Corded Power Tools
Published: October 2002
Though longtime staples of electricians, corded power tools continue to evolve into ever-more effective, efficient workhorses. Design modifications include refinements that make them easier to use, more comfortable to work with (ergonomic rubber grips and contoured handles that make it easier to control and hold the tool), safer and lighter. They can provide more power for the weight than earlier models. In addition, some of the more mature tool lines have improved the line of sight to the work material by, for instance, changing the blade location on a circular saw. Tools may also reflect refinements that solve unique application problems, such as a recap saw featuring swiveling as well as a scrolling mode, and drills introducing improved fans permitting higher amp ratings and, therefore, more power. Other improvements include motor brushes featuring longer life and brush assemblies with fewer parts. In general, tools with fewer parts are easier to maintain and possibly offer improvement in reliability.
The adoption of keyless chucks or blade clamps in various tools has eliminated the need for an Allen wrench or other specialized tools for removing or installing bits and blades, a welcome improvement for an electrician working in a crawl space, on a ladder or anywhere a quick bit/blade change without ancillary tools is expedient. Likewise, some newer jigsaws have quick-setting tilt bases that adjust without an accessory tool.
When performing alteration work, electricians can select from a myriad of power tools, including reciprocating saws, demolition hammers, rotary hammers, core drills, rotary cutters and right-angle drills.
A jack-of-all cutters, recips are great tools for demolition and alteration work because they can sink their teeth effectively into just about anything. They feature straight exposed blades that can cut into conduit, threaded rod, stubbed pipe, the sides of panel boxes and troughs, studs and drywall. Cutting with a straight or orbital reciprocating motion, the sturdy portable tool can also, with appropriate blades, cut cast or angle iron, stainless steel, brass, fiberglass, ceramic tile or marble.
Two old sayings ring true here: "Different strokes for different folks" and "You pay your money and you take your choice." Saws are available that offer short strokes, longer strokes up to 1 1/4 inches or adjustable strokes. Other features to consider are variable-speed triggers, fast blade switching, shoe adjustment, quick-blade clamp systems, vibration dampening, and ergonomic refinements to the tool's handle or heft.
Porter Cable 9740 Tiger Claw features an 11.5 amp motor, adjustable gear housing enabling a 180-degree pivot adjustment, and a 360-degree rotation of the nosepiece holding the blade, with 12 positive stops. Between the two adjustments, the tool accommodates a wide range of cutting positions in close quarters. When angled at 90 degrees, the unit is a brief 8 1/2-inches long. The tool, with variable speed ranges between 0-2,900 strokes per minute and a 1 1/4-inch cutting stroke, uses a keyless blade clamp design for fast blade change. The steel blade clamp accepts the blade upside down, for limited clearance applications, in addition to the standard position. A Quik-Change front shoe can be extended or removed for more blade teeth in cutting.
Making holes in concrete is pretty much de rigueur on construction sites. It is a rare new construction job where every sleeve and wall penetration is set before a pour. And even in that instance, someone, somewhere might have made a mistake and concrete penetration would be necessary to correct it. On renovations, hole penetrations for conduit and wire are part of the project.
To make a nice, neat round hole when the user will come in contact with rebar in the base material or needs to core holes larger than 2 inches in diameter, core drills fit the bill. A rotary hammer is used when the application calls for the drilled hole to be less than 2 inches in diameter and rebar is not present in the base material. For other shapes, electricians can use demolition hammers or rotary hammers. Noise and vibration are typically lessened when using a core drill rather than either of those hammers.
Demolition hammers are categorized by style of bit--3/4-inch hex, 1 1/8-inch hex (which is common), SDS-Max--or other proprietary style tool holder--and by weight. Rotary hammers are categorized by shank style, including spline (which is popular) and SDS Plus. SDS Plus, which is typically used for smaller hole-drilling machines, including rotary hammers, has a smaller shank (typically 1/4-inch diameter); SDS MAX, used for heavier-duty work, has a bigger diameter shank (typically 1/2-inch). In the marketplace, the SDS Plus is referred to just as SDS (slotted drive system) while the SDS MAX is referred to just as MAX. All demolition hammers are either SDS MAX or 3/4-inch hex or some proprietary system. None are SDS Plus. Some rotary hammers have chipping capability similar to demolition hammers but are not true demolition hammers. A true demolition hammer doesn't rotate.
DeWalt D25900K heavy-duty electric SDS MAX demolition hammer produces 3.7 to 18.5 ft/lbs of impact energy and can be adjusted from 1,020 to 2,040 blows per minute. The tool, with the motor positioned behind all the working parts for balance, has a rubber rear handle large enough to be held with two hands and features a convenient lock-on rocker switch. Sporting a compact in-line design and barrel-grip shaft for easy holding in horizontal and vertical applications, the 22-pound hammer has anti-vibration control that acts as a shock absorber. When chiseling, the D25900K features one-step chisel rotation with 12 adjustable settings for accurate positioning of a flat chisel rather than repositioning of the tool, a 19-position electronic variable-speed impact control dial controlling blows per minute and the impact energy, and anti-vibration control that acts as a shock absorber and helps the user feel fewer rebounds during operation.
