(e) Hex key
(j) Double Hex
... and the decision in choosing the right screwdriver for you will naturally be affected by the screws to be used and whether your chosen screwdriver is designed to deal with these. If you are looking to buy a screwdriver set or a cordless one they will come with a choice to fit a selection of screws, so you should be okay. However a brief understanding of the different type of screw heads will help you understand where and when each type are going to be used, and our brief guide is designed to do just that!
The most common one you are likely to come across is the Slotted head screw, as this has been around for many years and is seen as the simplest form, found in many applications. Whilst these can be used with power tools, they are more likely to be used with standard screwdrivers as the power tool is often too strong and may slip out of the slot causing damage to the screw, the item being worked on and potentially injure the user.
The Phillips and even more so, the Pozidriv screws were designed to work with power tools controlling the torque applied ensuring an efficient screw application without the potential of damaging the screw or the item worked on. It is important to use the correct screwdriver on each of these otherwise the screw head may become damaged, making the removal of the screw difficult.
The Torq-set screw is a cruciform screw drive used in torque-sensitive applications, like aerospace, and is similar to the Phillips head but the arms of the cross are off set. Naturally a Phillips screwdriver would not fit this screw.
Where you are dealing with security issues it is a good idea to use One-Way screws, as whilst they can be put in using a conventional screwdriver, they are designed so that their removal in the same way is impossible, as the screwdriver will just 'cam out' or slip out of the head. A special extractor is needed for their removal. The Spanner screw is designed for similar useage although it is more to prevent tampering rather than to add security, requiring a special pin spanner to drive the screw in or out.
As you can see many of the screws have been designed for different applications, and for each type of screw you will find differing sizes, both in the length of the screw and the size of the head, and differing materials providing varying strengths to the job. The variations shown, including those not detailed, provide more, or less control for the user when driving the screw in, thus minimising any damage caused.
It can be somewhat of a minefield, but by allowing a little time to choose the correct screw for the job whilst ensuring that you have the most appropriate screwdriver to drive it in with, will mean that the job will have been completed to a much higher standard.
Enjoy your DIY!