Break Testing

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Fun te$t! But, dang. If you've got some extra ca$h. I'll take some new Amsteel blue for some "tests." (Or, I can use it for work).
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Mark. Can you test the 1/2" inch Amsteel with a bowline & running bowline? That's what I'm using for crane jobs.

So, the Amsteel didn't snap, but rather kept on fraying apart. Why did the machine back off and not continue to sever it?
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Why knots. Try using hitches. Cow or double clove. They are stronger.

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Simply because I'm a tight wad and I don't want to spent extra money purchasing more length. And I don't want to take the least amount of time in the tree as possible...
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Like I've stated many times before... I use 1/2" Amsteel blue for my crane jobs. I've done hundreds of picks with running bowlines attached to the loads. No problems.

Before I used the product for the jobs I did the research. I didn't want to "throw out the baby with the bather water," so I tried it. I understand the "text book" arguments with HM ropes, I've done plenty of research with this subject and I have examined the results:

Sure there is a little slipping in the bowlines, but not enough to freak out about and never continue to to use the rope.

I have not seen anything cut into itself either. Sure after a pick, the rope will sort of stay molded into shape, but the beauty of the rope is this; In a matter of seconds, you can push and pull the section free from that mold and it is ready for more.

I would be worried with my practice, to use a HM rope on crane jobs, if I tied the bowlines in the same place on every pick and if the diameter of the log was the same every time.--Because if I did, then I could see that the rope would have a good chance to cut into itself...
 
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That sling that broke at 25% of rated strength was being used in the field shortly beforehand, right? That means that if the operator was counting on, say, a 5:1 safety factor, they might actually have been operating right at the edge of failure. Scary. If I owned that sling, I'd be looking really hard at the rest of my gear, as well as at company practices regarding weight estimation, vectoring, impact loads, minimal radiuses, etc.
Fair leads,
Brion Toss

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The round sling broke at 75% of rated capacity.15,000# higher than the working load. The sling had been down graded to moving logs at ground level before being taken out of service.
 
Oops,
Sorry, I simply read the "25%" figure in the video -- typo? And I am very glad to hear that the sling in question had been downgraded for easy work before being taken out of service; this transforms it into a Good Example.
As for continuing to tie Bowlines in Amsteel, even after having done the research, I can only say, Wow. It reminds me of a crane driver I once knew, who said he much preferred to use old, rusty slings, because, "They don't whip around so much when they break." Logical, just not particularly rational.
If you have 1/2" Amsteel, you start out with about 34,000lbs potential maximum break, assuming a competent splice. If you tie a Bowline in it, you can assume that you have just thrown away at least 2/3 of that strength, so have about 10,000 lbs left. Let's just ignore for the moment the many incidences of slippage well below this load, and not just in textbooks. If what you hope to pick up weighs one ton, that is still a 5:1 safety factor. Not bad.
But while anything heavier might not result in a break,the whole point of a safety factor is to stay a relatively known distance away from even the possibility of a break; how close to the edge are you getting with those Bowlines? And why? You could get about the same strength, with no slippage, at a couple of bucks per foot cheaper, using 3/4" double-braid Dacron, or go with 7/8" and still save lots of money. Or, how about splices? Maybe a sacrificial Whoopee in the system? Hi-Mod rope is an astounding tool, but it needs some consideration. Given that consideration, there can be wonderful rewards. For one thing, splicing allows you to use smaller, cheaper rope.
Fair leads,
Brion Toss
 
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I would personally never use a bowline on a crane job. In line cow hitch or a better timber hitch only, no knots. Knots reduce rope strength way too much for crane applications.

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How about clover hitch? I seem to remember you saying that you used clove hitches backed up with two half hitches (although you called it a 'double clove hitch').

Is the inline cow hitch backed up with a half hitch? Seems like it should be.

What about a cow hitch at the end of a line, backed up with a half hitch? A cow would be easier to untie than a clove--is that why you've changed?

What's a "better timber hitch"?

Thanks Norm.
 
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I would personally never use a bowline on a crane job. In line cow hitch or a better timber hitch only, no knots. Knots reduce rope strength way too much for crane applications.

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How about clover hitch? I seem to remember you saying that you used clove hitches backed up with two half hitches (although you called it a 'double clove hitch').

Is the inline cow hitch backed up with a half hitch? Seems like it should be.

What about a cow hitch at the end of a line, backed up with a half hitch? A cow would be easier to untie than a clove--is that why you've changed?

What's a "better timber hitch"?

Thanks Norm.

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I use a cow hitch for crane work now. It IS much easier to untie after loading. It is backed with a half hitch or 2, always.

