1. Why do you need a rotary hammer?

Builders, installers, and repair and finishing masters use rotary hammers to perform various tasks. Depending on the design and characteristics of the rotary hammer, it can be used to:

  • Drill and bore holes in hard and dense materials like concrete, stone, brick, and building blocks;
  • Cut large diameter holes in walls and partitions for installing outlets and switches;
  • Create grooves needed for concealed installation of internal communications like electrical wiring or thin pipes;
  • Remove plaster, ceramic tiles or dried cement mortar;
  • Mix construction mixtures, adhesives, and paints and varnishes;
  • Perform demolition work related to the destruction of concrete, brick or stone masonry, ceramic blocks, etc.

It's worth noting that there are specialized devices designed to perform individual tasks from this list: drills, wall chasers, jackhammers, and hand mixers. However, unlike them, a rotary hammer is a universal tool suitable for performing various types of work.

Examples of work performed with a rotary hammer: drilling, demolition, and core drilling.

2. The most important characteristics of rotary hammers

The key characteristics of rotary hammers that determine their capabilities and areas of application are power and impact energy. Household class tools generally have a power up to 1000 W, which is sufficient for making holes in brick or concrete walls for dowels. Powerful devices (from 1500 W and above) are primarily used for continuous work with heavy loads.

Based on the maximum energy of a single strike, rotary hammers can be conditionally divided into these classes:

  • < 2 J — compact and lightweight tools designed for drilling small holes with a diameter of up to 5 – 8 mm;
  • 2 – 4 J — universal mid-class rotary hammers that can be used to drill holes with a diameter of 10 – 14 mm and dismantle finishing materials;
  • > 4 J — tools for drilling deep, large-diameter holes, working with coring bits and brick masonry destruction;
  • > 8 J — powerful professional rotary hammers that can work with bits larger than ⌀50 mm and crowns over ⌀100 mm, and break concrete quickly and effectively.

To prevent customers from getting confused by watts and joules, manufacturers often directly state the maximum drilling diameter in concrete and brickwork in the characteristics of rotary hammers — this is the most objective parameter by which an instrument can be accurately selected for specific tasks.

Each manufacturer has models of different types and sizes in their range of rotary hammers.
Popular Powerful Rotary Hammers

3. Impact mechanism and motor placement

The maximum impact energy, instrument size, and weight largely depend not only on the engine's power but also on other factors — in particular, the design of the electro-pneumatic impact mechanism.

A swing bearing mechanism provides moderate impact force (no more than 3 – 4 J), but it is relatively compact in size. Such impact mechanisms are equipped in rotary hammers with horizontal (longitudinal) motor placement. Due to this configuration, the tool has a narrow and elongated body, which is suitable for working in tight and hard-to-reach places, openings, and gaps.

A crankshaft mechanism is more complex and larger but delivers powerful blows that quickly and effectively crush building materials. Impact mechanisms of this type are equipped in rotary hammers with vertical motor placement. Tools with this configuration are sometimes called "barrel" due to their characteristic body shape. Barrel rotary hammers are generally quite large and powerful. They are used for working with larger bits and coring bits, as well as for dismantling brick and concrete structures.

Left — a rotary hammer with horizontal motor placement, right — with vertical placement.

4. Operating modes: drilling, hammer drilling, and chiseling

Due to the features of the impact mechanism design, rotary hammers with horizontal motor placement are (usually, but not always) three-mode. That is, depending on the task, you can choose one of three functions:


Large and powerful barrel rotary hammers with high impact energy may not have a non-impact drilling mode because using such a tool to create holes in wood and metal is simply impractical. Many models even lack the reverse function—made to simplify the gear mechanism construction, thus making the tool more reliable.

Function switch on a three-mode rotary hammer.
Popular Rotary Hammers with Chiseling Mode

5. Types of chucks and the difference between them

Since regular jaw chucks familiar to everyone from drills and screwdrivers are poorly suited for power tools with high torque, special chucks were designed for rotary hammers (SDS+, SDS-Max and some other varieties). They feature internal splines (which transmit torque to accessories without slipping) and specific locking mechanisms (which center the drill bit shank and prevent it from falling out). These chucks allow for attaching and removing accessories without keys. However, each is designed to work with accessories (bits, chisels, and points) of only its standard.

  • Bits SDS+ have shanks ⌀10 mm with four slots (two guiding and two holding). SDS+ chucks are usually fitted to lightweight household and semi-professional rotary hammers designed for medium-duty tasks (drilling brick, removing plaster or tiles, etc.).
  • Bits SDS-Max have a thicker shank (⌀18 mm) and five slots (three guiding and two holding). Due to the increased size, they can withstand greater load. Therefore, SDS-Max chucks are installed on powerful professional-class rotary hammers intended for demanding tasks (drilling large diameter holes in concrete, demolition, etc.).

The difference between SDS+ and SDS-Max bit shanks.

