Hollow Spectra Techniques: Advanced Splicing Effects

[pametfisher]

In another thread on strength testing of Spectra lines (Hollow core braid tested, brands compared) there has been a very (some might say too) detailed discussion of how line holding techniques effect the measured tensile strength of Spectra lines. My experience strongly suggests that how a woven line is held at its ends is the most important factor in tensile strength testing, and that poor holding leads to large errors. I use splicing for hollow and solid lines and believe it is the best way to hold Spectra lines when testing them.

That discussion productively digressed into some tests on the effect of mono/fluoro (simulating spliced leaders) embedded into hollow-weave Spectra test samples. You can read the results in the thread.

There were also some measurements and theories discussed regarding the possibility that there were meaningful strength reductions in spliced end-loops due to the final splice tag that gets buried in the load-carrying portion of the Spectra line.

Although I concede that a reduction in strength is theoretically possible, I made some measurements this morning of several test samples. The measurements follow. (Note: No sample, not one, broke at a splice boundary. All broke in the clear line.)

Sample 1: Outside splice only, rubber band Serve so no discontinuities due to tag or glue (photo below): 40# PP Hollow Ace: Lifted 65 lbs. - Broke at 67.5 lbs.

Samples 2, 3: 40# PP HA: Clear line, two full end-loops, tags out for : Lifted 62.5 lbs. - Broke at 65 lbs.

Sample 4: 40# PP HA: Line to Line spliced in Center, two full end-loops, all tags in: Lifted 62.5 lbs. - Broke at 65 lbs.

Sample 5: 40# PP HA line to line Spliced to 80# JB, two full end-loops, all tags in: Lifted 65 lbs. - Broke at 67.5 lbs.

The most stressful test was Sample 5. It had 80# JB spliced into 40# PP HA. It lifted the same load as the reference Sample 1 which had no splicing discontinuities.

Conclusion
While it might be possible to measure a "tag step down effect" in End-Loop and Line-to-Line splices (with enough samples), the effect in these measurements seems less than 4% and difficult to distinguish sample to sample variation from "possible tag effect". For use in fishing, given the many benefits of hollow-weave Spectra and splices, these tests today say that it is safe to continue to make End-Loops and Line-to-Line Splices in the usual way (instructions at the bottom of the page, here).

[bigreddog]

Thank you. I was following along as best I could on the other thread, but I did not see the practical at least when it came to tapering the ends of insertions. Almost all of the discussions of windon/connection failures center around failure of the serve/nail/crimp.

I would bet that what Paulus is doing is really valuable for aerospace or robotics applications. I do appreciate the work that is involved and there is a lot of good information coming out of that testing.

[Stryper]

another thread one would be wise to bookmark, thank you

[DenisB]

In another thread on strength testing of Spectra lines (Hollow core braid tested, brands compared) there has been a very (some might say too) detailed discussion of how line holding techniques effect the measured tensile strength of Spectra lines. My experience strongly suggests that how a woven line is held at its ends is the most important factor in tensile strength testing, and that poor holding leads to large errors. I use splicing for hollow and solid lines and believe it is the best way to hold Spectra lines when testing them.

That discussion productively digressed into some tests on the effect of mono/fluoro (simulating spliced leaders) embedded into hollow-weave Spectra test samples. You can read the results in the thread.

There were also some measurements and theories discussed regarding the possibility that there were meaningful strength reductions in spliced end-loops due to the final splice tag that gets buried in the load-carrying portion of the Spectra line.

Although I concede that a reduction in strength is theoretically possible, I made some measurements this morning of several test samples. The measurements follow. (Note: No sample, not one, broke at a splice boundary. All broke in the clear line.)

Sample 1: Outside splice only, rubber band Serve so no discontinuities due to tag or glue (photo below): 40# PP Hollow Ace: Lifted 65 lbs. - Broke at 67.5 lbs.

Samples 2, 3: 40# PP HA: Clear line, two full end-loops, tags out for : Lifted 62.5 lbs. - Broke at 65 lbs.

Sample 4: 40# PP HA: Line to Line spliced in Center, two full end-loops, all tags in: Lifted 62.5 lbs. - Broke at 65 lbs.

Sample 5: 40# PP HA line to line Spliced to 80# JB, two full end-loops, all tags in: Lifted 65 lbs. - Broke at 67.5 lbs.

The most stressful test was Sample 5. It had 80# JB spliced into 40# PP HA. It lifted the same load as the reference Sample 1 which had no splicing discontinuities.

