Tree felling is not a standard practice. After all, it is an ancient art that has been practiced and developed since man has been harvesting timber. It is no surprise then that there are multiple techniques available to the modern feller. A primary difference in these techniques is the style of notch used in the cut. There are three different types of tree felling notches used. They are the conventional notch, Humboldt notch, and the open-face notch. Each has distinct advantages, disadvantages, and uses, and in this article we will cover all three as well as our recommendation for the best style. First however, it is important to grasp the fundamentals and understand exactly what the notch does when felling a tree.
The Purpose of a Tree Felling Notch
When felling a tree, a notch serves three purposes. First, its depth of cut determines the length of the hinge. The deeper the cut and the larger percent of the tree’s diameter, the longer the hinge. Second, the lateral apex of the notch determines the direction of fall. Finally, the angle of the notch determines the duration of the fall during which the tree remains attached to the hinge and the point at which it breaks off. The point at which the notch closes is the point at which the tree is severed. It is this last function that primarily differentiates the functions of the various notches, so with that in mind, let’s take a closer look at the three main types of notches used in tree felling.
The most common type of notch used in tree felling is known as the conventional notch. The conventional notch consists of a 45 degree angle with the bottom side flat and parallel to the ground. The back cut is then made slightly above the notch’s lateral apex.
The primary advantage of the conventional notch is the tree’s ease in severing from the stem. With the notch closing halfway through the descent, the tree has plenty of time to break off from the hinge. Moreover, placing the back cut sightly above the notch’s apex allows the tree to sever along the grain of the wood, which helps it break more easily.
Secondarily, with a bottom cut the is parallel to the ground, the conventional notch allows for extremely short stumps–totally flush with the ground if the feller is skilled. That can add a nice bonus to the wood utilization when the logs are sold by the cord or ton. In such situations, the less wood left on the stump, the better.
The primary disadvantage of the conventional notch is a direct result of its advantage: Because it severs halfway through the tree’s descent, it creates an uncontrolled descent for the second half. This lack of control does increase the risk of felling and create more potential for unpredictable movements, such as the bottom of the stem kicking up and toward the operator when the tree’s top hits the ground. Such events are fairly common with the conventional notch, so it requires that more precautions are taken.
Secondarily, with a flat bottom, gravity doesn’t doesn’t pull the notch away after you cut it as would happen with other notches. Instead, you have to manually push it away. For small to medium size trees, that can be little more than a nuisance, but when felling larger trees, with notches that can weigh up to 50 pounds, that inconvenience can take its toll.
The second and much less common type of notch is the Humboldt notch. The Humboldt notch is essentially an upside-down conventional notch featuring another 45 degree angle with the flat side on the top rather than the bottom. Once more, the back cut is aligned slight above the notch’s apex.
The Humboldt notch has similar advantages compared to the conventional notch, with an important differentiation. In this system, the bottom cut is angled, which allows the notch to more easily fall free. This is an important benefit to larger trees, and so it is primary used with larger timber. In fact, the notch gets its name from Humboldt county, California–an area known for its redwood trees.
Additionally, because the angle is on the stump instead of the log, the Humboldt notch can be advantageous in valuable trees with butt swell or otherwise low-value stump wood. It ensures the value in the primary butt log is as intact as possible.
The Humboldt notch carries the same safety disadvantages as the conventional notch. The log detaches halfway through descent and is uncontrolled from that point.
Additionally, compared to other notches, the Humboldt notch is a bit tougher to execute. Before getting used to it, an unfamiliar feller may describe the handling as awkward compared to other notches.
An open-faced notch differs the most in comparison to the other notches. Instead of a 45 degree angle, the open-faced notch features a 70-90 degree notch, the top portion of the angle ranging from 50-70 degrees, and the bottom portion ranging from 20-30. The back cut is then placed even with the apex with the notch.
The advantages of the open face notch are clear. With a substantially larger angle and a back cut that requires the hinge to break instead of split, the open face notch maintains control of the stem for substantially longer. Done properly, the stem will only sever as it hits the ground. Such an advantage makes the open face notch an objectively safer method of felling timber the vast majority of the time, particularly when paired with a bore cut.
The primary disadvantage of the open face notch is that it can occasionally be too good at controlling stems. If lacking experience or felling trees with more pliable types of wood, such as many softwoods, the stem may not always totally sever as they hit the ground, and it may be necessary to make a quick cut at the hinge to sever it totally. But this is a quick fix and never much more than a small inconvenience.
Which Tree Felling Notch Is the Best?
Of all the different types of notches used for tree felling, which is best? While each may have specific scenarios where they work better, the open face notch has the advantage of safety, which far outstrips the advantages of the other notches. We highly recommend and promote its use, particularly for beginners.
That said, Once you get experience under your belt, it is a good idea to experiment with other methods. Doing so helps to be your understanding of the physics of tree felling and increases the tools available to you, which is never a bad thing. Whichever of the different types of notch you choose to use, always remember to be careful and use the utmost caution when felling trees.