Types of Screw Heads and Bits

How To Choose A Screwdriver Bit

Screw Bits

Not all screwdrivers are the same, in fact there are several different types, and for each type you will need the correct screwdriver bit. I have written this guide with some of the most common ones that you would likely encounter, to assist people who are not sure of the exact type of screwdriver bit that they need.

Phillips

Phillips screw drives are one of the most common you will find. Many of the screws around your home or office will have this type of screw head. The cross shape recessed into the circular shape of the screw head is the main identifying characteristic of a Phillips screw head and a Phillips screw bit is designed specifically for this type of screw.

Phillips Tamper-resistant

Although they are nowhere as common as the the regular Phillips screw heads, there may come a time when you need a Phillips tamper-resistant screw bit. They have the same size options and shape a the regular Phillips but what sets them apart is the fact that they will have a tamper-resistant pin located in the center.

Pozidriv

This is a very common screw head in Europe but you won’t come across it much in the United States. It can be considered to be an improved Phillips as it looks similar but has four more contact points that allow for greater torque application as they reduce the chances that the bit will cam-out. These screwdriver bits also decrease wear and create a larger driving surface.

Slotted

They are the original screw heads but slotted screws are certainly not as popular as they once were. A slotted screw drive will have a single straight line recessed from one end of the screw head to the other. These screw heads require a bit that has a tip with a flat blade and is the correct size.

Torx

A torx screw head has a 6 pointed star shape recessed into it. They are commonly used in electronic devices but are increasingly being used in other applications. You will need a torx bit for your screwdriver to work with one of these.

TORX Plus

The Torx plus is a relatively new screwdriver bit design. It is an improvement on the regular torx design in that it allows for more torque to applied, even if you are driving at very high speeds. The torx plus can do this because it allows for more contact between the screw head and the driver.

Square or Robertson

This type of screw will require the use of screwdriver bits are known as square recess bits or roberston bits. The are sometimes called roberston because they were invented by a Canadian named P.L. Roberston in 1908. They are very resistant to cam-out and this feature makes them more reliable than slotted or Phillips bits.

Tri-Wing

Tri-wing screws have three slots that are evenly spaced out on the screw head. They are most commonly found on electronic devices where manufacturers want to discourage consumers from doing home repairs. You will need tri-wing screwdriver bits to unlock this type of screw and these bits can be found individually or as a part of a screwdriver bit set.

Spanner

Screw heads with two holes at the top are known as spanner, snakes eyes or notched screws. They are commonly used where manufacturers want to discourage tampering for example in electronics but they can also be used in a wide variety of other applications as well. Spanner bits will have two small identical round pins that fit into the holes on the spanner screw head.

Internal Hex

When you are assembling furniture or doing some other task that require the use of an allen key but doesn’t have enough space for you to use one, you can try using an internal hex screwdriver bit. They have the same hexagon shaped head as an allen key but they are designed to fit into your drill to give you access when you have obstacles that limit the use of a n allen key.

Nutsetters

Nutsetters have a hexagon shape similar to internal hex drives but the nutsetter bits fit over the screw rather than into it as the the hex bits do. For applications where you will use impact drivers nutsetters are ideal because they are able to handle torque.

Drywall Bits

These are basically Phillips bits that have a metal ring near to the end. The purpose of the metal ring is to prevent the from going past the the surface of the material. When you are screw driving with these bits the ring will be pressed against the and stop the screw from going any further.

Closing Words

You should always use the correct screw bit for the type of screw head that you have. Even though some of them may look the same or very similar using the wrong one can cause damage to the screw bit itself or the screw head. To avoid getting into an unwanted situation where you have damage to any of your tools, check and make sure that you are using the correct screwdriver bits before you start working.