Most basic electric drills can cope with tough plaster or brickwork, when fitted with a suitable masonry bit. But harder materials – such as concrete or stone – need a special hammer drill.
As well as having a purely rotary action, these deliver rapid blows to the chuck and bit. This greatly speeds up the drilling process when used in conjunction with special hammer bits.
If you need to drill hard materials regularly, it is well worth buying a hammer drill of your own. Rut for occasional use it is better to hire one – preferably the heavy-duty industrial variety – which can cope with a far greater range of materials than almost any of the basic drills on the market.
As an alternative, some drill manufacturers include a hammer attachment in their range of basic drill accessories and this may be another point you need to consider.
Chuck size
An important item to check when buying any drill is its chuck size. This gives a rough guide to the largest hole that can be made.
Most electric drills are fitted with either a 10mm or 13mm chuck. Tightened fully, this will hold a 1.5mm bit allowing you to cope with very fine work. The largest bit you can use varies according to the type of material you are drilling – in mild steel roughly the same size as the chuck; in hard masonry around one and a half times its size; and in soft materials about twice the chuck size.
All electric drills have a key which is used to adjust the chuck. This has a serrated end which meshes with the teeth on the chuck allowing it to be opened and closed.
When deciding which drill to buy check that the key engages smoothly with the teeth on the chuck and that it is comfortable to hold and use. This prevents long-term damage to the chuck which is expensive to replace. Special rubber straps are available to hold the key on the drill lead and prevent it being lost.