Typically used only on concrete and masonry, rotary hammers combine rotation and percussion for simultaneous spinning of the bit and a motor-driven, piston-generated hammering action, independent of operator-applied pressure. The bit, which does not slip during operation, as one in a drill or hammer drill might, pulverizes the material without the hand buzz that can accompany a hammer drill doing the same work.
Sporting a 7.4-amp motor with electronic speed control, the 1 1/8-inch Hitachi DH30PC SDS Plus rotary hammer features three function modes: hammer and drill, for drilling holes in concrete; hammer only, for light duty chiseling in concrete; and drill only, for penetrating steel and wood. A change lever facilitates mode switching, and a variable lock on the 10.6-pound tool provides for easy adjustment of the working angle of chisels. The tool, which has a no-load speed of 0-850 rpm, is equipped with a replaceable carbon brush, which prolongs armature life. The tool is also equipped with a depth gauge that allows the user to drill multiple holes to a specified depth.
Makita HR2431 1-inch SDS Plus rotary hammer is powered by a 6.5-amp motor supplying up to 1,050 rpm and 4,900 bpm. For overhead drilling in concrete and masonry, steel and wood, the unit, which weighs 6.2 pounds, includes a built-in dust collection system with integrated fan that delivers the collected dust and debris to a bag supported by an internal frame. The HR2431 employs a dual-purpose mode selector for "hammering with rotation" and "rotation only," addressing all drilling applications in a variety of materials. A large, easy-to-hold trigger in the rear D-handle reduces operator fatigue, and a straight side handle provides added support for all-position drilling, especially overhead. A one-touch sliding chuck facilitates easy SDS Plus bit changes.
Big holes ...
Developed for wet and dry concrete coring applications, the Hilti DD 130 core rig features a three-speed, 15-amp motor. The compact, lightweight tool can be used vertically or horizontally for single-worker, handheld wet and dry concrete coring applications requiring holes from 1/2-inch up to 6 inches in diameter. The unit, which features a low noise level and is "true running" for consistently precise holes, can also be mounted on a stand for high-volume wet coring. The UL-listed DD-130 features a built-in ground fault interrupter to help protect the operator and the motor. The rig, which can switch from wet coring to dry coring at the touch of a button, has a Hilti BI quick-connect chuck and uses Hilti diamond core bits that can be retipped with easy-to-use change modules on bits 1 3/8 inch up to 6 inches in diameter. An optional portable water tank for water supply and a water collector for water containment and removal are available.
And little holes
Making holes in existing surfaces for new switches, receptacles and high hats always poses the risk of damaging surrounding surfaces. Some surfaces, such as plaster, lath, ceramic tile or laminate, are too hard to cut,or cut repetitively,by hand. An electric-powered rotary cutter can speed the work while providing accuracy. With a 3.6-amp motor that delivers 30,000 rpm with spiral cutting bits, the BoschWeighing 2.5 pounds, the compact tool can cut a multitude of different materials found on the job and could be useful for installing high hats and switch and receptacle boxes without defacing the surrounding surface. The cutter permits tool-less attachment or removal of the depth guide, a spindle lock for single-wrench bit changes and a true-collect system for less run-out and secure clamping of bits. 1638 rotary cutter cuts a variety of materials in place.
Right-angle drills allow electricians to drill through joists and studs for conduit and cable runs. With handle and motor at a 90-degree angle, perpendicular to the work, these drills work well in close quarters where maneuverability is limited. In some cases, the right-angle tool allows drilling where other drills can't, such as between joists and studs.
Metabo AD626 1/2-inch, triple-action gear-reduction angle drill features an automatic safety clutch to protect against kickback in the event of a bit jam, double insulation and autostop carbon brushes. A winding protection grid deflects debris from armature windings, extending motor life. The tool's electronic speed control enables the user to vary the speed within the operating range. The 7.3-pound, 6-amp tool, with a maximum torque of 310 inch/pounds, and a capacity of 5/8 inch in steel and 1 9/16 inches in softwood, comes with a carrying case, a geared chuck and chuck key, a clamping bushing, and a side handle. The no-load speed is 0-550 rpm; rated input is 650 watts.
Milwaukee Electric Tools' new 1680-20 1/2-inch Super Hawg high-torque drill for drilling holes in studs and joists, features a 13-amp Milwaukee-built motor, 1750/ 450 rpm, and a Roto-Lok rotating handle that allows the operator to maintain the grip and body position of the switch and direct the chuck in 90-degree drilling angles. The low-gear clutch protects the gear train from sudden high-torque stalls. The positive control T-bar front handle sports a low-profile design for a good grip where the most pressure is applied, without the bulk of a bale handle. A two-position auxiliary handle fits either side for additional grip or bracing. The tool also has a thumb-operable rocker reverse switch. EC
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