Chainsaw Safety

Photos provided by the Central States Center for Agricultural Safety and Health (CS-CASH)

Chainsaws are valuable labor-saving devices used by many farm, ranch, and home owners. However, in the hands of an untrained operator, a chainsaw is extremely dangerous. A chainsaw at full speed runs more than 30 ft. of chain past a single point on the bar in the split-second it takes for a user to react.

Safety Precautions to Reduce Risk of Injury or Death

Take the following steps to reduce the risk of injury or death when using a chainsaw:

• Read the device’s instruction manual and safety manual, and then follow all recommended guidelines for the use of the chainsaw.
• Store the device’s manuals in a place where you can easily find them, and contact the company should you need to replace them. (Most chainsaw manuals are available online.)
• If you have never used a chainsaw, seek the guidance of a qualified mentor before using the chainsaw.
• Wear all personal protective equipment (PPE) recommended for chainsaw use while operating the chainsaw.
• Know the chainsaw’s limitations, know your own limitations, and take your time and rest often so that you remain alert for potential hazards.

Personal Protective Equipment (PPE)

Apply the following recommendations and information regarding PPE whenever you operate a chainsaw:

• Clothing: Clothes should fit well and should not dangle or have ragged edges that can get caught on limbs, bark, or the saw.
• PPE: All PPE required for operating a chainsaw must fit the operator properly and be in good condition.
• Leg chaps: Protective leg chaps made from ballistic nylon or Kevlar protect the legs from the running chain saw.
• Hard hat: Wear a properly fitted hard hat that is comfortable and provides protection from small falling limbs or debris.
• Face protection: Wear either a full-face shield or safety goggles or safety glasses with side shields to protect your face from flying wood chips, twigs, and sawdust.
• Hearing protection: Wear earplugs and/or earmuffs to protect your hearing from the noise levels associated with running a chainsaw, which can exceed 90 decibels (dB). Use hearing protection with a minimum noise reduction rating (NRR) of 25 to reduce your risk of noise-induced hearing loss.
• Footwear: Wear steel-toed high-top boots with aggressive-treaded soles to protect you from slipping and to protect your feet from potential contact with the saw chain or with heavy falling or rolling objects.
• Gloves: Wear leather gloves to protect your hands from cuts, abrasions, or splinters. You can wear specialized woodcutter’s gloves that have slip-resistant palms and are made of synthetic cut-resistant material similar to the material in leg chaps.

To learn more about PPE related to operating a chainsaw, view the following video by Progressive Farmer:

Chainsaw Selection

There are three size classes of chainsaws. It is important to identify the one that is the best match for the job(s) that you need to complete.

• Small-sized chainsaws have 8-in. to 14-in. guide bars and are designed to do light work, such as cutting small branches and felling very small trees.
• Medium-sized chainsaws have 16-in. to 22-in. guide bars and work well for felling, limbing, and bucking trees in the diameter range of 8 in. to 22 in.
• Large-sized chainsaws are designed for professional users and usually have guide bar lengths greater than 18 in. These chainsaws are designed for heavy daily logging use.

After you have determined the appropriate size chainsaw for your needs, select a chainsaw that is quiet and balanced and equipped with the following safety features:

• Front hand guard: The front hand guard is a paddle-like device, located ahead of the front (top) handle of the chainsaw such that it stops an operator’s left hand from coming in contact with the chain if this hand slips off the handle.
• Chain brake: Chain brakes, a feature of gas chainsaws, reduce the risk of injury, if activated, by stopping the saw’s chain immediately if kickback occurs. Usually, the chain brake is activated by contact with the front hand guard, but it also may be activated by a sudden jerk of the chainsaw (inertia activated feature). It is strongly recommended to purchase chainsaws with both types of chain brake activation in the chain brake system.
• Throttle trigger interlock: This feature prevents the accidental opening of the throttle.
• Stop switch: The stop switch should be easy for an operator to activate with his or her right thumb while gripping the saw’s rear handle.
• Antivibration system or vibration damping: An antivibration system can reduce operator fatigue and decrease the strain placed on the operator’s hands. Vibration damping (achieved through rubber bushings and/or metal springs on the chainsaw) reduces the operator’s exposure to vibration.
• Rear hand guard: A rear hand guard on the lower part of the chainsaw by the rear handle protects the operator’s right hand from a broken or jumping chain.
• Reduced kickback or antikickback chain: Most consumer chainsaws are equipped with low-kickback chains or chains that are designed to have reduced kickback energy.
• Chain catcher: This feature is designed to catch a broken or jumping chain.
• Continuous pressure throttle: This feature shuts off power to a chainsaw when pressure is reduced.
• Muffler: The muffler limits the noise level of the saw and directs hot exhaust gases away from the operator.
• Spark arrestor: A spark arrestor prevents sparks from being ejected by the exhaust.

