guying an oak leaning significantly over shed/towards house

[southsoundtree]

If you hung the machine through a redirect overhead, you would have that much hold-back force, adjusted for your loss at that angle, I believe.

 

[Sfoppema]

If you hung the machine through a redirect overhead, you would have that much hold-back force, adjusted for your loss at that angle, I believe.

I am not sure I fully understand what you mean. Any angle of an anchor point that is not exactly 90 degrees from the felling direction is not going to work right, doesn't matter how hard you pull. You could probably get it to work, but with a tree that size, I wouldn't want to have the mini attached as an anchor. Anything under or over 90 degrees will result in a shockload on the anchor point in the amount that is created by a large free falling tree.

West coast powerline row guys use 9/16+ guy lines on giants. I've seen anchor points that the ropes caved in big porties. That's not the type of force Im looking for on my mini! Gotta be right on 90 degrees. And, once again, I wouldn't be so sure about using it for anything bigger than that tree.

 

[southsoundtree]

We are talking about two different things, I believe.

You are saying you need a 90* to the Lay-retainer line for supporting the hinge through the arc of the fall. I fully agree. You don't want the line going slack by being 'forward' of the oak, to then be jerked by a slack line if the hinge fails before ground-fall, nor being too tight to the point of swinging the tree by being 'behind' the oak. A Little behind would help with rope-stretch, I think.


I'm talking about how much hold-back force the mini-has.

Weight is a downward force.
If the mini was hung from rigging through a block plumb-overhead to the mini, it would have all 3000# applied to the line, redirected at the block, multiplied by the moment-arm/ lever length (height to anchor-point in oak).

Your rope is at a 45* angle to the downward force of 3000#. It would take (barely greater than) 3000# of vertical force to lift it. The rope is not oriented opposite to this max force (the weight of the machine). I don't believe you will get all of that 3000#.

Vertical component of moving weight at a 45 degree angle

Here's an easier one. I use the leg press machine at the gym so I don't have to worrying about hurting myself while lifting heavier weight. The weight glides on a track that looks to be 45 degrees.

physics.stackexchange.com

I think your 3000 pound machine may be more like 2122.5 pounds of force at a 45*.

You would get the full force of that moment-arm/ lever if 2122.5 was directed horizontally at the oak's anchor-point. I believe you get less. Consider what happens as the rope goes farther from horizontal, more toward vertical, as if the machine was parked closer to the tree.

I don't have any google-math to help me on this at the moment.
Consider how a truck loses traction by being lifted when pulling at a 45* angle, rather than being redirected to horizontal/ 0*, or even better, coming from below horizontal upward to the hitch (truck gets pulled downward into the ground a bit, increasing traction).


I tried to find a video to explain it better, but to no avail, at the moment.




When I'm trying to figure out how forces affect things, I try to push the mental exercise to the extreme (how does rope angle affect the force on the rope: vertical weight of a hanging mini, versus horizontal force on a mini with the entire weight supported by the ground, relying on traction versus weight).

 

[Sfoppema]

Gotcha I see what you are saying. Had enough with just the mini on that one, but that's a good trick to have in the bag if the occasion calls for its use!

 

[southsoundtree]

Anchoring your mini to an anchor tree may be a good option. Triangularly between two, perhaps.


As far as getting the whole counter-weight, I don't know if it's possible to get a mini to lift itself. If you raised the loader-arms, and pretensioned the rope on the bollard of a BMG, then lowered the arms, you might get it partway there.

 

[evo]

Anchoring your mini to an anchor tree may be a good option. Triangularly between two, perhaps.


As far as getting the whole counter-weight, I don't know if it's possible to get a mini to lift itself. If you raised the loader-arms, and pretensioned the rope on the bollard of a BMG, then lowered the arms, you might get it partway there.

From my experience pulling with the mini is to get the max pull is to pull low horizontal or even slightly downwards. So for any lifting, heavy guy, taglining, or the such it always pay to have a redirect down low from the high point. This aids in traction.

I’ve pulled using the rear tiedowns with a line off the bollard in front. Pull till you loose traction, then snug up the bollard line, and raise and curl to gain a little more.

 

[southsoundtree]

Wholly agree.

 

[Daniel]

If you hung the machine through a redirect overhead, you would have that much hold-back force, adjusted for your loss at that angle, I believe.

There are lots of other ways to take a single line and create a mechanical advantage system that holds far more than the anchor from the machine. redirects etc, especially with all those nearby anchors.

That tree didn't look too big and the Mini should have been fine especially as he said if he was able to stand it up significantly.

I would have been a little cautious about just using wedges though I would put a pull line in on it as well.

The problem with using an overhead anchor point to change the line angle is that you stand a chance of significantly overloading that line when the falling tree moves below the height of the redirect block

 

[Sfoppema]

There are lots of other ways to take a single line and create a mechanical advantage system that holds far more than the anchor from the machine. redirects etc, especially with all those nearby anchors.

That tree didn't look too big and the Mini should have been fine especially as he said if he was able to stand it up significantly.

I would have been a little cautious about just using wedges though I would put a pull line in on it as well.

The problem with using an overhead anchor point to change the line angle is that you stand a chance of significantly overloading that line when the falling tree moves below the height of the redirect block

The tree had slight favor up the hill. If you are over 90 it's unlikely that the wedges alone will make her fall as the rope will be holding the tree back. Wedges wouldn't move the tree against the pull of the rope. Under 90 and she'd pull off the stump and hopefully the rope would catch/direct her reasonably well.

If you're right on she should fall nice and easy with the wedges. I was being cocky. A line would have been easy to set and pull from, but where's the fun in that?