Published: January 2007
The rotary power drill is one of the most basic tools for electricians; however, there are times when standard rotary models can’t get the job done as efficiently as specialized drilling tools, and for drilling hard materials, a hammer drill is often the best tool choice.
A hammer drill is two tools in one—a conventional rotary drill for working in wood and soft materials and a hammer drill for drilling masonry, cinder blocks, concrete, metal and hard materials. Change from one mode to the other instantly with the flip of a switch.
The most significant recent development in hammer drill products is the addition of lithium-ion battery-powered cordless models. Using the technology, hammer drills are lighter, meaning they can be more powerful and longer lasting at the same weight as most other battery types. Now, lithium-ion-powered tools are replacing the old corded models and are virtually changing all trades, making it more convenient to be in all forms of construction. In addition, electrical contractors are usually the first trade on the job site, so having a long-lasting power tool is important.
Hammer drills are only one option for drilling in hard materials, and they have their limits. Manufacturers suggest for jobs requiring multiple deep holes in hard concrete and steel, a rotary hammer is a better choice. As with any tool or piece of equipment, pushing a hammer drill beyond its capabilities reduces production and causes excessive wear.
Five leading hammer drill manufacturers comment on the current line of hammer drills:
Bosch, Jason Feldner, tool representative: “Hammer drills are primarily used for drilling into masonry and light concrete up to 1-inch diameter holes to install anchors and fasteners for boxes, to hang pipe or any other fastening application.
“In drill-only mode, the tool is used for drilling into wood or metal, such as using step drill bits in boxes. In hammer drill mode, the bit rotates or grinds the material while receiving an impact, similar to how a chisel works so the tool hammers the bit while drilling.
“For corded models, increases in durability continue to make the tools better. The addition of rotating brush plates offers enhanced brush life and makes for an overall longer-lasting tool.”
DeWalt, Eric Bernstein, group product manager: “A hammer drill outperforms a conventional power drill in its ability to drill into masonry, such as concrete, brick, block, mortar and stone. A conventional power drill is not able to drill though these types of materials.
“In general, hammer drills are all ½-inch in size, which refers to the size of the chuck. Manufacturers that list the size of the hammer drill as anything else (such as 5/8-inch) are referring to the maximum hole size that unit can drill, not the required chuck size. “For residential electricians, an electric hammer drill is a great tool because it is multipurpose and versatile, and can drill through wood, steel and foundation to anchor things such as conduits and panel boxes.
“Cordless hammer drills are a popular and viable option for electricians who are completing smaller jobs and are using lighter masonry materials [stucco, block or brick] to drill holes less than 3⁄8-inch in diameter. Users that require a high number of holes to drill or larger holes than 3⁄8-inch are encouraged to move forward with a corded drill for their jobs, as the main difference between a corded and cordless drill is capacity and the speed of application. From a corded hammer drill standpoint, the most noticeable difference has been an improvement in ergonomics.
“Lithium-ion battery hammer drills are available. However, it is important to note that the battery chemistry of a hammer drill does not affect the performance of the product. The difference is in the internal makeup of the tool and its features, such as number of beats per minute.
“Commercial electricians, however, primarily drill through steel and concrete and not wood. For example, a common application for commercial electricians is drilling overhead on a concrete ceiling anywhere from ½-inch to 1½-inch deep for a drop-in anchor to then install threaded rod to hang all of their wires overhead. For applications such as these, a rotary hammer is a better tool because it has an electro-pneumatic mechanism that creates energy and will not take much exertion from the user.”
Hilti, Jeff Fabian, product manager, drilling systems: “The latest hammer drills continue the trend of smaller in size with more power. Systems providing additional operator protection in the event the tool starts twisting are becoming more prevalent. Advances in electronics allow tools to better monitor operating conditions to optimize performance.
“Cordless hammer drills are becoming more and more popular. There are both cam-action and electro-pneumatic cordless tools on the market. In cordless, the cam-action tools are more popular. NiCd still is the majority of the market, but Li-Ion is making its place in the market.
“When selecting a hammer drill, it is important to understand the applications being done. For example, many times electricians have a need to drill overhead, so weight can be an important feature to evaluate. Working comfort is important if the user needs to drill many holes in a day. A dust-removal feature can also be an important feature. Some drills have an accessory to attach to the drill to help collect the concrete dust. This can be important if electrical work is being done in hospitals, computer rooms or even overhead drilling to minimize the dust from getting into the tool or on the user. I would definitely compare the service on the tools in terms of warranty or service guarantee—a lifetime service one year limited warranty.”
Milwaukee, John Sara, senior product manager, cordless tools: “Electricians use hammer drills in a variety of applications, but typically they are for drilling and driving anchors in walls, floors and ceilings. These anchors fasten uni-strut, circuit breaker boxes, outlet boxes, conduit straps, threaded rod and even wire pullers to the floor.
“Today’s hammer drills are more powerful, lighter, smarter and more environmentally friendly because of lithium-ion technology. In addition, our new V18 hammer drill features a clutch bypass so that the user can switch between hammering and drilling without changing the clutch setting.
“The most popular hammer drills among electricians are dependent on the job at hand. Currently, professionals favor the 18-volt drills because of their power, run-time and tool platform expandability. Electricians also use 14.4-volt drills due to their compact design and weight.
“Cordless hammer drills are very popular because of their added convenience. With the introduction of lithium-ion battery technology, cordless tools have longer run time and more power, which increases job-site productivity. For example, our 28-volt lithium-ion line offers more power and two times the run time with the weight of an existing 18-volt battery and up to 50 percent longer run-time with a pack that weighs the same as a 14.4-volt NiCd pack.”
Ridgid, Jon Van Bergen, TTI North America product manager—professional corded tools: “Hammer drills accomplish holes through masonry and concrete much faster and more efficiently than conventional drills.
“Clutches are becoming more popular in traditional hammer drills. They are almost standard equipment for rotary hammers and offer users much better control. Manufacturers are also more aggressively addressing anti-vibration technology, reducing size and weight and also increasing blow force.
“Cordless hammer drills are widely used. They are routinely included with most popular brand combo kits. They are becoming more popular as the professional demands added functionality from one tool. All of the major manufacturers offer lithium-ion-battery powered hammer drills.
“The first consideration in selecting a hammer drill is the material that will be drilled. Other major considerations are hole size, ergonomics, amperage, blows per minute and impact force.”
IT’S A WHAT?
Manufacturers say hammer drills often are confused with rotary hammers and even demo hammers. Each is a distinct type of tool.
Traditional hammer drills create a hammer action through spinning disks teeth on them that rotate against each other. The tooth of one disk rides up and down the opposing disk’s tooth to create a forward-backward motion.
A rotary hammer works like a hammer and chisel. Within a rotary hammer is a piston (the hammer) that moves front to back through the gearbox. When the piston goes toward the chuck it hits a striker on the bit and pounds the concrete.
Comparing the two, a hammer/drill chips, and a rotary drill pounds. A hammer/drill “hits” more often, but with less force than a rotary hammer. Hammer drills are more appropriate for making holes in block or brick; the rotary hammer is better for drilling holes in dense poured concrete.
The demo hammer is an entirely different class of tool, which is used for large-scale chipping and hammering. Demo hammers only hammer—they don’t bore holes. EC
GRIFFIN, a construction and tools writer from Oklahoma City, can be reached at 405.748.5256 or firstname.lastname@example.org.
SOURCE: JON VAN BERGEN, TTI NORTH AMERICA PRODUCT MANAGER—PROFESSIONAL CORDED TOOLS.