Documenting my hand-sewn eye process

moss

Well-Known Member
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I think its a little OTT but good on you.

Just for fun try a few different things and test them on a rig, that way will give you good idea of what works and what does not, i'm a firm believer that less is more, so when something is stitched to high heaven....does that effect the cover and core of the rope in a negative way and whats left is reliant on the stitched threads?

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I'm following the model of machine stitched eyes which have even greater stitch density than I'm able to do. They test very well so while it is intuitive to think that too many stitches could weaken the cordage fibers that does not seem to be the case. I think it's more like a weave, the sewing process done well is not destructive to the rope fibers, they remain intact within the sewn area.

As far as OTT goes, the first round of break tests showed excellent strength but they still needed to be stronger so I went with stronger thread and pre-compression of the join as described earlier to gain more strength. My "2nd generation" technique has not been pull tested but are testing very well in the field, have been put through the paces and are very strong and stable. The eyes are on course to outlast the climbing ropes and hitch cords they're sewn into.
-AJ
 

moss

Well-Known Member
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You should also go through the sides to compress the rope, adds a great deal of strength.

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Makes sense but I can't get the same stitch density that way. I could use stronger thread but there is probably some equation that would show that less stitches with stronger thread is less effective than more stitches with a thinner (but still very strong) thread. In other words I think there is a sweet spot for high stitch density and strong enough thread, I believe I've found it through trial and error ;-)
-AJ
 

moss

Well-Known Member
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Another question, are there official recommendations from rope companies or otherwise?

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Ummm, don't think so. Hand-sewing to replicate machine sewn life-support eyes is such an unlikely practice that I doubt rope manufacturers have any data/best practices on it.
-AJ
 

InTheTree

Active Member
Moss, thanks for the link for those needles! Let us know how those 2nd generation stitches break test. I like the splicing process my self but can see benefits to sewing eyes. Great documentation on it!
 

moss

Well-Known Member
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Moss, thanks for the link for those needles! Let us know how those 2nd generation stitches break test. I like the splicing process my self but can see benefits to sewing eyes. Great documentation on it!

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I really think splicing is superior in many ways, my "cordage path" led me to stitching first but I forsee some splicing activity in my near future ;-)
-AJ
 

moray

Member
Location
Maine
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As far as OTT goes, the first round of break tests showed excellent strength but they still needed to be stronger so I went with stronger thread and pre-compression of the join as described earlier to gain more strength. My "2nd generation" technique has not been pull tested but are testing very well in the field, have been put through the paces and are very strong and stable. The eyes are on course to outlast the climbing ropes and hitch cords they're sewn into.

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Excellent strength? How about the actual numbers? And how did the tested item fail? I would guess the sewing threads started snapping and caused a cascading failure from then on.

From a safety and engineering point of view, I would think you should use enough stitches so their bulk strength exceeds the tensile strength of the rope by a significant factor X to be determined by testing to give a splice that is stronger than the rope. The stitching thread will never be able to efficiently take load because the orientation is nearly crosswise to the load, but to the extent that they experience tension they very efficiently press the two halves of the splice together producing the friction that holds the whole thing together. Your method of compressing the splice as it is stitched seems very sound, and makes the inherently loose stitches of the Speedy Stitcher tighter and more machine-like, but even loose stitches can make a strong splice if there are enough of them. That is the number of stitches I would use if I wanted complete confidence in my stitched eye.

Splices are simpler because you only have to be concerned with the length of the bury. The tension of the stitching is an important factor (and a big unknown) in the case of hand stitching. But if you know from testing that 150 loose stitches (the worst possible case) of such and such thread gives you an unbreakable eye, then you no longer have to worry about tension.
 

moray

Member
Location
Maine
There are a couple of other vulnerabilities or unknowns about hand stitching that seem worth mentioning.
Even though we don't know the tension in the thread, it is virtually certain that it is not uniform. At the very least this would mean that it is underperforming and would need to be derated compared to thread under uniform tension.
Related to this is the ziz-zag stitching pattern. Gorgeous as it is, I think it is engineering-wise not such a good idea. If the two legs of the splice start to move with respect to each other when under tension, the zigs in the stitch pattern will lose tension while the zags will increase in tension. This might even cause internal abrasion where the two stitch threads interlock inside the rope. The motions we are talking about here are very small but they will certainly be present. Maybe none of this is really important, but how would we know without some extensive series of tests?
I really like the clean short splices that can be made with stitching, but the engineering issues seem very complex and murky compared to the much simpler case of the standard bury splice.
 

moss

Well-Known Member
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Excellent strength? How about the actual numbers? And how did the tested item fail? I would guess the sewing threads started snapping and caused a cascading failure from then on.

