Screws are commonly used fasteners that are available in a wide variety of styles and sizes. Their use is widespread and has led to standardized sizing. Standardized sizing provides consistency and ensures that screws are compatible with other fasteners like nuts, washers and bolts. Screw sizes are categorized by driver type (flat, Phillips or hex), length, shank diameter and threads per inch.
This article explains the details of these factors and how to determine which screw size is right for you or your project. Jaycon Systems engineers often use small screws to hold plastic parts or printed circuit boards together, and the right size screw can make all the difference. This can be especially important if the part is a complex piece or has intricate features. Using the wrong size of screw can lead to loose or unstable connections.
The screw size designation is typically located on the head of the screw. The first number listed is the head diameter, then the shaft or shank diameter and finally, the number of threads per inch. The shaft diameter and head diameter are the same, but the number of threads varies between different types of screws. Generally speaking, the larger the screw, the more threads there are.
Screws are categorized in two ways: imperial and metric. Screws with an imperial system measurement label list the gauge first, followed by the length and then the thread count in a format such as “10-35 x 2.” Screws that are measured in metric units will usually have the threads listed last, and will be marked as such with a mm measurement paired with a decimal value, for example 4 mm x 1 mm.
In addition to these sizing systems, there are other specifications that are common amongst screw types. For example, some screws have special coatings that protect the materials they connect to, while others are designed for specific purposes. Drywall screws, for example, have a curve at the point where the threads meet on the shaft to prevent tearing of the drywall. Wood screws have coarse and fine threads to accommodate different wood thicknesses.
With all these variations, it can be tricky to understand what each number means and how to measure a screw’s head or shaft to get the right diameter and threading. But this information is crucial for any construction or DIY job, and the intricacies of screw sizing can be easily understood with the help of a simple chart. By understanding these concepts, it’s easy to get the most out of your screws and complete your projects. 3/8 in to mm