Splicing how to guide

[knot_moving]

Can you give more detail or direct on where to find out how to prestretch and measure lines balanced through a pulley?

There is a really good description of how to prestrrt house flying lines in this forum - if link takes you to the search page, then just search on "lineset" or "making a lineset"

http://nwkite.com/forums/t-11649.html&highlight=lineset

I am starting to build up a bar and lines & saw this reference somewhere else

[foilholio]

A couple things to point out from that link. Sleeves protect the line ends wearing not cutting the pigtails. 15 inch splices are crazy, 70 to 100x diameter bury is fine which for most line is about 10-15cm+loop. Interesting advice warning about prestretching with a weight attached being dangerous, good advice! I was testing a line breaking recently. It was a tiny little 2meter bridle and it hit may hand with such force it grazed the skin and almost opened a cut! I won't(shouldn't ) be using a shackle in future when I prestretch. I don't think a car is needed to prestretch line as I have had good results just using my body weight, you can throw yourself against the line and easily create much more force than you weigh, some lines you can even break!

He is very vague on getting the lines even. This should have been done when splitting the double length lines. A pulley will do or maybe even something thing smooth and round like a screwdriver shaft will work. You mark the same point on both lines, near the end that needs splices, while they are both under the even tension of a pulley. You also want quite a bit of tension while doing this so any slack or low level shrink is taken out, i.e. lean against the line a bit while marking it. Also while still on the pulley spin it a bit and then recheck your marks, this checks the pulley wasn't sitting on a flat spot. The mark should be not on where the splice will go but close enough so you can compare the lines match from that end. You could make more marks or another closer if that will help you cut them or something. When making the marks for the splices to finish them, make them on both lines at the same time, while they are lined up. This way you may get them perfectly aligned with no adjustments.

[edt]

He is very vague on getting the lines even. This should have been done when splitting the double length lines. A pulley will do or maybe even something thing smooth and round like a screwdriver shaft will work. You mark the same point on both lines, near the end that needs splices, while they are both under the even tension of a pulley. You also want quite a bit of tension while doing this so any slack or low level shrink is taken out.

I assume you want to prestretch your lines right before you measure them to take out low level shrink as you call it. Then what I do is send my lines through an o ring back and forth the required numbers of times, but I always leave slack. Then I can tell that the line that is drooping lowest is the longest, while the line that is tightest is the shortest, and can adjust them to be exactly the same. If the lines are completely tight then it can be a problem if your pulley gets stuck or there is friction anywhere maybe a line is grabbing that screwdriver, then the lines will look the same length but one might be under more tension than another one. I just find it vastly easier to measure line lengths while they hang slack. Not that it matters too much how you measure your lines. I do the same thing when I am tuning a control bar. I always see people trying to tune their control bar, attach the kite end to a pole and then grab the bar and pull it tight. Yeah now maybe you will have the lines close but they won't be exact. If you pull the control bar enough to lift the lines off the ground but leave them slack you can adjust the lines to within millimeters. When you pull it tight, well, one line might be under more tension than another line and you'll think it's ok. Maybe it's close enough I just like my bars to be tuned exactly. If you let them hang slack you know they are under exactly equal tension because only the weight of the line is pulling on them.

[foilholio]

The main prestretching is when they are stretched together as one with your body thrown against them before you compare and level them. Adjusting based on visual tension is very inaccurate, I used to do this but not with O rings and it is not accurate. The line needs some load applied to gauge it's actual length, after all the kite does not barely tension the lines in flight does it? The pulley can get stuck but the rope/line will still slide, in reality if it does stick it is only a very minor deviation and you can check for this as I said. You will not get accurate line lengths measuring a slack line, I have been dealing with the thousands of bridles on foil kites for so long now and you will get no where comparing or measuring slack lines. Lines need shrink removed evenly and to be measured with exactly the same force to be accurately compared, a slack situations does not do this. It matters how you measure if you want it to be accurate, when you deal with many bridles this becomes important, otherwise things end up all over the place. If you were to follow how I stretch and check lines you will find your slack compared lines different by quite a lot indeed. Once lines are made even if they then become uneven you can restretch them to be level again and they stay like that for a long long time. using a pulley produces an even force and so lines can be made even. Comparing lines with slack is very inaccurate. Lines can behave differently with different amounts of tension applied. You can get them behaving most similar by first prestretching them with quite a lot of force. Then you can measure them at a force closer to their general working load, which is far away from slack.

Anyway stretch you lines together as one with full body weight or more. Compare them on a pulley thing. Then get back to me.

[edt]

thanks for the comments foholio.

[foilholio]

HAHAHA

I must say the car stretching thing I will try some day. My first test of splice vs sewn end, I just joined them together attached to a car and post. I pushed the car and used it's inertia to break them, and so the splice won. See I had my doubts too This was many many years ago though before the precursor to switch was even thought up and dimitri was just a young kitten, well almost .

[Johnny Rotten]

Deltee duplicate post

[Johnny Rotten]

The stitch or splice needs to take the load evenly onto the larkshead otherwise it would be weaker or slip. Try cutting half or all the stitching off your front lines and get back to me

Ha ha good timing, unrelated to this post I was out yesterday and one of my sketchy stitch jobs gave up on life after a few years of use rode it for 3 hours like that. (half stitches gone) complete with underwater kite loop and a jammed safety, mild deathloop scenerio (not caused by the line breaking or failed stitching) and some WELL powered tricks. Wouldn't advise it, again performance in gusts and jerks would be diminished greatly but it held up to all that abuse just fine. pics are a pain in the butt, but I can attach one if you need it. I'm using basic polyester sail thread for those joints. Didn't take it up to rated load but worked the crap out of it that's for sure.

