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Kite Tech Tips: Brummel Splice

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foilholio
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Re: Kite Tech Tips: Brummel Splice

Postby foilholio » Mon Apr 30, 2018 2:51 pm

Gunnar 50% is for the lock on the Brummel not including the tail. If you do too short a tail or don't set it right and the lock takes load it weakens the line.

And I said the no taper basically doesn't reduce strength (or much) but causes the line to wear at that point over time.

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Re: Kite Tech Tips: Brummel Splice

Postby edt » Mon Apr 30, 2018 3:05 pm

Yeah Foilho and I have different views about what the taper does. Grunnar is just talking to me I think there in that criticism. I think the taper is critical, but that's from my own testing. I also used to hold a much dimmer view of the Brummel a couple years ago too, didn't think it was as strong as the simple splice with a lock stitch and long bury but after doing my own testing I have come around to the idea that the Brummel with a long bury is within 1% the strength of a simple splice

OzBungy
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Re: Kite Tech Tips: Brummel Splice

Postby OzBungy » Tue May 01, 2018 3:27 am

So how do you make an accurate Brummell splice? Don't you have to pull it apart and remake it if it's the wrong length?

The only reliable way to check length is to make a splice, load it under a specified tension then check and adjust if necessary. Where's the scope for adjustment in a Brummell splice?

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Re: Kite Tech Tips: Brummel Splice

Postby ronnie » Tue May 01, 2018 10:50 am

OzBungy wrote:
Tue May 01, 2018 3:27 am
So how do you make an accurate Brummell splice? Don't you have to pull it apart and remake it if it's the wrong length?

The only reliable way to check length is to make a splice, load it under a specified tension then check and adjust if necessary. Where's the scope for adjustment in a Brummell splice?
I don't think there is scope for adjustment. I did some experiments measuring how much the line changed in length after splicing. I marked a distance on the line from the centre of the loop to a mark beyond the splice and measured how much the line shortened after splicing. It's then a case of repeating the splicing method as consistently as you can.

This is the video I worked from. I found it almost impossible to get the doubled, tapered line and doubled guitar string back through the line. I then got a thin knitting needle that was the maximum diameter that would go up the centre of the line, and loaded the line onto it, then removed it before passing the guitarline through and pulling the line end back through.


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Re: Kite Tech Tips: Brummel Splice

Postby topmick » Tue May 01, 2018 1:16 pm

I use brummel where I can to connect, then stitched long bury for accurate line measurements.

OzBungy
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Re: Kite Tech Tips: Brummel Splice

Postby OzBungy » Tue May 01, 2018 1:49 pm

ronnie wrote:
Tue May 01, 2018 10:50 am
.....
This is the video I worked from. I found it almost impossible to get the doubled, tapered line and doubled guitar string back through the line. I then got a thin knitting needle that was the maximum diameter that would go up the centre of the line, and loaded the line onto it, then removed it before passing the guitarline through and pulling the line end back through.

It should just take practice to be able to pull the splice through. I have never not been able to pull the line through with a splicing tool or guitar string. The worst has been not being able to get the tool or wire into the line in the first place because the line is too thin (the wire passes all the way through and doesn't go down the middle), or on thick lines where the centre core has bound up and there's no tunnel to push through.

The splice in that video is a bit of a worry. It's sort of a half brummel. It's actually quite easy to pull apart if you grab the line and the loop in the right place. I admit that it is unlikely to happen without help, but it could. A true brummel is almost impossible to get apart again once it's finished. (In fact, I just spliced a line with both kinds of brummel ends. The half brummel was easy to pull apart. The MacDonald Brummel took some serious "reverse engineering" to get apart.)

I think it ultimately comes down to embracing the act of splicing, and specifically committing to a simple straight splice with nice long, sewn, tapered bury. It's strong. It's accurate. It's easy to do. It's the way any professionally done splice will be done (in thin lines). It's also the only one you can do in place if you're repairing a foil kite bridle or brake line.

