More things broken

JeffGu said:
And just for you @moss I'm going to try to remember to snap a photo the next time I'm at the house the wife and I call "the shop"... we have anywhere from half a dozen to three dozen turkey vultures circling the area all the time. Kind of creepy, at times. Hoping it's not an omen.
Click to expand...

I was out in “the field” a few years back studying a winter crow roost, approx. 6000 crows gathered every evening, very cool phenomenon. I stopped at a sandwich place after and chatted with the proprietor about what I was doing. She said “I don’t like birds, they’re bad luck”. I replied, “All birds?”, “Yes, all birds are bad luck”. Ha, must be hard for her to go outside.

I knew that someone would have turkey vultures in their backyard! You’d never attempt to get close to their nest, the stench is formidable! They are graceful flyers.
-AJ
 
DSMc said:
The real problem with hand sewn eyes is not their strength potential but the difficulty in controlling all the variables involved in making them.
Click to expand...

I've visited some famous wooden sailling ships...HMS Victory, USS Constillation and USS Constitution aka Old Ironsides are the most famous. All of them have rigging in place where the rope ends are whipped not spliced. There are some large diameter ropes in critical locations

That got me thinking about whipping eyes in our rope applications

I had the good fortune to spend some time with Brion Toss and asked him about seizing eyes on ropes. He said that it would certainly be possible to design an overlap and seizing that would be strong enough in a static application. Since arbo, and current sail rigging, is more dynamic the load/unload cycles effect on the seizing would be so unknown and undependable

Like David said here, and others too, sewing does work but the variables are hard to control
 
moss said:
I knew that someone would have turkey vultures in their backyard!
Click to expand...

It took me quite awhile to figure out why they're back there, year after year. The farmland over there still has a lot of trees, and this batch of vultures keep nesting there. The railroad tracks running through there are usually hauling grain (mostly corn) and a lot of it ends up on the tracks. This attracts a lot of doves and pigeons, and the vultures hunt them. Most people think they're just carrion eaters, but they're quite good at hunting their own food if nothing volunteers to die for them.

I did a lot of tree removals down in Saline county, and the landowner there had lots of them. They would not only hunt the doves and pigeons that hung out around the old barns and grain silo, they would also hunt the (mostly stray) cats. We sat on his deck and watched them grab one right out of the yard, when it crossed in the open. He only had one cat left of his own, and she was slinking around the yard staying close to buildings and bushes, etc. because she figured out the vultures were much too big to grab anything that's close to such objects.

Fascinating animals... butt ugly, as birds go... but beautiful in flight.
 
JeffGu said:
It took me quite awhile to figure out why they're back there, year after year. The farmland over there still has a lot of trees, and this batch of vultures keep nesting there. The railroad tracks running through there are usually hauling grain (mostly corn) and a lot of it ends up on the tracks. This attracts a lot of doves and pigeons, and the vultures hunt them. Most people think they're just carrion eaters, but they're quite good at hunting their own food if nothing volunteers to die for them.

I did a lot of tree removals down in Saline county, and the landowner there had lots of them. They would not only hunt the doves and pigeons that hung out around the old barns and grain silo, they would also hunt the (mostly stray) cats. We sat on his deck and watched them grab one right out of the yard, when it crossed in the open. He only had one cat left of his own, and she was slinking around the yard staying close to buildings and bushes, etc. because she figured out the vultures were much too big to grab anything that's close to such objects.

Fascinating animals... butt ugly, as birds go... but beautiful in flight.
Click to expand...

See? I just love learning more about turkey vultures on a “breaking stuff” thread.
-AJ
 
Tom Dunlap said:
I've visited some famous wooden sailling ships...HMS Victory, USS Constillation and USS Constitution aka Old Ironsides are the most famous. All of them have rigging in place where the rope ends are whipped not spliced. There are some large diameter ropes in critical locations

That got me thinking about whipping eyes in our rope applications

I had the good fortune to spend some time with Brion Toss and asked him about seizing eyes on ropes. He said that it would certainly be possible to design an overlap and seizing that would be strong enough in a static application. Since arbo, and current sail rigging, is more dynamic the load/unload cycles effect on the seizing would be so unknown and undependable

Like David said here, and others too, sewing does work but the variables are hard to game control
Click to expand...

