4 things to know before buying a rotary saw
When you need to cut the really hard stuff like concrete and steel, a rotary saw is the right tool; here's what to know before and after making your purchase
Power saws have been an important part of the firefighter's tool cadre for many years. Today, most departments carry a variety of power saws including, but not limited to circular or rotary saws, chainsaws, and reciprocating saws.
We now see diversity in the types of rotary saws available for firefighting and rescue work. That selection includes petroleum power, two-stroke engines; electric-powered saws; electric-power with vacuum system; and electric-power with wet-cutting kit.
Rotary saws are the saw of choice when the task demands high cutting-blade speeds in order to get through materials like concrete, cinder block, asphalt, stone masonry, cast iron, aluminum … you get the picture — hard stuff.
While there are many departments use rotary saws for cutting wood, such as during vertical vent operations on a wood-framed dwelling, several saw manufacturers recommend that operators not use them for cutting wood and wood products. Chainsaws with the manufacturer's recommended chain provide a better tactical option for wood cutting operations, are less expensive to purchase and maintain, and take up less storage space on fire apparatus.
Once you've determined that you need to purchase a rotary saw, keep these factors in mind:
- Where will it be stored on the fire apparatus?
- How heavy can the saw be? A lighter saw is easier to handle if you're not too experienced.
- How is the saw designed? Good ergonomics can be just as important as low weight. Look for low vibration levels in the handles and a slim and well-balanced saw body.
- Any ergonomic evaluation should be conducted by personnel wearing the full personal protective equipment ensemble including SCBA.
The last item, the evaluation, should include ease of locating all operational features of the saw; starting and stopping the saw; carrying the saw up and down a ladder; and troubleshooting or making an applicable repair to the saw — that is, a repair that a firefighter could be expected to make in a hazards area.
The major saw manufacturers have a variety of rotary saws to choose from, so you don't have to accept a "one size fits all" model. Yes, they all have an engine and a blade, but beyond those basic elements there is a great deal of flexibility.
Rotary saws fall into the "high risk, low frequency" category. Repeat after me: pay close attention to the general safety messages and information contained in the user or operator manual.
The saw manufacturers are doing a good job of putting together useful and informative materials for their specific products. You can capitalize upon that information by integrating the operator manual into your department's standard operating guidelines. The manufacturers have made this even easier to do because they've made those documents available for PDF file download so getting the most current copy is not an issue.
This approach will enable you to spend more time on outlining the department's tactical expectations for the saw operator and less time on how to take care of the saw. This also provides a more objective and accurate care and maintenance section in the SOG for your rotary saw by using the most recent operator manual as the focal point.
Pop Quiz Question: Why do two-stroke gasoline engines require a gas/oil mixture? Answer at end of this piece.
Saw care and maintenance
It is important to touch upon some best practices that may not be included in the manufacturer's recommendations, for example daily or weekly operational checks.
How many times have you seen this scenario in a fire station? Firefighter is doing saw maintenance, so he takes the saw from compartment, starts it, makes it wail at maximum rpms for say 20 seconds — or until somebody tells them to knock it off — and finishes by taking the saw from "60 to 0" and shutting it off.
Let's take a look at a better way. Good practices for this type of check would include:
- Make sure all fluid levels are within normal limits.
- Inspect the blade for missing teeth, cracks or deformities.
- Ensure that all guards and safety features are in place.
- Ensure there are extra blades and the selection of blades outlined in the SOG.
- Properly start the saw and get the engine up to its normal operating temperature by running at idle speed for two minutes.
- Increase the engine speed to it maximum rpms for 30 seconds.
- Bring the engine speed back to idle for no more than 30 seconds.
Every saw manufacturer has specific recommendations for the start-up and shutdown sequences for their particular saw. Make sure your SOG reference the information from the manufacturer.
The idling-down process is very important because failing to do so will allow the engine's carburetor to flood with unburned fuel, not a good thing for a saw that's about to return to its place on the apparatus.
It is probably a good idea to include this start-up and shutdown sequence following the saws use in tactical operations in your SOG. Think about it: the saw went to work without a proper warm-up and was likely shut down without a proper cool down. This procedure might extend the saw's life.
Oh, the answer to the pop quiz question. Two-stroke gasoline engines use a gasoline and oil mixture because the engine depends on the fuel to lubricate its internal parts. This feature is what enables a two-stroke engine to run efficiently regardless of its orientation.