I decided to test my splices on ultra-tech and beeline. Using the locking brummel with a 1" eye and a 4" bury and 30" over all length. I put them on a machine that can pull/push and record breaking points. To hold the rope we put 5/8" bolts through the eyes and then added tension slowly. With a straight pull the beeline broke its frist strand at around 3689lbs right above the end of the bury and then contunited to break strands one by one at less and less weight and the ultra-tech broke all at once on the top of the eye at around 3900lbs. My theories on the ultra-tech is that the bolt basicallty just cut through the eye. My question is why such low breaking strengths? I will say since I was just testing the splice I didn't have the jacket on or splice whipped and the tails had been climbed on a little bit used as Vt's with Double fishermens knots attached to the biner. Whats everyone's thoughts? At least I know my splice won't fail.
rope testing
- Thread starter PurdueJoe
- Start date
- Location
- Nashville, TN
that is not where they should break, and if you plan on climbing on a splice, it needs to be 5400# Tinsile strenghth
sounds like the bolt might have been cutting into some strands
sounds like the bolt might have been cutting into some strands
- Location
- Hawaii
purdue joe, I would do some research on how those breaking strengths are usually tested. There are obviously a lot of factors to consider in your experiment, and I'm sure that the pros that normally test for breaking strength etc... have come up with methods to reduce error in the tests.
jp
jp
NickfromWI
Participating member
- Location
- Los Angeles, CA
Joe, keep in mind that typically, these ropes would be spliced with a much deeper bury and a much more gradual taper that what we typically do for a friction hitch cord. Shorter tapers put more stress on less rope, which leads to lower break results.
[ QUOTE ]
that is not where they should break, and if you plan on climbing on a splice, it needs to be 5400# Tinsile strenghth
[/ QUOTE ]
Not necessarily. Joe was pulling in a straight line something that is typically used in loop form. Thus, half of the 5000 (or 5400, whichever you prefer) is what would be needed.
FWIW, Yale recommends doing 2 locks before burying a long fid's worth of tail, and only tapering the last inch.
Any pics?
love
nick
[ QUOTE ]
that is not where they should break, and if you plan on climbing on a splice, it needs to be 5400# Tinsile strenghth
[/ QUOTE ]
Not necessarily. Joe was pulling in a straight line something that is typically used in loop form. Thus, half of the 5000 (or 5400, whichever you prefer) is what would be needed.
FWIW, Yale recommends doing 2 locks before burying a long fid's worth of tail, and only tapering the last inch.
Any pics?
love
nick
R
rich_h
Guest
The locking Brummell is probably the main cause for the low break strength. Like Nick said the splices are usually tested with a much longer bury and more than likely with the standard Class II industrial Double Braid splice. The "non locking" splices are technically much stronger than the locking Brummell. Since your hitch cord is so short you unfortunately can't use one of the non locking types of splice, so we do the best we can with the locking type.
Am I off base with the strength difference from locking to non locking? Anyone have solid numbers on this?
Am I off base with the strength difference from locking to non locking? Anyone have solid numbers on this?
R
rich_h
Guest
Sorry, I am probably wrong on the above, more than likely they test the Ultratech and Beeline splices with "core to core" splices for Class II cordage.
NickfromWI
Participating member
- Location
- Los Angeles, CA
[ QUOTE ]
... more than likely they test the Ultratech and Beeline splices with "core to core" splices for Class II cordage.
[/ QUOTE ]
I don't know what Samson does with UT, but my guess is they do the core to core splice with a long bury. Yale made/designed Beeline just for us, so they know that the long bury was not an option. They use a double locking brummell (see Mobius Brummell) with a bury of a long fid (2/3rds of a fid) to a fid in length. They are using a 1/4 fid, since the splice is for the 1/4" vectran core.
I'm getting a few beeline broke soon, so I'll be able to see how it compares.
love
nick
... more than likely they test the Ultratech and Beeline splices with "core to core" splices for Class II cordage.
