spider leg rule?

[RANDY10]

What is the golden rule of the spider leg guys? I've seen some put the leg at the tip and some the opposite? I what works best for you to balance the load?

 

[flyingsquirrel25]

I normally put the rope at the base and leg at the tip. Only because the rope is probably stronger than the leg. Dont think (or know) it matters, whatever works best for you. But mine normally balance out good.

 

[KevinS]

Look up 'swl' under the general discussion area here on the buzz. For me it's on page 4 so you have to go back a bit.

Now the first posts are about something different but look lower down and you will find good explanations for answers for your question.

Hope this helps

 

[SRTsteve860]

for everyone else to save the searching:

http://www.treebuzz.com/forum/showflat.php?Cat=0&Number=373947&an=0&page=3#373947

-Steven

 

[Treezybreez]

I prefer to tie the rope at the tip, have the rope tensioned and then you can easily tell where to tie the legs. The Tenex spider legs are probably stronger than the rope anyways.

 

[DonaldRobertson]

[ QUOTE ]
I prefer to tie the rope at the tip, have the rope tensioned and then you can easily tell where to tie the legs. The Tenex spider legs are probably stronger than the rope anyways.

[/ QUOTE ]

The main rigging line is stronger than the tenex spider leg.
Reason being is that if your using a 1/2 inch rigging line then you would want to use a 3/8th diameter spider leg which has about a WLL of 400 lbs choked.

If your using a 5/8 inch rigging line then you would use a 1/2 inch spider leg and a half inch spider leg has a WLL of about 850 lbs choked.

The goal is to use a smaller diameter spider leg compared to your rigging line, at least thats what I learned to do.

 

[tuttle]

A good trick is to get some sticks and thin cord, mess about with it to see how the balance works.

 

[Treezybreez]

[ QUOTE ]


The main rigging line is stronger than the tenex spider leg.
Reason being is that if your using a 1/2 inch rigging line then you would want to use a 3/8th diameter spider leg which has about a WLL of 400 lbs choked.

If your using a 5/8 inch rigging line then you would use a 1/2 inch spider leg and a half inch spider leg has a WLL of about 850 lbs choked.

The goal is to use a smaller diameter spider leg compared to your rigging line, at least thats what I learned to do.

[/ QUOTE ]

When I am using spider legs the pieces I am cutting are rather large, so I use a 3/4" bull rope and 1/2" Tenex Spider legs. 13,100 lbs is plenty for tip tying. It doubles if your using two. Besides the bull rope sees a lot more use, so if you figure in cycles to failure...

 

[TreeLogic]

I know i could be totally wrong here, but wouldn't spider legs and lowering line be sharing the load equally, in a balance configuration?

I'm trying to imagine things like 2 people carrying awkward furniture, with a heavy end and a light end, but it's not quite the same. With a spider leg everything connects to the same line, and up above the work.

 

[tuttle]

It depends on the balance, if the main line is on the pivot point, it has got the full load.

The point I made above is the mess about at home on your office desk, that way you can establish a method when you need to from memory of doing a mess about 200 times.

 

[KevinS]

The spider legs if you use one or more should obviously balance the piece and share the load but that only counts at the working end of the rigging line.

Above your prusik(s) will see the whole weight.

The anchor side will see the whole weight from let's say your porty up to your rigging point.

The rope at say the block and the block sling will both be seeing up to double(if using a single rigging point)

So if you're using the strength of your rope plus multiple spider legs just remember you can use 10 spider legs but the top of your rope is where you have to figure your swl for.

 

[TreeLogic]

Thanks Kevin. I was asking more about what was going on below the prusik, and when everything is balanced properly, whether one leg would take more of a load than the other. You make good points though, that are important to be aware of.

 

[southsoundtree]

[ QUOTE ]
The spider legs if you use one or more should obviously balance the piece and share the load but that only counts at the working end of the rigging line.

Above your prusik(s) will see the whole weight.

The anchor side will see the whole weight from let's say your porty up to your rigging point.

The rope at say the block and the block sling will both be seeing up to double(if using a single rigging point)

So if you're using the strength of your rope plus multiple spider legs just remember you can use 10 spider legs but the top of your rope is where you have to figure your swl for.

[/ QUOTE ]

Very important consideration. IF all the legs were hooked on the hook, then each would take a partial load.