A chainsaw is a portable, mechanical saw which cuts with a set of
teeth attached to a rotating chain that runs along a guide bar. It is
used in activities such as tree felling, limbing, bucking, pruning,
cutting firebreaks in wildland fire suppression and harvesting of
firewood. 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. Chainsaws
are sometimes used for cutting ice, for example for ice sculpture and
in Finland for winter swimming. Someone who uses a saw is a sawyer.
2.2 Drive mechanism
2.3 Guide bar
2.3.2 Oil holes
2.3.3 Grease holes at bar nose
2.3.4 Guide slot
2.3.5 Bar types
2.4 Cutting chain
2.5 Tensioning mechanism
2.6 Safety features
5 Working techniques
6 Cutting stone, concrete and brick
7 See also
9 External links
Historical osteotome, a medical bone chainsaw
Typical of the earliest chainsaws, this
Dolmar saw is operated by two
The origin is debated, but a chainsaw-like tool was made around 1830
by the 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. The prototype of the chain saw familiar today in
the timber industry was pioneered in the late 18th century by two
Scottish doctors, John Aitken and James Jeffray, for symphysiotomy and
excision of diseased bone respectively. The chain hand saw, a fine
serrated link chain which cut on the concave side, was invented around
1783-1785. It was illustrated in Aitken's Principles of Midwifery or
Puerperal Medicine (1785) and used by him in his dissecting room.
Jeffray claimed to have conceived the idea of the chain saw
independently about that time but it was 1790 before he was able to
have it produced. In 1806, Jeffray published Cases of the Excision of
Carious Joints by H. Park and P. F. Moreau with Observations by James
Jeffray M.D. In this communication he translated Moreau's paper of
1803. Park and Moreau described successful excision of diseased
joints, particularly the knee and elbow. Jeffray explained that the
chain saw would allow a smaller wound and protect the adjacent
neurovascular bundle. While a heroic concept, symphysiotomy had too
many complications for most obstetricians but Jeffray's ideas became
accepted, especially after the development of anaesthetics. Mechanised
versions of the chain saw were developed but in the later 19th
Century, it was superseded in surgery by the Gigli twisted wire saw.
For much of the 19th century, however, the chain saw was a useful
McCulloch electric chainsaw
The earliest patent for a practical "endless chain saw" (a saw
comprising a chain of links carrying saw teeth and running in a guide
frame) was granted to Samuel J. Bens of San Francisco on January 17,
1905. His intent being to fell giant redwoods. The first portable
chainsaw was developed and patented in 1918 by Canadian millwright
James Shand. 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 operates as
Festool producing portable
power tools. Other important contributors to the modern chainsaw are
Joseph Buford Cox and Andreas Stihl; the latter patented and developed
an electrical chainsaw for use on bucking sites in 1926 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
World War II interrupted the supply of German chain saws to North
America, so new manufacturers sprang up including Industrial
Engineering Ltd (IEL) in 1947, the forerunner of Pioneer Saws. Ltd and
part of Outboard Marine Corporation, the oldest manufacturer of
chainsaws in North America.
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
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 skidder (chainsaw) crews have been replaced by the
feller buncher and harvester.
Chainsaws have almost entirely replaced simple man-powered saws in
forestry. They come 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.
There are three main types of chainsaw sharpeners - Handheld File,
Saw and Bar Mounted.
The cutting chain seen here features the popular chipper teeth style
A chainsaw consists of several parts:
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. Combustion engines today (2016) are supplied
through a traditional carburetor or an electronically adjustable
The traditional carburetor needs to be adjusted, i. e. when operating
in high or low altitudes, or their fuel oil-to-gasoline ratios must be
adjusted to run properly. Electrically influenced carburetors make all
adjustments automatically. These systems are provided by most large
chain saw producers. Husqvarna calls its "Autotune," and it is
commonly standard on most saws of the 5XX saw series.
To reduce user fatigue problems, traditional carburetors can be
de-vibrated (protected from vibrations) or they can be heated as well.
Many saws offer a Winter and Summer mode of operation. Winter mode
applies in temperatures below 0 °C / 32 °F where inside
the cover a hole is opened leaving warm air to the air filter and
carburetor to prevent icing. In warmer environment the hole is closed
and both units are not ventilated with warm air.
To ensure clean air supply to the carburetor, chainsaw producers offer
different filters with fine or less fine mesh. In clean surrounding
air a less fine filter can be used, in dusty environment the other.
The fine filter keeps the air clean to its optimum (i.e. 44 µm)
but has the tendency to clog. This leads to the engine dying.
The engines are designed so that they may be operated in different
positions, upside-down or tilted 90 degrees. Early engines died when
tilting (two man saw from Dolmar,
Germany from 1930 to 1937).