Chainsaw Maintenance and Fueling

A chainsaw that is in proper working condition is safer and easier to operate than a poorly maintained machine. Before using your chain saw, take the following actions:

• Make sure the chain is properly sharpened.
• Make sure the chain is properly tensioned on the chainsaw bar.
• Make sure the chain oiler reservoir is filled with proper bar and chain oil.

Maintaining proper chain tension during chainsaw operation is important because a loose chain could come off and a tight chain could bind and overheat. When you are sharpening the cutters on the chainsaw chain, wear gloves and cover the chain with a heavy rag. Make sure your chain oiling system is working properly. To learn how to sharpen your chainsaw, watch the following video from Progressive Farmer:

Allow the chainsaw to cool 5 minutes before refueling, and use a funnel or flexible nozzle to avoid spills. Make sure the chainsaw is at least 20 ft. away from any sources of ignition prior to fueling. If any fuel is spilled, wipe the saw dry before starting it. Move the chainsaw at least 10 ft. from the fueling area before attempting to start it.

Chainsaw Operation

Always engage the chain brake before attempting to start the chainsaw. There should always be two points of contact with the chainsaw (other than the hand on the starter rope) when starting the chainsaw. Study and practice the two approved starting methods for the gas-powered chainsaws described in your chainsaw operator’s and/or safety manual. Never hold the starter rope and use the weight of the saw to “drop start” the saw—you risk serious injury from recoil of the chainsaw bar. For information about starting a chainsaw, watch the following video from Stihl titled “How to Start a Stihl Chainsaw”:

Maintain secure footing and balance during operation of the chainsaw. Always hold the chainsaw firmly with the right hand on the rear handle and the left hand on the front handle. Use an encircling grip (fingers over/thumb under on each handle). Remember to turn off the chainsaw, engage the chain brake, and carry the saw with the bar facing rearward and the muffler away from you when walking more than 50 ft. or across hazardous terrain. Engage the chain brake when moving short distances (less than 50 ft.) with the chainsaw running.

Addressing Pull-in, Pushback, and Kickback Reaction Forces

(Source: University of Missouri with permission granted from Stihl Chainsaw, Inc.)

Violent reaction forces occur when the teeth of a chainsaw catch on something or when wood closes in and pinches the saw chain, causing the saw chain to stop instantly. The resulting reaction forces cause the chainsaw to be pulled away from the operator (pull-in force—frame 1 of image above), cause the chainsaw to be pushed back toward the operator (pushback force—frame 2 of image above), and/or cause kickback toward the operator (kickback force—frame 3 of image above). The pull-in force occurs when the chain on the top of the bar is being used to cut an object. The pushback force occurs when the chain on the bottom of the bar is being used to cut an object. The kickback force occurs when the chain on the upper quadrant of the nose of the bar (frame 4 of image above) comes in contact with another object.

 All of these forces happen quicker than the operator can react. Proper PPE; stance (body, foot, and arm position); grip on the chainsaw; and cutting techniques may significantly reduce the occurrence of and risk associated with these reaction forces. Poor control of these reaction forces by the untrained operator, careless operator, or inattentive operator may result in serious or fatal injury.

The kickback force generally is regarded as the most dangerous of the reaction forces because the blade of the chainsaw usually is thrown into the head, neck, or shoulder area of the operator, resulting in serious or fatal injury. The end result of an uncontrolled pull-in or pushback reaction force may be a kickback reaction. If the tip of the chainsaw blade is pulled into another object in the case of a pull-in reaction or strikes solid material as the tip exits the cut at the end of the pushback reaction, a kickback force results.

Take the following precautions to prevent kickback:

• Hold the saw firmly with both hands using an encircling grip.
• Do not cut limbs or brush with the nose of the guide bar.
• Begin and continue cutting at full throttle.
• Cut only one log at a time.
• Use caution when reinserting the chainsaw blade into a previous cut or withdrawing it from the current cut.
• Be aware of the location of your guide bar nose at all times when starting or operating the chainsaw and do not let it come into contact with an object.
• Do not attempt a chainsaw cutting technique called bore cutting (plunge cutting) without hands-on training and supervised practice to teach you to properly do this cutting technique while helping you become proficient with this technique.

Felling a Tree

Proper felling of a tree with a chainsaw is a planned operational process that results in causing a tree to fall from a standing position to a predetermined location lying on the ground while minimizing risks to the saw operator, coworkers, the residual forest stand, and any other important objects in the immediate area. This complicated process involves hazard analysis, site assessment, and a careful evaluation of the tree’s properties (health, weight distribution, leans, and entanglements with other trees or vines). The results of this analysis are used by the faller (the saw operator) to plan the felling job. The faller sets up escape routes, chooses which specific felling techniques are needed, plans the sequence of events, and selects the tools he or she will need to complete the felling job safely and effectively. The faller communicates the plan to all coworkers and is responsible for the safety of all coworkers and others in the immediate area.

The process of felling a tree with a chainsaw should never be attempted by the untrained chainsaw operator. A faller needs to have had hands-on training in this activity by a skilled professional and supervised practice under the guidance of this skilled professional because of the complicated and inherently dangerous nature of the activity of felling trees.

