A Bit About Driver Bits: PH, PZ, SQ & Hex Explained

In any woodworking class, understanding the various tools and accessories is crucial for both students and instructors. Among these tools, driver bits are essential for fastening screws and completing projects efficiently. But with so many different types—like PH, PZ, SQ, and Hex—it can be confusing to know which one to use. Let’s break down what these abbreviations mean, their specific uses in woodworking, and the differences between driver bits and drill bits.

What Do PH, PZ, SQ, and Hex Mean?

 

• • PH (Phillips): The PH, or Phillips head, is the most common type of driver bit. It’s designed to fit into screws with a cross-shaped indentation. Phillips head screws are known for their self-centring design, which helps prevent slippage (known as cam-out). This makes them ideal for general woodworking tasks where stability and control are needed.
    

• • PZ (Pozidriv): The PZ, or Pozidriv, is similar to the Phillips head but with additional smaller ribs between the cross slots. This design offers more contact points, reducing the chance of slippage even further. Pozidriv bits are often used in applications where higher torque is needed, such as in heavy-duty woodworking projects.
    

• • SQ (Square/Robertson): The SQ, or Square (also known as Robertson), driver bit features a square-shaped tip. While this bit is particularly popular in North America, it is also commonly used in Australia. The SQ bit is prized for its ability to hold screws securely on the bit, reducing the risk of slippage. It’s often used in cabinetry and other precise woodworking projects where a secure fit is crucial.
    

• • Hex (Hexagonal): The Hex bit, as the name suggests, has a hexagonal shape. Hex bits are commonly used with screws that require a higher level of torque, making them ideal for tasks involving metal or where a very secure fastening is needed. In woodworking, Hex bits are often used for assembling furniture or securing large, heavy components. The hexagonal shape provides a solid grip, reducing the likelihood of stripping the screw head.
    

What Do The Numbers On The Driver Bits Mean?

When selecting a driver bit, you’ll notice that they come in various sizes, typically indicated by a number. Here’s what those numbers mean:

 

• • PH2 vs. PH3:

     

    • • PH2: The PH2 is the most commonly used Phillips bit size. It’s typically used with standard wood screws ranging from 3.5mm to 5mm in diameter. In woodworking classes, a PH2 bit is ideal for most general-purpose screwing tasks.
    • • PH3: The PH3 bit is larger and used for screws that are 6mm in diameter or more. This bit is better suited for more heavy-duty tasks, such as securing larger pieces of wood or dealing with tougher materials.

• • PZ1 vs. PZ2:

     

    • • PZ1: The PZ1 bit is smaller and used for finer screws, usually in the 2.5mm to 3mm range. This makes it ideal for delicate woodworking tasks where precision is key.
    • • PZ2: The PZ2 is similar in size to the PH2 but is designed for Pozidriv screws. It’s used for screws around 3.5mm to 5mm in diameter, making it a versatile choice for a wide range of woodworking projects where higher torque is required.

• • Hex Bit Sizes: Hex bits come in various sizes, typically measured in millimetres (mm) or inches. The most common sizes used in woodworking range from 2mm to 8mm. For example, a 4mm Hex bit is often used for assembling furniture, while a larger 8mm Hex bit might be used for securing heavy-duty components in place.

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Understanding the differences between PH, PZ, SQ, and Hex driver bits—and the various sizes like PH2 vs. PH3 or PZ1 vs. PZ2—can significantly impact the quality of your woodworking projects. By choosing the right bit for the job, you ensure that your screws are driven accurately and securely, making your woodworking class projects more successful.

Remember, while screwdriver bits are essential for fastening screws, drill bits are your go-to tool for creating holes. Having a clear understanding of these tools will not only help you in your woodworking classes but also make your projects smoother and more enjoyable.

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