Set up for rigging

O

okietreedude1

Location
Enid, Ok
How would you set up your block and port a wrap if using a 5/8" double braid lowering line.

block in tree - 5/8" double braid, 5/8" hollow braid (tenex/yalex), 3/4" db, or 3/4" hb, or larger (specify)

porty on base of tree - above same options.



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I was in attendance at a seminar last week that was done by Ken Palmer. He was saying that if you are using a 5/8" lowering line, use the same size (5/8") for your block and step up at least one size (3/4) for the porty.

In talking w/ Splicer Nick, he (and I tend to agree) said he thought it best to step up both the block and porty to the same size.

We'd like to know your opinions.

Thanks!
 
No offense, but I think you heard Ken wrong. Seeing as he is the president of Arbormaster, I highly doubt that he would recommend such. Load at the block is, in most cases, double the load at the base of the tree, (or if not double, significantly higher).
 
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No offense, but I think you heard Ken wrong. Seeing as he is the president of Arbormaster, I highly doubt that he would recommend such. Load at the block is, in most cases, double the load at the base of the tree, (or if not double, significantly higher).

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I bet you are right. Ken knows his stuff.
 
As i said at the TreeHouse:


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The Block has 2 legs of pull on it; the Porty and Load positions only have 1. Everything being equal/unbuffered/ Zer0 friction; the Porty and Load connections take equal force. Any friction in between and the Load connection takes more Loading than the Porty connection. That is for lowering and holding; if lifting or pretightening by pulling Porty with truck; that re-versus to Porty having more force on it when friction in system.


Zer0 friction; and closed angle on legs to pulley/block will give 2x loading to it. Increasing friction and/or more open angle on legs of pull on block/pulley will give 1xLoad<2xLoad.


Therefore IMLHO; the Porty connection generally takes the least force of all 3 positions, but all ways less than the pivot of the block/pulley position.

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But, if things were unequal in the setup; then he might be write. Like if the attachmeant of the block was in basket formation to a krab/block; then that would be 2 1/2x strength of same in choke(for unleveraged basket) and 2x line strength. So block in basket vs. Porty in choke might tilt model some. Especially if the block attachmeant was taking inline forces and the Porty attachmeant was taking forces leveraged across it's bindings(as it usually is). Like if block is on horizontal support, and the Porty on vertical; the block sling would more likely take inline forces; and the Porty sling perpendicular. Also, the block would take less than 2x with lines spread to wider teepee.

i wasn't there; just trying to give Mr. Palmer every benefit of the doubt..
 
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No offense, but I think you heard Ken wrong. [ QUOTE ]


I think you heard Ken wrong as well.
Always step up 1 or 2 sizes with your block sling; i.e., 5/8" lowering line, 3/4" block sling. The Porty sling can be the same size as the lowering line.
 
Isn't the rule of thumb that the main line should be the weakest part of the system?

On that basis alone I always step up one size for attaching the block. I don't use a porty so can't comment.

MAybe if you were using multiple rigging points then it wouldn't matter. I always have each block ready to go with the corresponding sling attached one size larger than the maximimum diameter that that block can handle.
 
Just have a question for some of you guys/gals.

The standard sling used for most blocks is probably the 3/4" Tenex, with around 22K tensile strength. Using a 10:1 to determine the SWL, it would be 2200 lbs., then to take the "double effect" on the block, then the SWL would be 1100 lbs. If you were using a 5/8 DB with a tensile of around 16K wouldn't the sling be the weak link? Should this be a cause for concern or no? Should we beef up our slings, eg. amsteel, tech 12 etc.?

Just wondering:)
 
You'd need to account for the lack of stretch in the sling when you switch to dyneema or technora fibers. You could end up with a higher rate of sling breaks, even though the slings are 'stronger'.

love
nick
 
WP, most rigging hardware is rated 5 to 1. So, what Yale Cordage has done is rate their rigging lines at 5 to 1. Check their website.
I have used technora and vectran slings for anchoring a block with no worries. They are both pricey fibers. I tried a dyneema sling for a block and the exhaust from my chainsaw melted some of the strands (an expensive lesson learned). I could have made the notch cut 1st and then set my block, but I think dyneema is a poor choice for working around chainsaws.
The common set up I use is a 3/4" DB for the block sling when I use a 5/8" DB lowering line. I found that hollow braids really cinch up when loaded and are hard to untie. Plus, they 'pick' easy.
As long as you up size your sling, there should not be any issues.
 
I use 3/4" Tenex sling and usualy 9/16 db, then I will step it up to 5/8 if I want a little more strength for the bigger stuff (normally false crotching). Then I got to thinking that I never bump up the sling for heavier stuff, even though it is facing 2X the weight (approx). It was just a question, I think I am usually well within the SWL of my equipment.

Thanks
 
So if you are using a 3/4 double braid mainline what size sling would you use for you block? I seen a guy a while back using a eye and eye 2" webbing and a 3/4 shackle to rig large pieces down. Has any one else used such a set up? What about the .8" endless loop slings that Sherrill sells would they be sufficent for attaching a block?
 
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So if you are using a 3/4 double braid mainline what size sling would you use for you block? I seen a guy a while back using a eye and eye 2" webbing and a 3/4 shackle to rig large pieces down. Has any one else used such a set up? What about the .8" endless loop slings that Sherrill sells would they be sufficent for attaching a block?

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Upgrade the sling size to 7/8" or 1".
Eye & eye webbing slings are not adjustable. I would never choose to use a non ajustable sling for drop hitching. Was this guy dropping and lowering log sections off the spar?
When you say "endless loop slings", are you saying a fixed loop or adjustable loop?
 
He was dropping sections off a leaning tree. He was using the webbing sling choked to the spar. The endless loops I was refering to where no adjustable.
 
In drop hitch situations, the shorter the throat, the less force there is on the anchor. When using a fixed length eye & eye sling (choked) or fixed length loop, you can't control the throat length.
 
The use of 12 strand hollow braid cordage in the form of a Loopie Sling ups the MBS of the sling greatly doesn't it? Is it doubled or not quite that much?
 
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The use of 12 strand hollow braid cordage in the form of a Loopie Sling ups the MBS of the sling greatly doesn't it? Is it doubled or not quite that much?

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I would go with 2x the strength times 80% due to the splice.
Then if it's 'choked', 66% of the strength. Allot depends on the 'choke' angle too.
 
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