The electric demolition hammer is not a standard item found in most electricians’ tool boxes. Indeed, even the most compact and lightweight demo hammer is too big and heavy to carry with the tools routinely used on most jobs.
Demo hammers are specifically designed to chip and break out concrete, brick and masonry. Corded electric demo hammers are available from several manufacturers in sizes approximately 10 to 75 pounds. Tools in the plus-or-minus 20-pound range are commonly used for electrical work. Demo hammers come in a carrying case or box with space to store bits.
While some tool users may not understand the distinction between hammer drills and rotary hammers, a demo hammer is clearly different from both. Rotary hammers and hammer drills rotate, like standard power drills. Demo hammers do not; they chip and break by a hammering action.
“Most modern electric demolition hammers utilize electropneumatic technology, in which an electric motor cycles a piston back and forth inside of the tool, compressing an air pocket, which, in turn, creates an impact to the back of a chisel that protrudes out of the tool,” said Aaron Brading, product manager at Hilti. “As the chisel moves back and forth, it creates a hammering impact on the surface that is being broken.”
Brading added that electricians routinely use demo hammers to cut a channel base to hide conduit runs; chisel around conduits, cables and existing holes; enlarge holes during restoration work; and drive grounding rods.
“There may be confusion with some about the terms ‘rotary hammer’ and ‘hammer drill,’ and the terms sometimes are used interchangeably, but the electric demolition hammer is pretty well differentiated from those two products because it is not a drill,” Brading said.
“There are situations where electricians may use rotary hammers with chipping functions to chip out a larger diameter hole in some material because they may not have had an electric demolition hammer available,” he said. “To accomplish this, the user can only use a pointed chisel and has to drill a series of smaller holes to weaken the base material to be removed. A rotary hammer in this scenario is frustrating, and a hammer drill is likely impossible due to minimal impact force and the high rpms. This practice will typically lead to low productivity for the user.”
When comparing different tool models of the same approximate size, Brading said impact energy is not necessarily accurate because there is not an industry standard on how that measurement is taken.
“Therefore, if one manufacturer measures the impact energy produced at the end of a piston, it will likely produce a higher measurement than another manufacturer that measures the energy at the working end of the chisel. The best solution for the contractor is to call each manufacturer and ask to demonstrate the tool against the competition,” he said.
In North America, Hilti offers five electric demolition hammers weighing 10, 15, 20, 30 and 60 pounds.
Mitch Burdick, product manager at Bosch Power Tools, said that electric demolition hammers are designed solely to chip or break up concrete, which means the tools cannot be used for drilling holes.
“Demo hammers are primarily used by contractors to perform concrete demolition and who have little or no need to drill holes,” Burdick said. “Demo hammers are available in a range of sizes with SDS-max chisels, and there also are heavier models with 11/8-inch hex. The user needs to assess the scope of demolition work and choose the most appropriate hammer for the job. It is important to note that the lighter hammers are for smaller jobs, and the heavier hammers are for larger, heavy-duty jobs. Some users may make the mistake of employing a rotary hammer when they should have moved up to a larger demolition hammer.”
Burdick pointed out that smaller, undersized rotary hammers will be pushed to their extreme and eventually lead to tool failure. Because hammer drills are all-purpose drills, they typically are not employed for jobs that require a demolition hammer.
When evaluating demo hammers, it is important to keep weight class and removal rate in mind, Burdick said.
“The industry most often references demolition hammers by their weight class and impact energy, which can range from 13 to 60 pounds and from 5.6 foot-pounds impact energy to 43 foot-pounds,” he said. “Most users are either looking to simply chip away small amounts of material or break large sections. A smaller and lighter hammer will serve as an excellent chipping tool, while a larger demolition hammer or breaker works better for high-stock removal.”
Rick Gambaccini, group product manager at Milwaukee Tool, said that a user has two options to demo concrete: a rotary hammer or demo hammer.
“A demo hammer is just a derivative of a rotary hammer that does not rotate,” he said. “While a rotary hammer has multiple functions and modes so it can drill and demo concrete, the demo hammer is a single-mode tool that is only designed to chip concrete.”
Brian Koll, assistant product manager at DeWalt, said that, because all demo hammers are designed for demolition by delivering impact, the biggest factor in considering the appropriate tool is matching the correct demolition hammer to the application at hand.
“The best demolition hammer for an application is very dependent on material, and performance is affected by orientation of the tool while in use,” Koll said. “In some situations, tool users may elect to use combination rotary hammers that have a ‘chipping only’ function. There is nothing wrong with this, provided that chipping accounts for less than 50 percent of their work. However, users needing a tool for demolition only need not spend the extra money on a combination hammer.”
Wayne Hart, communications manager for Makita USA, said select demo hammer models are equipped with antivibration technology.
“There is growing awareness among contractors of the importance of vibration reduction and dust containment during concrete applications and on selected models of demo hammers and also rotary hammers. We have reduced vibration and have an expanding line of dust-extraction systems,” he said.
For maximum production and efficiency, demo hammer bits must match the material being chipped or broken. A wide variety of bits is available for all size hammers for removal of surface material, general chipping, breaking concrete, making holes in concrete, breaking asphalt, driving ground rods, and other specialty applications. How easily you can change bits is an important consideration when comparing tools.
The term “ease of use” doesn’t necessarily come to mind with regard to demo hammers—using one is hard work. Even so, ergonomic design, the tool’s balance and vibration control are important considerations.
In addition to making the tool easier to handle, balance can help mitigate vibration. Different manufacturers have taken different approaches to softening the impact of vibration, including padded grips, rubber vibration bumpers, and isolating components that vibrate from other parts of the tool. DeWalt’s patented antivibration control incorporates a spring mechanism inside the hammering component.
Some users say they like tools with the handle, motor and bit in alignment, compared to those with motors offset from the center of the tool.
Positioning of controls also is a factor that affects ease of use. They need to be easy to reach and operate while wearing gloves.
Demo hammers are powerful tools that require both strength and finesse to operate. They also pose several risks of serious injury. Operators should wear eye and hearing protection, hard hats, gloves, steel-toe work boots, and, in many cases, a breathing mask appropriate to the application to protect from dust. Don’t allow bystanders in areas where they could be struck by flying chips.
Operating a demo hammer safely and productively could be described as an art rather than a skill, and it’s amazing what an experienced operator can accomplish.
Product manuals provide complete operating instructions with safety precautions. Some basics include positioning the tool so the bit strikes at a slight angle away from the operator instead of directly into the material. This way, the bit chips into to the material, rather than repeatedly hitting the same spot.
When working on a floor, it is recommended to begin at an edge for better debris control. For wall work, start near the center and work downward, so debris will fall down and away from the tool.
Because demo hammers only are needed occasionally, they are popular rental items.
United Rentals stocks three electric demo hammer models of 20, 35 and 60 pounds. Sunbelt Rentals inventories 12-, 25- and 75-pound models.
In addition to providing the tool for only as long as its needed and returning it, renting is a good way to become familiar with different brands and models, useful information if workloads later justify the cost of purchase.