PS. As I mentioned above, apart from a lot of years of doing splices and sewing bridle lines and stuff, I have been sitting here and trying all these splices out. Bog standard brummel is easiest if you don't want to sew, and has no twists to worry about. Straight eye splice best of all but you have to sew them.

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Re: Kite Tech Tips: Brummel Splice

Postby OzBungy » Wed May 02, 2018 2:22 am

I did a heap more brummels. It seems to me the most critical thing is getting the wire/splicing tool neatly through the middle of the line. It's easy to get it off centre, or to shred the fibres on the way through.

More and more I am convinced that the McDonald brummel splice is not a good thing. It puts two big twists in the line. You can remove one of them during splicing. The second one is unavoidable. A simple brummel passing the end through the bury is much neater and easier to do.

I notice that the brummels in general, and the McDonald brummel in particular is used for yachting ropes. The convenience of doing a McDonald brummel in a thick rope may be more desirable than avoiding twists and stuff.

A question for you guys who have done load tests, how did you do the test and how did you measure the load? Obviously static load is very different to shock loading. I would expect any line to withstand 200% in a static load test no matter how it was joined or spliced.

OzBungy
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Re: Kite Tech Tips: Brummel Splice

Postby OzBungy » Wed May 02, 2018 2:31 am

PS A twist free McDonald Brummel

The use of needles vs guitar string is irrelevant. It's just a different method of getting the line through itself. I prefer the guitar string and/or the wire splicing tool.

The real difference to Gunnar's method are:
- Step 1. Gunnar starts at the bitter end and pulls the standing part through to make a loop. That inverts the line and puts a permanent twist in it. https://youtu.be/Fo5lgO-DUk4?t=4m6s

This video starts at the standing part and pulls the whole bitter end through. That means the first twist is avoided completely. https://youtu.be/4WW7Qvg3VjI?t=35s

- Step 2. Gunnar pulls the loop back through itself, which puts in a second twist. https://youtu.be/Fo5lgO-DUk4?t=5m1s

This video pulls the loop through the bitter end. https://youtu.be/4WW7Qvg3VjI?t=55s

That ends up with a single twist that is easily removed at the end. https://youtu.be/4WW7Qvg3VjI?t=1m19s

To put it more simply, mark your loop end points and bury. Start from the standing part (the main part of the line) and work your way to the end. Take the twist out of the bury before you finish off.

phpBB [video]

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Re: Kite Tech Tips: Brummel Splice

Postby foilholio » Wed May 02, 2018 5:41 am

Twist free is important. There is so much correct information already available I wonder why Gunnar made his vids, especially if he doesn't do it right?
OzBungy wrote:
Tue May 01, 2018 3:27 am
So how do you make an accurate Brummell splice? Don't you have to pull it apart and remake it if it's the wrong length?

The only reliable way to check length is to make a splice, load it under a specified tension then check and adjust if necessary. Where's the scope for adjustment in a Brummell splice?


You can leave space in the lock for adjustment. But yes you can have to undo the brummel and redo it which makes them a pain.

It is possible to make accurate spliced lengths without adjustments. You need to prestretch the line, then use accurate pen marks, using the edge of the pen mark. When I balance two lines I mark across both with the pen so they line up as one pen line and the edge is my guide. Can't emphasize stretching lines before you do stuff with them enough. Hidden shrink will forever have you altering lengths. The amount of new flying lines I have seen that are not accurate makes me think it's normal.

You can run into issues with one off bridle replacements where different materials shrink different. But in general it is not an issue.
Last edited by foilholio on Wed May 02, 2018 1:16 pm, edited 1 time in total.

jannik
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Re: Kite Tech Tips: Brummel Splice

Postby jannik » Wed May 02, 2018 7:51 am

foilholio wrote:
Wed May 02, 2018 5:41 am
...Can't emphasize stretching lines before you do stuff with them enough....
With how much weight and for how long do you stretch? I'm about to make new lines.


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