The handheld power hammer drill is a basic electrician’s tool that is two drills in one—a conventional drill for working in wood and soft materials and a hammer drill for drilling 3/16- to ¼-inch holes in masonry, cinder blocks, concrete, metal and other hard materials. The user can switch from one mode to the other instantly.

A common hammer drill application for electricians is making holes for installing various types of boxes or other wall-mounted devices. In addition, hammer drills are used for creating pilot holes for mounting various fasteners that secure conduit or other routing materials to a masonry wall.

Hammer drills are available in cordless and corded models, but, as with other cordless tool products, marketing efforts of most manufacturers are actively emphasizing and promoting the benefits of lithium-ion cordless models. The most commonly used hammer drills are 18-volt (V) models, but new 12V tools are surprisingly productive and can be carried in a tool belt, pouch or even a pocket.

Considerations when evaluating hammer drills include the material that will be drilled, sizes of holes, blows per minute, amperage, impact force and ergonomics.

Major suppliers of hammer drills include Bosch (www.boschtools.com), DeWalt (www.dewalt.com), Hilti (www.hilti.com), Hitachi (www.hitachipower­tools.com), Makita (www.makitatools.com), Milwaukee Electric Tool Corp. (www.milwaukeetool.com), Ryobi (www.ryobitools.com), and others. Greenlee (www.greenlee.com) recently added a line of lithium-ion power tools that includes a hammer drill model.

“Looking back five to 10 years, we have seen significant improvements in cordless hammer drill designs,” said Jason Felder, group product manager, Bosch Cordless Power Tools. “In some cases, today’s models are nearly half the size of their predecessors. Tools have shrunk in size for a number of reasons, one being the continuing improvements in lithium-ion battery technology. The lithium-ion battery now is one of the lightest parts of the entire tool.

“However, lithium-ion technology has not changed the basic design of the hammer drill. It still utilizes a light impact mechanism that allows a masonry bit to break up material as it rotates at high rpms. What lithium-ion technology has offered is the ability for cordless hammer drills to provide more run time in a lighter weight package.”

Felder said that, in addition to battery weight, hammer drills have become lighter and more compact because of impressive new drive train designs and motor optimization that are among of the most efficient ever developed, resulting in more power, more run time and smaller sizes.

Corded hammer drills still are in demand, Felder said, because they operate on a consistent power source and don’t need batteries.

“But looking forward, electricians and other professionals clearly recognize the opportunity to ‘cut the cord,’ especially useful when working in locations where power is not yet available,” he said. “While cordless is growing significantly, the majority of hammer drills still are corded, but … improving battery technology and run time will continue to erode away at the corded share.”

The benefits of brushless tool motors are receiving much tool buyers’ attention.

“Brushless motors offer better overall efficiency, more compact design and the elimination of the need to change carbon brushes because they are ‘electrically’ commutated,” Felder said. “They are best utilized in tools for applications requiring extended run times and will be especially productive when paired with higher amp batteries, which will be coming to market in early 2013.”

Wayne Hart, Makita USA communications manager, calls the 18V lithium-ion battery the true sweet spot in cordless tool technology, providing a power-to-weight ratio that is ideal for commercial and industrial applications.

“Hammer drills and many tools first introduced with higher and lower voltages have since migrated to the 18V platform,” Hart said. “Makita engineers design tools around the company’s 18V battery, so each tool—including hammer drills—has superior ergonomics and balance. In addition, the slide-style 18V battery has allowed our engineers to design the tool’s grip around the human hand, not the battery, which was typical with pod-style batteries. Makita’s hammer drill line includes a compact model, another powered by a brushless motor, and a new high-torque model delivering maximum torque of 750 inch-pounds.”

Regarding brushless motors, Hart said the company’s brushless motors are engineered to deliver up to 50 percent longer run time with increased power and speed and longer tool life.

Christian Coulis, Milwaukee Cordless Group Product Manager, said that drills and hammer drills typically are the most common tool purchased by first-time cordless tool buyers because their portability allows for greater work production.

“The percentage of cordless tools over corded is definitely growing as tool buyers switch to cordless at an increasing rate,” Coulis said. “However, corded power tools are still used for certain applications, and some power tools used by electricians are only available in a corded model.”

Coulis said most hammer drills on electrical projects are 18V models, but the 12V tools offer users a different level of power in a compact form.

While lithium-ion technology has not required a need for change in the basic design of how hammer drills function, when it comes to shape/form, lithium-ion batteries allow for design changes in the tool’s mechanics because they provide a more advanced power supply, Coulis said.

“The weight savings with a lithium-ion powered products typically comes from the fact that lithium-ion is the most efficient way of transferring energy in the power tool industry,” Coulis said. “The reduced weight of the lithium-ion battery creates a very large benefit in the drilling categories, as users demand the smallest and lightest products but do not want to sacrifice performance.”

Outside of battery technology, Coulis said that motor technology also is advancing quickly. Milwaukee’s new line of FUEL tools combines the best motor, battery and electronic capabilities in one package.

“This combination creates the best performance and durability that cordless power tools have ever seen,” he said. “Previously, a high-performance 18V hammer drill would have roughly 350 inch-pounds of torque. We offer a model today that has 725 inch-pounds of torque while being smaller and lighter, having more run time, and superior durability.”