Power Hand Saws
Published: December 2009
The power hand saws electricians take to jobs today are smaller in size, lighter in weight and more productive than models they were using five years ago, largely because of the lithium-ion revolution in professional tools.
The types of saws most often used by electricians are available in lithium-ion powered tools in a variety of sizes, and lithium-ion technology has made it possible to develop lighter weight cordless band saws and track saw models.
Lithium-ion drives advances
“Lithium-ion is allowing us to do a variety of innovative things in the cordless saw category,” said Shane Moll, vice president, marketing and tools general manager for Milwaukee Electric Tool Corp. (www.milwaukeetool.com).
“Lithium-ion power allows us to increase the performance and capabilities of traditional cordless saws like reciprocating saw and metal cutting circular saws, while also reducing their weight,” Moll said. “Just as important, lithium has allowed us to bring tools, such as 18-volt [V] compact band saws and 28V deep cut band saws, into the cordless arena. We have also been able to make tools like our 12V saw that are compact and lightweight enough to take the place of manual hand saws.”
Perhaps sooner than anticipated, lithium-ion tools are replacing older cordless platforms.
“Demand for nickel cadmium [NiCd] products in the market has fallen dramatically, and Milwaukee and many others are no longer developing NiCd-based saws,” Moll said. “NiCd is quickly becoming the VHS of the power tool industry due to the technological, ergonomic and environmental benefits of lithium-ion.
Edwin Bender, group product manager for cordless tools at Bosch Tools (www.boschtools.com), said most types of saws used by electricians are available in lithium-ion models.
“Lithium-ion is where the cordless tool industry has shifted,” Bender said. “NiCd battery-based saws continue to lose share to the lithium-ion based systems. And in order to optimize the performance of lithium-ion based tools, electronics have been introduced into the tools in order to both optimize performance and also manage the batteries to ensure they last a long time. Advances continue to be made in motor technology as well that make the tools more powerful than ever before.”
Saws That Aren’t Really Saws
Hole saws and cutters are accessories used with power drills. Hole saws provide a quick way to make holes in studs for cabling; holes for recessed lighting in drywall, plaster and ceiling tile; and for making knockouts in electrical boxes. Rather than a self-contained saw, a hole saw is an attachment used on standard portable drills. The round hole saw blade, available in different sizes, simply replaces the drill bit. A wide range of bit sizes is available to cut different materials, including wood, steel, aluminum, fiberglass, tin and plastic. New materials and advances in cutting edge designs have improved cutting efficiency of the hole saw products.
Hole cutters differ from hole saws in that they can adjust to different hole sizes with each model able to make cuts in a variety of diameters. A circular plastic shield contains dust and shavings. Electrical applications include cutting holes of multiple sizes for tungsten, halogen and parabolic aluminized reflector (PAR) lamp cans, light-emitting diode (LED) fixtures, security devices, in-ceiling and in-wall speakers, and carbon dioxide detectors. Hole cutter suppliers say the tools save time in cutting, clearing the plug and work site cleanup. —J.G.
In general, the cordless market is growing faster than the market for corded tools. However, there are job conditions where corded saws offer advantages.
Bender said many prefer corded saws during early phases of construction when a large number of cuts requires extended running time that drains batteries of corded models.
Corded saws also may be more productive in situations where making cuts has high power demands.
Milwaukee’s Moll pointed out there are distinct applications and uses for both corded and cordless tools.
“To be a successful brand in professional power tools, it is necessary to support the heavy-duty applications required on [the] job site with both corded and cordless tools,” he said.
“Users most often choose corded tools for heavier applications with long duty cycles,” he said. “Other factors that influence the choice of corded tools include size, weight and cost.”
Today’s cordless saws feature several advances.
“Motor technology, material options and manufacturing capabilities combine to allow more powerful and durable corded tools in smaller sizes,” Moll said. “In addition, with more sophisticated electronics modules in place, we can add features, such as constant power technology, which maintains constant speed and power under load for unmatched cutting performance.”
Advances in Cutting Accessories
No matter how innovative the designs of basic power saw products, whether corded or cordless, cutting performance depends largely on blade design. Today, saw blades use the latest in materials and cutting edge design to deliver maximum cutting efficiency and durability, and the trend continues for a variety of blades for specific materials and applications.
In the reciprocating saw blade market, there has been a dramatic shift away from carbon steel blades and toward premium performance blades made with bimetal construction, said Web Shaffer, director of global product management for cutting accessory manufacturer Lenox (www.lenoxtools.com).
“Bimetal reciprocating saw blades are made by welding two different types of metal together,” Shaffer said. “This process creates a significantly more flexible and durable product than blades made entirely of carbon steel. The advantages have shifted the market almost entirely to the bimetal construction, which today comprises over 95 percent of the reciprocating saw blade market.”
