Dent's book - question on side-boring

pantheraba

pantheraba

Dent\'s book - question on side-boring

I am working my way through Douglas Dent's book "Professional Timber Felling , a Procedural Approach"...a lot of good information. I would like to ask y'all a few questions.

As I read it, a bore cut (from the side) is primarily used for leaners. Once the central bore cut is made only the holding wood behind the face and the backstrap is left.

1. Is the final cut made from the back or do you just continue cutting from the internal cut so that you are cutting away from the face as the tree releases?

Dent says, "The final step is to cut off this back holding wood, allowing the tree to fall freely." [pg. 103] It is not clear if it is important for the direction of the final cut...towards the face as in a 'regular' cut or towards the back of the tree (opposite direction from a 'regular' backcut).

2. How are "corner-nips" made? He says to use them when bore cutting...to "nip the corners of the holding wood".

3. Any guidelines for how much backstrap to leave if the final cut is done from the back towards the face and in towards the cavity caused by the side-boring cut?
 
Re: Dent\'s book - question on side-boring

1.The final cut can be made either way. If you are wedgeing on a non front leaning tree it is easier to finish from the back.
2.I usually make the corner nips just unde the hinge. the pupose of this is to prevent tearing. Especiallyif you arein the tree.
3.Backstrap size is determined by species, condition of wood fiber and amount of lean(weight) itis holding. I dont know any specific measure.
 
Re: Dent\'s book - question on side-boring

At one demo of bore cutting I heard another option for cutting the strap. Make a cut into the trunk wood just below the kerf. That way you make a sort-of barber chair release instead of a pop release.

Like all new things, try it with small ones out in the open.

To practice some of these new techniques I've taken advantage of chunking spar wood. Instead of doing a flopper and then chunking the trunk on the ground into manageable pieces, I've done the chunking on the stump. If I need to simulate side lean I've had a rope tensioned off to one side.

Who says we don't get paid to play?
 
Re: Dent\'s book - question on side-boring

If cutting from the back toward the bore i woud definately cut just below the kerf just in case you overcut. that would prevent the saw being grabed as in a jump/snap cut.
 
Re: Dent\'s book - question on side-boring

[ QUOTE ]
At one demo of bore cutting I heard another option for cutting the strap. Make a cut into the trunk wood just below the kerf. That way you make a sort-of barber chair release instead of a pop release.

[/ QUOTE ]

Is this what you mean by a cut below the kerf?
 

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Re: Dent\'s book - question on side-boring

Cutting straight out from the back can cause the sapwood to tear taking the saw with it. It is considered best practice over here to cut down at a 45 - 60 degree angle to release without fear of the tree taking the saw. Keep the cuts parallel and make sure they overlap. Don't be tempted to lean over the saw to cut the far side first - you may get caught in a barber chair. This is especially important for heavy forward leans. If the technique is used to release tension in the heartwood, this type of release is inappropriate, as wedges cannot be driven/felling lever effectively inserted. If there is no fear of the tree suddenly releasing, I'd just continue out the back, or cut under the back cut like Tom explains.

If the tree is larger than the saw bar, make a bore cut from both sides. The cuts don't have to meet, just overlap no more than an inch. But they must extend the same distance to the rear, so they are both released with one cut. The weight of the lean will eure it doesn't hold, and it will snap clean like a step cut.

As a guide for the strap, it should be at least as thick as your hinge. But as mentioned, this depends on many factors.

Cutting the corners of the hinge:
I cut down diagonally at ground level 60 degrees, preventing a split running up the sapwood of the tree.
In the tree, I cut in about 5% of diameter, just under the
the face cuts. This helps prevent sapwood tearing down the tree.

Just a guide, the specific situation will dictate what is best to use.
Take care!
 
Re: Dent\'s book - question on side-boring

To keep from tearing out; as an option to nipping corners; you can walk a 'chalk line' around the back from corner to corner on the hinge. This also helps line the cut(s) up.

i think it is preferable, though not as easy to nip corners from bottom, not top. The corners are the most highly positioned leverage of pushes and pulls. Thus, another reason for corner nipping is to make sure there isn't tooo much push from either side on close/ tooo early a close one/both sides in this key position; that could throw things off, to the opposite direction.