[/ QUOTE ]
I don't know what Samson does with UT, but my guess is they do the core to core splice with a long bury. Yale made/designed Beeline just for us, so they know that the long bury was not an option. They use a double locking brummell (see Mobius Brummell) with a bury of a long fid (2/3rds of a fid) to a fid in length. They are using a 1/4 fid, since the splice is for the 1/4" vectran core.
I'm getting a few beeline broke soon, so I'll be able to see how it compares.
love
nick
Everyone thanks for the info, I'm sure my "testing process" was no where near the standard, but you have the use the tools that are given to ya. My main concern was to make sure the splice didn't pull out. By the way Nick, Tyler showed me the foot locking lanyard with the thimble you made for him, very nice. I'll have to try it out and see if I like it.
rfwoodvt
New member
- Location
- This side of eternity.
[ QUOTE ]
The locking Brummell is probably the main cause for the low break strength.....
The "non locking" splices are technically much stronger than the locking Brummell. Since your hitch cord is so short you unfortunately can't use one of the non locking types of splice, so we do the best we can with the locking type.
Am I off base with the strength difference from locking to non locking? Anyone have solid numbers on this?
[/ QUOTE ]
I'm curious on why there should be a difference. is it because of the bend at each lock? If so then why not a lessening of strength on the "in and out" type 12 strand?
I think that there may be a number of factors to consider, not the least of which is the bolt used to pull. As we all have read, bending the rope weakens it whether over a sheave, ring or in this case, bolt.
The larger the bend radius the less the rope is weakend.
Also, untill properly dressed, set and in some cases seized, the throat of a splice can abraid, or glaze itself as tension is being drawn.
How quickly were the ends pulled apart on these cords? how well dressed & set were the throats of the splices?
Not sure if any of this would make a difference in this case, but it is worth studying....
The locking Brummell is probably the main cause for the low break strength.....
The "non locking" splices are technically much stronger than the locking Brummell. Since your hitch cord is so short you unfortunately can't use one of the non locking types of splice, so we do the best we can with the locking type.
Am I off base with the strength difference from locking to non locking? Anyone have solid numbers on this?
[/ QUOTE ]
I'm curious on why there should be a difference. is it because of the bend at each lock? If so then why not a lessening of strength on the "in and out" type 12 strand?
I think that there may be a number of factors to consider, not the least of which is the bolt used to pull. As we all have read, bending the rope weakens it whether over a sheave, ring or in this case, bolt.
The larger the bend radius the less the rope is weakend.
Also, untill properly dressed, set and in some cases seized, the throat of a splice can abraid, or glaze itself as tension is being drawn.
How quickly were the ends pulled apart on these cords? how well dressed & set were the throats of the splices?
Not sure if any of this would make a difference in this case, but it is worth studying....
R
rich_h
Guest
"I'm curious on why there should be a difference. is it because of the bend at each lock? If so then why not a lessening of strength on the "in and out" type 12 strand?"
Rick I think the strength drops due to the fact that the locking Brummell doesn't have the ability to "slip". It is firmly locked in place with each leg of the splice passing through each other. The "straight bury" and "through and through" 12 strand hollow braid splices each have the ability to "slip" and therefore usually break at weakest spot of the taper, not at the actual splice like the locked Brummell.
I am sure someone here can explain this better, it is actually easier to show you with some splices than explain it in words.
Rick I think the strength drops due to the fact that the locking Brummell doesn't have the ability to "slip". It is firmly locked in place with each leg of the splice passing through each other. The "straight bury" and "through and through" 12 strand hollow braid splices each have the ability to "slip" and therefore usually break at weakest spot of the taper, not at the actual splice like the locked Brummell.
I am sure someone here can explain this better, it is actually easier to show you with some splices than explain it in words.
- Location
- Port Townsend, Washington
I haven't tested these particular lines, but it seems there's something very wrong here. I've seen nothing to indicate that locked Brummels are weaker than unlocked, for one thing. Using just a multiple Brummel we've had consistent breaks in the high 70's per cent. It might be that there was slack in the system, or that the bury was too short to matter (likely), or some other glitch.
