Breaking Splices, Sewn Eyes and Other Strange Things.

[Richard Mumford-yoyoman]

Thank you for sharing these videos, Richard. I think video documentation of these pull tests provides valuable information regarding the possible failure reason.

In your tests, you did use sewing an eye on the other end of the spliced test objects. Sometimes the stitching end failed before the spliced eye. Do you consider, that you stitching could have been somewhat better and i general to be supperior to the spliced eye?

Yesterday i came about some other public sources of information with pull test results. They are made by Evans Starzinger. Evans did publish several test on his (and his wifes) website, but this site is now active anymore. But the information is still to be found on the web.archive.org: https://web.archive.org/web/20160715154948/http://www.bethandevans.com:80/load.htm

Some of the same test and some more is to be found on this sailors forum thread: http://forums.sailinganarchy.com/index.php?/topic/154025-ropeknotsplice-load-testing/&

/Viggo

That is some good info. I really don't want to get into a pissing contest as to which is stronger as there are a lot of variables including the fact that manufactures provide all kinds of instructions on hand splicing and NOTHING about sewing. Marlow has some of the best data on there Vega rope and others about testing etc. Vega is a bitch to splice, so splicers say but there are instructions for it. The cover is so tight that most don't attempt it or find it impractical. I like the rope as it is static and the tight cover gives it more protection from snagging in the tree or picking on ascenders but yet it is still very knotable. Ask any splicer what they think of it and it will be ALL negative. The stuff is supper strong and breaks with high numbers on a sewn eye.
Anyway, I have found breaking stuff that it depends on the construction of the rope. The trick is to get the core and cover to share the load equally if I want to get the big numbers. I've used a 9" bollard or drum to get a very gradual bend radius thinking that would give me maximum strength, makes sense as that's what often breaks a rope in a knot is the tight turn radius. But even then, the grip on the cover from the smooth steel surface of the drum was enough to break the cover first and then the core. Ropes with parallel running strands in the core tend to slip out and the cover breaks early. Ropes with Dyneema or like fiber, strong but very slippery, will actually pull the core thru a stopper knot after the cover has separated. The long stitch I use is great unless the core is slippery and I get the same results as the drum, the cover will break leaving the core to break next. If too many stitches are placed in the core and not enough holding the cover the core gets weakened.
Short story, there isn't one but I have learned a lot still without being a splicer. Sometimes I feel like I'm trying to discover the recipe to Coke Cola.

 

[Richard Mumford-yoyoman]

Word of caution again, these are the thread slicers that will cut the core of your rope.

 

[Gymnast]

Word of caution again, these are the thread slicers that will cut the core of your rope.

View attachment 56458

You are quite right, Richard. And on this Photo you can see how Sharp the leather type points on the needles are. These two needles are new and not grinded for use on rope nor fabrics. The best would be to find right type of needles and avoid grinding.

 

[Gymnast]

[U]yoyoman[/U] - I agree that a drum used for termination of rope should be the best way to keep high strength. With my small Things for test I have used the same method to measure breaking strength of sewing thread. Then the size of the drum becomes a bolt of about ½ inch.

 

[Richard Mumford-yoyoman]

[U]yoyoman[/U] - I agree that a drum used for termination of rope should be the best way to keep high strength. With my small Things for test I have used the same method to measure breaking strength of sewing thread. Then the size of the drum becomes a bolt of about ½ inch.

But my point was that with modern double braid ropes, the drum or large diameter bollard does not give us the maximum breaking strength. As the rope stretches around the drum the friction of the cover makes it separate first. So people that get bent out of shape with a sharp aggressive toothed ascender, should realize that the same cover ripping action could still occur because the rope is basal anchored over a limb, (essentially a bollard). I still don't like a Texas kick or chest ascender life support connection for that reason.
The threads we use, generally are 3 or 4 strand and do not have core/cover slipping qualities so yes, a 1/2 bolt works great just like a large bollard works for most 16 strand rope.
One last thing, these are some of the reasons, after all of the recent talk of rope bridges, I use a good old fashioned 16 strand Arbormaster on my bridge.

 

[Gymnast]

Sorry Yoyoman. I did not read your ealier post carefully - I did now twice. Measuring the "right" breaking strength of a kernmantel rope seems difficult. I suppose that standards for ropes makes some directions to an "agreed" test method. But for now I have not read them. We cannot suppose, that every manufacturer of a kernmantel rope actually do make a ballanced rope.

When I look at your video, it is visible how the mantel and core slips individually near the spliced eyes.

 

[Crimsonking]

But my point was that with modern double braid ropes, the drum or large diameter bollard does not give us the maximum breaking strength. As the rope stretches around the drum the friction of the cover makes it separate first. So people that get bent out of shape with a sharp aggressive toothed ascender, should realize that the same cover ripping action could still occur because the rope is basal anchored over a limb, (essentially a bollard). I still don't like a Texas kick or chest ascender life support connection for that reason.
The threads we use, generally are 3 or 4 strand and do not have core/cover slipping qualities so yes, a 1/2 bolt works great just like a large bollard works for most 16 strand rope.
One last thing, these are some of the reasons, after all of the recent talk of rope bridges, I use a good old fashioned 16 strand Arbormaster on my bridge.

Do you keep the core in it, or flatten it?

