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 Page 1 of 2. Messages 1 to 20 | 21 to 22
Author
best cord for big bros?
robbio
22-Aug-2017
9:04:50 PM
Attention fellow big bro owners:

So i have a bunch of big bros that need cord. Trango recommends slinging with 5.5 tech cord that has a breaking strength of at least 3000 pounds (13.6KN).

No nearby outdoor shops seem to sell anything like this (everyone sells 5mm accessory cord, but that's only 5-6KN of so).

Anyone had any luck with any specific cords?

Has anyone used 5mm (actual size is 5.5mm) blue water titan dyneema cord for this purpose? If so does it thread through the holes ok?

I have heard that Beal 5.5mm dyneema cord is a tad spoogy to thread through the holes easily despite being the recommended thickness. Same problem with the Edelweiss aramide 5,5 cord supposedly.

Maxim 5mm tech cord sounds promising, but i can't find it online...

I have emailed trango but i am impatient so i thought i should annoy chock stoners while i am at it.

Cheers.

Crepuscular
22-Aug-2017
9:31:59 PM
I have a similar issue, but only with one #3 big bro.

I've been able to get some new 6mm cord through the holes which is rated at 8.8KN. I couldn't easily find anywhere to order a short length of dyneema cord from & wasn't too sure how well it holds knots in any case. I guess one could put a sling around one end of these devices after placing them?
egosan
23-Aug-2017
7:11:28 AM

>Maxim 5mm tech cord sounds promising, but i can't find it online...

http://www.libertymountain.com/products/5474/NTN02583/tech-cord

http://www.gearexpress.com/new-england-maxim-5mm-tech-cord-spool.html

rightarmbad
23-Aug-2017
7:20:45 AM
Big Bros are only rated at 12Kn.
The cord is a loop, not a single strand.

goshen
23-Aug-2017
8:01:04 AM
I had no probs with 5.5mm spectra cord from Bogong (pretty sure it was there). Fitted though fine, not a tight fit - you just got to make sure you melt/taper the ends slightly.
The Rock Robster
23-Aug-2017
8:56:50 AM
On 22-Aug-2017 robbio wrote:
>Attention fellow big bro owners:

I believe they're called "Big Broners"
TimP
23-Aug-2017
10:47:50 AM
On 23-Aug-2017 goshen wrote:
>I had no probs with 5.5mm spectra cord from Bogong (pretty sure it was
>there). Fitted though fine, not a tight fit - you just got to make sure
>you melt/taper the ends slightly.

After I melt the cut I quickly roll it under a steel ruler while it's still soft to give a nice catch-free taper. Also a wind-proof lighter with element is good for the melt. I reckon this process gives a better result than a hot-knife.
Don't breath the fumes! (I finally set up Steve at Rock Hardware with an extractor fan, have wanted to do that for years)
allnewmaterial
23-Aug-2017
6:15:12 PM
Knots in dyneema and spectra weaken the cord significantly. (Anyone remember that DMM video where run a bunch of drop test onto knotted slings?)
If slinging with this low-elongation stuff then you'd def' want to get it sewn.
Otherwise just go for fully nylon cord.
Timbigot
23-Aug-2017
7:57:45 PM
Yeah don't tie knots in cord, that's crazy you'll die
Dave_S
24-Aug-2017
7:27:35 AM
On 23-Aug-2017 allnewmaterial wrote:
>Knots in dyneema and spectra weaken the cord significantly. (Anyone remember
>that DMM video where run a bunch of drop test onto knotted slings?)
>If slinging with this low-elongation stuff then you'd def' want to get
>it sewn.

Even if the 13.6kN strength of the cord is halved, that's still 6.8kN breaking strength, which is more than enough. And the elasticity of the cord is irrelevant unless you're clipping it straight to your harness and then taking a factor 2 fall directly onto it. As soon as dynamic climbing rope is part of the equation, the elasticities of all stiffer components, whether they are nylon or dyneema, become irrelevant.

Tying a loop of 5.5mm Dyneema cord through the Big Bro, using a triple fisherman's knot, is how the manufacturer recommends that you set it up.

Duang Daunk
24-Aug-2017
8:26:44 AM
On 23-Aug-2017 allnewmaterial wrote:
>Knots in dyneema and spectra weaken the cord significantly.

And this doesn't happen with...?
What's so special about those cords other than requiring particular knots bro?
allnewmaterial
24-Aug-2017
3:14:28 PM
Sorry, my last was a crappy comment. Gotta retract: I had in my head the idea of that flat dyneema sling material on which a double/triple fisherman's wouldn't dress well. Hence my comment about sewing.

But that old DMM video is still a good yarn. Shows a 60cm dyneema sling with an overhand knot breaking during a factor 1. And how an overhand in a nylon sling can (in some circumstances) act like a shock absorber. But yes, I agree that a wobbly human in a harness on a lead rope is very different to the dead weight used in drop-tests.

Goshen
25-Aug-2017
7:48:58 AM
Also - don't forget that Dyneema cord still has a nylon sheath - which protects the dyneema core. So tying knots looses no less strength (practically) than knots in a regular rope.

The issue with spectra is that it has a low melting point, and loaded knots can cause enough heat via friction they 'melt' under tension. So beware of tying knots in 'naked' spectra/dyneema, but the sheathed cord is fine.

IdratherbeclimbingM9
25-Aug-2017
6:25:59 PM
+1 for spectra, and tapering the cord end (plus patience in fitting), and the rated strength is greater for a loop than a single strand.

gnaguts
26-Aug-2017
4:25:51 PM
On 25-Aug-2017 Goshen wrote:
>Also - don't forget that Dyneema cord still has a nylon sheath - which
>protects the dyneema core. So tying knots looses no less strength (practically)
>than knots in a regular rope.
>
Yeh?
Ur sure itz knot a dyneema sheaf?

>The issue with spectra is that it has a low melting point, and loaded
>knots can cause enough heat via friction they 'melt' under tension. So
>beware of tying knots in 'naked' spectra/dyneema, but the sheathed cord
>is fine.

When havU heard of a real life example of spectra melt in use?
Tha only time i heard of it tha knot fused a bit an there woz no safety issue.
Carnt quote tha source tho, as woz a while bak an ive since 4got.
widewetandslippery
27-Aug-2017
5:36:13 AM
The cord that lets you throw them the furtherest away

gnaguts
27-Aug-2017
5:21:47 PM
On 27-Aug-2017 widewetandslippery wrote:
>The cord that lets you throw them the furtherest away

U dont like em huh , or RU suggestn wire swage insted?
robbio
7-Sep-2017
7:20:43 PM
Well i got some cord in the end. Got some blue water 5.5mm titan cord from climbinganchors.com
(rockhardware normally stocks it for less $ but is out of stock atm).

Feeds through the holes without too much fuss, just had to heat the ends (i used a miniature gas torch) and smoothed them out (while wearing leather gloves).

I should have made them longer though, at 80cm each, after tying triple fishermen's the loop ends up very small indeed. I will go 90-100cm in length when i do them next time (in 10 years)....



IdratherbeclimbingM9
8-Sep-2017
9:01:17 AM
On 7-Sep-2017 robbio wrote:
>should have made them longer though, at 80cm each, after tying triple fishermen's the loop ends up very small indeed. I will go 90-100cm in length when i do them next time (in 10 years)....

Same thing happened to me once. I swapped them out by reslinging other pro with the shorter loops, as I found longer ones more advantageous on the big bros.
rightarmbad
8-Sep-2017
9:20:20 PM
Undo two of the pesky fishermen.
Double is plenty, there is your extra cord.

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There are 22 messages in this topic.

 

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