Typically a centrifugal clutch and sprocket. The centrifugal clutch
expands with raising spinning speed towards a drum. On this drum sits
either a fixed sprocket or an exchangeable one. The clutch has three
jobs to do: When the saw runs idle (typically 2500-2700 rpm) the
chain does not move. When the clutch is engaged and the chain stops in
the wood or another reason, it protects the engine. Most important it
protects the operator in case of a kickback. Here the chain brake
stops the drum and the clutch releases immediately.
Clutches and drums can be in two positions: either turned outside
(Husqvarna) or inside (Stihl).
An elongated bar with a round end of wear-resistant alloy steel
typically 40 to 90 cm (16 to 36 in) in length. An edge slot
guides the cutting chain. Specialized loop-style bars, called bow
bars, were also used at one time for bucking logs and clearing brush,
although they are now rarely encountered due to increased hazards of
All guide bars have some elements for operation:
The lower part of the chain runs in the gauge. Here the lubrication
oil is pulled by the chain to the nose. This is a very important
At the end of the saw power head there are two oil holes, one on each
side. These holes must match with the outlet of the oil pump. The pump
pumps the oil through the hole in the lower part of the gauge. (See
Saw bar producers provide a large variety of bars matching different
Grease holes at bar nose
Through this hole grease is pumped, typically each tank filling to
keep the nose sprocket well lubricated.
Here one or two bolts from the saw run through. The clutch cover is
put on top of the bar and it is secured though this/these bolts. It
depends on the size of the saw if one or two bolts are installed.
There are different bar types available:
These bars consist of different layers to reduce the weight of the
These bars are solid steel bars intended for professional use. They
have commonly an exchangeable nose since the sprocket at the bar nose
wears out faster than the bar.
These bars are laminated bars with a small sprocket at the nose. The
small nose reduces the kickback effect. Such bars are used on consumer
Usually each segment in this chain (which is constructed from riveted
metal sections similar to a bicycle chain, but without rollers)
features small sharp cutting teeth. Each tooth takes the form of a
folded tab of chromium-plated steel with a sharp angular or curved
corner and two beveled cutting edges, one on the top plate and one on
the side plate. Left-handed and right-handed teeth are alternated in
the chain. Chains come in varying pitch and gauge; the pitch of a
chain is defined as half of the length spanned by any three
consecutive rivets (e.g., 8 mm, 0.325 inch), while the gauge
is the thickness of the drive link where it fits into the guide bar
(e.g., 1.5 mm, 0.05 inch). Conventional "full complement"
chain has one tooth for every two drive links. "Full skip" chain has
one tooth for every three drive links. Built into each tooth is a
depth gauge or "raker" which rides ahead of the tooth and limits the
depth of cut, typically to around 0.5 mm (0.025"). Depth gauges
are critical to safe chain operation. If left too high they will cause
very slow cutting, if filed too low the chain will become more prone
to kick back. Low depth gauges will also cause the saw to vibrate
excessively. Vibration is not only uncomfortable for the operator but
is also detrimental to the saw.
Main article: Tensioner
Some way to adjust the tension in the cutting chain so that it neither
binds on nor comes loose from the guide bar. The tensioner is either
operated by turning a screw or a manual wheel. The tensioner is either
in a lateral position underneath the exhaust or integrated in the
The lateral tensioner has the advantage that the clutch cover is
easier to mount but the disadvantage that it is more difficult to
reach nearby the bar. Tensioners through the clutch cover are easier
to operate, but the clutch cover is more difficult to attach.
When turning the screw, a hook in a bar hole moves the bar either out
(tensioning) or in, making the chain loose. Tension is right when it
can be moved easily by hand and not hanging loose from the bar. When
tensioning, hold the bar nose up and pull the bar nuts tight.
Otherwise the chain might derail.
The underside of each link features a small metal finger called a
"drive link" (also DL) which locates the chain on the bar, helps to
carry lubricating oil around the bar, and engages with the engine's
drive sprocket inside the body of the saw. The engine drives the chain
around the track by a centrifugal clutch, engaging the chain as engine
speed increases under power, but allowing it to stop as the engine
speed slows to idle speed.
Dramatic improvements, chainsaw safety devices and overall design have
taken place since the chainsaw's invention, saving many lives and
preventing countless serious injuries. These include chainbrake
systems, better chain design and anti-vibration systems.
As chainsaw carving has become more popular, chainsaw manufacturers
are making special short, narrow-tipped bars for carving. These are
called "quarter tipped," "nickel tipped" or "dime tipped" bars, based
on the size of the round tip.
Chainsaw manufacturer Echo sponsors a
carving series, as well as carvers such as former Runaways singer
Cherie Currie. Some chainsaws such as the RedMax G3200 CV are built
specifically for carving applications.