Thus, the type of chuck determines what range of accessories can be used with this tool (note that SDS-Max accessories are more expensive than SDS+ bits and chisels). Some rotary hammers come with jaw chucks (keyed or quick-change), allowing for the use of regular inexpensive drill bits with round shanks.

6. Features of corded and battery rotary hammers

With more and more wireless tools available for sale, the question arises regarding which is better — battery-powered or corded rotary hammers. Each has its advantages and disadvantages.

  • Battery rotary hammers are autonomous and mobile tools. They are typically not very powerful, so they're often used for relatively simple tasks (e.g., making a few holes in the wall for fasteners or removing tiles in the bathroom before repair). On the other hand, due to their compactness and low weight, cordless rotary hammers are ideal for field crews (installers or finishers) who constantly need to carry their tools with them.
  • Corded rotary hammers usually have more power and impact energy. Therefore, they are more suitable for serial drilling of many holes, not to mention gouging or demolition work. But naturally, the construction site must have access to an outlet or generator.

The main advantage of battery rotary hammers is the ability to work anywhere.

As practice shows, when choosing a rotary hammer for minor repairs at home, the difference in technical characteristics fades into the background (for simple tasks, special power or high impact force is not required), and the price of the tool plays a significant role. In this regard, battery rotary hammers outright lose to corded ones, as wireless technology is more expensive. But if you already have batteries from other tools (e.g., a screwdriver or trimmer), you can buy a rotary hammer of the same brand and system as a "bare unit" (i.e., without a battery pack and charger) and save a lot.

Popular Battery Rotary Hammers

7. Additional features — extended capabilities

When selecting a rotary hammer, consider the additional features and mechanisms that allow for faster and more accurate work, ensure safety, or reduce user stress.

  • Speed regulator allows for adjusting the rotational speed of the chuck and the proportional frequency of blows depending on the substrate characteristics and accessory size, while constant electronics automatically maintain speed even when the tool load increases or decreases.
  • Anti-vibration systems, implemented as mechanisms with counterweights or at least spring-loaded handles with energy-absorbing inserts, significantly reduce user stress, allowing for longer work without hand fatigue and health risks.
  • Safety clutch (mechanical or electronic), which instantly turns off the tool when a bit is jammed in concrete, protects the user from "kickback."
  • Brushless motor is more economical in terms of battery power consumption, which is crucial for battery tools, and it is also more reliable during work in dusty and dirty conditions typical of construction sites.
  • Soft hammer function should interest professionals who use rotary hammers not only for drilling concrete, which requires high impact energy, but also for drilling more brittle materials like brick or ceramic wall blocks.
  • Built-in backlight allows for working in poorly lit areas, eliminating the need to carry flashlights and lamps.
  • Dust collector connected to the rotary hammer and synchronized with the tool allows you to manage without a vacuum cleaner if you need to make a couple of holes in the wall without leaving debris and dirt.

Working with a rotary hammer with a connected dust collector.

The functions, mechanisms, and features mentioned above increase the tool's cost. But in many cases, the price difference justifies itself, especially if it concerns rotary hammers for professional builders and installers.

8. Impact drill or rotary hammer

Is a rotary hammer necessary at all if there are impact drills? With a drill that has an impact mechanism, it is quite possible to make a couple of holes for dowels in brickwork or lightweight concrete blocks if you need to hang a shelf. Therefore, this tool also has its niche — occasional use for relatively simple tasks. But it isn't suitable for serious work. Why? Because the impact mechanism of a drill is not at all like that of a rotary hammer. The effect of the blow is achieved using two wavy washers (ratchets) installed between the gearbox and the chuck. When one washer "jumps" over the other, the drill tip moves back and forth (with an amplitude of literally fractions of a millimeter) and gradually crushes the brick. The impact force is so weak that the user has to lean on the drill with their weight to make a hole. Therefore, impact drills have limited use and cannot fully replace a rotary hammer.

Impact drill mechanism washers (indicated by arrows).
Popular Impact Drills

9. Conclusions and recommendations

A rotary hammer, like any other tool, needs to be chosen for specific tasks and usage scenarios. When starting the search for the most suitable model, you must ask yourself several questions:

  • What work is planned to be performed with this tool?
  • How often and with what load will the device be working?
  • What features are essential, and which ones can be dispensed with?

By understanding the scope of tasks, you can fairly accurately select a tool. For example, to solve household issues in a new home, it's quite enough to have a compact, lightweight, and not especially powerful household-class rotary hammer (perhaps even without a chiseling mode). For extensive or prolonged repairs in an apartment, something more powerful and versatile is required, such as a three-mode rotary hammer with 1000 W. For a field installation team involved in installing boilers, air conditioners, or heating boilers, an autonomous battery tool is best. And for work on a construction site, it's better to buy a powerful corded rotary hammer, with which you can drill and bore large diameter holes and perform demolition work of varying complexity.