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A chainsaw (or chain saw) is a saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. Modern chainsaws are used in activities such as tree felling, limbing, bucking, pruning, cutting firebreaks in wildland fire suppression, harvesting of firewood, for use in chainsaw art and chainsaw mills, for cutting concrete, and cutting ice. Precursors to modern chainsaws were first used in surgery, with patents for wood chainsaws beginning in the late 19th century.

A chainsaw (or chain saw[1]) is a portable saw that cuts with a set of teeth attached to a rotating chain driven along a guide bar. Modern chainsaws are typically gasoline-, electric-, or battery-powered and are used in activities such as tree felling, limbing, bucking, pruning, cutting firebreaks in wildland fire suppression, and harvesting of firewood.

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A precursor of the chainsaw familiar today in the timber industry was another medical instrument developed around 1830, by German orthopaedist Bernhard Heine. This instrument, the osteotome, had links of a chain carrying small cutting teeth with the edges set at an angle; the chain was moved around a guiding blade by turning the handle of a sprocket wheel. As the name implies, this was used to cut bone.[7]

One of the earliest patents for an "endless chain saw" comprising a chain of links carrying saw teeth was granted to Frederick L. Magaw of Flatlands, New York in 1883, apparently for the purpose of producing boards by stretching the chain between grooved drums.[8][9] A later patent incorporating a guide frame was granted to Samuel J. Bens of San Francisco on January 17, 1905, his intent being to fell giant redwoods.[10] The first portable chainsaw was developed and patented in 1918 by Canadian millwright James Shand.[11][12] After he allowed his rights to lapse in 1930, his invention was further developed by what became the German company Festo in 1933. The company, now operating as Festool, produces portable power tools. Other important contributors to the modern chainsaw are Joseph Buford Cox and Andreas Stihl; the latter patented and developed an electric chainsaw for use on bucking sites in 1926[13] and a gasoline-powered chainsaw in 1929, and founded a company to mass-produce them. In 1927, Emil Lerp, the founder of Dolmar, developed the world's first gasoline-powered chainsaw and mass-produced them.

World War II interrupted the supply of German chain saws to North America, so new manufacturers sprang up, including Industrial Engineering Ltd (IEL) in 1939, the forerunner of Pioneer Saws Ltd and part of Outboard Marine Corporation, the oldest manufacturer of chainsaws in North America.[14]

In 1944, Claude Poulan was supervising German prisoners cutting pulpwood in East Texas. Poulan utilized an old truck fender and fashioned it into a curved piece utilized to guide the chain. The "bow guide" now allowed the chainsaw to be utilized by a single operator.

McCulloch in North America started to produce chainsaws in 1948. The early models were heavy, two-person devices with long bars. Often, chainsaws were so heavy that they had wheels like dragsaws. Other outfits used driven lines from a wheeled power unit to drive the cutting bar.

After World War II, improvements in aluminum and engine design lightened chainsaws to the point where one person could carry them. In some areas, the chainsaw and skidder crews have been replaced by the feller buncher and harvester.

Chainsaws have almost entirely replaced simple man-powered saws in forestry. They are made in many sizes, from small electric saws intended for home and garden use, to large "lumberjack" saws. Members of military engineer units are trained to use chainsaws, as are firefighters to fight forest fires and to ventilate structure fires.

The first electric chainsaw was invented by Stihl in 1926.[15] Corded chainsaws became available for sale to the public from the 1960s onwards,[16] but these were never as successful commercially as the older gas-powered type due to limited range, dependency upon the presence of an electrical socket, plus the health and safety risk of the blade's proximity to the cable.[17]

For most of the early 21st century petrol driven chainsaws remained the most common type, but they faced competition from cordless lithium battery powered chainsaws from the late 2010s onwards.[18] Although most cordless chainsaws are small and suitable only for hedge trimming and tree surgery,[19] Husqvarna and Stihl began manufacturing full size chainsaws for cutting logs during the early 2020s.[20] Battery powered chainsaws should eventually see increased market share in California due to state restrictions planned to take effect in 2024 on gas powered gardening equipment.[21][22]

Chainsaw engines are traditionally either a two-stroke gasoline (petrol) internal combustion engine (usually with a cylinder volume of 30 to 120 cm3) or an electric motor driven by a battery or electric power cord. In a petrol chainsaw, fuel is generally supplied to the engine by a carburetor at the intake.

