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Cordless Reciprocating Saws Shift To Lithium Ion Batteries

Issue 12 and Volume 14.

In the arsenal of tools rescue teams carry, cordless reciprocating saws are among the most used.

They’re versatile, not extremely expensive and they do a lot of the detail work big hydraulic tools can’t easily handle.

While there are many manufacturers of reciprocating saws, three seem to dominate the fire rescue market – DeWalt, Makita USA Inc., and Milwaukee Electric Tool Corporation with its iconic Sawzall.

Each of them touts features exclusive to its brands and advises purchasers to pay attention to stroke per minute, battery life, vibration suppression and blade-locking mechanisms.

Jim Watson, product manager for DeWalt Industrial Tools, which is headquartered in Baltimore, Md., said firefighters and rescue personnel should try a variety of reciprocating saws before settling on a particular brand or model.

Perhaps the most important feature of a cordless reciprocating saw is the battery, which can range from 18 to 36 volts. Saws using the latest technology have lithium ion batteries, although there are still a few using nickel cadmium (NiCd).
Watson said DeWalt is moving to lithium ion batteries, which last longer and produce more power than NiCad. Another advantage, he said, is a fully discharged lithium ion battery used by DeWalt can be fully charged in one hour.

Unlike NiCd batteries, Watson said lithium ion batteries lose very little charge when they are not in use, an important feature when saws are stored in apparatus compartments away from chargers. However, he said, they operate best when they are on a charger awaiting use. He said DeWalt designed its new line of lithium ion battery cases to be “backwards” compatible, so they will work on older equipment that was sold with NiCd batteries. 

DeWalt recently went to a 36-volt platform, which gives firefighters and rescuers more power and cutting time on the scene, according to Watson. The company still has its line of 18- and 28-volt tools.

“The higher the voltage, the longer the run time,” Watson said. “The 36-volt unit seems to be the choice of fire departments today.”

Twice The Run Time

Makita has a battery system that ranges from 7.2 volts to 24 volts. Its 18-volt lithium ion battery will fit 35 tools in the company’s collection, said Wayne Hart, communications manager for Makita USA, based in La Mirada, Calif. He said Makita sells a wide assortment of corded reciprocating saws, which are much bigger and can handle virtually any situation, but they are limited by the availability of AC power and cord length. He said cordless is the choice of many professionals,  including fire and rescue personnel.

Milwaukee Tools headquartered in Brookfield, Wis., boasts that its new 28-volt lithium ion batteries offer twice the run time with less weight than 18-volt NiCd batteries.

Saws with lithium ion batteries are about 20 percent more expensive than those with NiCd batteries across all manufacturers. Lithium ion batteries appear to be a good investment for fire/rescue applications because the extra power provided by higher voltage and the longer continuous run time seem to match rescue needs more closely than NiCd batteries.

Vibration

While battery life and power are major determining factors in the effectiveness of saws, vibration is an important consideration. With blades moving at thousands of strokes per minute, excessive vibration slows effective cutting and causes unnecessary and premature user fatigue.

“To gain good tooth engagement, you don’t want a lot of vibration,” Watson said. “On top of that, you don’t want a lot of vibration transfer to the user either. You are pushing down a bit on the saw to make it engage, and you don’t want that vibration transmission to you.”

To reduce vibration, DeWalt makes reciprocating saws with a counter-balance ergonomic design. “We have found the sweet spot for reciprocating saws,” Watson said.

The design includes a top grip for bearing down and a handle and trigger large enough to accommodate a gloved hand. When selecting a saw, Watson said, “Be sure you can grab the handle with a glove on.”

For Makita, reducing vibration is achieved with trademarked Anti-Vibration Technology (AVT), an exclusive counter-balance system.

“The difference between saws is profound,” Hart said. “We have great products for demolition and rescue work with more power and less vibration.”

Milwaukee also has a counter-balance system to reduce vibration as well as a non-slip soft grip handle designed to reduce operator fatigue.

Strokes per minute and stroke length must be considered when shopping for cordless reciprocating saws. All three major manufacturers offer variable stroke speed controls, typically by triggers on the handles, with speeds to 3,000 strokes per minute. 

Blade Attachment
Experts say the longer the stroke length, the better the cut as more teeth engage during cutting. DeWalt and Milwaukee reciprocating saws both operate with a 1 1/8-inch stroke length. Makita has a 24-volt reciprocating saw with a stroke length of 1 1/4 inches, a length the company claims is best in class.

Related to blade stroke length is blade attachment. All three manufacturers have adjustable shoes that allow more use of the blade for longer blade life. For attaching and removing blades, all three have hand-operated clamps using either a lever or a rotating knob and clamping sleeve.

Watson, the product manager for DeWalt, said his company uses a keyless blade clamp permitting the discharge of spent or broken blades without having to touch them. “Blades that are used hard get hot,” he said.

With the DeWalt system the clamp lever on the side of the tool is moved up to release the blade and pushed down to lock the blade in place.

Bi-Metal Blades

Milwaukee and Makita both have twist collar blade-clamping devices that don’t require tools, but do require the user to loosen or tighten a knob to release or clamp the blade. 

When it comes to the blades themselves, there are many options depending on the job the reciprocating saw is required to perform. 

Watson recommends a heavy-duty bi-metal demolition blade capable of cutting a variety of materials. In auto extrications, the saw will have to go through metal, rubber, plastic and glass in most instances, he said, and in fire applications, it will be used to cut through a host of building materials.

Watson said the term bi-metal refers to two kinds of metal that are combined to form the blade and give it flexibility to prevent it from breaking. “We have found that bi-metal [demolition] blades are very fast cutting and work well in the field,” he said. 

Hart, the communications manager for Makita USA, said one of the most important things rescue personnel and firefighters need to keep in mind when selecting blades is to steer clear of consumer-grade blades. “It’s very important to pick the right blade,” he said. “They must be matched to the task.” 

DeWalt, Milwaukee and, to a lesser extent Makita, all make their own blades. Another very highly regarded maker of fire/rescue-grade blades is Lenox, which produces of a variety of them, including bi-metal demolition blades for reciprocating saws.

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