Basic selection of screwdriver bits

This hand tool is a replaceable attachment for tightening screws and bolts. We select the appropriate type of a bit and the size of its profile according to the screw groove. When fastening the screw, we insert the bit into a screwdriver for bits or into a ratchet adapter. We can also attach the bit to a cordless screwdriver or wrench, which is usually used for larger screwing. The body of the bit is usually hexagonal, which is inserted into the given tool. They are usually 6.35 mm wide (1/4") and their length varies depending on how deep we need to go into the area when screwing. The most commonly used bit length is 25.4 mm. However, we can also come across bits of a different diameter - for watch screwdrivers, the bits are narrower (about 4 mm), then there are 10 mm or 5/16" bits.

Existing types of bits differ in the shape of the working part. On this basis, the following groups are distinguished:
Standard
Special
Combined

STANDARD
Slotted S - used for tightening and loosening screws with a flat groove. The Latin letter S is an abbreviation for the English word "slot". This shape is not very suitable for transmitting high torques.
Cross PH - Two right-angled crossed profiles with a groove form a cross-groove profile. Most often used in car repairs and bulky objects.
Cross PZ - They are designed for working with wood or other similar materials with a similar structure. At the same time, bits such as PH are more suitable for working with metal. In addition, the Pozidrive bit has notches between the arms of the cross, which increases grip and reduces the risk of damage to the screw.
Torx TX - Asterisks marked with the letter T with a number. The bit is characterized by the presence of six front surfaces, with the help of which it is in contact with the screw. They are used in the assembly and disassembly of household appliances and cars. The torx bit with a hole increases the reliability of the twisting process, the implementation of which does not require any special effort.
Hexagonal HEX - They have a large contact area with fasteners. Hexagons can be used, for example, in the manufacture of furniture, in the installation and disassembly of plumbing or heating systems.

SPECIAL
Tri-wing - A characteristic feature of these bits is the presence of 3 blades for stabbing. Bits are used in the assembly of household appliances and electronics, but also in the aviation industry.
Four-wing (torq-set) - a bit is called Tri-Wing, which has 4 blades.
square (robertson square) - Nozzles of this shape are marked with the letter R. It is mainly used in the assembly of furniture.
Spline XZN - these bits are most often used in European cars.
SP - This slot is also called Snake-eye. In addition, it is also called the head intended for a fork key.

COMBINED
Double-sided - the bits are longer and have tips on both ends. It saves space and time spent looking for a different size.

A lot also depends on the material. Bits for soft joints are most often made of chrome-vanadium steel (CrV), while bits for hard joints are made of even higher alloy steel. They can also be surface-treated, for example, with titanium nitride.
Various accessories can be added to the bits, such as a bit holder, reducer or adapter, angle attachment (gear member).
If you use the bits more often, it is more advantageous to buy a set of bits. You can then buy individual bits as needed. However, bits are often included in tool sets.