- Location
- Longmont, CO
3/8 Beeline Bridge
- Thread starter Treezybreez
- Start date
Treezybreez
Been here much more than a while
- Location
- Lancaster, SC
Thanks Jamin, I responded to the picture over in the Awakenings section. My response does not mean I am defending my bridge I agree that it should be tested.
- Location
- rhode island
[ QUOTE ]
Thanks Jamin, I responded to the picture over in the Awakenings section. My response does not mean I am defending my bridge I agree that it should be tested.
[/ QUOTE ]
Have you been using it?
Thanks Jamin, I responded to the picture over in the Awakenings section. My response does not mean I am defending my bridge I agree that it should be tested.
[/ QUOTE ]
Have you been using it?
I tested this rope a while back:
8mm Beeline
I haven't used my hitch cord much, so I don't know what the cord looks like when it is well worn, but it seems like there should have been some visible sign that the bridge was getting weak. Even if the core was severed the cover would still have plenty of strength, and it is visible, and the wear should be evident. Something doesn't add up...
8mm Beeline
I haven't used my hitch cord much, so I don't know what the cord looks like when it is well worn, but it seems like there should have been some visible sign that the bridge was getting weak. Even if the core was severed the cover would still have plenty of strength, and it is visible, and the wear should be evident. Something doesn't add up...
- Location
- rhode island
Jamin's pic has nothing to do with tensile strength. It has everything to do with the self abrasive quality of technora.
[ QUOTE ]
Jamin's pic has nothing to do with tensile strength. It has everything to do with the self abrasive quality of technora.
[/ QUOTE ]
Your powers of perception far exceed mine; I can't look at one blurry picture of a broken rope and declare that I know why it broke.
In the picture it appears that both the core and the cover broke at the same spot. Since both cover and core are made from different materials, and both are very strong, and the forces on the bridge are presumably very low, and the vectran core has tremendous flex-fatigue resistance and abrasion resistance, it seems highly peculiar that both parts of the rope gave up the ghost at the same spot at the same moment.
Jamin's pic has nothing to do with tensile strength. It has everything to do with the self abrasive quality of technora.
[/ QUOTE ]
Your powers of perception far exceed mine; I can't look at one blurry picture of a broken rope and declare that I know why it broke.
In the picture it appears that both the core and the cover broke at the same spot. Since both cover and core are made from different materials, and both are very strong, and the forces on the bridge are presumably very low, and the vectran core has tremendous flex-fatigue resistance and abrasion resistance, it seems highly peculiar that both parts of the rope gave up the ghost at the same spot at the same moment.
- Location
- rhode island
Technora and vectran are very similar fibers. Technora is a little more slick thus slightly less self abrasive. Bee line 8mm has a vectran core and a 75%/25% technora/polyester cover. Based on what is known about these fibers and aramid bridge failures it is a safe assumption that the bridge failed due to the self abrasive nature of the fibers. What do you think happened?
- Location
- Longmont, CO
[ QUOTE ]
Thanks Jamin, I responded to the picture over in the Awakenings section. My response does not mean I am defending my bridge I agree that it should be tested.
[/ QUOTE ]
I don't think it's a totally wrong idea to use the Beeline for short periods of time. That's sort of my warning.
Thanks Jamin, I responded to the picture over in the Awakenings section. My response does not mean I am defending my bridge I agree that it should be tested.
[/ QUOTE ]
I don't think it's a totally wrong idea to use the Beeline for short periods of time. That's sort of my warning.
[ QUOTE ]
Technora and vectran are very similar fibers. Technora is a little more slick thus slightly less self abrasive.
[/ QUOTE ]
Ordinary polyester fibers are not particularly slick; do you therefore think they must be much more self-abrasive than Technora or Vectran? Why do you think self-abrasion has something to do with slickness? And can you cite a reference indicating, as you claim, that Technora is less self-abrasive than Vectran?
Technora and Vectran actually belong to two distinct classes of polymer: the first is a polyamide (aramid) and the second is a liquid crystal form of polyester. Whether or not they are "very similar fibers" depends on what particular property you are considering. Here we are speculating about a bridge failure which may or may not have something to do with similarities or differences between the two fibers.
[ QUOTE ]
Bee line 8mm has a vectran core and a 75%/25% technora/polyester cover. Based on what is known about these fibers and aramid bridge failures it is a safe assumption that the bridge failed due to the self abrasive nature of the fibers.