Cool info! Makes me think, and maybe this has been done, I’d love to see load testing simulating what actually happens in day-to-day climbing, constant “low” dynamic loading. Enough work probably has been done with load cells to know the actual average load peaks while a climber is working (say sampling from 5 climbers of different body weight and climbing styles/techniques). Working with those numbers a testing scenario might accelerate the load/unload cycles so we don’t have to watch paint dry. Say in 15 or 30 minutes load and unload to average climber peak loads every minute. This might offer interesting info on spliced eye “behaviors” as well as clarify why or why not a whipped eye vs. a sewn eye is better for “chronic” dynamic loading scenarios.

Please send Richard Mumford money now! ;-)
-AJ
 
I sent a post to Richard about spooling tension. The additive effect of putting wraps under tension on a spool will eventually crush it.
My thoughts about this may have some part to play in knots behind a rigging plate? We never or rarely undo the knots on a bridge and every time we lean on it we snug it again and again. Is it possible that over time the knot gets hard and brittle? Perhaps that constant snugging has cumulative/ detrimental effects?
 
moss said:
...load testing simulating what actually happens in day-to-day climbing...
Click to expand...

Yeah, I think sticking a digital load cell on the climbing device and just graphing the loads over a day's work would be quite revealing. I suspect the loads are extremely variable, but over a range that's very narrow for some climbers, and quite a bit wider for the Tarzan types.
 
JeffGu said:
Yeah, I think sticking a digital load cell on the climbing device and just graphing the loads over a day's work would be quite revealing. I suspect the loads are extremely variable, but over a range that's very narrow for some climbers, and quite a bit wider for the Tarzan types.
Click to expand...
Yes and as we all know a knot will snug and snug until it fails or punches off the rope. Add to that the continued pressure for months or perhaps years on the knot may change the physical properties of the textile?
 
Stephen Moore said:
Yes and as we all know a knot will snug and snug until it fails or punches off the rope. Add to that the continued pressure for months or perhaps years on the knot may change the physical properties of the textile?
Click to expand...
I suppose Richard could break test knots that have been tied and snugged for many years vs freshly tied and set knots? That might be an interesting test. He could even use rope near the same useage?
 
JeffGu said:
Yeah, I think sticking a digital load cell on the climbing device and just graphing the loads over a day's work would be quite revealing. I suspect the loads are extremely variable, but over a range that's very narrow for some climbers, and quite a bit wider for the Tarzan types.
Click to expand...
The average loads may never exceed a few hundred pounds, the cumulative loading would be impossible to measure.
 
I've had people ask me how strong a climb line is... and when I tell them, they're shocked that a rope that small has such a high breaking strength. It seems like a lot of overkill, but factor in all the variables and the reason is obvious. The big one is knots. If you choose a knot that reduces the MBS by 50% on that particular rope, the numbers go down so fast that by the time you allow for shock loading and other factors, the safety margin isn't quite as huge as tensile strength alone would seem to indicate. I really prefer splices, myself... I think the break test data for splices is a lot more consistent than it is with knots. In fact, break testing knots is pretty interesting in itself... tie the same knot in the same rope a dozen times, and the break data is still a lot more variable than making the same splice in the same rope a dozen times.

One could almost say... there's too many variables involved in tying knots with enough consistency for them to be considered safe. Oh, wait... I must be thinking of hand sewn splices.
:inocente:
 
JeffGu said:
I've had people ask me how strong a climb line is... and when I tell them, they're shocked that a rope that small has such a high breaking strength. It seems like a lot of overkill, but factor in all the variables and the reason is obvious. The big one is knots. If you choose a knot that reduces the MBS by 50% on that particular rope, the numbers go down so fast that by the time you allow for shock loading and other factors, the safety margin isn't quite as huge as tensile strength alone would seem to indicate. I really prefer splices, myself... I think the break test data for splices is a lot more consistent than it is with knots. In fact, break testing knots is pretty interesting in itself... tie the same knot in the same rope a dozen times, and the break data is still a lot more variable than making the same splice in the same rope a dozen times.

One could almost say... there's too many variables involved in tying knots with enough consistency for them to be considered safe. Oh, wait... I must be thinking of hand sewn splices.
:inocente:
Click to expand...
Exactly! But even still - I trust my life to knots!
 
You must log in or register to reply here.

New threads New posts

Back
Top Bottom