Screws are used for an incredible range of tasks and the right type can make or break a project. Using the wrong size screw can result in a poor connection or even damage the materials you’re working with. Fortunately, knowing how to properly measure a screw’s diameter, length and threads can help you avoid such issues.
Measuring screw dimensions can be as simple as using a ruler or tape measure and as complex as using calipers. However, understanding the basic principles of measuring a screw will allow you to easily determine what you need for your next project.
Whether you’re installing a new door, making furniture or just building something for fun, screws are an indispensable tool for construction projects. But with so many different types and sizes available, choosing the correct one for your project can be confusing.
The most important measurement when it comes to selecting the proper screw is its diameter. Screws come in a variety of diameters and are often labeled with three figures, a gauge number (like #6 x 1-1/4″), a thread count (like TPI) and a length, usually given in inches or millimeters.
The gauge number represents the screw’s overall diameter, which may or may not include the head, depending on the type of screw you’re using. For example, a wood screw has a head that’s flat or pan-shaped, while machine screws have a hexagonal or square heads. A screw’s major diameter is measured from the crest of one side of the thread to the crest on the other, while the minor diameter is the distance from the root of the thread to the tip or blunt end of the screw. pilot hole for 1/4 lag screw