When it comes to screw measurement, there are three essential measurements every tradesperson should know: gauge, length, and threads per inch (TPI). Screws are available in a wide variety of sizes to suit almost any construction task, from woodworking to metal roof installations. The wrong size can split a board or damage the structural integrity of a building, so getting it right is crucial. This article explains how to read the label on a screw box and choose the correct size for your job.
When choosing a wood screw, it’s important to keep in mind the type of lumber you’re working with and how the joints will be used. For instance, end joints tend to be weaker than face joints because they join the ends of boards with less wood fibers. Consequently, you’ll need longer wood screws than normal to ensure that the screw can penetrate deep enough into the secondary piece to provide strong support and stability.
To determine the screw’s diameter, you need to measure its width beneath the head of the screw. This is known as the root diameter or minor diameter, and it’s usually the first number on a screw size label. Screws can also be measured by their shaft length, which is the section of the screw that goes into a material without the head. For example, the Duraspin screw mentioned above is given a length of 1-1/4″, meaning that the screw will go into a material of that thickness to a point just above its head.
The screw’s pitch is the distance between adjacent threads. For imperial screw sizes, this is expressed as a decimal number between 0.0 and 1.0, and it’s often given as the second number on a screw size label. For metric screw sizes, the pitch is measured in millimeters and usually given as a number preceded by “M” or the letter “mm”: for example, M6 has a thread pitch of 6 mm.
Whether you’re working in imperial or metric measurements, knowing how to measure screw diameter and pitch will help you select the proper size for your project. If you don’t have access to a screw size chart, you can use a screw gauge, which consists of strips of metal with various screw sizes cut into them. By systematically testing each strip with the appropriate screw, you’ll be able to find the exact size of your screw.
Many people are confused by how to choose the right screw for their projects because there are so many different types and sizes of screws. However, with a little bit of knowledge and practice, it’s easy to determine which size screw you need for your project. Simply follow these tips and you’ll be able to choose the right screw for any situation with confidence. Good luck! The next time you have a project that requires screws, make sure to check out our selection of collated fasteners. We’ve got everything from metal roofing screws to standard drywall screws. 1/4 screw diameter