Conclusion
While it might be possible to measure a "tag step down effect" in End-Loop and Line-to-Line splices (with enough samples), the effect in these measurements seems less than 4% and difficult to distinguish sample to sample variation from "possible tag effect". For use in fishing, given the many benefits of hollow-weave Spectra and splices, these tests today say that it is safe to continue to make End-Loops and Line-to-Line Splices in the usual way (instructions at the bottom of the page, here).

In an equivalent vein of presentation

a) 40#PP effects don't tell you much about 60# or 80#or 130% or other brands than PP ( haven't we often seen wide ranging differences between different products ).
b) other tests have shown results of :-
............... 10% for JB80 in JB80
.............. 7.5% for PP130 in PP130.
c) your test results for braid strength have consistently been in a higher band than anyone else & considerably so with some lines ( eg JB80).
d) The statement that the way the line is held can significantly affect the results is correct with respect to low abnormal results ............it is not with respect to abnormally high results.
e) cyclic loading has been seen to increase braid strength from "work toughening" the fibres .............some braid manufacturers are using this as a post braiding line tretment.
f) we simply don't know the insertion effects of a full range of products & sizes yet.

I think the conclusion you make is not supported with sufficient data to infact be safely conclusive & is pre-emptory with risk.

The inference that gluing ( dependant on glue type) can introduce discontinuities in the fibre form ( I assume relative to your rubber band technique) is not supported by any data & any supposition that a long external splice does not contain discontinuities in fibre form as a result of sleeve friction is merely supposition.

Repetitive testing with accurate test equipment with controlled standard strain rate increase is the accepted world standard for tensile testing.
The results of control samples identifies whether there is variability in the sample holding method ( along with other variables ). with straight samples at standard length ( 500mm unsupported line) and external splices in test machines controlling all other test parameters accurately,the only cause of result variability is sample variability & the effectiveness of the sample holding.

Data please.
- sample length
- strain application history per test piece .
- glues compared. ( we are talking glues on external splices for testing purposes here.............not fishing purposes..........we all know external splices have practical risks in fishing applications, that don't exist in testing).

[pametfisher]

Today I made up and tested 4 samples of Western Filament 60# Hollow-Weave Indicator line for strength testing. Three were samples with end loops, the fourth was line-to-line spliced to Cortland C16 130# to simulate a 130# Spectra topshot added to the WF 60# indicator. The results below.

Sample 1: Lifted 92.5 lbs. broke at 95 lbs.
Sample 2: Lifted 92.5 lbs. broke at 95 lbs.
Sample 3: Lifted 100 lbs. broke at 102.5 lbs.
Sample 4 (line to line spliced to 130# Cortland C16): Lifted 95 lbs. broke at 97.5 lbs.

Although I tried again to see a tag-stepdown effect ...

PF

[oldtrackster]

work toughening is interesting. So, when new braid is loaded on a reel should you troll a diving plug with it in order to toughen it up? Or should you target blackfin to toughen it up? If work toughening is a reel effect it seems that the line could be worked in the normal routine of fishing in order to increase the tensil strength of the line before fishing for the big boys?

[conchydong]

Very consistant. Excellent work. It looks like "inline" splicing does not cause any weak spots. BTW I heard Tuf-line is very very similar to JB as they are both supposedly produced by Western Filament. Does the JB 60 test pretty close to Tuf-line?

[pametfisher]

Very consistant. Excellent work. It looks like "inline" splicing does not cause any weak spots. BTW I heard Tuf-line is very very similar to JB as they are both supposedly produced by Western Filament. Does the JB 60 test pretty close to Tuf-line?

JB 60, 80 and 100 seem to test just the same to me.

[pametfisher]

work toughening is interesting. So, when new braid is loaded on a reel should you troll a diving plug with it in order to toughen it up? Or should you target blackfin to toughen it up? If work toughening is a reel effect it seems that the line could be worked in the normal routine of fishing in order to increase the tensil strength of the line before fishing for the big boys?

I have not seen any conclusive evidence that UHMWPE (Spectra, Dyneema, or Ultra High Molecular Weight Polyethylene) is strengthened by work-toughening. I don't think it would bring you any value.

I test by "single-lifting" and by "incremental-lifting". Both seem to give the same results. Some are under the mis-impression that I only incremental lift. Incremental lifting is done to "get in the ballpark". The work-toughening idea has been advanced to suggest why some of my numbers measure higher than other testers (btw, not Paulus. His results and mine on most samples, other than White JB, look about the same to me now). I believe there are two reasons:

1. Sample to sample variation

2. IGFA problems with holding spectra braid on the test machine.

That's my 2 cents.

