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Crimping

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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GilbertG.

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Jul 28, 2004
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MONO TESTING

Here are the results! I finally found some time over the weekend to do this test. This info should be useful for the techies and those who rig their own lines. But I want to take some time to describe the test setup first, just to let everyone know that this isn't a complete fraud. I'll try to not be too technical as it may confuse people. Please pardon the length of the post. Keep in mind, I am performing this test in as scientific a manner as possible within a messy workshop. No bias on my part, just interested in seeing which methods work. I'll make a comment here and there but feel free to draw your own conclusions from the results. Also, I provide a more qualitative than quantitative description of the results since there is very little statistical basis behind the data. That is, a lot more testing would have to be done to back up any hard claims. Here goes...

TEST SETUP:

The first picture shows a manual hydraulic tension tester that I built a while back. This is a very simple test rig but similar in function to more sophisticated machines used in industry to test the strength and behavior of metals and other materials. Those machines are capable of pulling tens of thousands of pounds. This little test rig is capable of pulling up to 2200 lbs.

The second picture shows the crimped mono in the test rig ready to go. I tested all the samples in this fashion. The load is applied by manually pumping the hydraulic pump. The load being held by the test sample is monitored by a pressure gauge. A conversion factor is needed to change PSI to lbs. I used a 500 pound dynamometer to verify the conversion factor which is simply the calculated cross-sectional area of the push rod.

The third picture shows the 300 lb test monofilament line, the 2.2 mm double barrel crimps, and the crimping pliers that were used. The crimps and the crimping pliers are specifically made for crimping fishing line. The pliers are made by High Seas.

I crimped up three samples of each of the setups that were discussed earlier in the thread plus a couple of variations. There's an endless number of combinations you could come up with, but I was limited in time and supplies to be able to expand the scope of the test. Each sample is a 9-inch long piece of mono with a crimped loop at each end.

Method A uses a single crimping sleeve with two good squeezes about 1/3 of the way from each end of the sleeve. Two squeezes leaves the ends of the sleeve a bit flared.

Method B uses single crimp with three squeezes spaced equaly along the crimp. The crimp ends do not flare out using this method.

Method C uses the same single crimp method as A except that the tag end was burnt with a lighter to produce a melted ball as Brad had suggested. (Careful burning the ends! Some of the hot plastic spattered onto my skin and gave me some burn blisters. Ouch!!)

Method D uses two crimping sleeves for each loop and are butted up against each other. Two squeezes on each crimp. The tag ends were not burnt.

Method E uses two crimping sleeves for each loop similar to D except that the sleeves were spaced about an inch from each other. Two squeezes on each crimp and the tag ends were not burnt.

RESULTS:

Method A - This method will not work if you intend to hang on to big fish! The crimp will allow the line to slip through well below the rated load of the mono. As I ramped up the load, it only held for the first 30% to 40% of the rated load. It then started slipping both on the main line and the tag end until the tag end pulled completely through the crimp.

Method B - This worked a lot better than method A. The crimp stayed in place until about 70% of the rated load at which point the crimp started to slip and draw tight against the pin on the test rig. Analagous to the tightening of a noose. Once tight, the line continued to hold up to about the rated load of 300 lbs. The main line then snapped underneath the crimp and then pulled out from both sides. The tag end did not pull through.

Method C - The results were also pretty good with this method. The crimp stayed in place until the crimp started slipping down the main line at about 50% of the rated load. Once the loop was drawn tight, the line continued to hold the load. The main line snapped approximately at the rated load and the tag end with the melted ball never pulled through! Although the slipping was significant, the melted ball resisted pulling through the crimp. (Brad, you da man! I'll be doing this from now on.)

Method D - The double crimping method also worked well. The crimps stayed in place to a higher sustained load of about 75%. Then surpisingly, it too started to slip and tighten down around the pin. Once tight, the crimps and the mono continued to hold the load. It finally broke at the rated load.

Method E - The one-inch spaced double crimps behaved a little differently than the double crimps butted up against each other in D. The crimps stayed in place until about 80% of the rated load before any slipping occurred. The crimps also slipped at different rates. However, the end result is similar in that it sustained the full rated load before before breaking.

A few observations while doing these tests. The lines always snapped either directly under or near the crimp, never in the middle of the main line. This is logically the weakest point since both compressing of the line and the bending around the loop can introduce local stress concentrations in the line. The main line will stretch ("strain") significantly as the load is increased. I didn't get a good measurement, but I would estimate the line stretched to twice its original length before breaking. The line also remained at a longer length, permanently stretched, after the line broke. This phenomenon is known as "plastic deformation" or "yielding".

