Instructional Instrument Lab: Drill and Screw Thread Information
| Manager/Instructor: Stan Cotreau | 32 Lyman Laboratory, 17A Oxford
Street, Cambridge, MA, 02138 (617)495-5217 | 617-594-4631 (cell) | |
Screw Thread Terminology:
Major Diameter
The largest diameter of the thread. This is the distance between the crests of the thread measured perpendicular to the thread axis.
Pitch Diameter
The diameter of the thread used to establish the relationship, or fit, between an internal and external thread. The pitch diameter is the distance between the pitch points measured perpendicular to the thread axis. The pitch points are the points on the thread where the thread ridge and the space between the threads are the same width.
Minor Diameter
The smallest diameter of the thread. This is the distance between the roots of the thread measured perpendicular to the thread axis.
Thread Angle
The included angle of the thread form.