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Tree Falling Direction ?

Started by Robert11, April 20, 2014, 02:27:02 PM

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Robert11

Hello,

I'm a retired Engineer, not a logger, but have been thinking
about this a bit.  Looks like a terrific Forum, and am hoping
that someone might explain the following for me.

Have a chainsaw which I have used over the years for cutting
some brush and limbs.  Never any sizable trees. 
But have one or two I would like to take down now, hence this question.

Have read many, many, sites that have the pix's, videos, and descriptions
on how to make the various cuts.  All pretty much the same.

Let's assume that I have a perfectly uniform cylinder of wood.
Absolutely uniform.
No lean, whatever, in an any direction.  Straight up-and-down.

So, I make the initial Face Cut to about 30% or so of the tree's diameter
as everyone recommends.
I then leave another inch or two for the Hinge.

But, the weight vector, going thru this hypothetical cylinder's c.g,  is of course at
exactly 50% of the diameter.

So, it's BEHIND the Hinge.  (the Hinge would be at most 40% or so of the diameter).

Therefore, my cylinder (a hypothetical perfect tree) would tend to fall backwards,
Not in the direction of the initial face cut.

a.  what am I, as usual, missing ?

b. or, is it necessary therefore for a tree that has no initial lean to always use Wedges
    to have it fall in the direction of the initial Face cut ?

c. why not just make the initial Face Cut perhaps 60% or so of the diameter; then,
    I would imagine, it would absolutely always fall forward.

    Must be some good reason why this apparently is never done ?

If anyone might explain this to me, and what I am missing, would be most appreciative.

Thanks,
Bob

JohnM

Welcome to the forum, Bob.  Here's my (very non-professional) opinion.

Quote from: Robert11 on April 20, 2014, 02:27:02 PM
Let's assume that I have a perfectly uniform cylinder of wood.
Absolutely uniform.
No lean, whatever, in an any direction.  Straight up-and-down.
No such thing.  Unless you're cutting perfectly plump telephone poles the branches alone will pull it one way or the other.  I believe the answer to 'b' is yes. :-\  That's all I got. :) ;D ;) 
Lucas 830 w/ slabber; Kubota L3710; Wallenstein logging winch; Split-fire splitter; Stihl 036; Jonsered 2150

donny hochstetler

you are a smart man,  just last week I took my training to become a MASTER LOGGER in the state of ohio, I was explaining this excact thing to the instructor, in front of a group of people with various comprehension levels :D there were some that got it n others couldn"t see into it,including some very experianced loggers , but you r spot on,  this is why when you r cutting nice straight timber, u cant figure ouy why they all want to set back on you, I always pop in a small wedge, set it tight, make ur cut, then just tap in the wedge, n move back into ur escape route,  there r times i might make my notch a little deeper, but 4 the most part  that does work, but usually when they have to much back lean, i"ll cut them n put in maybe 3 wedges, set m tight, finish cut, then take skidder n gently aply preasure works  very well n is very safe

Holmes

Welcome to the FF Robert11.   Your hypothetical tree situation : b  not  always wedges, just give it a push with your arm  :) c:  yes that cylinder will always fall forward.  The problem is you will never find that cylinder to cut,  wind plays a big factor in direction of fall.   Good question
Think like a farmer.

chester_tree _farmah

Wedges are your best friend. The tree has to have a good lean in it for me not to pop one in. Nothing worse than pinching your saw and than trying to get it out with out the tree destroying it. Don't forget about tensions and any spiral grain.
254xp
C4B Can-Car Tree Farmer
Ford 1720 4wd loader hoe

Left Coast Chris

Hi Robert,

The center of gravity of a tree will always prevail if you do not have wind.  If the center of gravity is somewhere from the center forward then it will fall forward.   It is never in the center but if it were, it would not fall at all (theoretically).   Since you removed a tiny bit of weight with the front notch, theoretically the center of gravity would move back a tiny amount putting it very slightly on the back side of the center allowing it to come back.   No one is that good at finding the center of gravity on a tree.

