Thread Pitch
Thread pitch is the distance between two consecutive thread crests. It also indicates how far a screw advances axially in one complete revolution.
For metric threads, the pitch is stated directly in millimetres.
For inch threads, the term pitch is used, but technical tables state the number of threads per inch (TPI) rather than the pitch directly.
The conversion formula is:
Pitch [mm] = 25.4 ÷ TPI
Depending on the ratio of diameter to pitch, the following thread types are distinguished:
| Thread type | Pitch-to-diameter ratio | Typical characteristics |
|---|---|---|
| Steep thread | large pitch relative to diameter | rapid movement, high feed rate, lower self-locking |
| Coarse thread | standard pitch (normal thread) | standard in engineering, versatile |
| Fine thread | small pitch relative to diameter | precise adjustment, high self-locking, greater strength |