The following important training and skills-development activities are needed to safely and effectively fell trees:

• Hazard assessment, mitigation, and avoidance techniques
• Tree evaluation (tree size-up) procedures
• Planning the felling job based on tree, site, and hazard information
• Safety zone and escape route planning
• Chainsaw cutting techniques specific to felling trees
• Chainsaw operator skills necessary to execute felling cutting techniques
• Knowing how, when, and why you use special felling tools (wedges and felling levers)
• Controlling the entire felling process
• Knowing your skill level and your limitations
• Knowing what hazards make the job too dangerous to attempt

Limbing

Limbing is the process of removing the branches and limbs from a fallen tree. Limbing with a chainsaw is perhaps the most dangerous activity the chainsaw operator does in the course of daily chainsaw operation. This is because of the following circumstances:

• Felling the tree may have caused serious overhead hazards (widow makers) that may pose a direct threat to the chainsaw operator when limbing.
• Felling the tree onto the ground created complex forces in limbs, branches, and tree stems which are released when these objects are cut with the chainsaw.
• The fallen tree poses a complex collection of hazards that change as the chainsaw operator removes the limbs.
• The chainsaw operator is forced to stand and work close to the hazards related to the fallen tree.
• The chainsaw operator must constantly recognize, evaluate, mitigate, and/or avoid the hazards related to the fallen tree.
• The chainsaw operator must cut in close proximity to his or her feet and legs.
• The end of the chainsaw bar is used to make limbing cuts, and the kickback zone must be avoided.
• An escape route must be maintained behind the chainsaw operator at all times.
• Removing limbs from the tree may destabilize it, causing it to roll, drop, swing, or rise suddenly.
• The chainsaw operator must stay aware of the slope of the terrain and stay on the uphill side of the fallen tree.

The process of limbing a fallen tree should never be attempted by an untrained chainsaw operator. A chainsaw operator attempting to limb a tree needs to have had hands-on training in this activity by a skilled professional and supervised practice under the guidance of this skilled professional because of the complicated and inherently dangerous nature of the activity of limbing fallen trees.

(Video Source: Husqvarna.com.)

Bucking

Bucking is the process of using a chainsaw to cut a tree into lengths of wood usable as pulpwood, saw logs, or firewood. The bucking process usually follows the limbing process but may be combined with the limbing process to help reduce forces on the remaining limbs by removing weight (log length portions) from the previously limbed areas of the tree stem. The hazards associated with this operation are mostly related to sudden movement of the bucked section, the remaining tree stem, or both following or during the bucking cut with the chainsaw. There is a strong possibility that serious or fatal crush injuries may result if an untrained chainsaw operator attempts to buck tree stems. Hands-on training in this activity by a skilled professional and supervised practice under the guidance of this skilled professional will help to minimize the risk of these injuries. The following important training and skills-development activities are needed to buck trees safely and effectively:

• Assessing the presence of binds (forces in the tree stem due to its position on the existing terrain) at the point where the bucking cut is to be made (see the images below)
• Recognizing, mitigating, or avoiding the hazards to the chainsaw operator caused by binds
• Chainsaw cutting techniques specific to bucking safely and effectively
• Chainsaw operator skills necessary to execute bucking cut techniques
• Recognizing terrain features which may lead to sudden log or stem movement (cut from the uphill side)
• Providing adequate escape routes
• Use of wedges to control bucking cuts (avoid unwanted stem movement or chainsaw contact with the ground)

(Source: University of Georgia.)

One of the most common problems during bucking is running the chainsaw into the ground. A sawbuck can make this task easier by holding the log still at the appropriate working height so that you can safely cut the tree into the appropriate lengths. Another useful device is a log jack (adapted peavey), which can lift one end of a log off the ground for bucking. Log jacks are commercially available or can be built in a farm shop.

(Video Source: Progressive Farmer Magazine.)

Additional Safety Recommendations

• Never operate a chainsaw alone. Always work with a competent adult partner.
• Because operating a chainsaw can place strain on the back, stretch and strengthen your back muscles to decrease the strain.
• Stay low to the ground, and do not operate your chainsaw at a level higher than your waist.
• Do not permit a child to operate a chainsaw. Do not use a chainsaw in close proximity to children or pets.
• Tell other people where you are going to be working and when you expect to return.
• Always know the location of other people in your group, especially when felling a tree.
• Maintain at least 2½ tree lengths between you and other persons operating chainsaws when felling.
• Make sure your chainsaw is sitting upright during transport to avoid spillage of gasoline.
• Never transport a chainsaw in the passenger area of a vehicle because the chainsaw could become a dangerous projectile or a source of highly flammable liquid in the event of an accident.
• When working with a chainsaw, make sure you have a complete first-aid kit with you and the current training to use this kit to control or treat severe bleeding, second-degree burns, broken bones, and shock.