Getting your chainsaw pinched is one of the most common and frustrating problems encountered by inexperienced chainsaw operators. It is easy to underestimate the forces involved with cutting wood, so it can be incredibly easy to get your bar, chain, or both stuck under hundreds if not thousands of pounds of pressure. That’s a good recipe for broken and bent bars and chains, substantial time delays, and an overall unpleasant experience. As common as this problem is, there is good news: it is 100% avoidable. Avoiding saw pinches only requires an understanding of the forces involved, knowledge of proper techniques, and the development of an eye for estimating those forces and matching them with proper techniques. In this article we will cover everything you need to know to begin building this skill set and prevent your chainsaw from getting pinched.
Let’s begin by discussing the fundamental forces in a log: Compression and Tension.
Understanding Compression and Tension
As the Taoists have Yin and Yang and congress has Democrats and Republicans, loggers must contend with compression and tension. In case you missed middle school physics class, compression refers to the force of matter pushing together, and tension refers to matter pulling apart. Because a log is little more than a massive lever for various forces (a standing tree even more so), there will always be parts of the log under tension and parts under compression. It is only a question of how much tension and compression the wood is under. Take a look at the diagram below to see how compression and tension can manifest in a log in a couple situations where the main force is gravity.
Compression
Compression is the main culprit of a pinched chainsaw. When the teeth of the chain chisel away wood in an area under compression, they remove material that structurally supports the stem and prevents the wood from collapsing in on itself, thus, the chain becomes the new support material. The cut will close in on itself and push against either side of your bar and chain. That’s how your chainsaw gets pinched.
Tension
Tension by itself is not going to pinch your saw, as its forces result in the opposite of a pinch, but that doesn’t mean it shouldn’t be understood and dealt with appropriately. For one, cutting wood under extreme amounts of tension, (such as a spring pole) is dangerous. Releasing tension without releasing compression can result in the tension pulling away fibers, resulting in barber chairs, sudden snap backs, and other unpredictable and dangerous outcomes.
Thus, tension and compression must be dealt with individually and properly. Here is how to approach them safely while preventing your chainsaw from getting pinched.
Preventing Pinches When Felling Trees
A pinch while felling a tree can… put you in a pinch. Not only can it be a dangerous situation with your only felling tool suspended under thousands of pounds of unstable, ready-to-fall timber, but it can be a difficult situation to work yourself out of. Prevention is key, and in this case, prevention is simple: Use a felling wedge.
Usually, felling wedges are used to wedge into the back cut and gradually displace the tree’s center of mass until it falls in the desired direction. In this case, however, the wedge serves a simpler purpose as a place holder. When gently inserted into the back cut as it is being cut, the wedge replaces the structural support of the removed material, and the tree can fall back onto the wedge instead of the bar of your saw. If your bar does still get pinched, simply pound the wedge a bit to bring the tree back up and off the saw. Its that simple.
Ideally, bore cutting is a better method of making a back cut partially for this reason. It allows you to leave structural support at the back of the stem as you set the hinge (thus working to effectively prevent the chainsaw from getting pinched), and it allows for better wedge placement prior to releasing that support. You can read more about how to bore cut here.
Preventing Pinches When Cutting on the Ground or on Suspended Logs
Preventing your chainsaw from getting pinched when cutting logs on the ground or when the log is suspended in air is a bit tricker than when felling standing timber, as the forces aren’t as obvious or readily identifiable. Nonetheless, with practice and a keen eye, it is just as preventable.
First, it is important to identify which side is under tension and which is under compression. Again, this can be tricky, as it requires judging centers of mass, fulcrums, and other generic physics terms. You will likely misjudge many times and that’s ok. It happens to the best of us, and your skills will improve. Once you have your best guess, begin by cutting into the compression side by about 1/3 the way through. This allows the compression to be released, but not so much as to pinch your saw.
With that cut made, proceed by finishing the cut on the tension side and allowing the cuts to meet. You will notice that as your second cut goes deeper, the compression side will collapse in on itself while the tension side pulls apart and provides a larger cutting area. Its quite a contrast from dealing with an increasingly tight pinch.
It is important that the cut on the compression side is not skipped. Without that release cut, the cut on the tension side will eventually (and likely suddenly) switch to compression as you approach total severance. And again, not providing space for compression to release can result in sudden release of tension, especially when dealing with spring poles.
Preventing Pinches When Limbing
Pinches that occur when limbing a felled tree are more common and a bit tougher to avoid. Luckily, they are rarely serious and usually a nuisance that requires a light tug to fix. While limbing thicker branches, you may need to take more precautions and release compression first as you would for a regular log. When branches are small to medium in diameter, however, that can be impractical, as branches are pushed in every direction, and it is impractical to meticulously cut each one. In this situation, there is only one good solution: Full throttle. Going wide open on the saw to maximize momentum helps the saw to overcome any compression force and sever the branch before it brings the chain to a stop.
Warning: Cutting Spring Poles and High-Tension Wood
It cannot be said enough: When felling and cutting timber, we are dealing with immense amounts of stored energy that is often hidden or deceivingly benign. Do not get comfortable, as these forces can present grave dangers, and nowhere is this more true than with spring poles. Spring poles are what are created when a tree is felled on top of a smaller tree, bending it back without breaking it. The bent tree works as a spring storing unfathomable energy that can be suddenly and instantaneously released if improperly cut. If you are in its way when it is released, all that energy will be absorbed by your limbs, torso, or face with potentially fatal consequences. Spring poles are hidden killers, so it is important to keep a watchful eye for these situations.
If you encounter a spring pole, DO NOT CUT THE TENSIONED SIDE. Always cut a spring pole from the COMPRESSION and only gradually. The high amount of energy must be released and defused incrementally.
The safest way to do this is to find the apex of the bend–the peak of the bend where the two sides create a sort of point. From there, release the compression by slowly and carefully shaving away layers of the wood as if you are slicing cheese. As you slowly work through the wood, the compression will gradually collapse in on itself dissipating the energy and eventually breaking the stem, at which point the spring pole will be safe to cut normally. When cutting, be sure to position yourself away from the direction of a potential release.
As with all activities with a chainsaw, use common sense and be aware of your limitations. If you are not confident a threat can be dealt with safely, consider using a machine, winch, or come along to move the fallen tree off the spring pole.
Practice Makes Perfect
As mentioned throughout, these skills take practice. Have patience. While pinches are high on the list of aggravations that can drive a man to do horrible things, they will diminish with time so long as you take the time to understand how to prevent the situation and build proper technique. So as always, be safe and don’t forget to have fun, even if your saw is currently stuck under two thousand pounds of tree.