Buying a Corded Hammer Drill

Buying Guides - Power Tools

A hammer drill is a heavy duty tool that performs the function of drilling into dense and solid materials using a high frequency hammering action. While being especially applicable for drilling into harder materials such as concrete, masonry, and stone, these drills can also ease drilling into softer materials like wood or metal. These tools help to increase productivity by enabling the worker to exploit the mechanical force of the drill to plow through the hardest materials in the shortest time, saving both time and energy.

While mostly used by skilled workmen such as masons, carpenters, plumbers, and building contractors, these tools can also be used by ‘home-workshop’ enthusiasts. After boring a hole into a surface, the hammer drill can even be used as a hammer, using the vibrating action to hammer a bolt into the hole. This can be done by placing the bit tip of the tool over the head of the bolt and starting the tool. A rotary hammer drill is mainly used for masonry work, and uses its weight advantage to increase the impacting effect on the material being drilled. Sometimes the drill bit can be replaced by a screwdriver bit, allowing the user to drive a screw into the material.

Features and working of a hammer drill

The hammer drill consists of a chuck at its anterior end, which serves as a holder for the drill bit. This drill bit is a slender cylindrical part made of a reinforced metal. The bit is the portion of the tool that comes in contact with the target surface and initiates the drilling. When the drill is started, the chuck begins to rotate and at the same time initiates rapid forward and backward motion, resulting in a hole being bored where the bit is touched to the surface.

Hammer drills are powered by either compressed air or by electricity.

Hydraulic Hammer Drills: Those tools working on pressurized air are linked to air tanks or air compressors. When the trigger is pressed, the air is propelled to the chuck, causing the bit to hammer against the target.
Electric Hammer Drills: In the case of electrically powered hammer drills, the power is either supplied through Rechargeable batteries or through a power source. Further, hammer drills may be either corded or cordless. Cordless drills do not have a power cord and are thus completely portable. This enables them to be carried around and also to be used in the outdoors. Cordless hammer drills use extended run-time batteries which have the dual advantage of longer battery life and greater run time.

Most hammer drills have a steel reinforced collar encircling the chuck to protect this part that bears the most impact during use, and is also the most vulnerable in the event of the tool falling down. The drill uses a keyless chuck allowing the user to easily remove and change the bit in the chuck. A ratcheting single sleeve half inch chuck with carbide teeth holds the bit in a vice like grip.

A pneumatic hammer drill generates a full load rotation of around 1000 revolutions per minutes (rpm) and a hammering capacity of around 40,000 blows per minute (bpm). Electrically powered drills use around 14.4 to 24 volts to offer a performance varying between around 15,000 to around 50,000 bpm.

To create the most efficient drivetrain system, a unibody powertrain aligns the chuck, the gearbox, and the motor. For greater control in the hands of the user, some drills allow three speed modes; the first Level being around 450 rpm, the second speed being around 1400 rpm, and the third speed being approximately 2000 rpm. The variable speed feature enables the user to increase the precision of drilling on the work surface.

What to look for in a hammer drill

Considering the pressure under which the hammer drill works, most of these tools have an intrinsic overload protection facility that prevents the motor from overheating or burning out during prolonged use. Externally accessible brushes facilitate servicing of the tool.

A DuraShield housing increases the durability of the tool. All-metal gears also act to increase the life span of the product.

The handle of the drill is ergonomically designed with a soft padding to enhance the comfort Levels of the user. Additionally, the location of the trigger and the other controls is designed to enhance smooth operation of the tool. The hammer drill is also rendered with a 360 degree side handle to provide a two-handed grip (see the handle on the Bosch hammer drill to the left), increasing accuracy and stability.