A hammer drill may be sufficient for drilling small-diameter holes in soft masonry, some metals and other materials too hard for conventional drills, but when tackling harder materials, such as concrete or cement blocks and brick, a rotary hammer is the most efficient. Whereas hammer drills deliver rapid, low-impact blows, rotary hammers chisel and hammer with greater impact at a slower rate, making them the ideal choice for heavy-duty work.
Due to their robust nature, rotary hammers are bigger and heavier than hammer drills. However, as it has done with other classes of power tools, lithium-ion battery power is bringing lighter weight rotary hammers to the marketplace, adding to their overall appeal.
Andrew Plowman, vice president of product management, Milwaukee Tool, Brookfield, Wis., said rotary hammers are widely used for drilling holes in concrete for anchors and for drilling holes in walls or floors for conduit.
“Rotary hammers hit much harder than hammer drills, and the greater impact energy allows them to drill larger holes and work in a wider range of aggregate,” Plowman said. “A type of larger rotary hammer known as a SDS max usually is used for chipping through block walls or to drive ground rods. Depending on the geographic location, an SDS max can get through bedrock, but, in some areas, a breaker would be needed.
“With all of the power that is available in today’s lithium-ion battery packs, as well as advancements in motors and electronics, manufacturers continue to challenge conventional wisdom about what types of cordless tools can be effective. For example, we recently introduced the first cordless 18V SDS max rotary hammer,” he said.
Historically, electricians have needed generators to power corded SDS max rotary hammers, and some generators can’t support the larger models. ECs would have to drag a bunch of cords around wherever they needed to use an SDS max.
All of that has changed. With the introduction of its newest rotary hammer, Milwaukee Tool offers a full line of rotary hammer products that operate on the same battery platform, Plowman said.
“Electricians no longer are limited to an extension cord or generator when a large hammer is needed,” he said. “Very few situations require corded, and this is a huge productivity benefit.”
In general, there is an increased focus on ergonomics.
“For example, the cordless D-handle rotary hammer with an in-line design provides a much more ergonomic experience for users who frequently drill overhead or downward,” Plowman said.
There are three main bit-retention systems for rotary hammers: SDS plus, SDS max and spline holders. Bits with these shanks are widely available in the marketplace, as well as chisels for chipping and dry-coring accessories. As the industry continues to shift to cordless tools, Plowman said users should look for accessories that are optimized for cordless tools.
Job site dust is a continuing problem.
“OSHA has proposed standards to protect workers from exposure to respirable crystalline silica,” Plowman said. “Exposure to this type of silica can occur when using rotary hammers. Many manufacturers provide additional accessories to prevent users from inhaling or getting dust and contaminants into their eyes, especially when drilling overhead. An assortment of dedicated, universal dust extractors are available.”
Most professionals who work with concrete consider the rotary hammer their go-to tool—a workhorse that is primarily used for drilling, anchoring and light chiseling. Because of this, rotary hammers are designed to hold up under tough job-site conditions.
“Many contractors who work with concrete refer to any tool that drills into concrete as a hammer drill,” said Mike Iezzi, product manager, Bosch, Mount Prospect, Ill. “However, it’s important to note that there is a distinction between a hammer drill and a rotary hammer. The hammer drill is a versatile, high-torque drill meant for light drilling. A rotary hammer is a tool that employs an electropneumatic hammer piston to generate high-impact energy, which allows it to drill or demolish concrete in all-day applications.
“The rotary hammer is the workhorse of any construction site, providing the power and torque to drill and chisel in materials that range from concrete to steel. This would require additional power that batteries now are starting to provide. With higher density batteries, hammers have expanded into the cordless category. Today, many mobile users are starting to use cordless rotary hammers for all-day drilling as well as easy touch up jobs. In the next few years as batteries continue to extend runtime, there will be a trend for many more users to start adopting the cordless rotary hammer,” Iezzi said.