The cutting efficiency of any tool is influenced by the thickness of the chips it creates with each pass of the teeth through the material, Shaffer said. A more efficient blade design cuts thicker chips with each pass of the blade, minimizing friction and subsequent heat buildup. Excessive heat generation leads to premature blade dulling and/or blade failure. Therefore, a more efficient blade will generate less heat, meaning the blade will last dramatically longer than blades that cut smaller chips.
“The most recent performance gains in bimetal reciprocating blades have come from advances in blade geometry and surface coatings technology,” Shaffer said. “They increase user productivity and lower the cost per cut. In recent years, coatings such as titanium nitride have provided large performance gains for reciprocating blades. However, the most recent technology developments in reciprocating saw blade design have focused more on optimizing blade geometry. This entails designing a tooth shape, tooth pattern and tooth set optimized for each cutting application or [tooth per inch] TPI specification.”
Milwaukee’s Moll said cutting accessory product enhancements have come through new geometries, materials and treatments and have focused on delivering longer blade life, greater durability and faster cutting across a broad spectrum of applications.
“The core range of our reciprocating blades recently was upgraded with a unique combination of relief angles that form a radius on the back of the tooth that reduces stress buildup during cutting and substantially extends blade life. The addition of deeper gullets in conjunction with a positive rake angle delivers quicker chip removal and faster cutting speed,” Moll said.
There also has been a focus on solutions for difficult cutting applications, he said.
“To solve the frustrations associated with extreme metal-cutting jobs, ice-hardened blades utilize a proprietary cryogenic hardening process to minimize soft metal (austenite) and create more hard metal (martensite). The result is a blade that is more consistently hard throughout, for up to 50 percent longer life than standard blades.”
This specialized approach, Moll said, also led to the introduction of a line of blades optimized for new compact, cordless 12V lithium-ion reciprocating saws.
“The blades,” he said, “feature a thin kerf design, which reduces the amount of drag and resistance while cutting, resulting in up to 35 percent more cuts per battery charge compared to leading reciprocating saw blades. The short blade length allows for easier cutting access in confined spaces, an application in which the reciprocating saw excels.”
The most recent development, Moll said, is of diamond grit reciprocating saw blades, specifically designed for extended life and improved performance in cast iron, grade 5 tile, masonry and other abrasive and hard materials. Featuring coarse industrial diamond grit embedded in high-strength nickel alloy braze, the new blades last up to 30 times longer and cut up to two times faster than traditional carbide grit blades. —J.G.
Basic types of saws for electricians
Reciprocating saws are among electricians’ most-used cutting tools. Several manufacturers offer variable-speed reciprocating saws in models of various sizes and capacities. Sawing is accomplished by the fast-moving reciprocating action of the saw’s straight blade.
Reciprocating saws are used frequently for cutting holes in walls and flooring; cutting pipes made of steel, copper, iron and PVC; and for cutting large-diameter wire, angle iron and unistruts. These versatile saws can be used in confined areas that are inconvenient for band saws. Blades are manufactured from various metals and combinations of metals, and they contain tooth designs for cutting specific materials.
Spiral saws make cuts with a bit that has downward, parabolic fluting, which slices material being cut, rather than ripping it as with reciprocating saws. The slicing cuts, say proponents of spiral saws, make cleaner cuts than other types of cutting tools and facilitate making plunge cuts without first drilling a pilot hole. Spiral saws are used for many of the same purposes as reciprocating saws and, using a variety of available bits, can make freehand cuts in wood, plastics, laminates, vinyl, fiberglass, ceramic tile, marble and plaster.
Portable band saws make fast, clean cuts in rigid galvanized conduit and pipe, PVC tubing, steel rod and other solid materials. Steel band blades mount on rollers.
Band saws can make high-speed cuts through aluminum, angle iron, cast iron, copper, galvanized pipe and mild steel. Slower speeds are used to cut through tougher steel and electrical cable. A variety of blades with different configurations of teeth is available.
Handheld band saws now available in lithium-ion platforms have allowed lighter, easier-to-handle cordless models. A popular accessory for compact saws is a small table, which converts a portable band saw to a stationary unit.
Chop or cutoff saws are well-suited for projects requiring repetitive cutting of long pieces of flexible conduit, wire trays, struts and whips. Cutoff saws use abrasive circular blades. Some cutoff saws are handheld; other models mount on a base. The saw blade and protective housing swing down to cut through material laid across the platform’s flat surface. The swing arm locks into place when not in use for transporting the tool.
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at email@example.com.