Where's WYK been, and what trouble is he making?

[rwoods]

bitzer, I get the snipe now. Your wording "opposite of the face" had me confused. Being a firewood cutter, my face cuts are usually open enough that I don't have to worry about stalling (excepting of course stalling from sloppy over cuts, Unintended Dutchmans I believe is the term my W/C friends use). I use a snipe when I want to propel the stem from the stump.

Back to the depth of the face cut. I get the heart gutting but it would seem that the deeper the face the further back you move the transition point from compression to tension and you create more tension due to loss of leverage. At least that was my thinking. I usually cut deeper faces than the books recommend. I got called out on that recently and advised of the increased mechanical disadvantage of deep face cuts when you have to wedge a tree. Same principle would seem to apply with holding something down (tension wood) - the further back the pivot point the greater the tension and thus the greater the risk of a barber chair. Once again that was my thinking. I watched the BC video yesterday and thought it validated the approach of a shallow face. I am keenly interested in this as I don't want to lose my head to a chair.

In addition to red oak, I cut a few white oak which seem to be the most chair prone species that I cut. I have cut fewer than 100 ash of substance in my life - around 60 to 70 in the last four weeks. I haven't got them figured out but so far they are almost as much fun as poplar. Most were around 15" to 24" but fairly tall. Below is the largest diameter one I have cut. It was a pretty brushy field tree.



Thanks,

Ron

 

[bitzer]

bitzer, I get the snipe now. Your wording "opposite of the face" had me confused. Being a firewood cutter, my face cuts are usually open enough that I don't have to worry about stalling (excepting of course stalling from sloppy over cuts, Unintended Dutchmans I believe is the term my W/C friends use). I use a snipe when I want to propel the stem from the stump.

Back to the depth of the face cut. I get the heart gutting but it would seem that the deeper the face the further back you move the transition point from compression to tension and you create more tension due to loss of leverage. At least that was my thinking. I usually cut deeper faces than the books recommend. I got called out on that recently and advised of the increased mechanical disadvantage of deep face cuts when you have to wedge a tree. Same principle would seem to apply with holding something down (tension wood) - the further back the pivot point the greater the tension and thus the greater the risk of a barber chair. Once again that was my thinking. I watched the BC video yesterday and thought it validated the approach of a shallow face. I am keenly interested in this as I don't want to lose my head to a chair.

In addition to red oak, I cut a few white oak which seem to be the most chair prone species that I cut. I have cut fewer than 100 ash of substance in my life - around 60 to 70 in the last four weeks. I haven't got them figured out but so far they are almost as much fun as poplar. Most were around 15" to 24" but fairly tall. Below is the largest diameter one I have cut. It was a pretty brushy field tree.

View attachment 717555

Thanks,

Ron

I would put hickory, then white oak, then ash as the most chair prone trees that I cut regularly. The tree chairs on the compression wood not the tension wood. The compression wood is being highly compressed which causes the split from the pressure. The tension wood is being pulled apart and is the opposite. I know they teach a shallow face on hard leaners but that is counter intuitive. If you don't get that compression wood cut up you might as well not even face it. The tension wood just holds it to the stump .

 

[bitzer]

Here is an example of a hard leaner I swung today. I used the back corner of the stump(tension wood) to pull it around. The dutchman side is highly compressed and the pull side is highly tensed there by pulling the stump out. I have had hard enough compression on the dutchman side that it will crack the butt or the stump. Not split as in a chair mind you but a pressure crack.

 

[bitzer]

And cleaned up pick for doubters who don't think cuts like this are valid in saving out timber. The one little plug I pulled was closer to the compression and likely why it pulled. I've pulled high dollar walnut like this to save the entire stem and they clean up just fine .

 

[rwoods]

I am struggling to get my head around this tension vs compression stuff. I thought it was the pull (tension) that cause the split, thus the pitch for boring where you remove all the inner tension wood and transfer all of the tension to the trigger. This will keep my pea brain occupied for awhile. Thanks.

Whether I understand chairing or not, I still don’t like boring where I must pre-determine the minimum hinge necessary to direct the stem. Maybe if I cut more from a single species and uniform stands I would be better at guessing the hinge and be more comfortable boring. Nonetheless, routine boring still seems like a time waster. As does flare removal when a longer bar would get it done.

Ron

 

[Westboastfaller]

I don't know what he is getting at other than cutting all the compression wood behind the hinge first. Much like they teach on a reg bore cut; when a strap is used.

Or is he talking chair potential differences without the strap?

A properly placed undercut would likely be in the compression wood. A deep undercut may possible end in a neutral zone of the tree. So is he calling 50%+ U/C is in the tension zone and saying it has less chair potential with the deeper undercut??? IDK realy what he is saying for sure at this point.

