Screwdriver bits are designed to slot into power screwdrivers or electric drills, as well as some adjustable hand screwdrivers. The screwdriver bit, when used with power tools, allows fast and tight placement of screws as well as convenient removal of screws and bolts by reversing the rotation. Screwdriver bits are generally purchased in sets though replacement bits are available individually.
About screwdriver bits
Screwdriver bits come in different styles to correspond with the variety of screw heads in use. Designers of screwheads constantly seek a fastener that is quick and efficient to insert, with the least effort and minimal damage to either the fastener or the material it is being into.
Parts of a screwdriver bit
There are two main parts to the screw bit, the Shank and the Tip. he shank slots into the drill driver chuck or the screwdriver for use. It is shaped hexagonally and can be used in any standard sized driver chuck.
The bit tip is the part that sits in the fastener head and drives it into place. Screwdriver bits are commonly magnetic to hold the screw while it is being placed.
Types of bit.
The Phillips bit is the most commonly used. The crosshead design allows good control of the fastener and over-tighting is prevented by in-built camming-out (or slipping) when optimal tightness is achieved. It is simply graded by number so is easy to match the bit with the screw.
This design was developed as an extension of the Phillps head, with a double cross design or an additional cruciform overlaid at a 450 angle. With more cross parts to grip, greater torque can be applied. The Pozdriv screwbits are less recessed and less tapered than the Phillips for greater control and are designed not to cam out.
Torx screw bit
Star shaped torx screws are a tougher and more durable design of fastener.
The torx screw bit allows for greater torque without camming out. Six curved lobes attach to the fastener head and provide a strong grip. Designed to be tamper resistant for electronics and cars, they have become more widely used as the star shape applies an even rotational force by presenting a greater driving area.
Hex screw bits
Also known as Allen keys the hex shape of these screw bits provides a flush fastener that is used extensively in flat pack furniture, engines, machinery and bicycles. Sizing is based on their diameter measurements.
Slotted screw bits are rare beasts and have largely been replaced by the Phillips or other types. When used at speed, the slotted bits tend to slip easily and are not efficient to use.
The square or Robertson screw bit has been largely replaced by the newer designs, though can still be found among older sets.
Hardened steel and hardened steel alloys are the best construction materials for a tough, durable and corrosive resistant screw bit.
Find out more about screw bits and power tools form the componentry experts at RSOnline