How to choose an electric drill


Power tools make any task easier and faster. Popwer drills are the entry point for any DIY enthusiast.

If you are one of South Africa's many DIY enthusiasts, or even a professional contractor, an electric drill is probably the first power tool you will purchase and will be the most comon tool you will use. Modern electric drills have a variety of features and benefits, which can be confusing for anyone intending to buy one.

Corded or cordless

  • Corded drills have a lead, which needs to be plugged into an electrical supply. This limits the distance that you can work from an electrical socket if you do not have an extension cord. THe benefit of a corded drill is that you acn plug it in and start drilling – it isn't necessary to worry about batteries. Corded drills tend to be more powerful and have higher speeds than cordless drills. However, these drills do tend to be too bulky and fast to use as screwdrivers.

  • Cordless drills are now comparable in performance to most corded drills. A great advantage is that they can be used almost anywhere – until the battery is exhausted, of course. Having a spare (fully charged) battery pack will enable you to continue working uninterupted.

    Screwdriver Function
    For an electric drill to function as a screwdriver it needs to have a variable-speed setting, torque control and a reverse drive. When using a drill as a screwdriver, a fairly low speed is necessary, so variable speed control is important.

    The size of the screw, together with the type of material being drilled, will influence the torque required. Torque control ensures that screws are not driven in too far or too tightly. If you intend to use your drill as a screwdriver it should also have a reverse facility so that you can remove screws.

    The ideal speed for a drill bit depends on its size and the material being drilled. Generally, larger bits need to turn slower than smaller bits to prevent them from overheating and losing their cutting edge. Drills with variable-speed control are therefore ideal. Some electric drills have an adjustable trigger stop, which can be set so that the drill is limited to a speed suitable for the job. A slow speed can enable a corded drill to be used as a screwdriver.


  • Power is normally quoted in watts for corded electric drills: the higher the wattage, the more powerful the drill. This rating normally reflects the ‘robustness’ of the entire drill, as its bearings and gearbox should be more robust. When deciding on the wattage of the drill, consider how frequently you intend using it and how many heavy-duty projects you are likely to undertake.

  • Cordless drills are generally rated by voltage but also refer to the amps-per-hour usage. The two common types of batteries currently in use are Nickel-Cadmium (NiCad)and Lithium-Ion (Li-ion). 12V or 14,4V cordless drills are lightweight and ideal for occasional smaller maintenance jobs around the home, while 18V cordless drills are suitable for most home projects

    Hammer action
    A hammer-action function allows the drill bit to ‘hammer’ its way into bricks and masonry. This type of action requires pressure to be applied by the user, which can lead to wear and tear on the bearings.

    Chuck size and type
    Chuck size determines the size of drill shafts that can be used. The common chuck sizes are 10mm and 13mm. 10mm chucks are suitable for most everyday tasks. Normally the larger the chuck size, the more powerful the motor. Traditional drill chucks needed a chuck key to open and close them. With a keyless chuck, these can be fi tted or removed with the flick of a wrist.

    Most drills have a pistol grip with the speed-control trigger built into it. Heavier drills need an auxiliary, usually detachable, handle so that the drill can be held steady. Drills are mostly designed to be held in such a way that the user’s forearm is in line with the drill bit, allowing more pressure to be put behind the bit. Always pick up a drill and try it in your hands for comfort before buying. Check whether the trigger and other controls are easy to operate.

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