Suggest walking around the tree and if you have a good eye for plumb you will be able to see which way it wants to go.   When I was in high school my grand dad taught me to use my tape measure as a plumb bob to detect the lean of a tree.  I don't do that any more but it helps you to develop an eye for plumb.   If after walking around the tree and sighting from different angles it is not obvious you may be able to first drop weight on one side and fall it opposite of that to get to go the direction  you want it to go.    If it is a straight conifer, wedges are the way to go.  Pulling with a cable is an option also if you need insurance if failure is not an option.

Suggest practicing with someone experienced on smaller trees first.

Let us know how it goes and stay safe.
Home built cantilever head, 24 HP honda mill, Case 580D, MF 135 and one Squirel Dog Jack Russel Mix -- Crickett

Farmer Jim

I may be completely off base, which is OK as that is where I normally am.  The tree you describe ( I've never found one that didn't want to go one way or another)  would have to be wedged.  I think it is easier to start the tip of the tree with the wedge when the hinge is not cut so as to be in the center of the tree.  The hinge is the fulcrum, the top of the back cut kerf (the end of what will be the log once it is down)  is the lever so it should be easier to start tipping the tree with a wedge acting on a longer lever. 
"I won't be wronged. I won't be insulted. I won't be laid a-hand on. I don't do these things to other people, and I require the same from them."  J.B.Books

Maine logger88

I think to answer your question on why have the notch go in 30% vs 60% is the hinge will be stronger and less likely to fall backwards if you go in 30%.
79 TJ 225 81 JD 540B Husky and Jonsered saws

g_man

Quote from: Farmer Jim on April 20, 2014, 04:11:27 PM
I may be completely off base, which is OK as that is where I normally am.  The tree you describe ( I've never found one that didn't want to go one way or another)  would have to be wedged.  I think it is easier to start the tip of the tree with the wedge when the hinge is not cut so as to be in the center of the tree.  The hinge is the fulcrum, the top of the back cut kerf (the end of what will be the log once it is down)  is the lever so it should be easier to start tipping the tree with a wedge acting on a longer lever.

I think this is the best answer for your hypothetical tree and why the hinge is best placed forward.

As you say, the tree will want to tip back and pinch the bar. You will need a wedge to prevent that and to tip the tree in the desired direction.

Ianab

Your logic is probably sound if you are cutting perfectly straight telephone poles, on a calm day...

Back in the real world. 99% of trees are not straight and perfectly balanced. Hopefully you are felling them in the direction of their lean, and in that case, they will fall with the 30% notch anyway.

If you are going against the lean, then you need to wedge anyway (or push, or pull or something). In that case the larger cut at the back gives your wedges much more lifting power.

If they are perfectly balanced phone poles, then it won't take much of a wedge to tip them over

There are other practical considerations too. 

The wedge takes 2 cuts of 60% of the log + 1 of 30%, VS 2 cuts of 30% and one of 60%. So in the first scenario you saw through 150% of the log, VS 120%. Actually worse, because of the angle of the cut.

If the log was perfectly straight, then it wont probably wont fall anyway. The hinge wood will hold it upright, so you are still left with needing to use a wedge to start it falling. Or cut away the rest of the hinge, and then it just falls at random (don't do this)

If you misjudge, really bad things can happen. The tree could sit down on your saw while you are cutting the wedge. Embarrassing, but probably not fatal. Or it could fall backwards with no proper hinge formed. Or pinch the saw while making the back cut, and no room to get a wedge in place.

So as a physics thought experiment, it's interesting. Keep it in physics experiment land where there is no friction, and all cows are perfect spheres, In the woods? It could get you killed.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

CCC4

Wow..leave it to an engineer to come up with so much theory! LOL! Sometimes over thinking a situation can just create the potential for bigger problems to arise. If you get to learning how to turn, pull and spin trees...you could get a headache.

Not everyone cuts the same at all...some are book taught and others have been lucky enough to learn from the school of hard knocks and lived through it.

Happy Easter...Welcome to the forum!  :)

chester_tree _farmah

Lol. Exactly.  If u don't hurt yourself after a while u learn how to do it safely. Not that I am Mr expert but when I look back on when I started cutting trees it scares me. We are lucky up here to have regional high school tech schools that offer logging training. If you are green best to ask someone to teach you. Or sign up for the Game of Logging course.
254xp
C4B Can-Car Tree Farmer
Ford 1720 4wd loader hoe

Gary_C

Your analysis is correct, but doesn't go far enough.

