How To Minimize Cutting Vibration
In the short term, a saw that vibrates excessively causes your hands to tingle and your elbows to ache. This adds to fatigue, reduces productivity, and increases the “work” of running a pro saw. Over the long term, excess cutting vibration is more than an irritating cutting characteristic. It can cause serious injury.
Compared to non-professional users, pro saw users are more prone to injury from vibration because you run a saw for hours at a time and do it almost every day. You may also have gotten used to damaging vibration or become desensitized to it. But beware, what may not bother you can still harm you. Some veteran timber fallers develop circulatory problems in their hands, such as numbness and painful sensitivity to heat and cold.
Vibration is not good for your saw engine either. It leads to premature bearing failure, and increases component failure due to cracking and fatigue. It also rattles components apart, damaging mounting points and stripping fasteners.
What Causes Vibration
On a pro saw, vibration is caused by two things: engine vibration and cutting vibration. Engine vibration is largely the domain of saw manufacturers. To their credit, thei engines in today's powerheads are better balanced and smoother running than their predesessor. Today's saws also feature handlebar supension systems that isolate the user from a saw's engine vibration. Other than choosing to run a new saw engine over an earlier model, and maintaining its engine and AV system, a pro saw user has little control of a saw's engine vibration.
Cutting vibration is different. It is caused by the action of the saw's chain's cutter teeth as it severs wood fiber. Like saw engine manufacturers, chain producers have also developed saw chain that vibrates less. But even with improvements in the design of saw chain, a saw's operator plays a big role in managing the cutting vibration his saw makes.
Uneven and Over-Cut Depth Gauges
There is no single cause of rough cutting saw chain, but there are a number of mistakes many pro saw users make. The most common is over-cut depth-gauges. Overly aggressive saw chain takes bigger bites of wood than it is designed for. In the process, cutting vibration increases. Many pro saw users don’t realize the “hungry” feel of an ultra-aggressive saw chain also causes it to vibrate more than it should.
This depth gauge is cut too low. It is also filed flat and should have a rounded nose. It is best to restore the depth gauges original shape.
Much of the time, when we see depth gauges that are over-cut, they are often also unevenly-cut. Since depth gauges control the amount of wood each cutter tooth takes, when they are uneven, each cutter tooth cuts a different amount of wood. This causes some cutter teeth to pull harder than others -- a recipe for vibration.
Uneven depth-gauges are usually the result of sloppy measuring. Some users count file strokes as a method for measuring how much depth gauges are being cut. The problem is, each file stroke does not remove the same amount of depth gauge material. Measuring by counting file strokes may seem to work when a chain is new, but after the depth gauges are cut several times, this is not the case. The inaccuracy of this method adds up and the depth-gauges are uneven.
Each depth-gauge should be measured and set accurately when it is lowered. Yes, this is tedious, but it is important. This is why many pros employ a depth-gauge grinder like the Silvey HDG-6. This makes cutting depth gauges much easier. Once set up, a hand crank advances the chain past the grinding wheel, quickly and easily cutting its depth-gauges in the process.
Other Causes Of Cutting Vibration
Unevenly sharpened cutter teeth can also cause vibration. All cutter teeth must be the same length and sharpened at the same angle. They must also all be sharp. As obvious as that sounds, for saw chain to cut smoothly, it is important for every cutter tooth to take the same size bite of wood. Anything that causes individual teeth to take different sized bites can cause vibration.
How Sequence & Pitch Affects Cutting Vibration
Most pro saw users who cut large softwood trees in the Northwestern US and Alaska, typically run long bars -- 32" and longer. These long guide bars are usually fitted with skip-tooth saw chain. While this combination works well when a such a bar is immersed in a big log, skip-tooth sequence is more prone to cutting vibration. The additional space between cutter teeth improves its cutting performance in deep cuts, but also causes skip-tooth chain to vibrate more. This characteristic is even more pronounced when skip-tooth chain is used to cut limbs and make other small diameter cuts. This is why, in many cases, it is best to run a full-compliment saw chain, even in combination with a long bar.
Another mistake we sometimes see is when skip-tooth chain is used on saws with bars lengths of 24" and less. With bars of this length, it is not possible to make a deep enough cut for a skip-tooth configuration to offer any benefit. Other than having fewer teeth to sharpen, the use of skip-tooth chain on a short bar will cut slower and cause more cutting vibration than a full-comp configuration. So on bar lengths of 24" or less, full-comp chain always the best choice.
Along with a chain's configuration, pitch makes a difference, too. We have noticed that main bearing problems occur more frequently on saw engines running .404" pitch than saws of the same model running 3/8" pitch. Since 3/8" pitch saw chain is a little smaller it generally runs smoother and is easier on the engine's bearings.
Today's Saw Chain Vibrates Less
There is an ongoing effort among today's saw chain manufacturers to reducing the cutting vibration of saw chain. Oregon Cutting Systems, for one, has developed special tools for measuring cutting vibration, and has used them to develop products that vibrate less. Their Vibe-Ban technology is a result.
Without getting too technical, Oregon engineers found that by removing a small amount of material from the base of each cutter tooth and its adjacent tie strap, the heel of each cutter will "float" above the rails on the guide bar. On earlier designs, when a cutter tooth impacted the wood, it released a jolt of energy into the guide bar. A small space between each cutter's heel and the bar rail, creates a "shock absorber" that dissipates much of the energy. Tests show it reduces cutting vibration by 25% or more.
They have found other ways to reduce cutting vibration, too. These are being incorporated into the newest chain designs. By reducing cutting vibration, saws perform better and operators are more comfortable and productive.
• Check the depth gauges on your saw chain. Make sure they are set at the proper height and set evenly. If they need to be lowered, don’t over-do it.
• Round the fronts of your chain's depth gauges after you lower them. Try to return them to their original shape.
• Sharpen your cutter teeth accurately. Maintain the correct angles and keep all cutter teeth the same length.
• If you run bar of 24" or less or cut a lot of limbs or small diameter trees, use full-comp saw chain. This is the smoothest and fastest cutting sequence for making short cuts.
If your saw has excess cutting vibration, hopefully this information helps you overcome it. As always, if we can help, please contact us. We don’t have all the answers, but we do have a lot of experience. On top of this, we can involve a host of technical experts if need be. So contact us if you have a question or problem with your pro saw chain. Our experience and resources are here for you... That’s why we’re the pro’s choice.