Commonly used for tree removal and other large-scale cutting projects, chainsaws are a very common and useful products. Chainsaws come in three basic "weights," each designed for a different type of job; a chainsaw with a higher weight rating has a longer guide bar around which the chain wraps.
Chainsaws are further classified by other factors including engine size and intended use. When set in motion, the chain's sharp teeth are designed to rip through wood or anything else that gets in their path. While sometimes used by artists to create wooden sculptures, chain saws are most commonly used for cutting down trees and dividing them into smaller, more manageable sections for use or removal. Despite its common nature, the chain saw has been called the most dangerous hand tool available on the open market.
One study, conducted by a major university in Poland, found that over half of all defects reported in chainsaws were related to the piston/crankshaft system (26%) or the saw's feeding system (25%). The feeding system includes the saw's fuel tank, fuel filter, and all elements of the fuel distribution and filtration. The least common defects were those related to the exhaust system, accounting for only 5% of all problems. However damage to other, non-defective parts is common as well, as the study found that frequently the failure of one system leads to damage in interconnected systems.
A common fuel feeding system defect was found to be the improper mixture of fuel in the carburetor. This can cause the saw to operate erratically, which can in turn cause damage to the engine's crank shaft. Unexpected changes in the saw's speed and power during use can cause kickback, which can lead to serious injury for an unprepared operator. Improper fuel mixing can also cause the saw to stall frequently, making it difficult to use.
A 1999 study by the United States Consumer Product Safety Commission focused on injuries related to chainsaw injuries found that a majority of incidents treated at US hospitals were the result of mistakes on the part of the operator. However there were a significant number of cases involving experienced operators using proper technique and safety precautions. It is speculated that a majority of these cases involved the use of defective equipment. The average chainsaw laceration injury requires 110 stitches to close, and about 80% of all chainsaw related injuries are to the extremities, generally the lower legs and arms.
Since chain saws are primarily used for tree removal and other outdoor work, they are more commonly found in rural areas. Many chain saw owners have them out of necessity, whether to cut logs for their wood-burning heating systems or as a means of clearing roads to provide access from remote locations after storms. Utility crews often carry chain saws in case the need for tree or limb removal exists, as do some fire and rescue units.
In 2006, MTD Southwest Inc. announced a recall of about 76,000 Troy-Bilt and Craftsman chainsaws. The recalled models were found to have flawed handles. The front handles were found to be prone to breaking off, making the saw very difficult to control and resulting in great potential for serious lacerations or amputation. At the time of the recall, two incidents had been reported, both of which resulted in minor injuries.
A 2005 chainsaw recall issued by Makita USA cited defective flywheels. The company had received reports of three incidents in which the flywheel had come apart during use, posing the threat for serious bodily harm and prompting them to recall 3,400 units.