Chainsaw safety features
Today's chainsaws show all a number of safety features to protect the
operator. All these features are not a 100% guarantee that the
operator will not be harmed. The best protection, even still, is
The chain brake is located in the clutch cover. Here a band tensions
around the Clutch drum stopping the chain within milliseconds. The
chain brake is released by the upper handle with the hand or wrist.
The brake is intended to be used in kick-back moments.
The chain catcher is located between the saw body and the clutch
cover. In most cases it looks like a hook made in aluminum. It is used
to stop the chain when it derails from the bar and shortens the length
of the chain. When derailing the chain swings from underneath the saw
towards the operator. The shorting prevents hitting the operator, but
it hits the rear handle guard.
Rear handle guard
The rear handle guard protects the hand of the operator when the chain
Some chains show safety features as safety links as on micro chisel
saws. These links keep the saw close to the gap between two cutting
links and lift the chain when the space at the safety link is full
with saw chips. This lifts the chain and lets it cut slower.
Logging near Apiary, Oregon
Two-stroke chainsaws require about 2–5% of oil in the fuel to
lubricate the engine, while the motor in electrical chain-saws is
normally lubricated for life. Most modern gas operated saws today
require a fuel mix of 2% (1:50). Regular gas from most gas stations
contain 5 to 10% ethanol which can result in problems of the
equipment. Ethanol dissolves plastic, rubber and other material.
This leads to problems especially on older equipment. A workaround of
this problem is to run fresh fuel only and run the saw dry at the end
of the work.
Separate chain oil or bar oil is used for the lubrication of the bar
and chain on all types of chain-saw. 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 refuelling. The
reservoir is normally large enough to provide sufficient chain oil
between refuelling. Lack of chain-oil, or using an oil of incorrect
viscosity, is a common source of damage to chain-saws, 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 and so leaves the chain under-lubricated.
Chain oil is either non-biodegradeable or degradable. Professionals
have to use biodegradeable oil in
Germany by law.
The oil is pumped from a small pump to a hole in the bar. From here
the lower ends of each chain drive link take a portion of the oil into
the gauge towards the bar nose. Pump outlet and bar hole must be
aligned. Since the bar is moving out and inwards depending on the
chain length, the oil outlet on the saw side has a banana style long
Chains must be kept sharp to perform well. They become blunt rapidly
if they touch soil, metal or stones. When blunt, they tend to produce
powdery sawdust, rather than the longer, clean shavings characteristic
of a sharp chain; a sharp saw also needs very little force from the
operator to push it into the cut.
Special hardened chains (made with
tungsten carbide) are used for applications where soil is likely to
contaminate the cut, such as for cutting through roots.
A clear sign of a blunt chain are vibrations of the saw. A sharp chain
pulls itself into the wood without pressing on the saw.
The air intake filter tends to clog up with sawdust. This must be
cleaned from time to time, but is not a problem during normal
A chainsaw operator wearing full safety gear using a gasoline-powered
Chainsaw safety features
Chainsaw safety features and chainsaw safety clothing
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 from the vibration and noise of
A common accident arises from kickback, when a chain tooth at the tip
of the guide bar catches on wood without cutting through it. This
throws the bar (with its moving chain) in an upward arc toward the
operator which can cause serious injury or even death.
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. 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, tinnitus or industrial deafness. These
symptoms were very common when such equipment was not de-vibrated. On
today's equipment there are damping elements (in rubber or steel
spring) lowering these risks. Heated handles are an additional help.
Newer, cordless electric chainsaws use brushless motors which further
decrease noise and vibration while being lighter and easier to wield
than traditional petroleum-powered models.
The risks associated with chainsaw use mean that protective clothing
such as chainsaw boots, chainsaw trousers and hearing protectors are
normally worn while operating them, and many jurisdictions require
that operators be certified or licensed to work with chainsaws. Injury
can also result if the chain breaks during operation due to poor
maintenance or attempting to cut inappropriate materials.
Gasoline-powered chainsaws expose operators to harmful carbon monoxide
(CO) gas, especially indoors or in partially enclosed outdoor
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. 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 July
19th, 2016 in the publication of the Final Directive for National Saw
Program issued by the United States Forest Service, USDA which
specifies the training, testing, and certification process for
employees as well as for unpaid volunteers who operate chainsaws
within public lands.
The new directive specifies Forest Service Manual (FSM) 2358 (PDF)
which covers classification of sawyers, their Personal Protective
Equipment (PPE) and numerous other aspects of required safety training
and behavior when operating chainsaws or crosscut saws on
Federally-administered public lands.
Chainsaw training is designed to provide working technical knowledge
and skills to safely operate the equipment.
Sizeup – This is scouting and planning safe cuts for the felling
direction, danger zones, and retreat paths, before starting the saw.
