Threading method--Thread basic concepts

Last artile we talked the most common thread forms, today will talked the thread basic concepts.

Thread basic concepts

Some basic concepts needed to understand when discussing threading.

1. Root/bottom - The bottom surface joining the two adjacent flanks of the thread
2. Flank/side - The side of a thread surface connecting the crest and the root
3. Crest/top - The top surface joining the two sides, or  flanks.

Pitch (P)  = The distance from a point on the screw thread to a corresponding point on the next thread measured parallel to the axis. Angle (β) = The angle included between the sides of the thread measured in an axial plane..
Major Dia.(D/d) = Bottom of internal thread / Top of external thread

Minor Dia.(D1/d1) = Top of internal thread / Bottom of external threadPitch Dia. (D2/d2) = Important to check with thread micrometer

This is the effective diameter of the screw thread; approximately half way between the major and minor diameters.