By Michael “House” Tain
The term specialized cutting techniques can cover a lot of ground; and depending on the experience or expertise of the operator, could include techniques that an arborist in another location may consider an “everyday” use. In short, a specialized technique is one that is considered the safest and most efficient for a particular woody situation. Part of the challenge of employing any cutting technique is knowing when — and, just as importantly, when not — to use them. The special situations that might call for a more technical cutting technique will run the gamut of the type of scenarios confronted by tree crews all over the world on a daily basis. It may be as seemingly simple as a bore or plunge cut to reduce the chance of splitting or “barber chair” when taking the top out, or as complex and gear-heavy as a key notch on a large wind-thrown tree laying on utility lines. In either case, along with the many others in which specialized techniques are applicable, the knowledge and understanding of their use and applicability is simply another valuable tool in the tree crew’s mental tool box. As with all tree care techniques and methods, the first time to use one of these is not when confronted with a live “real-world” situation with people and property on the line. Education, training and practice are the keys to safe dependable use.
This technique is one in which the operator uses the “starting” or “go” corner of the tip of the chain saw bar, the lower quadrant, to begin a cut in which they can then bore or plunge through the wood. As the tip of the bar also includes the “no” corner, the upper quadrant, which can result in violent kickback, this is definitely a technique to understand well and practice with before “go time.” However, once understood and practiced, the technique is extremely valuable in setting up the hinge in felling situations, removing internal pressure in forward-leaning trees or tops, and even bucking up logs on the ground. Prior to use, operators should learn the balance points of their saws and such useful features as felling sights in order to keep their cuts level and parallel in the desired manner. Well-sharpened chains are obviously integral not only to this technique, but to any safe, efficient use of a chain saw. However, operators should be aware that excessive filing of the depth gauges, often called rakers, on the chain will create a saw that is not only very prone to kickback, but will buck and shake during bore cutting.
One of the important concepts to keep in mind when using any specialized cutting technique is the presence of compression and tension forces. These are present in every tree whether it’s upright, on the ground, or sitting on top of a double wide, but the location and the reactions they create can vary widely with how the tree lays. An example would be a tree laying on utility lines without an excessive amount of wood beyond the lines. In most cases, the compression forces are going to be on the top or upper side of the trunk, with the tension forces on the bottom, or underside. Take the same tree and put enough of it over and beyond the wires and the forces will change, with compression underneath and tension on top. Operators must [bold>always<BOLD] Canada, is the acronym “CUT.”
Begin the cut on the Compression side
Finish the cut on the Tension side
“U” are in the middle
Looking at a mismatch showing the orientation of the pull line in order to pull it toward the side of the “low” cut. The top of this small tree would likely be hung in another or atop wires or houses. All photos by Michael “House” TainMismatch/bypass
This is the simplest of the specialized cutting techniques; and one many climbers have used even if they didn’t know the name of it. It is the same basically as the cuts used when “cutting and chucking” on the trunk or horizontal branch when aloft. In the case of a completely fallen tree that is being removed from wires or a trailer, the breaking and “chucking” part should be done from a distance with a pull rope or push stick. If breaking the cut in this manner, folks will find it much easier if they are pushing or pulling toward the side with the lower cut. The two cuts are offset from opposite sides of the tree or branch, depending on the location of those all-important forces, tension and compression. Also, species and wood size will dictate the amount of cut overlap required along with the distance between the cuts, but better to start out with too little and have to cut a wee bit more than to take too much and have the tree or branch collapse uncontrolled.
Knee cut or hinge
This technique works very similarly to the felling notch used to fell a tree, except, in this case, the operator desires to “fold” the tree back upon itself, out, away, and off whatever object it might be lodged in. An open-face notch is used on the upper side of the fallen tree, and needs to have at least a 90-degree opening to achieve the desired result. The hinge thickness needs to be about five percent of the tree’s diameter in this usage and requires good wood fiber present to be a viable option. In addition, the hinge must be set up using a bore cut, so small-diameter trees are not well suited to this technique. The goal is to be out and away from the tree at release, so the usual practice of cutting the “strap” right at hinge level or slightly below is not an option in this technique. A mismatched back cut is used below the level of the hinge, shorter in large-diameter and strong wood, farther in small-diameter or weak wood, to allow the whole thing to hold together until the crew pulls the installed line from a distance to start the process. A tree thrown over with the roots still attached can present some contravening forces that make the knee cut challenging, so in those situations the crew might wish to consider another technique.
A close view of a completed key notch to show the various cuts. Obviously, wedges would need to be in place during the utilization process, but this view shows the cuts more clearly.This technique is the most gear-heavy and complex of those discussed here. But given the right situation can be as “slick as a minner in springtime.” It requires a great deal of force to achieve release, thus a winch, GRCS, or some form of mechanical advantage system is a required component. A tongue or key is created in the trunk of the tree that “locks” the two parts together until the crew is ready to pull them apart. The key should be at least as long as the diameter of the tree; and trees experiencing more forces may very well benefit from the use of a longer tongue. The tongue will consist of basically the middle third of the tree when viewed from the side; and thus is created by carrying out two vertical, parallel-to-the-sides-of-the-tree bore cuts down until the chosen length is achieved. A horizontal bore cut is then made to create the end of the tongue, with care being taken not to cut into the outer thirds of the tree. Wedges are placed in this cut from both sides to lessen the likelihood of the saw being pinched as the cut is completed. The key notch is completed by cutting in from the sides to meet the edges of the tongue. As always, cut compression wood first and tension last, putting a wedge in the compression cut to aid with control of the existing forces. The tree should now be “locked” together by the key, and can be pulled apart from a safe distance with the aforementioned winch, GRCS, or mechanical advantage. Prior to pulling, the crew should remove the wedge from the end of the tongue on the side being pulled toward to avoid frustration and possible inappropriate language.
This brief introduction to specialized cutting techniques obviously does not discuss all the “ins and outs” of their safe and effective use, but it does provide some beginning concepts and knowledge that will assist tree crews in making them a part of their mental toolboxes. Once again, there is no substitute for “hands on” training and practice in any tree industry skill or method; and specialized cutting techniques, given the presence of sharp motorized cutting implements and large heavy woody objects, is definitely a skill that calls for practice prior to use.
Michael “House” Tain is a contract climber, splicer, educator and writer associated with North American Training Solutions www.northamericantrainingsolutions.com and Arbor Canada Training and Education www.arborcanada.com. He is currently located in Lancaster, Ky., and can be reached via e-mail at firstname.lastname@example.org.