Having tested stitching on lines it can contribute a lot to strength perhaps close to 100% if done over a long enough piece.

Agreed, but i don't believe on flying lines they are long enough....because they don't need to be. (I am referring to the typical unburied sleeved and stitched kite line) The larks head and stopper knot of most connections make sufficient friction that the stitching is rarely loaded and almost never in full tension unless the connection becomes loose.

For their intended purpose of comparing different joining splicing and bury methods your tests were fantastic and thank you for doing them. Please appreciate that they were not done on typical 600lb kite line. I would be extremely surprised if the thin POLYESTER stitching they use for 2-3 inches on kitelines is somehow able to hold near 600lbs of force. There just doesn't appear to be sufficient area of polyester to do that given it's strength. the friction from the larks head holds a great deal.

Also with kookproof connectors, one end isn't larksheaded.

Incorrect you need to consider the ASSEMBLED condition.
Both ends are larks headed.
one the kite puts a larks head on the kite line squeezing the crap out of it preventing slip through friction .
on the other end the kiteline puts a larks head on the kite end squeezing the crap out of itself preventing slip through friction
In the assembled condtion the effect is the same. it takes considerable load off the stitching.
In addition there is a stopper knot that acts to prevent slippage/unload the stitching.

Also flying lines are barely loaded in most use.

???!!!!
the flying lines combined carry 100% of the load the kiteboarder sees. they are THE MOST highly loaded part on the kite...and the smallest area

I think i get where you're coming from though
There was a video circulating around a while back with some poseur mowing the lawn and doing some dingle dangle jumps with some force gauges on the line and they didn't have much load...I advise against making conclusions or extrapolations from that......guys here have bent and broken bars.

Any joint I plan to stitch I test if under tension in it's assembled arrangement (without stitching) to determine if the line will come apart on it's own

If this is for a splice then it is fine, I do it to "set" the splice before stitching. If however this is for a line end that is "only" stitched, well this is one of the most pointless things I have ever read.

Then you are missing my point, You can fly your kite loading polyester sewing thread if you use enough of it and it's evenly distributed .....but understand you'll need ALOT and is difficult to guarantee/likely to fail... You can stress about brummel, bury depth and taper etc .... Or you can use a type of attachment method to ensure you're flying loading the 600lb dyneema....and the polyester or brummel/bury is back up only...

I have yet to come across a factory line that relies on stitching strength

Just about every flying line does and most kite bridles. I think you have observed things incorrectly. Testing these lines it is only the stitching that could be creating the strength there is nothing else. I am talking about testing them without larksheads too where they can still get 85-90%+ strength.

I'll take a look at some bridles (mot of my kites are C kites) but I suspect you are also wrong here...stitching is likely back up only in the assembled/usage condition and there is a Chinese finger trap bury going on

Again the stitching provides strength, on line ends that are solely stitched it provides all of the strength in combination of course with the line/rope fibers. You can observe this and you can test this and because of that I won't argue much on it further.

I haven't found an easy/practical way to get 600lbs through a test rig and load a line correctly without owning a 600lb force gauge. I know you tested lower rated line intentionally for this reason but send me a pic of what you did maybe I'll get some inspiration on how to make it go for heavier stuff and do it myself ....Or maybe you f'd everything up altogether, the last dude to test lines, got the units wrong....hey stuff happens.

[foilholio]

Agreed, but i don't believe on flying lines they are long enough

Maybe.

I would be extremely surprised if the thin POLYESTER stitching they use for 2-3 inches on kitelines is somehow able to hold near 600lbs of force.

That thin polyester or nylon is 10-30lb break strength, do the math.

???!!!!

As a percentage of break load.

guys here have bent and broken bars.

leverage, corrosion and fatigue.

you'll need ALOT

The ~10 stitches on my Pansh bridle ends disagree with you, with about 200lb break strength and no larkshead to be seen.

and is difficult to guarantee

paragliders and kiters the world over disagree.

Or you can use a type of attachment method to ensure you're flying loading the 600lb dyneema....and the 20lb polyester or brummel/bury is back up only...

A cowhitch alone is not strong nor secure. The stitching is not backup it is a primary contributor to the strength, without it things just fall apart as has happened to me multiple times when stitching on line ends completely failed.

I'll take a look at some bridles (mot of my kites are C kites)

now I am understanding you better you are a c kiter.

but I suspect you are also wrong here...stitching is likely back up only in the assembled/usage condition and there is a Chinese finger trap bury going on

I am not talking about splices but purely sewn ends as used on any and every sleeved line on paragliders and kites, no use of larks heads either. But what do paragliders know? obviously less than c kiters.

I haven't found an easy/practical way to get 600lbs through a test rig and load a line correctly without owning a 600lb force gauge.

You don't need a gauge. Break test a line with one end a sewn end with no larks head, i.e. with just rope threaded thru the loop and on the other end an unstitched cowhitch or infact any knot you like Simply use a car to facilitate the breaking. The cowhitch should slip, other knots will break or slip.

Or maybe you f'd everything up altogether

Thanks how nice of you. What tests have you done? Oh none. You know what, you don't have to agree with one little bit, you are free to find things for yourself, I don't have a monopoly on breaking pieces of string.

You know what I will actually test this though because I have never investigated what effect a larks head has on the strength, I suspect nothing.

[Mad_dan]

Just snapped a line on my core sensor 2 bar and on my bridle line. Not because of wear. Can, an should it be spliced or should I buy new lines. Dont want to alter the lengths with extra line if I dont have to. What would you do? Any tips appreciated....