To allow use in any orientation, modern gas chainsaws use a diaphragm carburetor, which draws fuel from the tank using the alternating pressure differential within the crankcase. Early engines used carburetors with gravity fed float chambers, which caused the engine to stall when tilted. The carburetor may need to be adjusted to maintain an appropriate idle speed and air-fuel ratio, such as when moving to a higher/lower altitude or as the air filter clogs. Carburetors are adjusted either by the operator or, in some saws, automatically by an electronic control unit.

Consistent improvement to overall chainsaw design, including adding safety features, has taken place over the years. These include chain-brake systems, better chain design, and lighter, more ergonomic saws, including fatigue-reducing antivibration systems.

As chainsaw carving has become more popular, manufacturers are making special short, narrow-tipped bars (called "quarter-tipped" "nickel-tipped", or "dime-tipped" bars, based on the size of their tips). Some chainsaws are built specifically for carving applications.[26] Echo sponsors a carving series.[27]

Separate chain oil or bar oil is used for the lubrication of the bar and chain on all types of chainsaws. The chain oil is depleted quickly because it tends to be thrown off by chain centrifugal force, and it is soaked up by sawdust. On two-stroke chainsaws, the chain oil reservoir is usually filled up at the same time as refueling. The reservoir is normally large enough to provide sufficient chain oil between refueling. Lack of chain oil, or using an oil of incorrect viscosity, is a common source of damage to chainsaws, and tends to lead to rapid wear of the bar, or the chain seizing or coming off the bar. In addition to being quite thick, chain oil is particularly sticky (due to "tackifier" additives) to reduce the amount thrown off the chain. Although motor oil is a common emergency substitute, it is lost even faster, so leaves the chain under-lubricated.

Protective clothing is designed to protect operators in the event of a moving chain touching their clothing by snarling the chain and sprocket, by using special synthetic fibers woven into the garment. Despite safety features and protective clothing, injuries can still arise from chainsaw use, from the large forces involved in the work, from the fast-moving, sharp chain, or the vibration and noise of the machinery.[29]

Another dangerous situation occurs when heavy timber begins to fall or shift before a cut is complete. The chainsaw operator may be trapped or crushed.[31] Similarly, timber falling in an unplanned direction may harm the operator or other workers, or an operator working at a height may fall or be injured by falling timber.

Like other hand-held machinery, the operation of chainsaws can cause vibration white finger,[32] tinnitus, or industrial deafness. These symptoms were very common before vibration dampening using rubber or steel spring was introduced. Heated handles are additional help. Newer, lighter, and easier to wield cordless electric chainsaws use brushless motors, which further decrease noise and vibration compared to traditional petroleum-powered models.

The risks associated with chainsaw use mean that protective clothing such as chainsaw boots, chaps, and hearing protectors are normally worn while operating them, and many jurisdictions require that operators be certified or licensed to work with chainsaws.[where?] Injury can also result if the chain breaks during operation due to poor maintenance or attempting to cut inappropriate materials.

Drop starting, or turning on a chainsaw by dropping it with one hand while pulling the starting cord with the other, is a safety violation in most states in the U.S.[34] Keeping both hands on the saw for stability is essential for safe chainsaw use.

Safe and effective chainsaw and crosscut use on federally administered public lands within the United States has been codified since 2016 in the Final Directive for National Saw Program[35] issued by the United States Forest Service, which specifies the training, testing, and certification process for employees and unpaid volunteers who operate chainsaws within public lands.

Chainsaws with specially designed bar-and-chain combinations have been developed as tools for use in chainsaw art and chainsaw mills. Specialized chainsaws are used for cutting concrete during construction developments. Chainsaws are sometimes used for cutting ice; for example, ice sculpture and winter swimming in Finland.

Special chainsaws can cut concrete, brick, and natural stone. These use similar chains to ordinary chainsaws, but with cutting edges embedded with diamond grit. They may use gasoline or hydraulic power, and the chain is lubricated with water, because of high friction and to remove stone dust. The machine is used in construction, for example, in cutting deep, square holes in walls or floors, in stone sculpture for removing large chunks of stone during pre-carving, by fire departments for gaining access to buildings, and in restoration of buildings and monuments for removing parts with minimal damage to the surrounding structure. More recently, concrete chainsaws with electric motors of 230 volts have also been developed.[39] 2351a5e196