being an academic testing,
in that isn't one of the main points to tie 1" tubular webbing that it
can be UNtied later? -- and this might be less easily done w/Beer knot.
AND, can one even implement the knot in the smaller webbing
-- where the hollow to receive material is smaller but the bulk of the
smaller tape isn't so much smaller (still about as thick in wall).
ALSO, NB: IFFFF this Beer Knot slips a bit more on being loaded,
then testing it in a loop joined by one such knot would likely
provide the bias of greater off-loading of force to the unknotted side.
Now, THAT is an academic concern (about actual strength of knot),
vs. a practical one (about effective strength of sling)!
Though perhaps it might be different for a conditioned (pre-loaded)
sling, where the Beer's possible slippage had already occurred.
This is largely a point that the testing that has so far been done
on this knot haven't been reported / examined wrt to this concern
to know the answer.
In reply to: ... but the webbing is six years old or so and so might not represent the purest sample.
BUT it WOULD represent precisely what YOU are putting your life on.
Which is more relevant: tests of pristine, never-been-used material,
or stuff that is seeing the regular action? How well has this knot held
up, and all (see remark above)?!
Thanks,
*kN*
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cintune
Sep 7, 2009, 8:23 PM
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knudenoggin wrote: Note that this will have some bias of being an academic testing, in that isn't one of the main points to tie 1" tubular webbing that it can be UNtied later? -- and this might be less easily done w/Beer knot.
Much less easily unless you're in the habit of carrying a fid, but then, welded water knots can become nearly impossible to untie too. These were done up with permanence in mind.
knudenoggin wrote: AND, can one even implement the knot in the smaller webbing -- where the hollow to receive material is smaller but the bulk of the smaller tape isn't so much smaller (still about as thick in wall).
knudenoggin wrote: ALSO, NB: IFFFF this Beer Knot slips a bit more on being loaded, then testing it in a loop joined by one such knot would likely provide the bias of greater off-loading of force to the unknotted side.
With enough force that might be so; I've seen no sign of slippage. Put a few stitches in each end to see if they got pulled or not, but it seems that after the knot is firly set there's just too much friction between the layers to allow easy slippage.
knudenoggin wrote: Now, THAT is an academic concern (about actual strength of knot), vs. a practical one (about effective strength of sling)! Though perhaps it might be different for a conditioned (pre-loaded) sling, where the Beer's possible slippage had already occurred. This is largely a point that the testing that has so far been done on this knot haven't been reported / examined wrt to this concern to know the answer. In reply to: ... but the webbing is six years old or so and so might not represent the purest sample. BUT it WOULD represent precisely what YOU are putting your life on. Which is more relevant: tests of pristine, never-been-used material, or stuff that is seeing the regular action? How well has this knot held up, and all (see remark above)?!
Good point. Best in all these cases if a series ranging from brand new to utter tat could be tested. Mine were purpose-made as kit for TR and rap/jug anchors, not for lead draws, so they haven't been subject to high-impact catches. As such, they've never failed or slipped. Would be happy to send' em in if Aric'd like to break them, though.
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knudenoggin
Sep 12, 2009, 2:33 PM
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adatesman wrote: tradrenn wrote: Are you (adatesman) having red webbing on a hook or something similar and pulling on a blue webbing ? Actually, it was a biner on each end.... [image]http://www.shariconglobal.com/misc/pulltesting/knots/webbing/WK3pull_sm.JPG[/image]
It should be noted that with such SHORT specimens, there is some
significant effect of the warping of the tape, as can be seen
clearly in this photo -- the tape rotating 90 degrees in a few inches.
(Something that might be avoided with careful tying.)
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slacklinejoe
Sep 30, 2009, 8:05 PM
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It's worth noting that yes, the coloring process can change the tensile strength of webbing. From my understanding, the webbing is essentially boiled in dye during the process and some colors boil longer to do it, as well as the dyes themselves may change the characteristics in the process.
This isn't new information, just not terribly well understood or publicized.
Having felt a LOT of webbing considering I go through miles of the stuff each month, the I can tell by feel which batches went through more processing than the others, which I've found can be indicative of changes in tensile strength.
While quite subjective, I've had batches of custom pink which had to be heavily dyed turned out exeptionally soft but which broke barely at the standard rating, but white (which is "natural" and never boiled) is stiff handling but breaks at a higher strength.
(This post was edited by slacklinejoe on Sep 30, 2009, 8:05 PM)
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knudenoggin
Oct 1, 2009, 4:41 AM
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slacklinejoe wrote: This isn't new information, just not terribly well understood or publicized. Having felt a LOT of webbing considering I go through miles of the stuff each month, ...
(maybe you shouldn't have publicized this! )
In reply to: While quite subjective, I've had batches of custom pink
In reply to: ... which had to be heavily dyed turned out exeptionally soft but which broke barely at the standard rating, but white (which is "natural" and never boiled) is stiff handling but breaks at a higher strength.
Okay, seriously, did you WEIGH the different batches?
I could believe the the costlier (to dye, etc.) stuff might
have been produced with a bit of cost-savings in material,
too.
Thanks for the info, (and the personal insights)
*kN*
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slacklinejoe
Oct 1, 2009, 4:51 AM
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In reply to: Okay, seriously, did you WEIGH the different batches? I could believe the the costlier (to dye, etc.) stuff might have been produced with a bit of cost-savings in material, too.
All of the mil-spec nylon webbing from the mill we use starts off as "natural" which is kind of an ivory white. It's all just how it is treated from that point. It's all from the same machinery and materials.
Weight / meter never changes, or at least not on a measurable level using my equipment.
I'm certainly not the first person to notice this situation, I thought I remembered seeing someone like Hugh Banner, Yates or someone like that having a published paper for military sources regarding the effects of dye lots on webbing strength. It dates back a ways. I tried to find it again on the web, but no luck.
As a manufacturer, I just have to live with variation from lot to lot and color to color, but thankfully the mills are always on the ball and even the most heavily processed webbing still exceeds their rated break strength.
It is also worth noting that not only does tensile strength vary, but elasticity varies even more from batch to batch.
The important part to note in this case is that yes, it is very possible that the blue webbing could be weaker than the red webbing, however both should be at least as strong as the specified rating.
(This post was edited by slacklinejoe on Oct 1, 2009, 4:53 AM)
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knudenoggin
Oct 1, 2009, 6:49 PM
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I do recall some arborist (or SAR?) rope listed with higher strength for white
with an orange fleck vs. the reverse, orange line predominantly.
It does make sense that all the extra treatment in dying will have
an effect. It would be more interesting to learn (if ...) that there
came differences between colors.
Then, again, the webbing is supposed to at least live up to its
rating; differences beyond that can be "interesting", but not so
likely to sway purchase & use. ('cept maybe some HotPink use, er-hem)
*kN*
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dugl33
Nov 7, 2009, 6:26 PM
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Aric -- next time you're in a testing mood, it would be great to see some "sharp edge" testing. Maybe a few different set ups, like around small edge radius steel block, over the point of some beefy angle iron, or over some real stone, for example.
Had to bail off a tied off block the other day. The block was bomber, and I wasn't nervous about the strength of the webbing or knot, but was a bit nervous about the webbing as it wrapped the block corners. Under what conditions is the edge the point of failure and not the knot?
Also, are you up for testing some old webbing such as slings from the early 90s, and old harness waist belts? Curious to see the real impact of age on rated strength. (Yes, I know this has done by others some before.)
Thanks for the testing....interesting stuff.
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