chainsaw

A chainsaw is a handheld power tool that cuts wood using a continuous loop of sharp steel teeth mounted on a guide bar. The chain rotates at high speed, typically 50 to 80 miles per hour, driven by a small engine (two-stroke petrol or electric motor) or hydraulic system. The teeth are angled and beveled to slice through wood fiber as the chain moves in one direction around the bar. Most modern chainsaws weigh between 3.5 and 5.5 kilograms and have bars ranging from 25 to 60 centimeters in length, though industrial models can be significantly larger.

Chainsaw teeth, called cutters, must be regularly sharpened and maintained. Each cutter has a depth gauge in front of it that controls how much wood the tooth can bite in one pass. Improper depth gauge setting causes the saw to either clog with sawdust or tear rather than cut cleanly. The chain itself runs on a bar lubricated by oil, and inadequate oil flow is one of the most common causes of premature wear and overheating. Two-stroke engines require mixed fuel (petrol and two-stroke oil at a specific ratio), while electric models eliminate this requirement but sacrifice power for convenience.

Variants and applications

Petrol-powered chainsaws dominate forestry and arboriculture because they deliver the highest power-to-weight ratio and work without cord limitation. Electric chainsaws, both corded and battery-powered, are increasingly used for domestic and light commercial work. Petrol models range from 30 cubic centimeter displacement engines for pruning to 100+ cubic centimeter models for felling large trees. Hydraulic chainsaws, mounted on boom arms on forestry equipment, are used in mechanized harvesting operations and cannot be moved freely by hand.

The chief hazards are kickback, where the spinning chain suddenly throws the saw or the workpiece toward the operator, and loss of control during cutting. Modern chainsaws include safety features such as chain brakes (activated by hand guard contact or centrifugal force), throttle locks, and anti-vibration systems. Personal protective equipment, particularly chaps and helmets with face protection, is essential. The cutting direction and chain rotation speed mean that even brief contact with the rotating chain causes severe laceration.

The term "chainsaw" derives straightforwardly from the chain loop of teeth that performs the cutting. The tool emerged in the 1920s as a mechanical improvement over earlier bow saws and reciprocating blade saws. It became dominant in forestry after 1945, particularly following the introduction of the Stihl MS 180 (1971) and similar professional models that combined lightweight magnesium frames with two-stroke engines. Today, chainsaw work remains a skilled trade requiring training in felling technique, maintenance, and safety protocols.