[/ QUOTE ]
Since only one of the three fibers is an aramid, it seems quite a leap to classify this as an "aramid bridge failure" or to assert it is a "safe assumption" that the failure was due to fiber self-abrasion. Were the non-aramid fibers self-abrading right along with the aramid ones?
[ QUOTE ]
What do you think happened?
[/ QUOTE ]
I frankly don't know what happened. If we could actually inspect the broken bridge we might have a better idea. An interview with the bridge owner would also be helpful. Without more information, I would have no idea how to come up with any sort of assumption about what happened, let along a safe one.
Technora and vectran are very similar fibers. Technora is a little more slick thus slightly less self abrasive.
[/ QUOTE ]
Ordinary polyester fibers are not particularly slick; do you therefore think they must be much more self-abrasive than Technora or Vectran? Why do you think self-abrasion has something to do with slickness? And can you cite a reference indicating, as you claim, that Technora is less self-abrasive than Vectran?
Technora and Vectran actually belong to two distinct classes of polymer: the first is a polyamide (aramid) and the second is a liquid crystal form of polyester. Whether or not they are "very similar fibers" depends on what particular property you are considering. Here we are speculating about a bridge failure which may or may not have something to do with similarities or differences between the two fibers.
[ QUOTE ]
Bee line 8mm has a vectran core and a 75%/25% technora/polyester cover. Based on what is known about these fibers and aramid bridge failures it is a safe assumption that the bridge failed due to the self abrasive nature of the fibers.
[/ QUOTE ]
Since only one of the three fibers is an aramid, it seems quite a leap to classify this as an "aramid bridge failure" or to assert it is a "safe assumption" that the failure was due to fiber self-abrasion. Were the non-aramid fibers self-abrading right along with the aramid ones?
[ QUOTE ]
What do you think happened?
[/ QUOTE ]
I frankly don't know what happened. If we could actually inspect the broken bridge we might have a better idea. An interview with the bridge owner would also be helpful. Without more information, I would have no idea how to come up with any sort of assumption about what happened, let along a safe one.
- Location
- rhode island
I meant to say vectran is more slick therefore less abrasive. I was posting from my phone. My source is Tom from All Gear. I talked to him about it at TCIA expo.
- Location
- rhode island
I definitely was wrong about them both being aramid. Oops. Vectran is self abrasive though.
Here are some interesting links about the fibers we are talking about.
Yarn-on-yarn abrasion
Fibers for sails
More fibers for sails
Yarn-on-yarn abrasion
Fibers for sails
More fibers for sails
Norm_Hall
New member
- Location
- Wauconda, (Chicago),IL,USA
It appears as though a sharp object was involved. I haven't seen fibers pull apart like that. There are usually more 'short and long' fibers in a "pull", as opposed to a cut.
Is it possible to take a close-up image with a clearer focus?
Is it possible to take a close-up image with a clearer focus?
I like what you guys are saying about using approved bridges against home spliced. I cannot splice and have no intention of learning, but I admire those who do. I just don't have the time and I feel safer using splices done by those that have years of experience. That said I would be unsure of using a bridge like the one shown, I would always be checking and checking and that would be counterproductive IMHO, obviously I do a visual check on my webbing bridge before climbing but that is it. I feel comfortable climbing because I know these bridges have be tested by the mfg. Paul. Also no offence to those who do their own splicing it's really quite commendable.
Great discussion going on here........ I've been thinking about these bridge failures for a while now...
2cents:
Rope is rated to be loaded end-to-end right?
When we "side-load" a rope.. as in the case of a bridge... I personally don't think that the "manufacturer MBS or SWL" can be relied on.
The fibers being pulled act as a 'finger-trap'... that much we all know... but what I haven't read in our discussions of bridge construction and usage (and failures) is the compression and tension forces that are being exerted on fibers that were meant to pull in a straight line and have all 360degrees of fibers taking up the load....
I think that compression forces on the inside of the bent bridge and tension forces on the 'top-side'...are totally out of the design specifications that a rope mfgr 'rates' a rope for.
That being said... I'm in 100% agreement with Blinky that we should NEVER put a cover over a load bearing bridge so as to preclude inspection!
