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static forces on hexes and cams
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NJSlacker


Oct 13, 2008, 11:57 AM
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static forces on hexes and cams
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Hey guys

I'm looking to set up a highline (slackline) with one anchor being entirely made up of hexes and cams, and backed up by a large boulder to the side

I was just checking what a static force would do to hexes and cams. There would be several (at least 6, possibly more), all equalized.


mushroomsamba


Oct 13, 2008, 11:59 AM
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Re: [NJSlacker] static forces on hexes and cams [In reply to]
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I'm not sure if I would invest the money on using cams for your anchor... thats really expensive seeings as you cant really use them for climbing after that. that being said, is bolting an option for your anchor?


NJSlacker


Oct 13, 2008, 12:12 PM
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Re: [mushroomsamba] static forces on hexes and cams [In reply to]
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Bolting may be an option, however I have never done it myself. Would the hexes and cams be unsafe for climbing after that kind of stress?


petsfed


Oct 13, 2008, 12:37 PM
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Re: [NJSlacker] static forces on hexes and cams [In reply to]
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NJSlacker wrote:
Bolting may be an option, however I have never done it myself. Would the hexes and cams be unsafe for climbing after that kind of stress?

There's no data either way. However, a constant load of a couple hundred pounds, with peak load being great enough to occasionally break webbing and carabiners? Yeah, probably not good for your cams and hexes.


kennoyce


Oct 13, 2008, 1:48 PM
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Re: [NJSlacker] static forces on hexes and cams [In reply to]
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As has been said, no real research has been done, but it is generally accepted that you don't use gear that has been used for a slackline for climbing. Just looking at this by cost alone, if you buy all the gear to put in a 4 bolt anchor you'll spend 20 bucks on the bolts, 50 on a hand drill, and 10 on a bit. so you've spent a total of 80 bucks, less than the price of 2 cams, plus if you ever want to do it again, you only have to buy bolts. You said that you've never bolted before, so find someone who has, and have them teach you how its done, then practice on some rocks in your backyard. While I believe we should try to do things as cleanly as possible, I also believe that with highlining, bolts are best. Just some things to think about.


USnavy


Oct 13, 2008, 6:29 PM
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Re: [kennoyce] static forces on hexes and cams [In reply to]
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In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength. A fall on a highline could easily generate over 12 kN on the anchors. From what I see its generally recommended to use 1/2" bolts. I plan on building a highline myself eventually and when I do I am going to use three or four glue in titanium staple bolts on each side and equalize them.


marde


Oct 14, 2008, 5:33 AM
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Re: [petsfed] static forces on hexes and cams [In reply to]
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petsfed wrote:

There's no data either way. However, a constant load of a couple hundred pounds, with peak load being great enough to occasionally break webbing and carabiners? Yeah, probably not good for your cams and hexes.
Someone actually made force messurements with slacklines:

http://www.lorenz-messtechnik.de/...surements/170243.pdf


petsfed


Oct 14, 2008, 8:16 AM
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Re: [marde] static forces on hexes and cams [In reply to]
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marde wrote:
petsfed wrote:

There's no data either way. However, a constant load of a couple hundred pounds, with peak load being great enough to occasionally break webbing and carabiners? Yeah, probably not good for your cams and hexes.
Someone actually made force messurements with slacklines:

http://www.lorenz-messtechnik.de/...surements/170243.pdf

I'm aware of the force measurements. I mean UIAA style tests of carabiners after being used in a slackline for an extended period of time. Tests that measure the impact on a carabiner (let alone cams, hexes and nuts) from high loads for long periods of time has not yet been done.


Partner angry


Oct 14, 2008, 8:27 AM
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Re: [petsfed] static forces on hexes and cams [In reply to]
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While I agree that bolts would be better, I'm going to interject a few things.

My 3/8" bolts have a shear rating of 4700lb and my 1/2" have a shear rating of 5800lb. Not a giant difference when we're talking about equalizing 3 or 4 of them. The only reason I use the 1/2" is that they tend to tighten down nicer in sandstone. It's not a strength issue, but a fatter bolt has more friction and has less tendency to be a spinner.

As for the cams/nuts/hex thing. I'd never want just one or two but assuming that you actually get the mess equalized, you are never putting those kinds of peak loads on a single piece. Of course this assumes you get it equalized just right. 1/6th of 15kn isn't really a huge problem, in theory.