That perfect cylinder has a bunch of limbs at the top that extend out in various directions and the distribution of those limbs will be the ultimate determining factor for the center of gravity of the whole tree. Plus those limbs placed far up in the tree make the tree very top heavy. So the true center of gravity is at a point well over your head and will be hard to determine from where you are standing.

So when you are felling that tree, the goal is not to find a place for the hinge that is exactly under that point of the center of gravity. The goal is determining how to move that point over your head in the direction you want to make the tree fall. And most times, you don't have to make it move very much and that is what makes wedges your best friend.

And when you can easily see the point of the center of gravity is in the direction you want it to fall, that's when you be especially careful. Because when you are making your final cut, those leaners can easily split early and those split ends can move far faster than you can get out of the way.

Plus when you are looking up at the top of the tree before making your cuts, make sure you look for any broken limbs that may come loose and fall on your head.   
Never take life seriously. Nobody gets out alive anyway.

OntarioAl

Robert11
As an Engineer you understand the concept of tension and compression.
While felling, bucking and limbing its all about working with  or creating zones of tension and compression.
The selection of the site for the notch determines  the direction of fall and designates this side of the holding wood as the side in compression (it is the tremendous compressive force generated that cleanly snaps off the holding wood when the two sides of the notch meet) cutting the wood on the opposite side releases the tension and the tree falls.
This is tree falling theory 101 but it takes years of training , acquired knowledge and experience to fell timber safely , productively and produce a quality product.
In your theoretical example experienced fallers recognize that the C of G will move as wood is removed on the felling cut so a wedge is inserted as soon as possible to keep the C of G fixed. When the felling cut reaches the holding wood (hinge) a few whacks on the wedge will move the C of G towards the notch to the point that the tree starts to fall on its own.
I fully agree with Ianab
So as a physics thought experiment, it's interesting. Keep it in physics experiment land where there is no friction, and all cows are perfect spheres, In the woods? It could get you killed.


My Thoughts
Al
Al Raman

thenorthman

Quote from: Robert11 on April 20, 2014, 02:27:02 PM
Hello,

I'm a retired Engineer, not a logger, but have been thinking
about this a bit.  Looks like a terrific Forum, and am hoping
that someone might explain the following for me.

Have a chainsaw which I have used over the years for cutting
some brush and limbs.  Never any sizable trees. 
But have one or two I would like to take down now, hence this question.

Have read many, many, sites that have the pix's, videos, and descriptions
on how to make the various cuts.  All pretty much the same.

Let's assume that I have a perfectly uniform cylinder of wood.
Absolutely uniform.
No lean, whatever, in an any direction.  Straight up-and-down.

So, I make the initial Face Cut to about 30% or so of the tree's diameter
as everyone recommends.
I then leave another inch or two for the Hinge.

But, the weight vector, going thru this hypothetical cylinder's c.g,  is of course at
exactly 50% of the diameter.

So, it's BEHIND the Hinge.  (the Hinge would be at most 40% or so of the diameter).

Therefore, my cylinder (a hypothetical perfect tree) would tend to fall backwards,
Not in the direction of the initial face cut.

a.  what am I, as usual, missing ?

b. or, is it necessary therefore for a tree that has no initial lean to always use Wedges
    to have it fall in the direction of the initial Face cut ?

c. why not just make the initial Face Cut perhaps 60% or so of the diameter; then,
    I would imagine, it would absolutely always fall forward.

    Must be some good reason why this apparently is never done ?

If anyone might explain this to me, and what I am missing, would be most appreciative.

Thanks,
Bob

Too sum up you are correct.  The hinge wood being towards the desired fall direction would allow the tree to sit back, infact in nearly straight timber its kind of a given that it will.  Its also why they sell wedges.

