A rotary hammer and a hammer drill are both power tools used for drilling into hard materials like concrete, brick, and stone, but they differ in mechanism, power, and applications. A rotary hammer, also known as a rotary hammer drill or a combination hammer, uses a piston mechanism to generate high-impact energy. This mechanism allows it to deliver more powerful and consistent hammering action, making it suitable for heavy-duty tasks such as drilling large holes in concrete or masonry. Rotary hammers often have a "hammer only" mode, allowing them to function as a mini jackhammer for chiseling tasks. They typically use SDS (Slotted Drive System) bits, which are designed to withstand the high impact and torque. In contrast, a hammer drill, sometimes called an impact drill or percussion drill, uses a cam-action mechanism where the chuck moves back and forth rapidly, creating a hammering effect. This mechanism is less powerful than that of a rotary hammer, making hammer drills more suitable for lighter tasks like drilling into softer masonry or concrete. Hammer drills are generally more compact and lighter, making them easier to handle for DIY projects. They use standard drill bits and can switch between hammering and regular drilling modes. In summary, the main differences lie in their power and intended use: rotary hammers are more powerful and suitable for heavy-duty applications, while hammer drills are lighter, less powerful, and better for lighter tasks.

1. **Purpose and Application**: Determine the primary use—drilling, chiseling, or both. For heavy-duty tasks like concrete drilling, opt for a high-performance model. 2. **Power and Battery**: Choose a model with sufficient voltage (18V or higher) for demanding tasks. Consider battery capacity (Ah) for longer runtime and ensure compatibility with your existing tools if possible. 3. **Impact Energy**: Look for higher impact energy (measured in joules) for more efficient drilling in hard materials. A range of 2-4 joules is suitable for most professional tasks. 4. **Speed and Modes**: Select a model with variable speed settings and multiple modes (drill, hammer drill, chisel) for versatility. 5. **Weight and Ergonomics**: Consider the tool's weight and design for comfort during prolonged use. A well-balanced, lightweight model reduces fatigue. 6. **Chuck Type**: SDS-Plus chucks are common for light to medium tasks, while SDS-Max is better for heavy-duty applications. 7. **Durability and Build Quality**: Opt for models with robust construction and features like anti-vibration technology for durability and user comfort. 8. **Brand and Warranty**: Choose reputable brands known for quality and reliability. Check for a good warranty and customer support. 9. **Budget**: Balance your needs with your budget. Higher-end models offer more features and durability but come at a higher cost. 10. **Reviews and Recommendations**: Research user reviews and expert recommendations to gauge performance and reliability. 11. **Accessories and Extras**: Consider included accessories like additional batteries, chargers, and carrying cases for added value.

The optimal drilling range for a rotary hammer typically falls between 1/4 inch to 1-1/2 inches in diameter for concrete and masonry applications. This range ensures efficient performance and longevity of the tool. For smaller holes, a rotary hammer may not be necessary, and a standard hammer drill could suffice. For larger holes, especially those exceeding 1-1/2 inches, a more powerful tool like a demolition hammer or a core drill might be required to handle the increased load and prevent tool damage. The optimal range also depends on the specific model and power rating of the rotary hammer, as more powerful models can handle larger diameters more effectively. Always refer to the manufacturer's specifications for the best performance guidelines.

The battery life of a cordless rotary hammer depends on several factors, including the battery capacity (measured in ampere-hours, Ah), the tool's power consumption, the type of work being performed, and the efficiency of the motor. Typically, cordless rotary hammers use lithium-ion batteries, which are available in various capacities, commonly ranging from 2.0Ah to 9.0Ah or more. For light-duty tasks, such as drilling into softer materials or using smaller drill bits, a 2.0Ah battery might last around 30 to 60 minutes of continuous use. For medium-duty tasks, like drilling into concrete or masonry with moderate-sized bits, a 4.0Ah battery could provide approximately 45 to 90 minutes of runtime. For heavy-duty applications, such as using large bits or chiseling, a 5.0Ah to 9.0Ah battery might last between 30 to 60 minutes, depending on the intensity of the work. The efficiency of the tool's motor and the presence of features like brushless technology can also impact battery life. Brushless motors are generally more efficient and can extend the runtime compared to brushed motors. Additionally, the tool's settings, such as speed and impact energy, can influence how quickly the battery is drained. Environmental factors, such as temperature, can also affect battery performance. Cold temperatures can reduce battery efficiency, leading to shorter runtimes. In practice, having multiple batteries and a fast charger can help ensure continuous work by allowing one battery to charge while the other is in use. This setup is often recommended for professional or extended use to minimize downtime.

Yes, a cordless rotary hammer can be used for light demolition work. These tools are designed to deliver high impact energy, making them suitable for tasks such as breaking up small sections of concrete, removing tiles, or chipping away masonry. The cordless feature provides greater mobility and convenience, especially in areas without easy access to power outlets. When selecting a cordless rotary hammer for light demolition, consider the following factors: 1. **Power and Battery Life**: Ensure the tool has sufficient power, typically measured in volts, and a robust battery life to handle the demands of demolition work. Higher voltage models (18V or 36V) are generally more powerful. 2. **Impact Energy**: Look for a model with adequate impact energy, measured in joules, to effectively break through materials. For light demolition, an impact energy of around 2-3 joules is usually sufficient. 3. **Weight and Ergonomics**: A lightweight and well-balanced tool will reduce user fatigue during extended use. Ergonomic handles and vibration control features can enhance comfort and control. 4. **Versatility**: Some models offer multiple modes, such as drilling, hammer drilling, and chiseling, providing versatility for various tasks. 5. **Durability**: Choose a tool with a durable build to withstand the rigors of demolition work. Features like a brushless motor can enhance longevity and performance. 6. **Accessories**: Ensure compatibility with a range of bits and chisels to tackle different materials and tasks. While cordless rotary hammers are effective for light demolition, they may not be suitable for heavy-duty tasks, which require more powerful, corded models or specialized demolition tools. Always follow safety guidelines and wear appropriate protective gear when using these tools.