The tree chairs on the compression wood not the tension wood. The compression wood is being highly compressed which causes the split from the pressure. The tension wood is being pulled apart and is the opposite. I know they teach a shallow face on hard leaners but that is counter intuitive. If you don't get that compression wood cut up you might as well not even face it. The tension wood just holds it to the stump .

lets not talk back strapping just yet.
When ever you get closer to your hinge the chair potential is at the greatest as you have removed the best 'holding properties of the structure. (As you were saying tension wood holds the tree up.) Same principal bucking a suspended heavy log as to where you want to finish the buck to protect the wood from its own weigh at times by releasing it from close to the top.


On a back cut (forward lean) the closer you get to the under cut the 'heavier the tree gets..And if its a heavy tree with lean then you have the potential there.
It just happens to be where a properly placed undercut would be. (in the compression wood) if its pretty deep undercut then perhaps it falls in a neutral zone. (Depends)

Other way you are going to greatly increase the pressure is a deep undercut
So now you have the worst of both Wolds. That makes it scarry when you have tall heavy unstable trees that
You have to fire straight down.That's with back strap.

*Edit

 

[bitzer]

The compression wood is the wood that is compressed. All the wood the tree is leaning on. The tension wood is holding the tree up. The wood in the back. Depending on how hard the tree leans determines how much of either type of wood you have.

Let's say the front 60% of the tree is under compression. That front 60% is where all the chair potential is. This is where you need to remove as much wood as possible either by face, gutting hinge, removing wood behind hinge(boring, coos Bay etc). The 40% of wood behind it is all under tension and being pulled by the weight of the tree which keeps it skybound until released or until the wood breaks.

Is there a point where putting a really deep face in would cause tension wood to become compression wood? Sure. As the tree leans more ahead new fibers can become compressed but this usually takes time and I don't let things sit around very long. You ever put the first kerf in a tree and have to refuel or something and you come back and it's sat down tight? It takes time.

Compression wood-forced together-fibers have no where to go under incredible pressure and split.
Tension wood-pulled apart-the fibers get ripped apart and have everywhere to go.

 

[bitzer]

It's a lot easier to slam that first kerf in then it is to cut the wood behind it I've found. Once you get that first kerf in deep you're golden unless the back wood is compromised somehow. You can't dilly dally with it tho. It needs to be wot all the way in.

All this advice is for hard leaning hardwood under 100ft tall. That's what I know and do. I don't mean a couple clicks off center either like that beech posted above . I mean stump pulling lean.

Conifers in the 150-200ft plus range are likely in a different ballpark but I'd still lean towards a deeper face cut. Sometimes you can only get so deep

 

[northmanlogging]

If a tall evergreen is leaning real hard, chances are it's a windfall, and then ya got more pressing issues then barber chairing... add such as what's the stump going to do, what else is going to try and kill me etc. But a coos is still better then a strap all day every day

 

[wyk]

If a tall evergreen is leaning real hard, chances are it's a windfall, and then ya got more pressing issues then barber chairing... add such as what's the stump going to do, what else is going to try and kill me etc. But a coos is still better then a strap all day every day

Exactly, there's different amounts of lean and on what, and chasing a cut is different if you aren't under a chair but on a root ball etc.

 

[rwoods]

... I don't mean a couple clicks off center either like that beech posted above . I mean stump pulling lean. ...

Gauging solely from the little bit of the stem you can see in the video, I would classify that beech simply as a typical tree not a leaner that requires special attention. You are describing the situation that I am wrestling. My pea brain is still processing this discussion. I appreciate you and the others taking the time to explain things.

Ron

 

[bitzer]

If a tall evergreen is leaning real hard, chances are it's a windfall, and then ya got more pressing issues then barber chairing... add such as what's the stump going to do, what else is going to try and kill me etc. But a coos is still better then a strap all day every day

Yep if I ever had the pleasure to cut out that way id start with what I know and go from there as I'm sure you would here. Probably find out in a hurry what's not working too. Yeah those half tipped trees or compromised stumps are a whole nother discussion. I just got done with 3 months of tornado blow down, hung up, twisted ********.

 

[bitzer]

Gauging solely from the little bit of the stem you can see in the video, I would classify that beech simply as a typical tree not a leaner that requires special attention. You are describing the situation that I am wrestling. My pea brain is still processing this discussion. I appreciate you and the others taking the time to explain things.

Ron

I love talking timber Ron. Wish you could see it in person. Makes it a lot easier.

 

[Westboastfaller]

Well, If there was any confusion, I sure did not help matters continuisly mixing up compression and tension (in my writing) Tired I was and still awake. The Zombie needs to wait before getting in to the discussion.