But even with 16-strand bridges, I am not aware of a machine, or testing method that can quantify the differences between the fibers in compression and the fibers in tension at the bridge connection. Pic attached.
Does anyone know of a testing method that can quantify those loads/forces?
2cents:
Rope is rated to be loaded end-to-end right?
When we "side-load" a rope.. as in the case of a bridge... I personally don't think that the "manufacturer MBS or SWL" can be relied on.
The fibers being pulled act as a 'finger-trap'... that much we all know... but what I haven't read in our discussions of bridge construction and usage (and failures) is the compression and tension forces that are being exerted on fibers that were meant to pull in a straight line and have all 360degrees of fibers taking up the load....
I think that compression forces on the inside of the bent bridge and tension forces on the 'top-side'...are totally out of the design specifications that a rope mfgr 'rates' a rope for.
That being said... I'm in 100% agreement with Blinky that we should NEVER put a cover over a load bearing bridge so as to preclude inspection!
But even with 16-strand bridges, I am not aware of a machine, or testing method that can quantify the differences between the fibers in compression and the fibers in tension at the bridge connection. Pic attached.
Does anyone know of a testing method that can quantify those loads/forces?
Attachments
Er... one at a time.... 
A few more comments...
- I don't use a bridge, I climb off a "master" saddle with sewn attachment points. When I think about why I chose this saddle, it is precisely because the side loading of a bridge rubs the 'engineer' side of me the wrong way... just a hunch.
- We splice all of our own gear here...some to mfgr specs, and others to suggestions of those who know (way) more than we do.... We break test our stuff. We strive for consistency and quality... we write and use repeatable 'recipes' for our splices....
- After splicing and massaging rope fibers in my hands, I can honestly say that I've never thought to pull test a freshly spliced piece of cordage with a SIDE-LOAD. It is counter intuitive to everything that we work so hard to preserve during the splicing process... smooth taper... in-line pull.
- There's got to be a measureable difference between side-loading a bridge and the similar side load on a spliced tight-eye.... I've never heard of a tight-eye failing a climber...why the bridges? There's got to be a really smart person out there somewhere who knows how to calculate these forces, and help us to decide what fibers are appropriate for this use.
Sorry for the long post(s)... but these 'broken bridge' discussions are really getting to me....
Cheers... think safe.. act safe...
A few more comments...
- I don't use a bridge, I climb off a "master" saddle with sewn attachment points. When I think about why I chose this saddle, it is precisely because the side loading of a bridge rubs the 'engineer' side of me the wrong way... just a hunch.
- We splice all of our own gear here...some to mfgr specs, and others to suggestions of those who know (way) more than we do.... We break test our stuff. We strive for consistency and quality... we write and use repeatable 'recipes' for our splices....
- After splicing and massaging rope fibers in my hands, I can honestly say that I've never thought to pull test a freshly spliced piece of cordage with a SIDE-LOAD. It is counter intuitive to everything that we work so hard to preserve during the splicing process... smooth taper... in-line pull.
- There's got to be a measureable difference between side-loading a bridge and the similar side load on a spliced tight-eye.... I've never heard of a tight-eye failing a climber...why the bridges? There's got to be a really smart person out there somewhere who knows how to calculate these forces, and help us to decide what fibers are appropriate for this use.
Sorry for the long post(s)... but these 'broken bridge' discussions are really getting to me....
Cheers... think safe.. act safe...
Attachments
- Location
- Longmont, CO
[ QUOTE ]
It appears as though a sharp object was involved. I haven't seen fibers pull apart like that. There are usually more 'short and long' fibers in a "pull", as opposed to a cut.
Is it possible to take a close-up image with a clearer focus?
[/ QUOTE ]
Good question Norm. We don't have that cord anymore. It was tossed.
I took a long look at it and it didn't look cut. I'd say there were a fair amount of long and short fibers, like a pull would show.
It appears as though a sharp object was involved. I haven't seen fibers pull apart like that. There are usually more 'short and long' fibers in a "pull", as opposed to a cut.
Is it possible to take a close-up image with a clearer focus?
[/ QUOTE ]
Good question Norm. We don't have that cord anymore. It was tossed.
I took a long look at it and it didn't look cut. I'd say there were a fair amount of long and short fibers, like a pull would show.
- Location
- Longmont, CO
Nice illustrations mark przekurat. It's difficult to do on Paint.
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