Possibly the bolt was a factor, but it doesn't sound like it was such a tight radius. It is also possible that the rope fibers had been permanently damaged by the previous use (HM doesn't like compression, and knots compress).
All in all, this speaks to the need for standards, so we have meaningful reference points, and thus meaningful information, not just knowing that things won't pull out. I'm looking forward to hearing of Nick's tests.
If you eliminate splice flaws as a possibility, get destruction tests done that are more in line with standard ones, and the thing still breaks so low, it might be time to consider a different configuration.
Possibly the bolt was a factor, but it doesn't sound like it was such a tight radius. It is also possible that the rope fibers had been permanently damaged by the previous use (HM doesn't like compression, and knots compress).
All in all, this speaks to the need for standards, so we have meaningful reference points, and thus meaningful information, not just knowing that things won't pull out. I'm looking forward to hearing of Nick's tests.
If you eliminate splice flaws as a possibility, get destruction tests done that are more in line with standard ones, and the thing still breaks so low, it might be time to consider a different configuration.
knudeNoggin
New member
[ QUOTE ]
Possibly the bolt was a factor, but it doesn't sound like it was such a tight radius. It is also possible that the rope fibers had been permanently damaged by the previous use (HM doesn't like compression, and knots compress).
[/ QUOTE ]
But such use is both expected and pretty darn light in terms of load!
If indeed it caused the surprising loss of tensile strength, then there needs to be
re-thinking about the real value of the line. Hi-mod lines are regularly hyped by users
as being oh-sooo-strong; the reality of their in-use strength seems to be less well
understood.
[ QUOTE ]
All in all, this speaks to the need for standards, so we have meaningful reference points, and thus meaningful information, not just knowing that things won't pull out. I'm looking forward to hearing of Nick's tests.
If you eliminate splice flaws as a possibility, get destruction tests done that are more in line with standard ones, and the thing still breaks so low, it might be time to consider a different configuration.
[/ QUOTE ]
Of course, if by this you mean that the testing wasn't done in quite the right way,
and so the comparison of test results is off, well, it's time to ask if the testing
was a fair model of expected use! Most times where such constructs get "put to the
test" in use it with a more sudden loading than slow-pull, I'd think.
(Kinda like looking for a lost thing where the light's better rather than where it
was lost.
)
By the way, to the OP, have you thought about testing your line (even the now
broken ones) tied to those bolts with a Strangle Noose (please, NOT "double
Fisherman's knot") ?? --might be good to see how that compares.
(I think Lazarus has some insight in to this.)
*knudeNoggin*
Possibly the bolt was a factor, but it doesn't sound like it was such a tight radius. It is also possible that the rope fibers had been permanently damaged by the previous use (HM doesn't like compression, and knots compress).
[/ QUOTE ]
But such use is both expected and pretty darn light in terms of load!
If indeed it caused the surprising loss of tensile strength, then there needs to be
re-thinking about the real value of the line. Hi-mod lines are regularly hyped by users
as being oh-sooo-strong; the reality of their in-use strength seems to be less well
understood.
[ QUOTE ]
All in all, this speaks to the need for standards, so we have meaningful reference points, and thus meaningful information, not just knowing that things won't pull out. I'm looking forward to hearing of Nick's tests.
If you eliminate splice flaws as a possibility, get destruction tests done that are more in line with standard ones, and the thing still breaks so low, it might be time to consider a different configuration.
[/ QUOTE ]
Of course, if by this you mean that the testing wasn't done in quite the right way,
and so the comparison of test results is off, well, it's time to ask if the testing
was a fair model of expected use! Most times where such constructs get "put to the
test" in use it with a more sudden loading than slow-pull, I'd think.
(Kinda like looking for a lost thing where the light's better rather than where it
was lost.
By the way, to the OP, have you thought about testing your line (even the now
broken ones) tied to those bolts with a Strangle Noose (please, NOT "double
Fisherman's knot") ?? --might be good to see how that compares.
(I think Lazarus has some insight in to this.)
*knudeNoggin*
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