 

[Westboastfaller]

bitzer,

it would seem that the deeper the face the further back you move the transition point from compression to tension and you create more tension due to loss of leverage.

Thanks,

Ron

A loss in 'base leverage', yes correct ^^ and a gain in leverage (The tree itself being the leverage object.

Hard to know where transition zones are before and after completion of an undercut as well in relation to size of undercut differences unless its has a parallel back strap. It makes sense there will be a 'neutral ' area before it goes into 'tension' So in a deep undercut then yes it would seem likely some of the neutral area would now transition and start to compress. as the base retreats . Much more compression and tension

 

[rwoods]

No falling today, but the steady rain and 45 degree temperatures kept my pea brain from overheating as I continue to process the depth of the face cut with hard forward leaners. Think I'll get out D. Douglas Dent for a little light reading.

I gained a new appreciation today for you guys. I bucked at the woodlot today in a slow steady rain. Found my rain gear of many years is not actually waterproof and I got soaked to the core. Also had my 125 bite me several times when starting it due to the slippery recoil grip and the decomp closing on me. I just thought who am I to complain as most of you regularly work in much harsher weather. My hat is off to you. My head is soaked anyway.

Ron

 

[rwoods]

Okay, my head was hurting before but staring at some of Mr. Dent’s Dutchman illustrations has it spinning. Nonetheless Mr. Dent says to use a deeper face with a heavy forward lean even though it increases the tension and thus the risk of a barber chair. Though he doesn’t say which is best - side boring vs “side notching” (appears to be the same as a Coos), he does say that face boring is the least desirable due to increased chances of pinching your bar and barber chairing. He says that the cause of barberchairs is the back fibers as severed start to “fall” while the forward fibers though under increasingly more pressure are not falling thus a split develops between the moving and the non-moving fibers. He doesn’t relate the split to compression. This is actually the process I thought was occurring but to cut a deeper face that actually increases the tension and the risk of barber chairing seems counterintuitive and it appears contrary to the BC materials. But I think it all brings us back to bitzer’s time analysis, the quicker you cut the less likely the chance of a barberchair and the less you have to cut the quicker you can cut. If you want to take your time then I guess you just need to go side boring and cut the tension wood front to back. Interesting side note. - Dent doesn’t describe the use of a trigger when side boring.

In all three methods, Dent recommends nipping the corners of the hinge.

Most all of my reasoning expressed here is based just on book knowledge. Your real world experience is welcome.

Ron

 

[woodfarmer]

I cut my face in an ash that was leaning several ways. Chose my intended direction of fall. Bored in from the front to set a wedge in the back to send the tree in the intended direction. I then cut the T from the low side (or what I thought was the low side) and proceeded to cut the high side. Damn tree went 90* to the right and sat down on my tsumura light bar. Got the power head off and the bar had a noticeable bow to it. Figured it was shot so tractor and winch to pull the now hung up tree off the stump. Thought at the least it might just break the tip. Pulled the tree off and wow the bar was not damaged other then a couple of the epoxy inserts or whatever they are made of were slightly damaged. So tsumura, light and tough and flexible.
Didn’t get any pics as I was working very quickly.

 

[woodfarmer]

I used a step up bore cut on the heavy leaner on the left but a humboldt and level back cut on the larger stem. I usually gut the heart.
It too was hung up so a little pulling back with the winch got it down

 

[Westboastfaller]

of the increased mechanical disadvantage of deep face cuts when you have to wedge a tree. Same principle would seem to apply with holding something down (tension wood) - the further back the pivot point the greater the tension and thus the greater the risk of a barber chair.



Ron

True Its all pretty much the same if you were to cut a conventional back cut though. They will increase both in tension and compression with the deep undercut.
Basically they change rolls as the holding wood is now the tension wood on a deep undercut back leaner and the compression is heavy on the wedges.

In terms of wedgng then now you
have shortend your base from wedge point to pivot so you have lost ratio advantage as well.



In regards to "tension wood" and "barber chair" above^^

I guess that's what bitzer must have taken the wrong way as it would appear and went down a different path. If it was on a stable back strap then obviously no the increased tension would not contribute to a barber chair.

If you have increased the tension by a deeper undercut then you would have increased the weight, then you have increased the compression. They all go hand in hand Ultimately its the offset leaning weight that splits the back cut. Its own weight overcomes it's integrity generally.

Other contributing factors are wind and other trees, Dutchman, shallow opening of undercut, defects, too much holding wood, snow load.
'Compression' can certainly blow apart a compremised trunk if cut wrong. Its all weight and force.

Bad judgments and bad workmanship go hand in hand along with good experience for some reason.

How many you guys barber chaired?