Understanding wood fiber -theory.

[davidwyby]

Fiber pull has more to do with hinge thickness.

I think it contributes. The front compression half of a thick hinge could act as a fulcrum to pull the rear half tension fibers. I think it has more to do with whether the face closes before the hinge breaks or not. If the face closes, the log become a claw hammer pulling a nail (right drawing). It’s almost standard, automatic for a western cutter to trim the pull off the stump after felling, not necessarily just because it’s a Humboldt, but because they tend to end up deeper and more closed.




If the hinge bends until broken, it pulls down into the stump, instead of out of the log (left drawing). This is why eastern cutters make vertical hinge walls.







Back to the ‘chairing topic, the flare trim face and bore cut keep the whole rigid log together and eliminates fractures.

My bone to pick with eastern cutting is the short bars and the requisite dancing around the tree. All this boring and stuff is also tedious and I think simply not worth it for western timber.

 

[davidwyby]

True. Sawmillers say to avoid the pith as it splits and quite often trees I cut are already cracked there. So to avoid a chair we need to get deeper in past the pith. That’s the tricky part. I have an idea for bore cutting out the face and leaving a collapsible kickstand in the front, but it’s very gimmicky and at that point one would be better off to just bore and trigger.

Then again, if we bore the pith out…OTOH, the grain running opposite the hinge will resist bending and maybe increase the chance of chairing.

So deep face prevents chairing but you gotta sink it into the rear third! 😆

 

[SeanKroll]

How much barberchairing do you run into?


Only a few species here, aside from loaded trees (e.g. felling a support tree holding a tipped tree) want to BC.



Thick hinge... lots of fiber pull. Undesireable for butt logs at the mill...$ deduction, to my understanding.


If I'm trying to hold a side lean, I'm looking to end up with a lot of fiber pull/ whiskers.





Side note: backchaining whiskers is SOP.

One- eye Guy was bottom-barring 'whiskers' and flung a whisker past his 'safety squint" into his eye. It got infected and he lost an eye.


No thank you!

 

[davidwyby]

How much barberchairing do you run into?

Little to none. It’s just not a thing with my short interlocking grain (also usually dead and resin baked brittle) trees. I could probably no face and normal back cut head leaners with no issue. Only time I can think of a chair was a salt cedar sapling years ago when I did it on purpose just to see.

Only a few species here, aside from loaded trees (e.g. felling a support tree holding a tipped tree) want to BC.

I just see it or potential for it in the many online communities I frequent where they are back east and dealing with EAB.

Thick hinge... lots of fiber pull. Undesireable for butt logs at the mill...$ deduction, to my understanding.

Yes, but seemingly less so in the west than the east. Fiber pull could ruin a veneer log if it makes it too short to get a full width peel methinks.

If I'm trying to hold a side lean, I'm looking to end up with a lot of fiber pull/ whiskers.


Yeah. Recent Mesquite side lean tapered hinge pulled with big tractor, pulled a huge chunk out of a nice log. :-(

Side note: backchaining whiskers is SOP.

One- eye Guy was bottom-barring 'whiskers' and flung a whisker past his 'safety squint" into his eye. It got infected and he lost an eye.


No thank you!

Makes a lot of sense. I have noticed myself back chaining such things.



Similar:

Recently I read somewhere something that made me smack my forehead. Cutting brush near the tip, back chaining greatly reduces thrown chains. As the bar passes thru the stick, the chain has already gone around the end of the bar and is much less likely to derail. Duh. Also throws junk away from you instead of towards.

 

[SeanKroll]

In guessing that's a thick hinge, pulled hard, giving lots of fiber pull.

Triple hinge/ whizzy might work enough without such fiber pull. Maybe not!

 

[SeanKroll]

I've recently found that whizzy/ sizwheels help steer some hard-to-steer branches-- doug-fir.

 

[davidwyby]

In guessing that's a thick hinge, pulled hard, giving lots of fiber pull.

Triple hinge/ whizzy might work enough without such fiber pull. Maybe not!

We pulled hard about 180 to lean. I didn’t get fancy with the cuts, just tapered hinge to hold against the secondary lean towards the camera.

 

[Nutball]

The left side hinge is not guaranteed to bend a worth while amount more than the right hinge. I've had it seemingly make no difference on some white oak. Multiple kerfs would have been better to force a slight bend in each kerfed section along the larger hinge height.

 

[Marc-Antoine]

I'm not good enough to line up perfectly the ends of the multiple kerfs and I know that one will prevail over the other and break too soon.

I had still some success in bending brittle trees like our maple (Acer pseudoplatanus). It came initially from a german vid which received a lot of bashing from how much time the guy took for cutting his tree. Not much explanations given in it but I filled the blanks with some thinking.
Say the hinge won't bend more than 20° before loosing its integrity (and you loosing the backleaning tree). The trick is to not allow the hinge to bend so much by putting an hard stop during the move, like what can do several shallow face cuts but all at the same location. To do that, I modify the sizwheel principle, not for its flexing ability, but to create the hard stop. I cut a full width sizwheel, only with an opening of a little less than the said 20°. The fibers split behind the hinge and flex at the sizwheel's bottom like usual and stop against the sizwheel's front without breaking. To move it further, I create a second flexing point a little higher by cutting an other 20° angle chunk at half of the sizwheel's front face. I call that a two stages hinge.
I guess a pic would help
I used that on trees leaning over fence walls and wires. Maasdam for the win ! These trees were on the small size, up to one foot diameter and somewhere around 50 - 60 feet high. The gain in the motion's range allowed me to pull them back neatly instead of loosing them sideways.
In theory several flexing points could be made on an appropriate sizwheel (or a continuous one with a rounded shape) to enhance the control's time, but I have to improve myself.

 

[Burnham]

Doesn't increased risk of barberchairing occur with this method?

 

[davidwyby]

@Marc-Antoine picture please!

When I originally made that sketch, it was from trying to figure out how to get brittle stuff to hinge. Everything I had heard was redwood or cedar based. I tried gap face with stump shot for a while and found they had to be cut exactly right and pulled to hinge. No bypasses whatsoever crating a fracture point, hinge thickness must be perfect to flex and not just snap off top or bottom. My current best theory is the “long hinge” from the Aussie that disappeared from arboristsite. Essentially the same cut, but with the back cut lowered to the center of the back wall of the gap face. This seems to force the whole hinge to bend. Pic below (red). More testing required. Euc will never be Doug fir. It’s all hard, short grain. No long alternating hard and soft fibers.

I think what Marc is referring to is a European trench cut? (Blue) But I don’t follow the further cuts.




When I posted that sketch again recently, I was more referring to how the Humboldt on the right as it is commonly executed becomes a fiber pulling claw hammer.

That may actually be the way to get Euc to hinge. Face that closes, thick hinge that gradually rips.

I think an early closing face is asking for a chair. The longe hinge might be, but the wood here doesn’t split.

 

[Nutball]

Should make for a good video at least, longer viewer engagement, more time for ads, ect.






I tried this on a white oak, It didn't help noticeably

 

[Nutball]

Maybe pump steam around the hinge for a few minutes to soften it.