How to Determine Screw Size Thread Count Step 1. Lay the screw down on a flat surface. Step 2. Place a steel rule down the axis of the screw . Step 3. Count the number of thread gaps within 1 inch of the screw . Step 4. Divide the count of thread gaps into the length. Step 5. Other Considerations. You will need both the thread diameter and the thread pitch to determine the thread size . If you are measuring Imperial bolt thread size , you'll need to record the measurements as thread diameter followed by a hyphen, then the thread per inch measurement . For metric bold thread size , the formula is the thread diameter ,. To determine the size of a pipe, the outside diameter of each pipe or fitting must be herepared to the table for size identification. For example, a 3/4 NPT pipe thread has an outside diameter of 1.050 inches . Each thread size has a defined number of threads per inch (TPI). The 3/4 NPT pipe thread has 14 threads per inch.

Thread Pitch. Metric fasteners are specified with a thread pitch instead of a thread count . The thread pitch is the distance between threads expressed in millimeters (measured along the length of the fastener). For example a thread pitch of 1.5 means that the distance between one thread and the … How Fasteners are Identified. Print this page . General. Fasteners diameter is measured either as a size number or as a direct measurement. For information on . The thread pitch or count describes how fine the threads are. This heremon knob and pull screw thread . The 8 refers to the size (diameter) of the screw , and the 32 means it has 32 threads to the inch. The diameter is measured at the shank of the screw . Screws are sized by gauge number and length. For example, an 8 gauge screw with 32 threads per inch and 1 in length would be written as: 8-32 X 1.

Dec 30, 2006 Each series assigns a pitch to diameter . For instance, a #10 UNC screw has 24 threads per inch, whereas a #10 UNF screw has 32 threads per inch. If a thread is specified by its series, look for the pitch in a table. Minor diameter is the smallest diameter of the thread , or the innermost diameter . There are thread gauges you can use to determine the diameter and threads per inch. For instance the 10 in 10-32 is the diameter, the 32 means it has 32 threads in a length of 1''. The larger the diameter number, the thicker the bolt.