As far as facing past center to account for the off center hinge, its not recomended as the tree may very well sit down on your saw and then your stuck there with a bar and chain going nowhere fast that you now have to make a second cut more or less into your bar and chain.  Making a face at 30% or 1/3 is more a rule of thumb, gives you enough meat on the hinge wood to do some good and allows you to make the cut without getting hung up.

On a perfect tree as you mentioned the wedge is merely there to take the weight of the tree, a few pops with your favorite wedge beater and over she goes. The wedges job is to lift the back side of the tree, the hinge wood now becomes hold wood and holds the face side to the stump, acting as a fulcrum and tipping the center of balance in the proper direction.

Now when you start talking about limb weight, belly-top-side lean then it gets interesting, if you feel its going more or less where you want it to go, face it up and back it down.  If its going some other direction, then I guarantee a wedge or some other device of maximum leverage is in order.
well that didn't work

BEEMERS

Id like to weigh in on this.First ..every opinion posted thus far is correct.everyone is right.Its just that with trees there are so many unforeseen factors that engineering cant cover.Ive had the trees that seem the simplest nearly kill me.and some that fron an engineering aspect look insanely deadly and go perfect and easy.Ive seen trees twist,turn,spin,and seemingly defy the laws of physics.So many factors such as stress in the wood ,species and hardness of trees..even temperature..hot or very cold plays a huge factor in what can happen.
Engineering and physics matched with common sense rules....but sometime its almost like a Zen moment..you feel that tree a little...I almost erased that last bit..but Im leaving it...someone will get that.
Apply physics to the wedge...a tiny lift at the base will apply a tremendous lean at the top increasingly so depending on the height of the tree.Use them no matter what...until you can recognize when you DONT need them.Wind can negate all you do..even moreso with tree with leaves on or big tops.
Never get your saw through your holding wood into your face cut.dont rush and always look UP!!Check out.."watch out for widow makers" in the General board.
Read much into Forestry Forum "Health and safety" board.
Youtube  "Barber Chair" or check the FF..that is a scarysumbeech.
Study what others did wrong.and when you cut a tree..if its right..study what happened and read the stump..how it all came together to make it work.....if its wrong...study the stump,the notch.the backcut,the holding wood or lack of..and usually you can reverse engineer what you did wrong.
But once in a while...some things happen that seem to defy the laws of physics.

SawyerBrown

Not an experienced logger, and maybe this should be a separate post, but yesterday I went to see some logs I'll be milling within the next few weeks, on some property being cleared for a house.  One thing I noticed was there were several logs with pretty significant splits from the felling process, which appeared to me to be caused by what I'll call an "offset hinge" --  the "hinge" was maybe 3-4" higher on one side than the other, causing a lot of tearing and the split.  I always thought of a "hinge" as a single line of wood, like a door hinge.  As is explained earlier in this post, a wedge will get the tree leaning in the right direction, so I'm not sure the reason why the hinge can't be "cleaner" resulting in less tearing.  Is there a good reason, or is this just sloppy / inexperienced logging?  It compromised what would have been some pretty nice cherry ...
Pete Brown, Saw It There LLC.  Wood-mizer LT35HDG25, Farmall 'M', 16' trailer.  Custom sawing only (at this time).  Long-time woodworker ... short-time sawyer!

thecfarm

Some wood will spit easier than others too. Maybe they was pushing the tree over with something and not giving time for the hinge to work the way it should?? The hinge being 3-4 inches higher SHOULD not matter that much. I always cut into each side of the tree,a straight line, a few inches,depending on the size of the tree too, to where I am going to put my back cut.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

LittleJohn

Winches, Wedges .... are your best friend, always easier to persuade the tree over with a push, pull or brute stength (ASSUMING perfect cylinder type stuff).  PLEASE NOTE: Please do not cut down power poles! :D Neighbors and power company both tend to complain

Winches and Wedges also help, with trying to guide tree to ground!

