Cordless drills are power tools with rechargeable batteries as power source.
Cordless power tools have the advantage of mains-independent operation. They are usually small in size and therefore easy to operate. They do not require a mains power cable, operate in the low-voltage range and can therefore be used safely in wet environments and outdoors.
Cordless drills are best choice for nearly all hand held drilling tasks on any DIY project. Cordless drills come in various sizes and with a number of different features.
In order to choose the right cordless drill, you will need to consider what uses you will need your cordless drill to perform and what is its main features.
Battery strength is one of the most important factors when choosing any cordless tool. For power tool operation these three types of storage batteries are mainly used. They differ with respect to their electrode materials and are named accordingly:
Be wary when evaluating battery strength, higher voltage batteries are not always the best. The type of battery plays a big factor in how the drill will perform over a period of time. Ah is where the cheaper tools fall on their face: 2.4 Ah are good, 1.4 Ah are bad. Greener design is also a factor: Li-Ion and NiMh batteries do not contain cadmium like NiCd cells, thus making them more environment friendly don't contain toxic cadmium, which can leach into groundwater if spent nickel-cadmium (NiCd) batteries are thrown out with trash instead of recycled. The disadvantage of NiMh batteries is that they have up to 50% fewer recharge cycles.
The problem of cordless drills battery is, the more voltage, the more weight. Consider this before you make your purchase.
When purchasing a cordless drill, check to see if you get an additional battery. If not, it might be a wise decision to purchase an extra one.
The power level of the drill is another important feature of the drill you choose. You will need higher voltage if you typically work on heavy materials. A good idea to buy a drill with voltage a little higher than your most demanding need, so you won't have to worry about enough power.
Cordless power tools have standard voltages between 2.4 volt and 36 volt. The following voltage groups apply in general:
Higher voltage cordless drills provide more power, but are also more expensive.
You will also need a charger when you buy your drill, manufacturers always include a charger when you buy your drill, these can take from 15 minutes up to 3 hours to completely charge an empty cell, this depends upon the type and quality of the drill/charger again with the better quality/faster chargers been sold with the more expensive drills, again look for Makita, Bosch and Dewalt as the market leaders. A fast recharge is not always good for the battery as recharging can generate excess heat which can shorten the life of a cell, again top quality units offer electronic thermal protection to prevent this happening.
Chuck size is another factor in determining the purchase of a cordless drill. For the average homeowner for a general-purpose tool a 3/8" should be fine, however for heavy-duty work a half-inch (1/2") chuck drill should be considered.
The keyless chuck is a practical standard today. All new drills are equipped with keyless chuck, they are much better than they used to be and can grip any drill or screwdriver bit securely.
1/2" cordless drill models often include a "hammer drill" feature which has little practical application for woodworking, but is great for drilling holes in masonry.
The simplest models of cordless drills run at a fixed speed (300 RPM). Better models have dual speeds (300 RPM - 800 RPM).
One of the most important features you will want to look for in a cordless drill is variable speed. Hard materials need a slower speed, soft materials a higher speed.
Most drills also have a variable speed trigger to make starting holes easier.
An excellent feature to have is an adjustable clutch, which will change the speed automatically depending on the density of the material. If you are not used to a cordless drill and how to adjust the speed, this may be ideal.
Reversible motor will allow you to back out any screws that you drill in.
An addition feature that makes screw driving more efficient is an adjustable torque clutch. This popular feature regulates the twisting power, called torque, that's applied to a screw, which simplifies jobs like driving multiple screws to the same depth.
Torque clutch can be mechanically blocked by a further switch position. This switch position makes the maximum torque which the motor can generate available for the drilling of large-diameter or very deep holes which requires the application of high torques.
Generally a drill/driver has around 8-16 torque settings and you can select the best setting for your work.
Most drill/drivers also have a drill setting where the clutch is ignored. This allow the motor's full torque be transmitted to the chuck and is generally used for drilling rather than screw driving.
Most cordless drills has a pistol grip type of handle wich provides ergonomic advantages for certain applications. In such shape the handle is behind the motor at right angles to it’s body.
The centre grip (T shaped drills) has become widely accepted as the most common construction type around the world. This provides a better balance to the drill. Most people find T grip handle more comfortable after holding the drill for a long time.
Weight of the drill can actually give you a good idea of how well its built, after all, steel gears are heavier than plastic ones. Bigger voltage drills weigh more, around 3.5 pounds for a 9.6 volt model up to around 8 or 9 pounds for a 24 volt model, so consider weight before you go for big drill. The new lithium-ion (LiIon) batteries offer a considerable weight saving over NiCd batteries.
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