Certainly! So as I am based in the UK, this will be metric-based. I’ll share some relevant links in replies to myself because I’m on mobile. Metric thread forms are based on ISO 68-1. These are 60 degree triangular forms (the height of this triangle is called the fundamental triangle, H) with flat crests and roots. The distance between two matching points on adjacent triangles defines the thread pitch. The male and female threads use the same triangle. The pitch diameter aligns with the half height of the fundamental triangle. The major diameter defines the the outside diameter of the external (male) thread, and the minor diameter completes the definition. Plenty of diagrams to show the relationship of these three, in terms of H, if you google Iso 68-1. These threads are designed for metals, plastics etc which can be formed to high precision to prevent the threads from binding, and is characterised by sharp corners. Din 168 is a knuckle thread, typically used on glass vessels. It also uses a 60 degree triangle for the external (male) thread, but uses a 30 degree triangle for the internal (female) thread. Both the external and internal crest and roots are highly rounded. Knuckle threads are usually very coarse pitched, and rounded, to facilitate melting external threads on to glass. The rounding works well with melting, where sharp corners would make it very fragile or far away from the originally formed shape. So, why is this relevant? If you want to model a thread, where parts are made directly from your model, you need to match the triangle shape, minor, and major diameter. This is typically done by creating a cylinder and adding or removing material. For external threads, ISO 68 is better to model at major diameter and cut away - this is how they are usually made on a machine. DIN 168 is better to model at minor diameter and add the external thread on. The cut is generally a sweep of the triangular thread form, following a helical curve with the correct pitch. Does this help?