chester_tree _farmah

Per the cherry. Sounds like inexperience or the logger was paid a flat rate or by the hour. There are techniques to avoid but splits. As cfarm says making a small cut on each side of the hinge helps. Splitstend to happen more on leaners. The best method I have found and now use on any tree large enough is the open face plunge as taught in game of logging. It takes a little more time but splitting a prime veneer log costs a lot more if u r getting paid by % of sales. Just look at the prices paid for a nice Veneer grade log compared to what maybe now a low grade saw log if you are lucky. If u use the traditional open face cut with out holding wood on the back the tree starts to fall  before the hinge is at the  desired thickness and it is much more likely to pull and split from that force. The open face plunge is also safer for the logger as u r not standing there continuing to cut while the tree is starting to fall. You wedge it than snip the holding wood on the backside and move away. If the tree barber chairs or rolls you are not right there with saw in the tree and your face down next to the butt. Learning to do a plunge cut safely is a prerequisite but isn't hard to do safely. Sorry for the rambling but since I found this cut I freaking love it.
254xp
C4B Can-Car Tree Farmer
Ford 1720 4wd loader hoe

mesquite buckeye

Good call cst. Leaners, especially hard leaners that are miscut love to barber chair. Also, hard falls across gullies or hitting a stump or a rock coming down can split a log. I have also seen logs that just want to split no matter how careful you are. These are usually high tension pretzel formers on the mill. ;D
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

redprospector

Ok, everyone can't be right!
So I'll go ahead and give my 2 cents.  :D
When I read Robert11's description of this tree, I didn't see the "perfect" tree like everybody else. I saw a fire killed conifer snag, that if it had a top, had very few light weight limbs that were just waiting to impale you at the very thought of smacking a wedge.
Probably just the way I think, which proves I'm a little different.  :D
It is surprising how many of the snags I described above are very close to being balanced, or near perfect center of gravity.
All of that said to reinforce the fact, truth that every tree, every situation is different, and that the 30% or 1/3 diameter is a rule of thumb that applies to the majority of tree's you would encounter.

On a tree (cylinder) as described by Bob, you wouldn't necessarily need to go 60% with your face to get it to fall without wedges, but just past 50% will generally do the job.
My disclaimer. I do not recommend that anyone use this method, period!
I have not been to a GOL class, nor have I been to any other type of "logging" school, other than the "school of hard knocks". But I did stay at a Holliday Inn Express last night.  :D

1996 Timber King B-20 with 14' extension, Morgan Mini Scragg Mill, Fastline Band Scragg Mill (project), 1973 JD 440-b skidder, 2008 Bobcat T-320 with buckets, grapple, auger, Tushogg mulching head, etc., 2006 Fecon FTX-90L with Bull Hog 74SS head, 1994 Vermeer 1250 BC Chipper. A bunch of chainsaws.

chester_tree _farmah

I went to the same school. :')

My reply was to sawyer brown who sounds like he is truly interested in learning the art. I need to figure out how to include the message I am replying to in my post. Or maybe I can't from my phone.....

Anyone else notice the original poster with the off the wall question has dissapeared? Someone was kind enough to inform me of these types of posts on forums. I never knew about them just saying. :-)
254xp
C4B Can-Car Tree Farmer
Ford 1720 4wd loader hoe

redprospector

Quote from: chester_tree_farmah on April 21, 2014, 01:36:49 PM
I went to the same school. :')

My reply was to sawyer brown who sounds like he is truly interested in learning the art. I need to figure out how to include the message I am replying to in my post. Or maybe I can't from my phone.....

Anyone else notice the original poster with the off the wall question has dissapeared? Someone was kind enough to inform me of these types of posts on forums. I never knew about them just saying. :-)
My reply wasn't directed toward anyone, just having fun bringing a different perspective to the conversation.
Sometimes I've got to stir the pot a little....just can't help myself.  ;)
1996 Timber King B-20 with 14' extension, Morgan Mini Scragg Mill, Fastline Band Scragg Mill (project), 1973 JD 440-b skidder, 2008 Bobcat T-320 with buckets, grapple, auger, Tushogg mulching head, etc., 2006 Fecon FTX-90L with Bull Hog 74SS head, 1994 Vermeer 1250 BC Chipper. A bunch of chainsaws.

chester_tree _farmah

No problem my friend. It's all good. Just wanted clarify and I do love that cut. :-)
254xp
C4B Can-Car Tree Farmer
Ford 1720 4wd loader hoe

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