Many of these tools use SDS-plus and SDS-max bit holding systems. SDS-plus is the ideal choice for smaller diameter holes and applications, with SDS-max being the best choice for larger-diameter holes and bigger jobs. Rotary hammers also feature a hammer-only mode for chiseling.
Need to make a quick hole through concrete and it doesn’t matter if it looks rough around the edges?
“Choose the rotary-hammer mode,” Iezzi said. “It is optimal for drilling in concrete, because the tool creates an impact that’s transferred through the drill bit to chip away concrete. Debris is scooped up and removed from the hole by the spiral action of the drill bit’s rotating flutes. Flip the tool’s setting over to rotation mode when there’s a need to drill a hole in wood or metal. This setting allows the rotary hammer to work as a drill. It also can be used when nearing completion of a through-hole to minimize or prevent blowout.
“Lastly, there’s the hammer-only mode. In heavier tools, this is a secondary option for breaking up concrete rather than drilling through it. In lighter tools, this mode can be pivotal for accelerated chiseling and chipping,” he said.
Bits are available with various features, and it is important to match the correct accessory with the appropriate application.
“Basic features of the rotary hammer have stayed the same, and most buyers are interested in the amps and impact rates,” Iezzi said. “Additional features being introduced to the market include kickback control to help prevent injury to the user in bind situations by stopping the hammer.”
John S. Schmidt, product manager, Hilti, Plano, Texas, said that rotary hammers have become more productive by focusing on reducing weight and increasing performance.
“Ergonomics and size have also played a major part in the evolution of the rotary hammer market,” he said. “Commercial trades want tools that are smaller and more compact because they often find themselves working in spaces where access can be an issue. Most rotary hammers require the use of SDS concrete drill bits designed to transfer the impact energy from the tool to the bit to deliver the best drilling performance in concrete and masonry base materials.”
Schmidt said customers have begun to adopt cordless rotary hammers because of the increased performance in both drilling speed and the increase in work per charge to allow them to become more productive.
“Cordless offerings have the additional benefit of increasing worker safety by reducing the number of cords on the job site, which reduces tripping hazards,” he said. “Cordless rotary hammers have increased in popularity because they are becoming smaller and more compact to fit into tighter spaces. Also, technology has increased worker comfort with additions such as active vibration reduction, which dramatically reduces vibration the user feels which improves productivity.
“Cordless rotary hammers have the power to complete difficult applications and can often outperform corded tools. Our new cordless rotary hammer is the fastest SDS rotary hammer, corded or cordless. While users appreciate productivity that cordless tools provide, they also like the additional safety that comes from reducing extension cords strung around the job site,” Schmidt said.
Rotary hammers are considered a mainstream specialty tool. When you need one, no other tool can do the job, said Richard Cacchiotti, concrete product manager, DeWalt, Baltimore.
“Tools constantly change as technology does,” Cacchiotti said. “The rotary hammer business is in the midst of a fundamental shift. Technology in batteries, motors and materials are driving users from corded to cordless. There are cordless tools that will deliver more than a day’s worth of work on a single charge with no compromises in performance.”
Brushless motors and lithium-ion battery packs are the main technology drivers in the world of power tools.
“However, dust collection with the new OSHA Table 1 requirements will be the next big frontier in rotary hammers,” Cacchiotti said. “Contractors, professional handymen, craftsmen and repairmen all rely on portability and power. Not only do these tradesmen need convenience, but they also will benefit from a job site that is not limited by the distance of the tool application to the power source. In addition, projects can be completed faster when there is no need to constantly search for power sources. This saves time and money.”
Rotary hammers have two primary tool holders that have a direct correlation to the power that is delivered through the bit—either an SDS plus or SDS max holder. The SDS plus bit can roughly withstand 4.5 joules of impact energy and the SDS max bits are capable of roughly 21 joules.
“The only times where we see corded tools preferred is in the SDS max combination and demolition hammer segment,” Cacchiotti said. “Currently, only two manufacturers offer cordless SDS max tools.”