RECIPROCATING SAWS AND AIR CHISELS

BY DAVE DALRYMPLE

Continuing the discussion on cutting techniques in a previous article (Fire Engineering, January 2006), which covered cutting techniques and methodology involving power hydraulic tools, let’s now consider the reciprocating saw and the air chisel (photo 1). Although they’ve been around a while, recent improvements in the tools themselves and in blades and bits have enhanced their use and application in vehicle rescue applications. Adding these to your toolbox can enhance a victim’s outcome by facilitating multiple tool use on scene.

RECIPROCATING SAW


Photos 1, 3, 6, 8, and 12 by Denyel Cusimano.

The reciprocating saw, or recip saw, has been used extensively for vehicle rescue for decades, although its use may have waned at different times. Today’s recip saw has had a resurgence as a result the advent of cordless or battery-powered saws (photo 2). Originally, the battery-powered saw didn’t have the “zip” to work well in the vehicle rescue environment. In the past eight or nine years, battery power and technology have made great strides, making the battery recip saw an excellent tool for cutting at a motor vehicle accident.


Photos 2, 4, 5, 7, 9, 10, and 11 by author.

Additionally, higher amperage motors have improved the 110-volt recip saw. Additional features on both saws include adjustable shoes to increase the area of the blade use, quick- or rapid-change blade chucks to facilitate blade changes, and even the ability to change the angle of the saw body to allow us to make cuts more easily. Battery accessories now include the Robopak battery pack from Aircraft Dynamics that works with all battery-powered tools, regardless of manufacturer; can operate multiple tools; and greatly increases usage time (photo 3). An adaptation of military technology, it provides one power source for different tools, different power needs, and different manufacturers.


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Although all saws have pluses and minuses, recip saw blades have made the biggest technological advance. Years ago, the bi-metal blades used for extrication were fairly thin in gauge and materials and needed soap and water to help lubricate and cool the blades from friction. They bent easily, wore out rapidly, and available sizes were limited to four or six inches.


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Now there are numerous options. A few years ago, specialty demolition blades came on the market and were used for extrication. They featured greater length and thicker gauge and were made of tougher materials; hence, they cut deeper, bent less (if at all), and lasted longer (photo 4). Even the need for blade lubrication was greatly reduced.

More recently, specialty blades made for vehicle rescue have emerged from a variety of manufacturers. They may feature variable teeth-per-inch pitch (10-14 tpi), titanium teeth, improved materials, and greater blade thickness; there are even blades designed for glass management that can greatly assist in cutting evolutions. Some of these new-wave rescue service recip blades actually extend the battery life of the recip saw by drastically reducing vibration as the blade cuts.

Operations. Let’s review some basics of recip saw usage. First, as with using a power hydraulic cutter, cut the materials at a 90-degree or right angle, which reduces the stress on the blade.

Second, remember that “the saw stays at 0 mph.” This means the blade shoe stays against whatever is being cut and slight pressure should be placed against the object. The blade does the cutting work. However, to use more of the blade and to gain a better cutting angle, you might need to move the saw a bit and even adjust the shoe in or out.

Also, ensure that the trigger is fully depressed and that the saw runs at its maximum rpm. Additionally, regardless of what is being cut or which tool evolution is performed, vibration must be minimized whenever and wherever possible.

The recip saw is an excellent tool for roof removal or displacement, especially on wide roof posts. However, in displacing the roof, you should watch for pressure and binding as the posts are cut, especially considering the damage to the vehicle and energy it absorbed from the crash.


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Strip interior trim to look for side curtain cylinders, adjustable seat belt brackets, and even structural reinforcements in today’s vehicles (photo 5). One type of vehicle reinforcement is a polyester-based foam that is forced or blown into the void areas of the vehicle’s structure; when this material hardens, it adds strength and limits noise. This material will slow the blade down as it passes through it because of the friction the sawing action creates; this friction can melt or bond the material to the blade and in between the teeth. Stripping trim also limits vibration, which will rob the recip saw of power. Hard protection is important here while making cuts because the blade’s length is passing into the occupant compartment.


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Although rescuers may be familiar with the windshield-removal cutting operation, they will need to cut side and rear glazing as well (photo 6). More and more vehicles are equipped with enhanced protective glass (EPG-i.e., laminated side and rear glass) and polycarbonate glazing.

The recip saw does an excellent job of cutting glass rapidly, but this generates more glass dust, so a dust mask is needed for respiratory protection. Also, a good blade to use on glass is a short (four-inch) wood blade (6-8 tpi). This will cut down on glass dust as well as save the extrication blade for cutting roof posts, since the finer teeth on these blades many times get gummed up or dulled by the plastic as the laminate glass melts from the friction.

Moving to the doors and sides of the vehicle, the recip saw can sever latches and hinges. Ensure your blade can travel freely past the object being cut and you have good visibility of what is being cut. Also depending on the blade used, even the high-tensile strength crash beams can be cut. Observe these cuts closely, and have patience; it might take time for the cut to be completed.


