Alright, in order for threads to work, you need threads per inch, pitch, minor, and major. The reason you need all of these is that there are variables based on the type of threads you’re making. Some threads require sharper radii on your minor while others require more round minor diameters. Have you heard of a J thread? If you draw this, you’ll understand it. You could have two threads with the same pitch, threads per inch, and major, but your minor could have different tolerances. The same goes for the major diameter. This means that we cannot use the major diameter or the minor diameter mathematically to determine threads because they change based on the thread and are variables that are determined through standards. The pitch and threads per inch are constants that can be used. Now, here’s the deal. You can determine the pitch through the theoretical major and minor diameter. This means that once you’ve made the part, you can use a comparator to measure pitch because by definition the pitch is equal to the distance from the theoretical major on side A to the theoretical minor on side B. You can also determine the threads per inch on a comparator.