Safely Limbing and Bucking Wood
Learning How to Limb a Tree and Buck the Wood Avoids Accidents
By Ben Hoffman
Bucking wood isn’t as easy as it looks. Learn how to limb a tree and buck wood safely.
Many country folks buy their firewood in long lengths and then cut and split them. For them, bucking wood is the major use of a top-rated chainsaw, and it may be worthwhile to get a saw of 60 cc to 70 cc with a 16- to 18-inch bar. My 52 cc Husky and 16-inch bar are fine for ash up to 24 inches, but a few more ccs would help with rock maple and oak. If you have had little experience with chainsaws, better to use chainsaw safety gear and get some practice cutting logs before learning how to fell trees. The most important consideration is to cut it to length ASAP so it can start drying. Cutting stems into products, called bucking, will develop some familiarity with the saw before delving into the more dangerous job of cutting a tree down.
On the surface, bucking wood into sections seems pretty simple, but consider some of the challenges. If the stem is perfectly straight, resting on perfectly flat, level ground, no problem—except keeping your bar and chain out of the dirt. Otherwise, you face tension and compression forces in wood that is under stress. Figure 1 shows a log resting on uneven ground, supported at two points. Midway between the two points, the log sags, causing compression in the upper half and tension in the lower half. In Figure 2, one end of the log is unsupported, causing the reverse. Cut the compression side and your saw will be pinched; cut the tension side, the stem may split. In both cases, cutting into a neutral side first does not release either compression or tension forces. Often, obstacles such as trees, rocks or stumps cause side pressures (Figure 3).
Start bucking wood by cutting the off side, then a little wood from the compression side, and finish by cutting the tension side. You can feel compression forces as they begin to bind your bar and can see tension as the saw kerf gradually opens. When cutting a compression side, slide the bar back and forth until you feel pressure, then switch to the tension side. Always, before cutting, try to visualize the stresses in the wood and how they will respond—each situation requires a different approach. Keep some wedges handy.
For those cutting timber from their woodlot, before bucking wood into logs, you must remove the limbs. Limbing is the cause of most accidents, though they are not as serious as those from falling. Long bars are probably the major cause of limbing accidents. Tension/compression forces are often present in limbs, sometimes severe (Figure 4) because branches on the underside of the stem are under pressure. Before cutting, analyze each limb to determine what stresses are likely.
Check the three limbs on the right of the tree in the photo on this page of the whole tree on the ground. The first limb is free with most of its weight to the right. Cut this limb from the top (tension side) and it will fall freely. But the second limb presses against the ground—cut it from the top, your saw will be pinched, so cut it from the underside. The third limb, under sufficient pressure that it is split, is too close to the ground to cut from the bottom. The best bet is to carefully make a V cut from the top, just beyond the split. To cut the V, as soon as you feel pressure against the bar, remove it and make the second side of the V. Then, widen the V until you get through the limb. To safely cut brush and hardwoods with branches bent sharply (Figure 4), make several shallow cuts to relieve tension.
Many conifers have whorls of limbs at the end of each year’s height growth and the stem is supported by many fairly small limbs. Scandinavians have developed several systems for removing such limbs, the lever (Figure 5) and sweep (Figure 6) methods. The lever method is suitable for trees with larger limbs fairly well distributed along the stem and the sweep method works well for slow-grown northern conifers with many small limbs.
To simplify limbing small conifers, fell them across another tree to hold them off the ground, preferably at waist height. With an elevated stem, you can slide the saw along the stem rather than carry it. Swedes often fell trees across an elevated roller, similar to a sawhorse with a roller on top. As the stem is bucked into sections, it is pulled across the roller rather than walking along the tree. One cutter I studied felled up to seven trees together so he could limb all of them at once.
Learn proper techniques for limbing and bucking wood before the tree felling starts.
Originally published in the May/June 2016 issue of Countryside.