What are screwdriver bits and bit sets?
An extremely familiar component in nearly all toolboxes and carry kits, screwdriver bits are the detachable and interchangeable slim metal components designed to be fitted into the chuck end of screwdrivers.
Manufactured explicitly for the purpose of driving and extracting screws, many modern screwdriver bit sets feature dozens of different bit shapes and sizes, attachments and accessories. Collectively, they’ll help everyone from novice users to seasoned pros tackle a very wide range of screw head types, and cover you in an incredibly varied range of tasks and applications.
When the process of inserting a bit and driving a screw is carried out correctly, the convenience of screwdriver bit sets offer a remarkably simple and efficient method of mating two surfaces together sturdily and reliably. With just a few simple caretaking steps observed, the same basic driving techniques will see you through any number of assembly, maintenance and construction tasks quickly and with minimal physical strain.
However, there certainly is a technique involved when it comes to driving screws properly - and, above all, the key to success lies in selecting the right screwdriver bit for the fastener type. Failing to do so can easily result in split timbers, ruined work surfaces, sheared or stripped screws, irregular hole shapes, damage to tools, and even user injury in the worst case scenario.
To help avoid this, a hugely diverse range of screwdriver bits and screwdriver bit sets is sold by suppliers and manufacturers worldwide, often designed to accommodate a myriad of different screw shapes and sizes. The ideal bit choice for any given project will depend chiefly on the specific screw type and size being used, as well as - to a lesser extent - the sort of surface you’re driving it into.
In this guide, we’ll explore some of the more common types of screwdriver bits you’ll find in kits sold by most dedicated stockists and wholesalers around the world, and offer some pointers on the relative pros and cons of each for particular applications.
We’ll also cover our brands of screwdriver bits, to give you an overview of trusted names you might like to look out for when it’s time to buy or upgrade your next screwdriver bit set.
How do screwdriver bits work?
Both in the US and internationally, the majority of screwdriver bit sets sold to professionals and hobbyists alike are typically manufactured for use in a compatible handheld cordless power tool. The tool in question may either be a dedicated cordless screwdriver, or a multi-purpose drill driver.
After securing the bit in the chuck of your chosen driver, the tip is then inserted into the drive head of an appropriately fitting screw. Once the bit is inserted into a screw head, the torque or rotation force provided by the screwdriver motor is is transferred directly through the bit attachment into the screw itself, driving it into your workpiece.
As noted in the introduction to this guide, different sorts of screwdriver bits are designed for different screw heads and sizes, and will often vary considerably in their precise configurations and features. However, more or less all screwdriver bits have a few basic elements in common - these include:
|Bit shank||Bit tip|
Common user errors and problems with screwdriver bits
The two most common complaints users tend to experience when using screwdriver bit sets are slipping or ‘camming out’, and stripping/damaging a screw head (or, less frequently, the bit itself).
The latter is most often caused by using the wrong size or type of screwdriver bit for the screw, although excessive wear to either part can also be a direct cause. Either way, the likelihood of either problem occurring is dramatically reduced by ensuring you select the right bit for the job at hand.
‘Camming out’ is the technical term for when a screwdriver bit slips out of the recessed slot in the head of a screw. It’s a fairly common issue when the torque of the driver tool suddenly exceeds the bit’s grip in the screw head, and if you’re unlucky enough it can easily result in damage to adjacent surfaces.
Although cam-out is generally seen as an undesirable outcome, some types of screw heads and screwdriver bits were in fact designed specifically to allow for it. The extremely popular Phillips head (cross or cruciform) shape is the most notable example - the original intent was to help avoid damaging workpieces through excessive torque or ‘overdriving.' Various other sorts of screw heads and screwdriver bits are explicitly manufactured to prevent cam-out, including both Pozidriv and Torx alternatives.
Different types of screw drive
Screwdrivers transfer force, or torque, to the screw through the screw drive. A screw drive is a system of shaped cavities and protrusions that allow the tip of the screwdriver to slot in perfectly into the screw head. The shape and size of the screwdriver tip must match the screw head you are working on or you run the risk of damaging the screw as you attempt to tighten it.
Of course you can use a traditional screwdriver to tighten or loosen your screws. However, a power tool will always be better equipped to provide more torque meaning your screwing tasks can be completed in a matter of seconds. This will prove particularly convenient if you have a lot of screws to tighten in one go!
Slotted drives are not well suited to power driving as the screwdriver tip tends to twist out (or cam out) of the screw head as soon as the tool gains any speed. Once used for every piece of furniture and machinery, slotted screws are now only really found on old items. Sizes generally range from 3 to 6.5 mm.
Often referred to by the code PH, the Phillips drive features a cruciform or cross recess. Though widely used, Phillips bits also tend to cam out of screw heads as the screwing speed increases. Phillips tips tend to range from 3.5 to 8 mm in size corresponding to sizes PH2 to PH5.
Pozidriv or Pozi tips all have PZ marked on them and feature a similar design to a Phillips drive. However, be sure not to confuse these bits with Philips bits at the risk of stripping your screws! PZ drives are cross-shaped but also feature a 45° rib between each slot. This design allows the screwdriver to get a better grip on the screw head. There are five common sizes: PZ0 to PZ4.
Sometimes referred to as star drives, Torx drives provide very good grip. Suitable for a wide range of applications, Torx screws are increasingly being used for tasks like installing decking. The design of this drive means that there's very little chance of the tip camming out of the screw head. Sizes can range from T1 all the way up to T100, with the largest sizes reserved for the automotive industry.
These bits feature the same star-shaped design as ordinary Torx bits. However, they also feature a post in the centre to prevent a standard Torx driver being inserted. These screws provide greater security as they cannot easily be interfered with. Sizes typically range from T10 to T40.
Nut setters are basically nut drivers designed to be used with a power tool instead of by hand. These tools are actually sockets rather than screwdriver bits and may feature six sides or twelve to fit snugly around nuts and bolts. They are often used for appliance repairs.
Triangular or Robertson
Triangular or Robertson (square) screw drives are not widely used these days. In fact, they tend to be dreaded by DIYers as it's not always easy to come across the bits to deal with them!
Hex or Allen keys
Hex bits or Allen screw drives are commonly used for flatpack furniture kits. These screwdriver bits feature a smooth hexagonal shank all the way up to the tip. Hex or Allen keys are measured in across flats (or AFs) meaning the length from two parallel flat sides.