Center of Balance

[TheTreeSpyder]

As i have worked in the field, i have been driven to master diffrent rigging puzzles, and to distill them to common, overriding components.

From Mr. Dent's book, i came away with a renewed view of my part in these equations, his terminology of 'causation' and 'mechanical analasys' have rung out in much more than the powerful models he presented; so much that their inertia carried on thru me into other aspects fo these models and theories to express the whys and wherefores of the motions we elicit. i find this to be both impowering as well as laying responsibility on us for each action and choice, even when we don't realize there are choices, or choices that make diffrences.

One of these things has grown to look at all this with 'mechanical analysis' and 'causations'. i find so much of what we do to work on leverage, and how to take advantage of it,while not letting it beat us; to stack it on our side, rather than against us.

In anything of any length (most of what wee due)in these exam-eye-nations, i find that the Center of Balance (CoB) is something to be realized and defined, for in these systems; i find it to be either that which you are trying to react on, or as a power to react on something else.

i find that there are 3 basic positions to monitor; the input force,the out put force and the pivot. The CoB is either one of the moving parts i feel (input or output); and is defined by that and it's own relation to the 3rd (non-moving) factor (pivot). That many things can be defined and manipulated by that understanding.

In things of length,that length functions as available leverage points (handles) for everything else, and understanding the CoB is more important to understanding these mechanix than the length.

So, with all that, i take consideration with every cut, hinge, and hitchpoint for how they affect the CoB,a nd if i am making my job harder or more dangerous by these choices i make in respect to this princi-pal.

For example, clearing neutral, low limbs while topping can actually make it harder to top, by changing the CoB; and so this flows to dropping trees and turning those models sideways; altering the CoB by cutting, hinge choice or hitchpoint can make all of the diffrrence in the world.

Here is an image i made with input from Joe, Murph and others to ex-press this

 

[Joe]

Hi, Ken;

1) When removing low limbs, there is less weight to pull over.

2) As the center of mass rises, it is easier to pull over because of 1, and the tree becomes more mechanically unstable.

3) Depending on the tree, as low limbs continue to be removed, the center of mass will lower instead of rise.

What is the likely outcome of the trees center of mass and mechanical stability when the top is removed 1st?

Remember these concepts apply when pruning.
Keeping levers in mind, doing what shouldn't be done by throwing Shigo out the window, how will pruning affect the physics of the tree?

Joe

 

[TheTreeSpyder]

1)When pulling in a leveraged situation, lowering the CoB grants more leverage from the same pulling point i beleive. In some situations when the lenght is cantilevered over, i can see the high CoB pulling the top over, but in cases where you have to pull the spar into the face from vertical, i think my way is best. But yours is a good observation in forward balanced spars, so i should include that in future models of this. Where i am kinda going with this, is to these effects in horizontal limbs, jsut starting with the easier illustrated verticals.

2) somewhat the same observations as 1)

3) Totally disagree, hence the diagram of turning the image sideways, if it is balanced on a CoB, taking weight away from the trunk side, will always make the opposite end heavier, thus showing that the CoB is shifted up,not down!

These observations don't refute Shigo, for liontailing a limb would move it's center of balance out from it's connection; so as the weight is taken off and the limb lifts up, it can be impacted to it's original point easily,then the total impact of that motion pushing the limb beyond that, while driven further by new high leverage CoB of the limb.

That is IMH,AO

 

[Joe]

Well Ken, you're over generalizing the many possible situations we encounter in the field. You're stating removing low limbs decreases leverage and low limbs should be left for this reason. I'm stating you don't know how removing low limbs affects the center of mass of a tree enough to make that claim. If you leave or remove low limbs, you don't know how much leverage is gained or lost. Tell me about the weight left before removing low limbs as opposed to the weight after removing low limbs. Then tell me where the center of mass is located and what the mechanical advantage will be in relation to where the line is located. Tell me how much pull is used to get the tree over. You can do that with only the trunk left standing. Because you think you're gaining a mechanical advantage by leaving low limbs doesn't mean it'll be easier to pull over. Mechanical stability is also affected. It may mean on a backward leaning tree it may appear more desirable to have a lower center of mass, but, a higher line is more desirable in many situations.

Yes, some trees center of mass will lower as you continue to remove low limbs. Low limbs to me being those limbs lowest on the crown. If some limbs are removed, the lowest limbs on the now raised crown to me are low limbs. You find the posts where Roger included some of his conifer removals and then tell me as those trees continue to be stripped out the center of mass continues to raise. Some of those trees are trunk wood. The center of mass will lower towards the heavier base. Then there are some decurrent species like mulberry and osage orange where removing a low limb means taking out half the tree because of codominant stems.

Joe

 

[TheTreeSpyder]

Now i see where you are coming from! (Kinda)

Certainly if there is only top weight to remove and you climb all the way up to it, and remove weight from the top, that will lower the center of balance, just as taking weight from below the center of balance will raise the center of balance. That is why in the diagram, i show refrence to limbs along its length above and below this CoB, also refrence in the diagram that i am speaking about removing the 'easy' limbs, refrences lower lying limbs, seperate from limbs in the crown.

Also, the CoB; liken to any other point in space; exists in 3 dimensions, here i am just refrencing the vertical level of CoB,as i know that it is confined within the spar on 1 dimension, am illustrating a spar without lean,thereby placing the CoB along the horizontal axis over the hinge roughly. Certainly, as the CoB moves along the horizontal axis, (forward or back) then, as we factor that in and get some lean, then that lean can help with a higher (or lower) CoB. Thus my refrence to the work to be done is to move the CoB forward to this position. If it already exists (lean) forward, then the work to be done is to move the CoB down, as it is now in that part of the arc drawn by it's motion pivoting on the hinge.

i guess i did general-ize captain, but pro-vided that pic to illustrate these things, in this simpler model to digest; as we move thru and past this point and it's lessons towards what wee tend to do more of; removing verticals (limbs) rather than horizontals (spars), and how these things apply there. Whereas, the dimension of the vertical axis (height) will be out of our worries generally, back to dealing with more of the length and distribution of adjustable weight along that length.

And i didn't even think of co-dominant stems! But would treat them as seperate unit spars.

So i append for even more clarity that removing limbs from below the CoB raises the CoB as illustrated; whereby removing limbs from above the CoB has the reverse effect. As either action makes the opposite point 'heavier'.

Y'all notice, that Joe and i might disagree about how the CoB is defined and affected by our actions (cutting, hinging and hitching points); we both know that it must be reckoned with; that it is of imperative importance in its place-meant in the works by definition. i kinda would suggest that the simpler model is a good place to start understanding and seeing this to get a grip and feel for this, before stirring in some of the more extended topics pro-posed.

For, in examples of a weight falling 5', thus having a force ~6x it's weight, with a small, heavy ball is one example of calculation of energies. But if, that weight is 20' tall, you don't calculate that falling force from it's base hinging(5' high) or top (25'high), but rather you would calculate that force as falling from the CoB (not neccesarily center of it's length, unless a smooth even weight distribution). The CoB is just as pervasive in all our work, whether realized or not, it is a defining 'causation' in the 'mechanical analysis'. The words of causation and mechanical analysis show the lending of empower-meant to us over these things, but also on that double edged sword, a resposibilty to recognize this and make the right choices. For even in not conciously choosing, wee still do!

Well, i must get my hair cut today, for it has been growing; i mention that only to try to stir more interest in this thread...........