Power saw basics: What firefighters need to know about cut-off saws and chainsaws
Detailing pre-use checks, proper PPE and saw-startup tips
The page came in for a report of a possible suicide in our area. Medical calls like this are never easy, but this one was even more unique and stressful.
Upon arrival, police officers stated that the individual was in the garage with the vehicle running. The family had indicated that the individual in the car was trying to harm themself. The garage had no exterior door to provide access, as it was an older home, and the door from inside the home was barricaded. The decision was made to cut the garage door and complete access to the patient. A gas-powered cut-off saw was used, entry was made, and the patient was removed and transferred to EMS standing by.
What’s more, the call was challenging because our agency had a roof blade on our cut-off saw, requiring a fast blade change before it could be used for the sheet metal on the garage door. In addition, not everyone on the crew had used a cut-off-type saw for making an opening in a garage door.
After this incident, the blade on our cut-off saw was switched to a metal blade to allow for a quicker option for cutting a door on an EMS call like this one or on the fireground. Our chainsaw provides an opportunity for making roof cuts so that we can go either direction on arrival with a metal blade on the cutoff saw.
When was the last time you talked about or trained on your power saws? Hopefully, it hasn’t been too long because they are an important tool and one that requires periodic training. If you work for an agency that routinely handles wildland calls or dispatches, chances are good that you have staff familiar with chainsaws. Even so, they may not have as much experience with cut-off-type saws. Training on these saws helps ensure that you can be efficient and effective when responding and have as much safety margin as you can when using your tools.
We commonly carry two power saws: a chainsaw and a circular cut-off saw (commonly called a K-12).
Cut-off saws use small two-cycle gas engines to drive a chain or blade to do the cutting. The saws can have many different blades or chains that can be specific or very general for certain materials. Cut-off saw blades can be standard metal cutting blades or be more roof-specific blades with more aggressive teeth.
Regardless of the blade type, once the saw is throttled up and the blade starts spinning, the gyroscopic effect of the bade can make the saw feel as though it wants to rotate or “walk.” This can affect the ease with which the saw can cut in a vertical surface.
Chainsaws also feature a small gas engine that will drive a chair around a bar. Many chainsaw blades will have a carbide material on the cutting teeth to make the chain more capable with various roof materials than a standard chain. The saw also will distribute a small amount of oil into the channel on the bar to lubricate the chain and help manage heat.
When checking a chainsaw, an excellent way to verify that the oiler is working is to run the saw at three-quarters throttle with the bar held a couple of inches from the ground. After a few seconds, you should start to see a slight stripe of oil on the floor; this verifies that the chain is receiving lubrication.
A quick note on fuel selection: Fuel with ethanol can be harmful to small two-cycle engines. Ethanol will absorb moisture when stored for long periods, will separate from the oil mixed with the fuel, and can start to break down components in the fuel system. It’s best to use gasoline with no ethanol content. Pre-mixed fuel options can also prevent fuel problems.
Take care when refueling a hot saw. The vapors in the fuel tank will likely be hot and have built up a little pressure. Open the cap slowly, and don’t allow it to pop off. This can produce a geyser of vapors – a situation that has been linked to injuries in wildland fires. It can also contaminate turnout gear or spray into a firefighter’s face.
Pre-use or pre-shift check
At the start of a shift – or following some different schedule – your saws should be checked to ensure they are ready to work. A quick safety check can be accomplished by doing a “black and gray check.” The “black check” is used for Stihl saws, meaning you check everything on the saw that’s black – these are the critical components. The “gray check” is used for Husqvarna saws, meaning you check everything on the saw that’s gray. In both cases, looking over all the grey or black items on the saw means you will check the following:
- Fuel and oil tank caps and tank levels
- On/Off/choke switches
- Throttle trigger and interlock
- Kickback brake on a chainsaw
- Recoil starting cord
- Compression release switch or button
- Vibration mounts
In addition, the following should also be checked:
- Blade mount bolt for circular saw
- Chain tightness for a chainsaw
Periodic maintenance is also important and generally straightforward. Checking the air filter can be important after the saw is used in a dirty or smoky environment. A chainsaw’s chain needs to be adequately tightened and will almost always loosen after the saw gets hot and the chain expands. If the saw is used for a quick roof opening or cutting assignment, it may not be an issue, but if used for a longer time, stopping briefly to tighten the chain may be required. Make sure you practice this on your agency’s specific saw type before you do it on a fire assignment.
Once you complete a quick check, it’s time to don proper PPE. This should include eye and ear protection, gloves, a long sleeve shirt, and pants or turnout gear. If cutting trees in the wildland environment, chainsaw chaps are another required piece of your PPE. Chaps have alternating layers of Kevlar fibers inside. If you accidentally contact your thigh or shin with your chainsaw, the fibers will be drawn into the chain and jam the sprocket to stop the chain quickly, generally in less than one rotation. This can be the difference between a ruined pair of chaps or a catastrophic injury.
A quick item to think about: What PPE do you wear when doing a daily or weekly check? Granted, you are not taking the saw up on a roof or out to the woods, but it’s still important to protect yourself. Consider what PPE may be necessary to wear for a check and when the saw is used on a call. Saws aren’t any quieter at the station than when they are up on a roof.
Start me up
When starting a saw, the most important thing is to maintain control of the saw so the cutting blade or chain can’t hurt you or anyone else. Circular saws can be easy to start on the ground, as they have larger handles and are easier to keep stable. This method will ensure that the blade will not contact anything during the starting process. You can also place a knee on the saw while starting to give it some more stability. Remember that once you start a circular saw and throttle it up, the blade will begin to spin. Once the blade is spinning, it generally will coast back to a stop, so you must be careful until it has stopped moving, even once the saw is shut down.
A chainsaw can be more challenging to start on the ground, leading to some picking the saw up and drop-starting it. This is a risky method where a firefighter holds the recoil handle in one hand and rapidly lets the saw drop away to start it. This can result in a saw that’s running being rapidly moved through the air.
A safer method is to place the throttle handle of the saw between your legs and hold the saw still with one hand while pulling the recoil handle with the other. This way, when the saw starts, it’s securely stabilized, reducing the risk of inadvertently cutting someone or something. Many saws also have a compression release feature. Pressing this button will make it easier to crank over the saw, reducing the force needed to start it.
A chainsaw always needs to be started with the kickback brake applied. This will prevent the chain from spinning while starting the saw and verify that this critical safety feature works correctly to stop the chain in an emergency.
Practice starting your saws to get a feel for the starting method. Consider putting the on/off/choke switch to full choke, then pulling the recoil cord until the saw “pops” and dies. Then, moving the switch to half-choke will allow the saw to start. Let the saw idle briefly before moving the choke off. If you are taking or sending the saw up to the roof, run it at various throttle settings while on the ground before sending it to the roof to ensure that it is warmed up and ready to go.
While the call I described at the start of the article was unique, it illustrates the importance of having your saws and staff ready to work when you least expect it. A power saw may not be the most common tool you use, but it can be a vital tool for us in many types of incidents. Train frequently with them, and practice starting and checking them to ensure that you are ready to safely use them when the time comes.