Screws are a handy tool for a variety of projects, but choosing the right size can be tricky. The wrong length or width can split wood, and the incorrect head type may not be able to handle lateral or sheer forces. Using the right screws for your job ensures that they will stay in place. The correct gauge also helps the screw resist corrosion, which can damage or weaken the material.
In general, screw sizes are based on their major diameter and pitch. The diameter is the largest dimension of a screw, while the pitch is the distance from one point on the thread to the next. There are two systems for measuring screw sizes, the imperial system and the metric system. This article will discuss the imperial system, also known as the Unified Thread Standard (UTS).
Measuring Screw Sizes
To determine the right screw size for a project, consider what the screws will be used to do. This can include whether the screw will be driven into wood or metal, and if so, what kind of drill or tool it will need to drive into. Also think about the weight that the screw will need to support, as well as how long it needs to remain in place.
The most important factor in deciding the proper screw size is the diameter, or “gauge.” To measure a screw’s gauge, take its overall length, and subtract 1/16” from that measurement. The remaining number is the screw’s gauge; for example, a 4”-long screw with a #8 gage would be 8 threads per inch. 5/16 to mm