The tree's location relative to other objects, support, and tension
determines a safe fall, splits off or if the saw will jam. Several
factors to consider are: tree lean and bend, wind direction, branch
arrangement, snow load, obstacles and damaged, rotting tree parts,
which might behave unexpectedly when cut. A tree may have to fall in
its natural direction if it's too dangerous or impossible to fell in a
desired direction. The aim is for the tree to fall safely for limbing
and cross-cutting the log. The goal is to avoid having the tree fall
on another tree or obstacle.
Felling – After clearing the tree's base undergrowth for the retreat
path and the felling direction; felling is properly done with three
main cuts. To control the fall, the directional cut line should run
1/4 of the tree diameter to make a 45-degree wedge, which should be 90
degrees to the felling direction and perfectly horizontal. Make the
top cut first then, the bottom cut is made to form the directional cut
line at the wedge point. A narrow or nonexistent hinge lessens felling
direction control. From the opposite side of the wedge, plan to finish
the final felling cut 1/10 of the tree diameter from the direction cut
line. The felling cut is made horizontally and slightly (1.5–2
inches; 5.1 cm) above the bottom cut. When the hinge is properly
set, the felling cut will begin the fall in the desired
direction. A sitback is when a tree moves back opposite the
intended direction. Placing a wedge in the felling cut can prevent a
sitback from pinching the saw.
Freeing – Working a badly fallen tree that may have become trapped
in other trees. Working out maximum tension locations to decide the
safest way to release tension, and a winch may be needed in
complicated situations. To avoid cutting straight through a tree in
tension, one or two cuts at the tension point of sufficient depth to
reduce tension may be necessary. After tension releases, cuts are made
outside the bend.
Limbing – Cutting the branches off the log. The operator must be
able to properly reach the cut to avoid kickback.
Bucking – Cross-cutting the felled log into sections. Setup is made
to avoid binding the chainsaw within the changing log tensions and
compressions. Safe bucking is started at the log highside and then
sections worked offside, toward the butt end. The offside log falls
and allows for gravity to help prevent binds. Watching the log's kerf
movement while cutting, helps to indicate binds. Additional equipment
(lifts, bars, wedges and winches) and special cutting techniques can
help prevent binds.
Binds – This is when the chainsaw is at risk or is stuck in the log
compression. A log bound chainsaw is not safe, and must be carefully
removed to prevent equipment damage.
Top bind – The tension area on log bottom, compression on top.
Bottom bind – The tension area on log top, compression on bottom.
Side bind – Sideways pressure exerted on log.
End bind – Weight compresses the log’s entire cross section.
Brushing and slashing – This is quickly clearing small trees and
branches under 5 inches (13 cm) in diameter. A hand piler may
follow along to move out debris.
Cutting stone, concrete and brick
A chainsaw cutting concrete. The hose supplies cooling water.
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.
Because the material to be cut is non-fibrous, there is much less
chance of kickback. Therefore, the most-used method of cutting is
plunge-cutting, by pushing the tip of the blade into the material.
With this method square cuts as small as the blade width can be
achieved. Pushback can occur if a block shifts when nearly cut through
and pinches the blade, but overall the machine is less dangerous than
a wood-cutting chainsaw.
Chainsaws in popular culture
^ Lennox, Doug. Now You Know: The Book of Answers, Volume 4. Toronto:
Dundurn Press. 175. Print.
^ The Endless
Chainsaw (US patent 780,476)
^ Wardrop, Jim (June 1976). "British Columbia's experience with early
chain saws". Material Culture Review/Revue de la culture matérielle.
2. Retrieved April 9, 2017.
^ "Steady Growth, Industry Firsts Noted in Long Pioneer History",
Saw Age August 1972.
^ ECHO Carving Series Archived September 27, 2007, at the Wayback
Chainsaw carving page.
^ Masters of the
Saw Safety Manual" (PDF). Stihl. 1999. Archived from the
original (PDF) on 2010-03-31.
Saw Safety Manual, pp. 12-16
Saw Injuries During Tree Removal After a
Disaster". Centers for Disease Control and Prevention. Retrieved 1
^ Vibration Syndrome. National Institute for Occupational Safety and
Health. Current Intelligence Bulletin 38: March 29, 2983. Retrieved
December 22, 2008.
^ Carbon Monoxide Hazards from Small Gasoline Powered Engines.
National Institute for Occupational Safety and Health. Retrieved
December 22, 2008.
^ Final Directive for National
Saw Program Federal Register. Retrieved
November 24, 2016.
Saw and Crosscut
Saw Training Course Student's Guidebook 2006
Edition. USDA, US Forest Service. 29 December 2009. Retrieved 18
^ a b c Jonsered Operator's Manual (1153137-95Rev.2). 2012-03-04.
^ Husqvarna Operator's Manual (115 42 1549 Rev. 6). 2009-12-29.
pp. 27–28; 43.
^ Electric concrete chainsaw 230V
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