why spider legs?

similar to what i do with my capacity scale.

I look back toward the truck and view how extended the boom is and view the angle of the boom.

I look at the tree section and say to myself, ok, I can cut it there and that should be about 60% capacity.

I'm usually right on. Often less.

If I'm not on the scale after the cut, I'll start taking bigger peices on the next cut.

I like 60% for any pick in the air.

I'll do 80-100% for a trunk pick where the cut is next to the ground.

You are guessing weights before you make the cut, (which is what I always did with a stick crane and opporator too), I am guessing it in terms of capacity. Same thing man. I'm just the operator too.

If your stick crane can do 5000lb at a certain location, and you are shooting for a 2500lb pick, that's pretty much the same thing I'm doing. You are shooting for 50%. I'm shooting for 60%.

I dont' have to count extensions, calculate the angle of the boom or memorize the crane chart. I just have to glance at the angle and length extended and know what is right.

I have to confess, I have always been able to say I haven't taken a pick in the air that ever reached 100%. But about two weeks ago, I had a pick swing out and spike it to 100%. No harm, but I didn't like it at all. Hot day, irritating honey locust and I should have re-done the slings or put on a control line because I KNEW it was going to swing out a bit, it just did it a little more than I thought. Was interesting to see the hydraulics sag down. The AOS did it's job and there was no bouncing. The crane company said I couldn't have hurt anything doing that. I just had the crane in last week for a checkup and some minor things fixed; after this and all is good.
 
We all make mistakes, especially on those hot muggy days, when I was learning (not that you are learning now it sounds like you have quite a bit of experince) there was more than a few times I pushed it to 100% and just like I mentioned before I still get surprized now and then.
 
I just wanted to point out that you can buy conventional stick boom cranes with radio remote also. Our little National does NOT have remote. I use a variety of cuts with our crane depending upon the situation,tree species, condition etc. We use spider legs mostly when making horizontal picks.
 
Yeah Kman, Remotes are being used for all sorts of equipment and proving to be very: safe reliable efficient & productive. I'll bet every crane OPP has done a few picks where they wished they had a remote...just for the safety alone! TNTTREE came down to our place last week. He comented that lots of people don't like the sound of running remote from the tree, but now that he's seen it he thinks it's great. Back to spiderlegs. I think the main reasons for spider legs are ballance of the pick; but just as important, is holding weak pieces together. If i have a weak piece (even if it's vertical) i'll spiderleg it. This way you're lifting from more than one point of attachment and less likely to break the one attachment & if the attachment would break the piece would not fall.
 
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but just as important, is holding weak pieces together. If i have a weak piece (even if it's vertical) i'll spiderleg it. This way you're lifting from more than one point of attachment and less likely to break the one attachment & if the attachment would break the piece would not fall.

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Thats the main reason to pretension before making the pick, if you pretension to the est. weight of the pick then you know whether or not it will break.
 
We've been over this in this thread, no matter how many slings you use if the hook isn't over the balance point the pick will move until it is.

If it didn't move after the cut with three slings then if he placed the sling directly under the hook where it was then it wouldn't move with that single sling.
 
On this particular limb that wasnt possible. The branch forked. If you only put one attatchment point the limb would have rolled and hit the wires underneath it. The center of gravity for this limb was in mid air and not on the limb.
 
One more note, I developed my crane rigging skills on the need simial to Allmarks. (Overhead utilities) In those senerios you can not make a mistake. Using the 3 spider legs in the pick made the predictability of the load very reliable and consistant.
 
I didn't say at the union, I said directly below the hook.

As you can see in that pic that he was right on his guess where the center of gravity was so if he placed the fewest possible slings (in this case two) directly below where he positioned the hook then the outcome would be the same. If he was off with his guess the outcome would still involve movement of the pick. Just read the thread ? number of spider legs = more stable in Crane Use.

I too have honed my skills near, sometimes over live power, now thanks to some smart judges the power company has legal obligation to shut off the power for me. 99% of my rigging has been with 1-2 6' or 15' slings.
 
One sling on each side of the fork would have caused excesssive movment.if one sling was on either side of the union, meaning to the right on the smaller wood it would have been butt heavy. If one sling was on one of the limbs to the right of the union and one on the bigger wood it would flip untill center mass was under the hook.
 
most of crane work in my experience has gone well, but has anybody here used a crane as a false crotch with a grcs? it works very well and with certain things, can eliminate alot of useless climbing to rig pieces that dont really need rigging. i see the need for spiders when working in very tight horizontal planes, but ive seen guys use them for entire trees. REALLY? Is that much effort needed?
 
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