Double finger trap

[ramon 0]

Has anyone looked at the finger trapped lines on a Jump Shack FireBolt? Apparently there are no stiches in any of the lines. The lines have a sort of complex double finger trap. it is supoosed to be very strong.

Any opinions?

thanks

Ramon

"Revolution is an abrupt change in the form of misgovernment.", Ambrose Bierce.

[Hooknswoop 19]

Saw that a while ago, very cool. Works great for making a loop for toggles.

Derek

[mjosparky 3]

It is finger trapped back on itself. I have used that method a few times and it works well. I think it was someone at Jump Shack that came up with the idea.
Sparky

My idea of a fair fight is clubbing baby seals

[darkwing 4]

It is usually called a no-sew fingertrap. It is easy to do, and pretty handy. Instructions are here

-- Jeff
My Skydiving History

[diveout 0]

my opinion is that if it's the same configuration as a brake line loop -it could possibly slip if the lines are handled in a certain way.

Why not just run a quick narrow zig-zag down the whole area, like precision does with their hma line sets?

I can't imagine it saves them that much money-maybee it does

[Remster 24]

How could it slip?

Remster

[hookitt 0]

Greetings diveout.

Take a good look at the instructions. It won't slip. IN fact, finger trap a line that way and it will make sense.

My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto

[ramon 0]

Cool

I wonder if it will be hard with 550 spectra...heh heh
I read the instructions, somewhat confusing...

There is a jump shack dealer in town I'll ask him if I see him

ramon

"Revolution is an abrupt change in the form of misgovernment.", Ambrose Bierce.

[FrogNog 1]

Quote

It is usually called a no-sew fingertrap. It is easy to do, and pretty handy. Instructions are here

I don't quite bet the running end insertion part. The picture they show has a finger trap at the top, then they take the running end of the line at the bottom and pull it through both the outer and inner lines at the finger trap.

And then where does it go? When they pull the running end through both pieces of line in the finger trap area, do they pull on the running end until the two "sides" of the hole they just went through turn 180 degrees on the long axis and the hole effectively turns inside out and looks like a little belly button and the running end is again useful for whatever else they want to do with it?

And am I right in assuming this can only be done on both ends of a line if the entire first new-sew-fingertrapped end can be pulled through the second fingertrap area outer and inner pieces?

-=-=-=-=-
Pull.

[mjosparky 3]

Quote

my opinion is that if it's the same configuration as a brake line loop -it could possibly slip if the lines are handled in a certain way.

Why not just run a quick narrow zig-zag down the whole area, like precision does with their hma line sets?

I can't imagine it saves them that much money-maybee it does

Its not the same configuration and it can't slip. Do you have a zig-zag at your house?
Sparky

My idea of a fair fight is clubbing baby seals

[diablopilot 2]

Quote

Do you have a zig-zag at your house?

Yes.

----------------------------------------------
You're not as good as you think you are. Seriously.

[diveout 0]

now that I see the diagram, it looks good-

I was thinking of something different- that will clearly not slip

carry on--- can someone post an actual pic of one of these lines?

[Cloggy 1]

I tried this yesterday as I wanted to lengthen my brake lines and don't have a sewing machine.

It's quite easy actually. After you make the loop you carefully poke a hole through the line, make sure you go through the middle of the outside and the inside line. (Yeah, I know it's just one line...).

Then, with a loop of thin wire (I used a paperclip) you pull the loop through the hole. You're right, effectively this sort of turns the fingertrap inside out, locking it. I pulled the loop through, I hope it doesnt NEED to be the running end...

(In the first pic, I loosened up the 'knot', to make it a bit more clear)

[sid 1]

there's a pictorial on my site http://www.sidsrigging.com/Articles/stitchless_fingertrap.htm

Pete Draper,

Just because my life plan is written on the back of a Hooter's Napkin, it's still a life plan.... right?

[linestretch 0]

that is pretty sweet. Sorta a mind bender until the light comes on. How much shrinkage do you get from this, if any?

my pics & stuff!

[teason 0]

Had a of canopy that needed new brake lines last year. Grabbed my scissors, microline and fid. Did it right on site at the DZ with very little down time.
Also changed the inboard brake lines on a canopy last week. Once again it was done in minutes, very little down time.

I think there is negligable strength loss(6% sounds familiar but I'm not sure) as it doesnot break at the shoulder. Maybe Sid or Nightjumper can answer that one.

I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.

[mjosparky 3]

Quote

Quote

Do you have a zig-zag at your house?

Yes.

But thats for sewing the holes in your shorts.

My idea of a fair fight is clubbing baby seals

[FrogNog 1]

Quote

I think there is negligable strength loss

Jumpshack says the knot (well, double-fingertrapped-regime) is stronger than a single length of the line itself, I believe.

I got my music wire, now I just gotta make fids.

-=-=-=-=-
Pull.

[mjosparky 3]

Quote

there's a pictorial on my site http://www.sidsrigging.com/Articles/stitchless_fingertrap.htm

Sid,
Nice picture lay out. I makes it very easy to understand.
Sparky

My idea of a fair fight is clubbing baby seals

[ramon 0]

Thanks

I'm no rigger and jumpshack's instructions were a little confusing. Good pics.

Ramon

"Revolution is an abrupt change in the form of misgovernment.", Ambrose Bierce.

[jerm 0]

Quote

I think there is negligable strength loss(6% sounds familiar but I'm not sure) as it doesnot break at the shoulder. Maybe Sid or Nightjumper can answer that one.

a rigger friend of mine had pull-test done on it and the weak spot was in the same place as a regular finger-trap, where the fingertrap ends and goes back to single line... the 'knot' is NOT the weak link.

Landing without injury is not necessarily evidence that you didn't fuck up... it just means you got away with it this time

[jerm 0]

it can be done at both ends.... the diagram shows feeding the losoe end through the double-line, but it can also be accomplished by feeding the loop end through the double-line. It's a little tougher to get through (especially with dacron brakeline... i gave up), but it ends up the same way.

Landing without injury is not necessarily evidence that you didn't fuck up... it just means you got away with it this time

[teason 0]

Just did some reading, it does break at the shoulder. My mistake. For some reason, I thought it broke where it goes through itself.

I wonder what the hell I was thinking of?

I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.

[alan 1]

Quote

a rigger friend of mine had pull-test done on it and the weak spot was in the same place as a regular finger-trap, where the fingertrap ends and goes back to single line... the 'knot' is NOT the weak link.

You and your rigger friend are quite correct on this. Sandy Reid of Rigging Innovations published an article or two in Skydiving Magazine a few years back that discussed the proper fingertrapping of various line types and where lines tend to break.

We have all read the discussions on Vectran, HMA, you name it lines, that have looked new or even been new and have broken. Then someone goes on to bash that type of line. Well, maybe the line is not as good as the other type, but we can't always just assume that. A new Spectra line that has not been cut and finger trapped properly can and will break unexpectedly just as HMA or any other line. Hot knife Spectra and cut it square instead of at a bias and you are asking for the line to break at the end of the finger trap. So, when people are talking about type X line breaking unexpectedly and not being as good or as safe as type Y, I tend to ignore it unless they provide some real information, like where did it break.

alan

[billvon 2,396]

>It's quite easy actually.

How much longer do you have to plan on making the line? I assume the "knot" takes up a bit of line.