You could put in Fixe Triplex bolts if you're worried about the impact and just take them out and patch the hole when you're done.


majid_sabet


Oct 14, 2008, 8:58 AM
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Re: [USnavy] static forces on hexes and cams [In reply to]
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USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength. A fall on a highline could easily generate over 12 kN on the anchors. From what I see its generally recommended to use 1/2" bolts. I plan on building a highline myself eventually and when I do I am going to use three or four glue in titanium staple bolts on each side and equalize them.

you are gov approved n00b


USnavy


Oct 14, 2008, 9:57 AM
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Re: [majid_sabet] static forces on hexes and cams [In reply to]
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majid_sabet wrote:
USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength. A fall on a highline could easily generate over 12 kN on the anchors. From what I see its generally recommended to use 1/2" bolts. I plan on building a highline myself eventually and when I do I am going to use three or four glue in titanium staple bolts on each side and equalize them.

you are gov approved n00b

That means a lot coming from you, the most decorated idiot on the entire website... Yes I was wrong, highline falls donít generate 12 kN. They generally generate more than that now that I am looking around... Just a jump on a slackline can easily generate 8 kN.

So tell me master Majid, do you believe itís a good idea to use cams that are rated for 12 - 16 kN in a application where they can easily see more then 12 kN? Please provide me with multiple MS Paint diagrams on how itís both safe and cost effective to use cams over bolts and be sure to include color coded pointers expressing small but important details in the diagram.


(This post was edited by USnavy on Oct 14, 2008, 10:02 AM)


majid_sabet


Oct 14, 2008, 10:20 AM
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USnavy wrote:
majid_sabet wrote:
USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength. A fall on a highline could easily generate over 12 kN on the anchors. From what I see its generally recommended to use 1/2" bolts. I plan on building a highline myself eventually and when I do I am going to use three or four glue in titanium staple bolts on each side and equalize them.

you are gov approved n00b

That means a lot coming from you, the most decorated idiot on the entire website... Yes I was wrong, highline falls donít generate 12 kN. They generally generate more than that now that I am looking around... Just a jump on a slackline can easily generate 8 kN.

So tell me master Majid, do you believe itís a good idea to use cams that are rated for 12 - 16 kN in a application where they can easily see more then 12 kN? Please provide me with multiple MS Paint diagrams on how itís both safe and cost effective to use cams over bolts and be sure to include color coded pointers expressing small but important details in the diagram.

yes you can use any active or passive protection to build a highline anchor but you need to remember that in real world situations, all non-fixed protections should be rated to no more than 5 kn therefore, you need to use several of them to construct your anchor. Highline itself and highline anchors are among the most dangerous of all in rope rigging and this is where the art of building simple and complex anchor build comes handy. Generally you want a good static line to construct your anchor with good master point to exceed 30kn .Other factors such as sag, distance between the anchors, load, number of highline etc plays big rule in building safe highline.

Next year I am headed to the middle east to do a highline over a dead volcano hole which is 400 feet across. we are going to use anchors made of steel rods on both side of the hole then build four separate anchors for two highline. once we get to the middle of the highline, we will rap another 300-600 feet in to the hole to see what is out there and then jug back up.

No one is ever done this over there so we look forward to be the first .


marde


Oct 14, 2008, 10:35 AM
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Re: [petsfed] static forces on hexes and cams [In reply to]
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petsfed wrote:
I'm aware of the force measurements. I mean UIAA style tests of carabiners after being used in a slackline for an extended period of time. Tests that measure the impact on a carabiner (let alone cams, hexes and nuts) from high loads for long periods of time has not yet been done.

Problem with the breaking biners is cyclic loading.
The given strength is breaking strength.
For cyclic loading aluminum alloys only have half the rated strength (in general)
So if you create a force of 10kN on a slackline that means that your biner rated to 24kN has next to no safety margin for cyclic loading.


USnavy


Oct 14, 2008, 11:07 PM
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Re: [majid_sabet] static forces on hexes and cams [In reply to]
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majid_sabet wrote:
USnavy wrote:
majid_sabet wrote:
USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength. A fall on a highline could easily generate over 12 kN on the anchors. From what I see its generally recommended to use 1/2" bolts. I plan on building a highline myself eventually and when I do I am going to use three or four glue in titanium staple bolts on each side and equalize them.

you are gov approved n00b

That means a lot coming from you, the most decorated idiot on the entire website... Yes I was wrong, highline falls donít generate 12 kN. They generally generate more than that now that I am looking around... Just a jump on a slackline can easily generate 8 kN.

So tell me master Majid, do you believe itís a good idea to use cams that are rated for 12 - 16 kN in a application where they can easily see more then 12 kN? Please provide me with multiple MS Paint diagrams on how itís both safe and cost effective to use cams over bolts and be sure to include color coded pointers expressing small but important details in the diagram.

yes you can use any active or passive protection to build a highline anchor but you need to remember that in real world situations, all non-fixed protections should be rated to no more than 5 kn therefore, you need to use several of them to construct your anchor. Highline itself and highline anchors are among the most dangerous of all in rope rigging and this is where the art of building simple and complex anchor build comes handy. Generally you want a good static line to construct your anchor with good master point to exceed 30kn .Other factors such as sag, distance between the anchors, load, number of highline etc plays big rule in building safe highline.

