What is the theoretical profile of the thread for a length of one pitch in the axial plane called?

The theoretical profile of the thread for a length of one pitch in the axial plane is referred to as the basic profile of the thread. This profile represents the geometric shape that serves as a standard reference for the thread, devoid of any tolerances or variations that may occur during manufacturing. It is instrumental in defining the essential dimensions and characteristics, such as the shape of the thread and the angle of the flanks, which are critical for ensuring proper fit and functionality in threaded connections.

Understanding this concept is crucial because the basic profile serves as the foundation for all other thread specifications and variations, including those related to fit and assembly. By establishing a clear standard, engineers can ensure that threads produced to this profile will function correctly across different applications, providing consistency and reliability in mechanical assemblies.

Other terms like effective thread or design form might relate to practical implementations or modified versions of the thread for specific applications, but they do not capture the theoretical basis that defines the essential geometric attributes of the thread itself as concisely as the basic profile does.