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These are some test results from my first generation stitched eyes using the Speedy Stitcher and no precompression, the thread was approxx. 45 lb. test twisted polyester:

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Blue E2E inline pull 4182 pounds (10mm Ocean Polyester, testing the strength of a single eye)
Note: As you predicted Moray, the stitching failed

Red E2E Basket hitch at 7240 the steel b)iner snapped. I put on a stronger one and the cord failed at 7880
(10mm Ocean Polyester, testing the strength of both eyes combined as used in a typical climbing system e-2e)
Note: With two eyes combined the cord failed

The snub nose Secret Weapon 7019 pounds. Ring intact.
(This was 8mm Ocean Polyester sewed with two eyes to a DMM ring)

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So as I mentioned, I'm now using 75lb. test nylon thread and am pre-compressing the join. This is why I believe the strength is excellent for use in a an e-2-e hitch cord.

I'm planning on pull tests for my "2nd generation" technique.

As mentioned earlier, I have no doubt that hand splicing is better, more efficient (timewise), more reliable etc. than hand stitching. I'm simply interested to see what can be done with hand stitching.
-AJ
 

moray

Member
Location
Maine
Those are impressive results, Moss. Clearly you have shown that you can stitch a very strong eye. I would not worry at all about using one of yours for an e-2-e.

I think all my worries would go away if you could show a bit of redundancy, that is, cut a couple of threads on a brand new splice and show that the tensile strength is still very high. This would give you some confidence that you could detect an incipient failure long before it became a safety risk.

Thanks for documenting your interesting experiments for all of us!
 

moss

Well-Known Member
Thanks for the comments Moray. I use clear protective shrink tubing over the stitches so visual inspection is easy. I think there is a misconception out there that for stitched eyes in general (machine stitching) that if several stitches are cut that the entire stitching will "zipper" and fail. I think this is not true, I've done some testing on machine stitched eyes where I slashed considerable stitches and the join was still quite strong. Clearly not as strong as the original but still quite enough for a climber to survive for example if they accidentally cut stitching while climbing. But the real key is to follow normal safety protocols and visually inspect stitched or spliced eyes before clipping in. What I'm seeing after climbing on the hand sewn eyes for many months is that the stitching is very stable and as mentioned earlier easily outlasts the normal service life of a hitch cord.
-AJ
 

Richard Mumford-yoyoman

Well-Known Member
Location
Atlanta GA
I have done a couple of these and I have confidence that Moss is going to perfect this system.
I have not had mine tested, I have used Z pattern rather then a zigzag pattern that I think addresses the issues you highlight about the zigzag. When pulled it has a uniform pull on each leg if the thread.
I think that ultimately it is the lack of uniformity that will give the hand sewn eye it's strength.
You can do things by hand that cannot be done with the machine. Along with the Z pattern you can also use an X as you look at it from a cross-section. You can also finish it with one lockstitch pattern running between the two lines.
I think handstitching with new methods will ultimately encapsulate more threads then you can do with a machine overcoming any slight inconsistencies in the tension.
Of course handstitching takes time and I don't think anybody has to worry about going out of business with their expenses sewing machines.
Keep up the good work moss thanks.
 

Hitman

New Member
Hooray for Moss, I've been hand sewing for a while, I was shunned in the splice rack a year ago, when I wanted to talk "hand stitching". So I got smart, had my stuff tested, much higher numbers than I expected, Sorry, I'm rambling...anyway, here's a loop I just turned out in a footlock prusic made of 8mm ocean with class 1 terminations.
 

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oceans

Well-Known Member
Location
MA, USA
Footlock Prusik with Floating False Crotch capability just below the loop?
Nice looking work...what are your break test numbers?
 

Hitman

New Member
Sorry it took so long to get back..
As for technique, I don't do any precompression, on the rope.(not that that isn't a great idea.) When I sew, I start with the inner chevrons that are touching, and am careful not to over tighten, I sew the full length of the splice, when I come to the end, I jump to the next set of chevrons and change directions, I sew straight across,(no X's) It is similar to welding two pieces of metal,(filling the gap) I can't take any credit for this, I got the idea after dissecting retired split tails purchased from reputable dealers. As far as tightness of stitching, I have found that by the time I reach top dead center of both sides It's rock hard and there is a point where it won't take one more stitch..... My break test cordage was 10mm Sirius Reep. Hand stitched in the fashion described above, two tight eyes, Basket pull,failed at 11,560 lbs cordage broke at the bottom of the basket , inspection of splices after test showed little distortion.

I'll get a couple more pics up soon Tom...
 

Hitman

New Member
I was thinking something like this...27kn dyneema loop by Blue Water and my cacoon.
 

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InTheTree

Active Member
Hitman that is some real nice work there. Good use of for the sewing technique! I've been planning on trying my hand at hand sewn. And now Luke and TreeStuff is break testing!
 

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