PF

[DenisB]

Work toughening occurs with high strain rates below ,but approaching, the limit of elasticity of the material ............AND.............by deliberate controlled deformation in the plastic deformation range which modifies the molecular structure of the material .

low strain rates ( such as towing a high resistance lure etc ) is not going to do anything.
Its not bad for packing line on the reel tho.

an example of work toughening is taking a nominal 60# braid and progressively lifting increasing weights by (say) 2.5# increments
ie
DIY Test style B:
- lift against a 50# weight
- set it down
-increase weight to 52.5# & lift against it
- set it down
-increase weight to 55# & lift against it.
increasing until the line breaks.

A simple reverse loading sequence demonstrates the different mean failure loads achieved in the testing method.
ie
with increasing load on the same test piece the test same is repetitively loaded & relaxed at high load at the top loads of the sequence and work hardens/toughens.
In the reverse loading sequence the loads start above the failure load and a single load is applied to the test sample it either fails or hold the load.
each sample is only loaded once.
failures in the reverse sequence are followed by a reduced load until the test sample holds the load.

The international standard tensile test for any material is a single test at a constant extension rate which increases strain ( tension load ).

DIY testing simulates the test by increasing the weight attached to the sample rather than by extending ( stretching) the test sample creating tension.
ie
DIY testing uses direct load to create tension............the International Standard uses a constant extension rate to create tension.

notwithstanding sorting out holding methods that do not introduce abnormally low test results .
The loading rate is the parameter that influences the test result.
Its why fishing lines tests are specified with a prescribed loading rate in a single constant increasing extension rate (20 cm per minute ).
- too fast & the sample can be shock loaded & fail low
- too slow & the sample can work toughen .
- some materials can creep at low loads & fail prematurely at slow extension rates.

DIY testing ( & yes I have done heaps of it over 30+ yrs ) only approximates the international standard tensile test when the constant weight application approximates an extension rate in the sample of 20cm/min.
Hence,
DIY testing using weights can only ever approximate a test done to the international standard when the weight is steadily increased at a constant rate in a single loading test.( DIY Test style A )

An alternative method of DIY where the test is set up to cyclic load the test piece at increasing repetitive weights as at DIY test style B above
provides a level of work toughening in what is not a single increasing strain test, but a series of increasing but independant strain test cycles.

I had the opportunity to run DIY test styles against a constant extension rate test machine quite some time back.
DIY test style B consistently resulted in abnormally high results compared to the International standard method or DIY test style A.

Using a reverse load sequence in DIY test style B ,ie lifting against a known weight ( rather than adding weight constantly to a sample) resulted in test results that were at a similar level to the other 2 methods.

DIY test equipment designed to lift against a known weight is very handy for proof testing constructions against a lower than maximum load and for testing creep .

A DIY test designed to use DIY test method B is incapable of examining work toughening , because it can create work toughening.
So how can it examine the effect...........

The scientific world is full of inadequately designed tests that result in misleading outcomes, sometimes because the effects of parameters were unknown at the time, sometimes in ignorance of known parameter effects.
There is an excellent paper by Prof Crispin Mount Miller on the subject of assumptions of the applicable physics affecting the validity of the assessment .........ie a true physical parameter, in its own right ............wrong application.
Often, the hardest part is designing a valid test that isolates the parameter to be tested.

I have undertaken comparative testing of line testing techniques & stand by my statements on the subject as I have actually done it & seen the seen the results
Anyone else who is prepared to make the effort can see it for themselves too.

Hypotheses & guesses are one thing ( informed or otherwise ).
Comparative testing & truth testing of hypotheses is entirely another.


So
That said
Exactly how is your DIY test equipment set up Roger & how do you exactly undertake your tests when you get " in the ball park " .


BTW
Many manufacturers in the thread & rope industries use work toughening in their manufacturing processes with man-made fibres.
They typically heat the material to soften it slightly & lightly deform the material with plastic deformation with either pressure or tension ( depending on the product ).
FWIW
the heating reduces the energy requirement in the toughening & enables higher process control.
The vast majority of super smooth twisted threads & braids are "heat set" to achieve more uniform smoothness, commercial open weave braided mesh 'fabrics' & knotted mesh weaves, too ..............toughening is a side result.

Heck even rod binding thread & industrial embroidery threads use the process.

2C FWIW