Next year I am headed to the middle east to do a highline over a dead volcano hole which is 400 feet across. we are going to use anchors made of steel rods on both side of the hole then build four separate anchors for two highline. once we get to the middle of the highline, we will rap another 300-600 feet in to the hole to see what is out there and then jug back up.

No one is ever done this over there so we look forward to be the first .

Thank you for making my point for me. Yes you can use trad gear but you can also use bolts and bolts are much safer and they cost less money then trad gear thus its a much more intelligent choice to use bolts over gear.


majid_sabet


Oct 14, 2008, 11:35 PM
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Re: [USnavy] static forces on hexes and cams [In reply to]
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USnavy wrote:
majid_sabet wrote:
USnavy wrote:
majid_sabet wrote:
USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength. A fall on a highline could easily generate over 12 kN on the anchors. From what I see its generally recommended to use 1/2" bolts. I plan on building a highline myself eventually and when I do I am going to use three or four glue in titanium staple bolts on each side and equalize them.

you are gov approved n00b

That means a lot coming from you, the most decorated idiot on the entire website... Yes I was wrong, highline falls donít generate 12 kN. They generally generate more than that now that I am looking around... Just a jump on a slackline can easily generate 8 kN.

So tell me master Majid, do you believe itís a good idea to use cams that are rated for 12 - 16 kN in a application where they can easily see more then 12 kN? Please provide me with multiple MS Paint diagrams on how itís both safe and cost effective to use cams over bolts and be sure to include color coded pointers expressing small but important details in the diagram.

yes you can use any active or passive protection to build a highline anchor but you need to remember that in real world situations, all non-fixed protections should be rated to no more than 5 kn therefore, you need to use several of them to construct your anchor. Highline itself and highline anchors are among the most dangerous of all in rope rigging and this is where the art of building simple and complex anchor build comes handy. Generally you want a good static line to construct your anchor with good master point to exceed 30kn .Other factors such as sag, distance between the anchors, load, number of highline etc plays big rule in building safe highline.

Next year I am headed to the middle east to do a highline over a dead volcano hole which is 400 feet across. we are going to use anchors made of steel rods on both side of the hole then build four separate anchors for two highline. once we get to the middle of the highline, we will rap another 300-600 feet in to the hole to see what is out there and then jug back up.

No one is ever done this over there so we look forward to be the first .

Thank you for making my point for me. Yes you can use trad gear but you can also use bolts and bolts are much safer and they cost less money then trad gear thus its a much more intelligent choice to use bolts over gear.
if you have bolts then you could load them up to 15 kn a piece but need min 2-4 for major highlines.

here are some photos of a 4x rope highline with its anchor in addition of 5x active pro anchor plus a backup.

Copyright Majid S

[URL=http://imageshack.us]

[URL=http://imageshack.us]

[URL=http://imageshack.us]

[URL=http://imageshack.us]

[URL=http://imageshack.us]


adatesman


Nov 22, 2008, 7:24 PM
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USnavy


Nov 22, 2008, 7:34 PM
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Re: [adatesman] static forces on hexes and cams [In reply to]
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Damm Majid thatís a lot of ghetto rigging! I like how you skipped wrapping the 12" thick tree but you used cams at a 120 degree pull angle. Crazy


(This post was edited by USnavy on Nov 22, 2008, 7:38 PM)


chrisJoosse


Jan 10, 2010, 10:14 PM
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Re: [USnavy] static forces on hexes and cams [In reply to]
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USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength.
That, and the fact that when they pull, they become high-speed projectiles.


mikebee


Jan 11, 2010, 2:42 AM
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Re: [marde] static forces on hexes and cams [In reply to]
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In reply to:
Problem with the breaking biners is cyclic loading.
The given strength is breaking strength.
For cyclic loading aluminum alloys only have half the rated strength (in general)
So if you create a force of 10kN on a slackline that means that your biner rated to 24kN has next to no safety margin for cyclic loading.

I've never rigged a highline from experience, but because of the immense forces involved, I've always assumed that people would use a steel biner for this application.
The couple of steelies I have have a 50kN major axis strength (which gives you a massive increase in safety margin, and I believe that steel doesn't suffer the same fatigue from heavy loading.


malcolm777b


Jan 11, 2010, 6:44 AM
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Re: [chrisJoosse] static forces on hexes and cams [In reply to]
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chrisJoosse wrote:
USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength.
That, and the fact that when they pull, they become high-speed projectiles.

Ummm....you realize you just resuscitated this thread that was over a year old to add good, but not terribly important information, right?


chrisJoosse


Jan 11, 2010, 8:20 AM
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malcolm777b wrote:
chrisJoosse wrote:
USnavy wrote:
In every article I have read about highlineing, its highly advised you donít use cams due to their limited strength.
That, and the fact that when they pull, they become high-speed projectiles.

Ummm....you realize you just resuscitated this thread that was over a year old to add good, but not terribly important information, right?
I understand, but don't particularly get why this is a big deal.


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