A "better Timber" has a 'round turn' at the throat, instead of a 'turn'. I personally have found that the hitch stays in place better. Been using it for approx. 5 years now. There is a pic of it in 1 of my earlier posts, on a coastal redwood.
 
You might be wise to heed Brion and Spidey Jamin.

You don't want to learn what they know the hard way mate.

BTW I like steel chokers and clevis' for my crane picks.

Just an opinion of course.

jomoco
 
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...Let's just ignore for the moment the many incidences of slippage well below this load, and not just in textbooks...

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As with the nature of Amsteel it get fluffy really fast with usage. Tie it around the limb of a tree a couple of times and it fuzzes all over. I guarantee I leave enough tail on the bowline that it won't slip. And like stated above, the stuff gets so fussy that it will not slip out.
 
The greatest benefit of Amsteel is simply the weight to strength ratio. Being a climber and having to move it around is very nice. That was pretty much my main choice to use the stuff. However, it is often too light. Many times it has a difficult time falling through branches to be lowered down the the climber.

Brion. Thanks for your contributions over here. However, the research you have show was the same I did. I even contacted Samson with this concern. They didn't have much concern with the way I was using it. And since they sort of gave me the green light, the why not go for it?

Brion, have you seen a tree being dismantled with a crane? I don't like to use chokers, straps, rope, etc... that have both ends spliced for one reason. I prefer the choice to be able to shorten the rope when needed. One spliced end (and the other with out a splice) is very useful for making each pick (load) attached differently. There are times where is is necessary to have that luxury. Especially for spider legging loads.

Soon I will be retiring the Amsteel and buy some 7/8" Stable Braid. But, it is not because I'm "worried" of the rope breaking.
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It is more or less taking advice from others who say so... Besides, the Amsteel has become so fluffy that it is nearly like Velcro. It wants sticks to everything...
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Thanks.
 
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You might be wise to heed Brion and Spidey Jamin.

You don't want to learn what they know the hard way mate.

BTW I like steel chokers and clevis' for my crane picks.

Just an opinion of course.

jomoco

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I'm gonna. I'm gonna.
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I used to use steel and a clevis, but I hated dealing with it. It is heavy to work with (especially tossing it around a large leader to choke it off. It gets kinked (and therefore the tossing it around a large leader get even more difficult). And it is always the same length. This makes it a draw back on spider legg'n stuff...
 
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How about an amsteel whoopie sling? This might be a good compromise for you to maintain the strength to weight ratio of dyneema...

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I do use a Amsteel whoopie for blocking down spars & stuff. I haven't though of it for crane work. I'm pretty sure my crane operator likes us to avoid the loads from hitting the cable...
 
I like Nick's idea of the whoopie sling, or even a loopie. Using knots is problematic for another reason no one has mentioned. I recently broke a number of knots in polyester, and in every case not only did the rope break at the knot, but there were clear signs of melting at the break site. Now I was pulling very slowly with a hydraulic setup. When a crane takes a load it can be far more sudden. This means as the knot tightens and reconfigures itself, it is generating the same heat my testing would generate, but much faster. The heat doesn't have time to dissipate, and the melting sets in earlier. I might test a knot at 35% of rope strength, but the knot might fail much sooner if the load were applied suddenly.
 
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How about an amsteel whoopie sling? This might be a good compromise for you to maintain the strength to weight ratio of dyneema...
love
nick

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A Dyneema whoopie might have a tendency to pull through the bury, due to the slippery fibers. I would not recommend a whoopie made of Amsteel.
 
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I use a cow hitch for crane work now. It IS much easier to untie after loading. It is backed with a half hitch or 2, always.

A "better Timber" has a 'round turn' at the throat, instead of a 'turn'. I personally have found that the hitch stays in place better. Been using it for approx. 5 years now. There is a pic of it in 1 of my earlier posts, on a coastal redwood.

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i think Cow or Timber are better with Round Turn instead of single Turn around Standing; like same in Dbl. Noose/ Scaffold. Then, for Timber; over, then under for first tuck of loose braid/ spiral, finishing in rear, all nips at convex locations.

Standard Dbl. Halfs are easier to tie if maid opposing like a Cow for finish, rather than the usual clove type finish. Of course if tied in bight, last one untied is a slip.
 
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I used to use steel and a clevis, but I hated dealing with it. It is heavy to work with (especially tossing it around a large leader to choke it off.

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I'm not sure what you meant by 'large leader'. I agree that a steel sling and clevis are too awkward to use for limb work, but I like them for the wood. But don't toss the sling, slide it.

Have the ground crew choke the clevis on the sling...
 

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