Guide to Self Tapping Screw – Self Tapping Screws vs Self Drilling Screws


Self-tapping screws are an important type of fastener used in construction, here let’s talk about the self-tapping screw uses, development, sizes, and differences between self-tapping and self-drilling screws.

What Is Self Tapping Screw and What Is It Used for?

A self-tapping screw is a type of threaded fastener that can create its own hole as it is driven into the material. The screw has specially shaped threads that can cut into and tap the material, allowing it to be securely fastened. A self-tapping screw is mainly used to secure wood, plastic, metal, brick and other materials together. Once the screw has created its threaded hole, it provides a connection between two or more pieces, holding them together firmly. Self-tapping screws simplify the fastening process, which saves time and effort during installation. Self-tapping screws can be used in a wide range of applications, including construction, automotive, electronics, woodworking, and DIY projects. They are suitable for materials where drilling or creating threads in advance may be challenging or not feasible.


The Development History of Threads

1. Machine screws have been used for centuries and have a uniform diameter and pitch along the threaded portion. They require pre-drilled pilot holes in the material before they can be threaded in. Machine screws are commonly used in applications where precise and tight fastening is required, such as machinery and metal fabrication.

2. The introduction of self-tapping screws revolutionized the fastening industry by eliminating the need for pre-drilling pilot holes. Self-tapping screws have specially designed thread geometry with cutting edges that allow them to penetrate and tap their own threaded hole as they are screwed into the material. This innovation simplified and accelerated the installation process, particularly in materials like wood, plastic, and softer metals. Self-tapping screws gained popularity in various industries, including construction, automotive, electronics, and consumer products.

3. Advancing further, self-drilling screws incorporate a drilling tip or point that can penetrate hard materials, such as metals, without the need for pre-drilling. These screws combine the functions of drilling and tapping into a single step, providing greater convenience and efficiency. The drilling tip typically has flutes or grooves for chip removal during the drilling process. Self-drilling screws are commonly used in metalwork, steel framing, roofing, and other applications where drilling and fastening in hard materials are required. They often have a higher hardness and stronger construction to withstand the drilling process.

Self Tapping Screws vs Self Drilling Screws, What Are the Differences

1. Function: Self-tapping screws create their own threaded holes in the material as they are driven in, eliminating the need for pre-drilling. Self-drilling screws, on the other hand, have a drilling tip that can cut through the material and create a hole as they are screwed in, providing a convenient all-in-one solution.

2. Pointed Tip: Self-tapping screws have a sharp, pointed tip designed to cut into the material and create the threads. Self-drilling screws have a drill-like tip that can penetrate and drill through the material.

3. Drill Bit Requirement: Self-tapping screws do not require a separate drill bit; they can be directly driven into the material using a screwdriver or power tool. Self-drilling screws often require a specific-sized drill bit to create a pilot hole before being screwed in.

4. Suitable Materials: Self-tapping screws are typically used in relatively softer materials like wood, plastic, and thin metal sheets. Self-drilling screws are designed for harder materials, such as metals, where drilling a pilot hole is more challenging.

5. Thread Design: Self-tapping screws have sharp and distinct threads that cut into the material to create the threads. Self-drilling screws have a unique thread design to help facilitate drilling and provide better grip during installation.

6. Speed and Efficiency: Self-drilling screws are generally faster to install since they combine drilling and tapping functions into a single step. Self-tapping screws may take longer as they require the screw to cut its own threads.

7. Applications: Self-tapping screws are commonly used in applications like construction, woodworking, electronics, and DIY projects. Self-drilling screws are often employed in metalwork, steel framing, roofing, and other applications where drilling and fastening in hard materials are required.

Self Tapping Screw Sizes Explained

– Diameter: The diameter of a self-tapping screw refers to the measurement across the widest part of the screw’s thread. It is typically denoted by a number, such as #4, #6, #8, etc., or represented in millimeters (e.g., 3mm, 4mm, 6mm, etc.). Larger-diameter screws generally have thicker threads and are used for heavier-duty applications. For example, a #10 self-tapping screw typically has a major diameter of 0.182 to 0.189, and a minor diameter of 0.135 to 0.141 inches.

– Length: The length of a self-tapping screw is measured from the base of the screw head to the tip of the threaded portion. It is typically specified in inches or millimeters. The required length depends on the material thickness being joined and the desired depth of penetration.

– Thread Pitch: Thread pitch refers to the distance between adjacent threads on a self-tapping screw. It is usually measured in threads per inch or millimeters. Different screw sizes may have different thread pitches to suit specific applications and materials.

– Head Type: Self-tapping screws can have various head types, including pan head, flat head, truss head, hex head, or round head. Each head type has its own purpose and function, such as providing a flush or countersunk appearance or accommodating specific driver types.