Side boring is similar to a climber's snap cut; in that they both assure less tension on the holding fibers at re-lease. With the front row as compressed fibre, and rear as tensioned, the distance betwixt is leveraged multiplier. So, in side bore, we make disconected area between the compression and temsioned fibers, giving more leverage/lower tension. Same as a snap cut, the kerf closes at the nose, this becomes compression, and the holding fibers are further back at release, than in a normal hinge. The differance is, that the compression area is connected in a side bore, while the compression are is disconnected in a snapcut. So a bore hinges, a snapcut doesn't. Proving that a compression/pivot doesn't have to be connected to work, like tensioned/holding fibres must be.

Mutley offering proof that in operating the sides of the faces seperately/ closing lean side first, we can change the compressive/pivot from a connected to a disconnected position. This pivotal change is very strong, and also gives tourqued power as it pushes while the opposite side is still pulling. Also, this places them a farther leveragaed distance apart, and more of an inline leverage too, similar too/or in tandem with similar strategies of maximizing the pull with a tapered hinge, only working the push strategies, rather than the pulls.

Or, something like that,
-KC
 
Re: Dent\'s book - question on side-boring

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For climber safety, "cut the corners" when making large topping cuts up in the tree. Imagine if, for some unforseen reason the tree begins to fall sideways, and rips down the trunk, across the flipline. Prevent this by cutting the corners !

After completing the face cuts, the climber moves around to the rear of the tree and begins to position the saw for the final cut.

On larger diameter stems, the climber cannot see at least one of these corners at a time. Depth perception is best when both objects we are comparing are in view simultaneously.

If a corner cut is in a plane with the floor of the undercut, later, it can be viewed from the back. From this angle, the corner cuts are merely extensions of the horizontal floor.

These cuts on either side of the face are great as a visual aid to the placement of the saw at the correct height of the backcut. It is common to make the backcut from one side of the face. The climber is staring right at one of the corners. The other corner is out of sight behind the curve of the trunk. If there is an extension in the form of a corner cut, then both sides can be seen while preparing for the backcut.

Some folks lean forward to reach around to feel with their hand where the location of the other corner of the facecut is on the far side of the tree.

Another technique is to place the bar of the saw in the facecut as a reference, then immediately pull it out and put the saw in position for the backcut. Using one uninterrupted motion prevents distractions while vertically swinging the hot, smoking, noisy saw directly in between the tree trunk and past the helmet, making sure it stops before hitting the climbers flipline.

Still other climbers start a shallow backcut where they think it ought to be, then idle the saw in the cut and step around to the far side to confirm that the cuts will line up correctly. Then they step back around to their stance. Oftentimes this stance will require secure enough footing to push mightily on the wood to 'convince' the tree to go over in good order.

All of these techniques result in allowing the climber to place the cuts in the intended location. But what about when we need that tree do more than fall straight into the headlean? If there are some modifications of the face needed, then there is good control to finesse the tree down into an ambitiously offsided lay.

That's another story.
 
Re: Dent\'s book - question on side-boring

[ QUOTE ]

For climber safety, "cut the corners" when making large topping cuts up in the tree. Imagine if, for some unforseen reason the tree begins to fall sideways, and rips down the trunk, across the flipline. Prevent this by cutting the corners !

......, the corner cuts are merely extensions of the horizontal floor.


[/ QUOTE ]

All you guys...thanks much for the clarifications. It makes sense now...sounds similar to why we undercut a limb to prevent tearing it down the trunk.

I appreciate everybody's input.
 
Re: Dent\'s book - question on side-boring

Especially when limb is horizontal, giving a kinda snap cut, by undercutting first. This makes the point of comrpession at tearoff, disconnected for no rip. But also, the disconeccted space above compression forces the tension fiber to be farther away. The tension is need for support, but has to be connected. So, this spaces tension and compression farther apart. For more support leverage/tension fibers under less load/ more sudden release and less tension fiber at release.

If, limb to be kerfed under is balanced across, kerf is straight across. But, if offbalace to 1 side, i kerf deeper up on that lean side first, then other side less. This gives more leveraged support, to the heavier side i think at the push of the close.

If i want more actoin to other side, i make small notch, with no clsoes on that side. This gives a releif (that system will be sniffing for as path of least resisstance) for the close on the other lean to push into. While also a pull that way, by the virtue of the loaded open face maid opposite the CG's lean. This will pull away from lean in tandem with the close pushing away from lean. The push coming from the loaded closed 'face'(of the kerf) on lean side.
 
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