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The recip saw works well when accessing the vehicle side using a third- or fourth-door evolution (photo 7). In a third-door evolution performed on a two-door vehicle, the vehicle side is removed just behind the door and before the rear wheel. The fourth door evolution originated from removing the side of a minivan opposite of its sliding door, but it now can be used whenever rescuers need to make access into the side of any vehicle. In performing the third- or fourth-door evolution, observe where the blade is and the depth of the cut being made. If the blade is too short, it will strike interior items and create tremendous vibration, slowing it down and possibly even bending the blade. If too long, the blade will cut into objects that rescuers would want to avoid, such as the floor, again slowing the operation. Be careful to observe these cuts in vans and large vehicles, since climate-control systems and power can be found in the sides of these vehicles.


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Elsewhere, use the recip saw for dash relief cuts, vertical relief cuts in the crumple zones, and even plunge cuts into the hood area to assist in locating batteries and to provide openings for nozzle insertion at engine compartment fires (photo 8).

Practice is the key to using the recip saw; in the hands of a skilled rescuer, it can be an amazing tool. Fairly inexpensive, the recip saw takes up minimal space and comes with a variety of power options. This tool is found in a wide variety of response vehicles today.

AIR CHISEL


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Like the recip saw, the air chisel has been used in vehicle rescue for some time. Originally an auto body tool, the modern air chisel is a powerful tool in the hands of a knowledgeable rescuer (photo 9). Today’s rescue air chisel can sever vehicle component materials including those in reinforcements, hinges, and latches. Although the auto body shop air chisel does a respectable job cutting sheet metal, it is woefully unprepared to handle roof posts and high-strength body materials.

The air chisel’s power comes from some sort of regulated compressed gas, usually compressed air, which generally limits cutting operations with this tool. Rescue versions of the air chisel can use large amounts of air rapidly, especially when cutting hardened materials or objects. Practice and knowledge are ways to reduce air consumption, as is matching the tool’s pressure to the material being cut. Although most of the rescue air chisels can flow at up to 350 psi, most times the pressure can be reduced to between 90 and 120 psi. That pressure range allows the tool to cut most vehicle materials readily and saves on unnecessary wear and tear. If hardened materials are encountered, the air pressure can be raised to help the cutting.

Ensure that the tool is well-lubricated with air tool oil and its bits are sharp. Air tool oil protects the tool’s piston from seizing and sharpened bits aid greatly in cutting materials. Once the air chisel is pressurized, treat it as a loaded gun-if not properly seated, the bit may leave the chisel when the air chisel is operated.

First, as with the recip saw, vibration is an enemy! Air chisels are impact tools, so the more an item being cut vibrates, the more power the tool needs to overcome that vibration and to continue the cut. Remove such items as interior and exterior trim, rubber or plastic gaskets, glass, and adhesives.


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Second, an air chisel bit is not like a recip saw blade. If you try to make a recip saw cut with an air chisel, you will bury the bit; more than likely the bit will get jammed or stuck. In all your cuts, you must remove or cut each layer before moving onto the next. On a wide panel or even a wide roof post, your cuts must almost make a “picture window” to properly cut the next part of the vehicle behind the outside skin (photo 10). On a smaller profile roof post, your cuts must circle the outside of the post, without plunging into the post. The rescue air chisel can also sever hardened items such as hinges and latching pins (the Nader pin). You must increase the air pressure to facilitate cutting and also rock the bit up and down to avoid keeping the bit solely on one area of both the bit and item being cut.

Third, the chisel bit’s length is a consideration. Most bits in the past were fairly short; today’s bits can be up to 12 or 14 inches long, allowing for better reach and more power and torque. The length also allows the addition of a hand grip for increased control.


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Operations. As discussed before, narrow profile roof posts require that rescuers “circle” the post cutting. Wider roof posts require a “picture window” to make cuts into the layer of roof post behind it. On door evolutions, it might be easier to cut around the latch than to try to sever it. To do this, make a “picture window” behind the latch, so you can see the actual back of the latch pin as it is mounted on the vehicle body (photo 11). Next, you basically “cut” around it to separate it from the vehicle, which allows the door to open, keeping the latch pin still attached to the latching mechanism. Otherwise, if you wish to sever the latch pin or hinge, you will need to make access or space to see these items to cut them properly.


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The air chisel really comes into its own when you need to perform third- or fourth-door evolutions. Air chisels make short work of sheet panels (i.e “picture window”), and this allows you to rapidly expose the inner body materials and reinforcements that will need to be cut (photo 12). The air chisel can make these additional cuts, or you can use other tools to facilitate cuts. With all these tool operations, you must ensure you have an adequate air supply and that hard protection is in place when making these cuts. The air chisel bits are just like a recip saw blade when making cuts into the occupant compartment.

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Reciprocating saws and air chisels are excellent tools for vehicle rescue. In the hands of the knowledgable, well-practiced rescuer, they are extremely effective and can greatly enhance the vehicle extrication victim’s outcome. These tools are simple additions to the rescuer’s toolbox and facilitate extrication methodology well. If you are not using these tools now, take a good look again at these options.

DAVE DALRYMPLE is a career EMS provider for Robert Wood Johnson University Hospital/St. Peter’s University Hospital Emergency Services in New Brunswick, New Jersey. He is also a firefighter/EMT/rescue technician and former rescue services captain of the Clinton (NJ) Rescue Squad. Dalrymple is the education chair of the Transportation Emergency Rescue Committee-US and serves on the Expert Technical Advisory Board of the International Emergency Technical Rescue Institute as the road traffic accident advisor.

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