Safe Use of Chainsaws

Taken from: Salim Hiziroglu and Bill Ross

A chainsaw is a highly versatile piece of equipment which is used for many applications, ranging from felling trees to cutting firewood. Chainsaws are also extremely dangerous. Accidents and injuries can result from improper use. Chainsaw accidents are commonly caused by contact with the chainsaw blade, while it is running. As with any equipment, chainsaws can only be used efficiently and effectively if safety and protection rules are closely followed. Some of the basic operating principles and safety aspects of the chainsaw are summarised below.

Chainsaw operators should match the saw to the job. Size of the saw should be determined based on the type of cutting. For example small, lightweight chainsaws, generally weighing less than 5 kg, are best for pruning and cutting very small trees, whereas saws weighing 8 kg or more, with up to 15 cm cutting bars, are suitable for large trees. Weight of the saw is also important for efficient cutting. Heavy saws result in extreme fatigue if they are used for a long period of time.

Before any cutting is done the following procedures should be followed :

  1. Read the chainsaw instruction manual.
  2. Wear the proper PPE - clothing, head, hearing, and eye protection.
  3. Make sure the saw is in good working condition. The saw should be cleaned and properly lubricated. Cutting edges should be kept sharp.
  4. Inspect the chain for damaged or broken teeth.
  5. The saw should be checked for proper chain tension.

Personal Protection Requirements

  1. Safety helmet: Safety helmets protect the head against any possible falling limbs or branches. There are different types of helmets on the commercial market. Helmets should be replaced according to manufacturers’ instructions.
  2. Hearing protection: Chainsaws may produce noise up to 120 to 130 decibels. In addition to possible long-term hearing loss, exposure to that level of noise for a long time may easily cause operator fatigue. Therefore, ear muffs must be worn to reduce accidents and protect hearing.
  3. Eye Protection: Goggles are most commonly used for eye protection in chainsaw operation. However, face screens are also very useful and they are designed to deflect or stop small particles such as wood chips. The best protection includes the use of both goggles or safety glasses and a face screen.
  4. Clothing: Proper clothing is neglected by many chainsaw operators. Tight but flexible clothing is ideal for operators. Leg, arm, and hand protectors made from woven nylon, Kevlar fibre, or similar material are highly recommended.

Chainsaw Operating Principles

All chainsaws should be equipped with a hand guard and chain brake. The chain brake can be used as a parking brake when the saw is started and moved between different cutting locations or configurations. Personal injuries can be reduced substantially by having a chain brake. The brake also acts as a safety device by stopping the chain rotation if a kickback occurs during cutting. A throttle trigger lockout unit is another important element of a chainsaw. This assures an operator’s right hand is in the throttle use position before the saw can be accelerated. The stop switch should be located within thumb reach of the operator. As soon as cutting is completed the saw should be turned off to eliminate possible accidents. Before starting the saw, the engine oil, air filter, sprocket, and cooling fins should be checked for possible blockage.

Correct chain tension is also a very important factor influencing proper cutting. A chain that is too loose will derail during cutting. On the other hand, if the chain is too tight it will bind and can result in an accident. To adjust the chain, the saw’s rear bar mounting nut is tightened, while the saw is held nose up and then the front mounting nut is tightened.

Starting a chainsaw improperly can cause serious accidents. The chainsaw should be started on the ground, while placing one hand on the front handle and the inside of one knee on the rear handle. This method is the safest way to give the operator good control over the chainsaw during the start. Starting the chainsaw by dropping is not only dangerous resulting in possible injury, but also may damage the saw. Before any cutting is performed, the chain should be run on the guide bar for about one minute at a fast idle speed and then tensioned for an optimal sawing.

Kickback and pull-in are two important factors caused by reactive forces in chainsaw operation. Unless the fundamental concepts behind these reactive forces are clearly understood, major injuries are possible. Kickback occurs when the rotating saw suddenly hits a solid object or the chain is pinched in a cut in the upper 50 percent of the saw tip. This can force the saw backward resulting in a serious accident. Kickback injuries can be prevented by holding the saw firmly with both hands, gripping the top handle with the thumb wrapped around it, and keeping saw speed fast when entering or leaving a cut. It also helps to keep the chainsaw properly sharpened. Many improved models of chainsaws are equipped with a safety tip or special chain which has an antikickback feature. Chainsaws can kickback for many reasons. The most common cause of kickback is catching a small hidden limb in the upper quadrant of the nose bar.

 

Additional causes of kickbacks

  • Slow running speed.
  • Accumulation of damp sawdust on the chain.
  • Twisting the saw so that the cutter grabs in the wood.
  • Extreme changes in wood characteristics, density, moisture, and defects.
  • Improper filing of the chain.
  • Improper tension on the chain.