How to Fell Trees Safely
Know the Right Tree Felling Cuts to Drop Standing Timber
By Ben Hoffman
Felling timber is one of the most dangerous jobs on the planet, but knowing how to fell trees safely can greatly reduce the odds of accidents.
Fortunately, back in the 1970s, a Swede named Soren Erikson came to America and began teaching safe methods for how to fell trees. His techniques are not only safer, they reduce the amount of effort needed. Back in those days, Scandinavians were using top-rated chainsaws with bars that were 13 to 14 inches long. Since then, probably because Americans think bigger is better, it is difficult to find a good quality bar shorter than 16 inches. I watched loggers in British Columbia cut 18- to 24-inch trees with 24- to 28-inch bars.
Long bars need more horsepower, meaning more weight, more gas, and more muscle fatigue. My main objection to long bars—they are more dangerous. The longer the bar, the greater the chance of striking a foreign object—rock, brush, limb. And if you strike it with the bar tip, the saw will kick back hard. Long bars are particularly hazardous when removing limbs from northern softwoods with multiple limb whorls around the tree stem. With a little finesse and chainsaw safety gear, you can cut those 24-inch trees with a 12-inch bar. This article will deal with falling average trees—straight, well-balanced crowns, very little lean, no rot—then we’ll look at the difficult trees which require more thought and care.
To drop a tree, you must make two cuts, the notch, on the side facing the direction of fall, and the back-cut. I don’t know how the aborigines did it, but I learned from my granddad using a crosscut saw and an ax. First, we made a saw cut at right angles to the direction of fall, then chopped out the notch (illustration below). He was right-handed, I was left, so we made a beautiful notch. Then we made the back-cut an inch or two higher than the base of the notch and sawed in (leaving a hinge) until the tree began to fall. When chainsaws came on the scene, the same technique was used, but instead of chopping out a notch, the top cut was made with the saw, hopefully meeting the bottom cut evenly.
The problem with this technique was that as the tree fell, the notch closed, the hinge broke and often the tree kicked back off of the stump. Kickback is a leading cause of fatalities and serious injuries. If the notch was 45 degrees—the most common practice—the hinge broke when the tree was halfway down, still dangerous; but sloppy cutters often made shallow notches and the tree broke before it reached the halfway point. The farther the tree falls before the hinge breaks, the less chance of kickback and the more time you have to get out of the danger zone.
To minimize damage to other trees, it is essential to drop the tree exactly where you want it and control its fall as long as possible—the open-faced notch is the key. A safe notch is at least 60 degrees, and as close to 90 as possible. And if the top and bottom cuts do not meet perfectly, the tree will fall to one side of its desired lay. The top cut is critical—it must face exactly where you want the tree to fall. Most saws have a raised “pointer”on the saw body—simply aim it where the tree should fall. Make the top cut first, then sight down the kerf to assure that the bottom cut meets it perfectly. If either cut is too deep on one side, the tree will fall more to that side. Some folks complain that the wide notch reduces the usable lumber from the butt log, but most comes out of the butt swell and sloping grain. A shallow notch minimizes loss in the butt log.
Many trainers teaching how to fell trees argue for the back cut to be at the same level as the “V” of the notch, but for weekend warriors, I recommend making it 1-1/2 inches higher. That lip is an added safety margin. To drop a tree precisely, you should keep the back cut parallel to the notch. If your hinge is thicker on one side, the tree will swing in that direction. (Actually, you can use this trick to start a tree in one direction, then swing it as much as 45 degrees to avoid an obstacle.)
Always, before you begin selective cutting of a tree, carefully examine the tree, the trees around it and the ground where it will fall. Are there dead limbs or other debris in the tree that may fall on you? When it falls, will it dislodge debris in nearby trees that may fall on you? Does the tree lean, or is the crown heavier on one side, or laden with snow that may affect its balance and direction of fall? A decided lean or unbalanced crown will affect the wood strength—compression in softwoods, tension in hardwoods. Are its branches intertwined with other trees in such a way that it may hang up rather than fall freely? When cutting a softwood with a dead top, pounding on a wedge can cause enough vibration in the top that the wood may break and drop on you. If the tree falls on a large rock or stump, it may break, or rebound.
Cut any brush that may affect your work, and always create an escape path behind the direction of fall, at an angle of 135 degrees. This is your protection in case of kickback. It may even be necessary to cut brush and small trees in the area where the tree will fall in order to make limbing easier and safer. Do not stand and watch as the tree starts to fall. Get out of there! If it is tipping slowly, you may need to cut more of the hinge, but be ready to move quickly in case it kicks back or rolls after falling.
The illustration below to the left shows a method of cutting when the saw bar is longer than the stump diameter. Simply make the back cut from the backside of the tree.
The illustration below shows how to fell trees that are larger than the bar length. Note that in both diagrams, the notch (undercut) is only about 1/4 of the stump diameter. A recommendation by one manufacturer is up to the width of the bar, but this could be too deep in small trees. A depth of 10 to 25 percent of the tree diameter is usually sufficient, with depth increasing as diameter increases. Deep notches just make more work and do not leave room to drive wedges behind the bar. A wise precaution—slip a wedge into the back-cut to ensure that the bar won’t be pinched if the tree tips back.
The importance of precise falling is to get the tree to the ground with minimal damage to surrounding trees, especially reproduction. You may think those large feller-bunchers used in the woods cause more damage than chainsaw falling, but they don’t. A machine can sever the tree, lift it vertically, move it to an opening where it won’t damage other trees, lay it on the ground and pile several trees together, minimizing skidder travel in the woods to collect trees.
Do you have any tips regarding how to fell trees in the safest way? Let us know in the comments.
Originally published in the September/October 2016 issue of Countryside.