General Cordless Drills Info

Cordless drills come in various voltages and all have their uses depending on the tasks performed and amount of use they get. The voltage is directly proportional to the power so the higher the voltage the higher the power that is put out. The most common being the 18V drill. Lets not forget there are a number of drills designed for specific tasks so we need to identify the tasks and surfaces the drill will be used for. The main advantage of the Cordless Drills over corded versions is the portability however when used for drilling larger diameter holes and for higher torque operations the batteries in cordless drills can quickly become drained. Most tradesmen will carry spare batteries to get around this and most modern drill batteries can be put on a rapid charge and charged in 15 to 20 minutes. The various functions and features and their uses are described below. It is useful to learn what these features do and how to use them to get the most out of your drill.

Cordless Drills Terms Explained

Below you will find a brief description of some of the common terms used when describing cordless drills. The terms are all common terms that can be relevant to any cordless design not just 12v models

Torque

The basic definition of torque is a twisting force. In terms of cordless drills the amount of torque is the amount of twisting force that the chuck can exhert on the tool it is holding. So the higher the torque or twisting force applied, the easier it will be to bore into a material or drive a screw into position providing the correct bit or tool is used. Also a higher torque machine will be able to drive home larger screws than that of a cordless driver with lesser torque. This is because the larger the screw generally the more resistance it put up when being driven into a material, therefore a higher twisting force is required to drive it fully home.

Torque Settings

You will note in the specifications section for each of the 12 volt models listed on this site the number of "torque settings". These torque settings allow the user to apply different levels of torque or twisting force by selecting the different settings indicated by numbers on the collar as shown in the image above. This ability to change the torque setting is very useful to allow control when driving screws into delicate surfaces such as plaster board so that the screw does not penetrate the board surface. Once the correct torque setting is selected when driving into a surface the drills clutch will activate when the selected level of torque is reached and allow the motor to continue to run by dissengage the drive so that the bit stops turning.

No-Load Speed

The no load speed is defined as the number of revolutions per minute of the spindle or chuck when idling ie. not under load.

Twin Speed

Cordless 12v drills tend to compensate for their lack of power by having a high no load speed. However because some larger tools or bits need to turn at a slower speed to avoid burning out and damaging the cutting edge a two speed motor is incorporated in some models. This has two different speeds pre set by the manufacturer which are usually selected by a switch on the machines body. This is why you will see two no-load speed values given in some of the specifications.

Variable Speed

The next step up in technology from a twin speed is the variable speed. A variable speed model varies the speed of the motor infinitely up to a pre-determined limit. This is controlled by the trigger. The further the trigger is depressed, the higher the revs per minute. Some variable speed models also have an adjustable trigger stop to allow the user to set a maximum speed that will not be exceeded giving that extra control required for some tasks.

Slow Start or Soft Start

Some variable speed models will have a slow start function for additional control. This allows the machine to start slowly as the trigger is depressed to avoid the bit or screw from slipping and causing damage to the work surface. Note: If operating at slow speeds for a prolonged period you should stop intermittently and run the machine at high speed for a while to keep the motor temperature down.

Chuck

The chuck is the device at the front end designed to hold the tool or bit being used. The chuck can be either keyed or keyless. Most cordless drills tend to use a keyless chuck. The keyed chuck uses a toothed "key" and a toothed ring around the chuck itself to tighten up the chuck around the bit or tool.

Most 12v cordless models will come with a keyless chuck. The keyless chuck does not rely on the use of a key and is easily operated. The keyless chuck is tightened by turning the barrel of the chuck usually clockwise while holding the collar or the chuck stationary. Releasing the chuck is operated in the same way but turning the barrel anti-clockwise. The two most common chuck sizes are the 3/8" (10mm) and the 1/2" (13mm). The 10mm is suitable for most general DIY tasks and will accept tools and bits with a shaft diameter up to 10mm. The 13mm is used for heavier duty tasks and will take bits upto 13mm in diameter.

Reverse Drive

When using as a powered screwdriver it needs to have the ability to remove screws as well as insert them into a surface. This is achieved by a reverse drive function. The reverse is usually selected by operating a switch somewhere on the machines body which then operates the chuck in the opposite direction to allow screws to be "backed out" or withdrawn from the workpiece.

Drilling Capacity

The capacity is usually quoted in millimetres and is the maximum depth that can be drilled of a certain material by the model in question. Most specificationss quote a capacity for boring into wood and metal. If the machine has a hammer function usually a capacity for masonry will be quoted also. This is designed to give a guide to the ability of that particular model and will not necessarily be exact as there are various types of wood and metal and all will bore differently to each other.

Hammer Action

The "Hammer action" is used for boring into brick or masonry. If your 12v tool has a hammer action it is usually selected via a switch on the machines body or using the torque setting collar. By selecting the hammer action this engages a ratchet/cam mechanism that rapidly hammers the chuck in and out to drive its way through masonry. When using on masonry this way a bit specifically designed for masonry should be used. It is also necessary to apply additional pressure when using the hammer function. The harder the surface the more pressure that is required. The hammering action is quoted in BPM which stands for blows per minute and it should be noted that this type of operation will put extra strain on the bearings and excessive hammer use may reduce the life of the machine.