There is a wide variety of machine screw sizes available on the market. The size of a machine screw is determined by its diameter and thread count. Some fasteners also have a specific head type, such as flat or countersunk. The length of a screw is usually measured from below the head to the tip. This measurement will depend on the head type, but it generally correlates with the length of hole that must be created for the screw. In addition, the stress area of a screw is another important factor. This is an indication of the strength of a screw, and is often used to determine which fasteners are suitable for various applications.
Measuring a screw can be a bit tricky, but there are a few simple ways to do it. One method is to use a tape measure or ruler. The other way to measure is by using a screw gauge. This tool is similar to a spark plug feeler gauge and typically has multiple metal leaves with serrated edges that match the threaded parts of standard screws. You can purchase these tools at most hardware stores or online.
A screw gauge is usually labeled with two numbers separated by a dash. The first number indicates the screw’s diameter and the second is the threads per inch (TPI). In general, a course screw has more threads than a fine screw of the same gauge. The screw’s major diameter is its functional width and the thread pitch is the distance between the threads in a given area of the screw.
It is possible to find a chart that matches up these measurements in either imperial or metric systems, but most fasteners will be listed with a combination of the two. Usually, the screw length and major diameter will be listed in inches and the TPI will be listed in fractions. For example, a screw with a diameter of 0.875 inches and 32 TPI will be labeled as “#10 – 35 x 2”.
Some manufacturers may list the measurement of a screw by the gauge and the length, but others will only give you the length. It is best to read the label on a screw before purchasing it to be sure that you know the measurements of the screw. In imperial systems, the screw will be labeled with a gauge number followed by the length, while in metric systems they are usually labeled with a decimal value and then the length is noted in millimeters.
It is very important to know how to correctly measure a screw, particularly in an emergency situation when you need to replace a missing or damaged screw. Knowing this information can help you make a quick decision as to what kind of screw you need for the job and avoid getting the wrong one. You can also learn more about measuring and matching up fasteners by reading our guide on Choosing the Right Fastener for Your Project. machine screw size chart