MY CONCLUSIONS:
After testing these 5 methods of crimping, the only method I would avoid is method A which allowed the tag end to slip through the crimping sleeve well below the rated load of the monofilament line. This was the method I was using before this test and I've proven myself wrong. Goes to show that I'm not biased. Methods B and C work equally well in my opinion despite the tightening of the loop. However, from now on I'm going to use a combination of these two; a single crimp with three squeezes and the tag end burnt into a ball. This will accomplish the same if not better than both methods. I wouldn't bother doing methods D and E because it accomplishes the same result as B and C but with more "bulk" associated with double crimps.

A reminder to use these results at your own risk! Don't suspend yourself off a cliff with triple crimped 300 pound test mono!!! And don't blame me if you lose a world record catch because of a slipped crimp.

Aloha, dive safe.

Gil
 

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GilbertG.

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Jul 28, 2004
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TEST RIG
 

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GilbertG.

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Jul 28, 2004
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MONO mounted in TEST RIG
 

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GilbertG.

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Jul 28, 2004
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TYPICAL TEST SPECIMEN
 

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GilbertG.

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Jul 28, 2004
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Method A
 

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GilbertG.

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Jul 28, 2004
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B
 

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GilbertG.

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Jul 28, 2004
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C
 

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GilbertG.

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Jul 28, 2004
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D
 

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GilbertG.

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Jul 28, 2004
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E
 

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GilbertG.

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Jul 28, 2004
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BROKEN TEST SPECIMENS
 

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GilbertG.

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Jul 28, 2004
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A - BROKEN
 

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GilbertG.

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Jul 28, 2004
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B- BROKEN
 

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GilbertG.

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Jul 28, 2004
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C - BROKEN
 

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GilbertG.

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Jul 28, 2004
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D - BROKEN
 

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GilbertG.

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Jul 28, 2004
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E - BROKEN
 

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GilbertG.

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Jul 28, 2004
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DYNEEMA KNOT TEST

Here's a another test I did on the side for Ed (portinfer). I was only able to test one sample of each set up as I was running out of crimps and the spare shooting line I found. I'm pretty sure it was Dyneema, Spectra or the like since it was sure strong,stiff and difficult to cut. But that didn't matter too much since we are just interested in how well the knots held.

SET UP:

The first set up is a shooting/reel line tied in a single knot to a crimped loop of mono. I'm not sure what the correct name is for this knot. I just followed what Ed had posted. I guess this type of set up could be used for disposable type wishbones as well. I rigged it into the test rig by tying the same knot on both ends of a piece of line and tying into the same piece of mono

The second set up is a double square type knot (again, don't know the proper name) which leaves a large loop at the end. The loop is connected to the mono by passing completely over the mono. As Ed described it, it allows the spear and mono to be quickly disconnected from the dyneema line without undoing any knots.

RESULTS:

As the load was applied to the first set up the knot kept drawing tighter. The tag end did seem to slip a little as it drew tight. Might be a good idea to keep the tag end at least a half inch long as it could pull through. The line finally broke at the beginning of the knot. The knot itself didn't break. The knot on the other end that did not break was practically impossible to undo with bare hands.

Not much to describe the results of the second test. The knots did not slip. And the line did not break. The mono broke! I think this is your better bet Ed. It should work as you intend it to.

Gil
 

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GilbertG.

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Jul 28, 2004
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BROKEN - first set up
 

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GilbertG.

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Jul 28, 2004
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Second set up - loop
 

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GilbertG.

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Jul 28, 2004
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second set up broken
 

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Bill

Bill

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Oct 17, 2001
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Thanks Gil. This subject has interested me ever since I first saw a mono leader at the dock in Honolulu in '69. Apparently no one had used a mono shooting line in S. California before and many of the competition divers laughed at it. The crew man that answered my questions and showed me how, taught me to melt the end, so I always used your method C and tested it by standing on the shaft while it was suspended by the line (tested the 'staple' that I installed in the shaft too). Nice to see your results using good equipment and technique.
Did you hear the story of the 500 pound Marlin that was caught last year? They forgot to squeeze the crimp. The crimp was one of the double holed ones, I think, and they probably used the twisting double loop method of attachment, but the melted blob was enough to hold. Of course I wasn't there, but it made a great story. How about one more test, to be released in Jim's column some Monday in the future?
Aloha
Bill
 
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