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C-IV Splice Results ???

Brocky

Brocky

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Just got back results from arbsession, email of the graph came first, had 40% reduction in break strength. I pay the extra to have broken bits sent back to me. Good thing this time, the splice survived, but rope broke at the drum they wrap it around, would have thought it was the splice otherwise. Wrapping drums are how a lot of rope manufactures determine the break strength of their ropes.D4E50805-D80D-44B6-B996-E56B28BB264C.jpeg
119E2BAD-4B7E-4EBD-BB12-B52B30BE5EF6.jpeg
 
Nice job on the splice. If I understand correctly the 40% loss of strength when it broke was because the C IV was wrapped around a drum? So the curve in the rope around the drum caused the lower break strength?
 
Yes, where it first contacted the drum is where it broke, the same happens with a knot, usually breaks where rope enters the knot. The question marks are that it broke so low, the splice should have been the weak point.
 
Was it a new rope? Would Sterling be interested in this information?


Sent from my iPad using Tapatalk
 
Brocky said:
Yes, where it first contacted the drum is where it broke, the same happens with a knot, usually breaks where rope enters the knot. The question marks are that it broke so low, the splice should have been the weak point.
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@Brocky had the sample you sent been tied around that point multiple times? Or was it brand new rope and that was the first or only knot tied in it? Bend radius can take tolls on rope strength as you suggested but something a lot of people do not realize is there is another factor with tying and bending ropes and that is flex fatigue. Some ropes weaken or lose strength much faster from being constantly tied or repeatedly bent. While technora and Kevlar as amazing materials, however it is my understanding that they are more effected by flex fatigue than UHMPE, polyester, or nylons. Perhaps that could have played a factor if the rope had been tied and untied numerous time as a stopper or possibly a figure 8 eye
 
Brocky said:
New rope, never used, any slack was milked out after the splice, don’t think it was faulty testing, here it is set up just before pull.

View attachment 51511
I have one more I was going to sell, but not possible now, will probably send it in to get tested.
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Did you provide them a little for a non spliced break test as well? I know we have MBS from the manufacturer but to me it is still important to provide and straight piece that has not been spliced or tied for a “benchmark”. It’s good that your splice wasn’t the weak point of the rope but it’s also worrisome that a new rope broke at that low of a static pull.
 
Both have straight buries of 12”, the break was 33” from the eye throat/entry point.

No test piece sent, did’t think necessary as Sterling states the break strength. Needed for something like dynamic rope testing though, where break strengths aren’t given.
 
Brocky said:
Both have straight buries of 12”, the break was 33” from the eye throat/entry point.

No test piece sent, did’t think necessary as Sterling states the break strength. Needed for something like dynamic rope testing though, where break strengths aren’t given.
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Did you have to tie a knot in the rope to perform the splice to keep from pulling out too much core/cover? I am asking because a lot of guys tie a knot 3 or 4 feet back from the area they are splicing to keep from pulling out core accidentally or from causing too much cover to milk back… perhaps that could be the factor that caused the weak point in the rope? Please don’t take that as me questioning you, I am simply as stunned as you are about it breaking away from the splice on new rope and I am pondering ideas for failure out loud. Please try to stomach my questions and thought process here
 
That is a good point, I do tie a figure eight on the bight about five to six feet back, but that is farther than were the break happened. It is a little bit of a struggle to milk the cover back, but I’m just leaning and pulling on the cover. Once done I untie knot and clip to the eye and then milk from the eye to the end. Then I grab it near the end and snap it a few times.
 
Brocky said:
That is a good point, I do tie a figure eight on the bight about five to six feet back, but that is farther than were the break happened. It is a little bit of a struggle to milk the cover back, but I’m just leaning and pulling on the cover. Once done I untie knot and clip to the eye and then milk from the eye to the end. Then I grab it near the end and snap it a few times.
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Ok follow me for one more second and I’ll stop lol, do you tie the figure 8 on the bite before or after you start the splice? If you tie it 5’ back and then say splice a 6” eye, there is at least one foot of rope, then the buried section of splice adds 12 or 13”, wouldn’t that put the weak spot roughly where the figure 8 on a bite was tied and where you probably pulled from the milk the cover (I know milking the cover is ridiculously hard)? I don’t know for sure but that seems like that could be where the flex fatigue occurred? Or maybe you just got some faulty rope, in which case the distributor you purchased it from, should be contacted so that they can have some of that batch sent back to Sterling, (just in case it was an issue in the tensioning or manufacturing process. You could possibly save someone’s life by giving the distributor a heads up. Bad batches of rope can happen from time to time.
 
It’s 5-6’ after determining bury length and eye size, also the loop of the eight goes on a 1/2” thimble, so no stress from a tight bend radius while milking.
 
Got it back and this one broke at the splice where the reduction of the core started, about eight inches from the eye, must have been the biggest stress riser. It feels like from the break to the eye is completely melted and hard, only the very end on the other end is melted. The last sample that broke at the drum had hardness a couple inches both ways from the break point. The first spike was the core breaking and the cover held on until nearly 2500 lbs, must be the break strength of the cover itself.
 
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