 

[Gymnast]

I've used a 9" bollard or drum to get a very gradual bend radius thinking that would give me maximum strength, makes sense as that's what often breaks a rope in a knot is the tight turn radius. But even then, the grip on the cover from the smooth steel surface of the drum was enough to break the cover first and then the core.

As you may now, I have not been active on this site for two years. I just now looked at all your pull test videos on your youtube channal. Very interesting - and thank you for sharing!

Did you consider to lubricate the drum? I suppose possible damaging stress on the mantel might be avoided this way. I suggest graphite powder, paraffin from candlelight, vaseline or teflon foil. The drum surface seems to me to have a somewhat raw surface. Its not like a spoon you would put in the mouth - I hope you get, what I try to say.

But the drum needs to be strong. More turns of rope with high stress will try to deform the drum.

 

[Richard Mumford-yoyoman]

Do you keep the core in it, or flatten it?

It? being the rope I use on my bridge? I keep it all.

 

[Richard Mumford-yoyoman]

As you may now, I have not been active on this site for two years. I just now looked at all your pull test videos on your youtube channal. Very interesting - and thank you for sharing!

Did you consider to lubricate the drum? I suppose possible damaging stress on the mantel might be avoided this way. I suggest graphite powder, paraffin from candlelight, vaseline or teflon foil. The drum surface seems to me to have a somewhat raw surface. Its not like a spoon you would put in the mouth - I hope you get, what I try to say.

But the drum needs to be strong. More turns of rope with high stress will try to deform the drum.

If I lubricate then I have changed the test sample. The drum is smooth and polished. Wax paper would be helpful without transferring substantially to the sample but still...?
So I basically have done enough sewn eyes that I can get above what I'm testing most of the time. It helps to have a test sample of rope before I pull a splice to see what is going to work best.

 

[Gymnast]

If I lubricate then I have changed the test sample. The drum is smooth and polished. Wax paper would be helpful without transferring substantially to the sample but still...?

I would not consider lubrication here a change of test object. Lubrication can in my oppinion not add any strength to the rope anyway.

Another way to see it is, that the aim of terminating the rope with the drum is to make this termination as strong as possible. The real test object is the terminations by splice, sewn eye or knot in the other end of the rope and you want this test object to fail in the test to measure these terminations performance.

 

[ghostice]

To

Not sure I'd want to use Freesole or like on a solely glued splice but I think Richard it might be worth a try on a sewn splice perhaps. Not just applied to the stitching but brushed into or flowed into the space between the two rope strands. Might also be worth trying saturating the stitching as above and then applying shrink tube to squeeze the glue into the rope further.

So in COVID downtime I've been following up on a few things - one is the possibility of glueing together rope ends on the sides which go between a sewn splice, giving greater resistance to shear. Apparently there are adhesives developed for synthetics/ polypropylene etc. and testing of sheer strengths etc. have been done:
https:// www.permabond.com/wp-content/uploads/2016/04/TA4610_TDS.pdf
So could it be hypothesized that glueing the two rope sides together, perhaps with a bit of squeezing flat for greater adhesive contact area, might strengthen the sewn splice?

(Edit: there's a couple 'a threads on the glue/ splice idea - I post this cross post only for completeness:
https:// www.treebuzz.com/forum/threads/glued-splices.42686/ )

 

[RyTheTreeGuy]

It is my understanding that the rope typically will fail before the splice. Particularly in sewn terminations because there isno change in rope diameter. Would be an interesting experiment for sure...There is also a chamce my understanding is completely wrong...lol

 

[Richard Mumford-yoyoman]

To

So in COVID downtime I've been following up on a few things - one is the possibility of glueing together rope ends on the sides which go between a sewn splice, giving greater resistance to shear. Apparently there are adhesives developed for synthetics/ polypropylene etc. and testing of sheer strengths etc. have been done:
https:// www.permabond.com/wp-content/uploads/2016/04/TA4610_TDS.pdf
So could it be hypothesized that glueing the two rope sides together, perhaps with a bit of squeezing flat for greater adhesive contact area, might strengthen the sewn splice?

(Edit: there's a couple 'a threads on the glue/ splice idea - I post this cross post only for completeness:
https:// www.treebuzz.com/forum/threads/glued-splices.42686/ )

A good sewn eye, one that approaches the rated strength of the rope, will break just outside of the sewn stitches. If there are too few stitches, they will break. If there are too many, it will break the core and or cover because of all of the disturbance to the rope fibers. Gluing may help a poorly sewn eye but should have no benefit to a well sewn eye and may be a detriment.

 

[ghostice]

Richard I am still left wondering if stretching the rope end to be "glue spliced" - to balance cover and core, then using a jig to align rope and compress/ flatten a bit on the insides being glued, allow surface glue to set and then stitch using proper needle and some sort of glue impregnated thread (a la Moss hand stitch pattern discussed in sewn stich thread) and then activate thread glue with heat or light, and lastly place more glue on rope and whip finish the whole splice, allow glue to setup and shrink cover the whole shebang. This way the cover and core are balanced, there doesn't have to be as much stitching perhaps and pattern may matter less and the whip finish makes yet another strength layer. Or is it the scotch talking to me again?

 

[ARLO]

Hi all. I am not a big fan of figure eight knots in tree work, but this video is really interesting.