BSW / BSF / Whitworth threads are used where clerance between male & female threads is to be controlled.
This uses Imperial system of units.
Specification :
Basic Dimensions- BS 84-2007 & Gauging Practice: BS 919 Part II - 2007.
Manufacturing Range :
Thread Plug & Ring Gauges from Diameter 1/8 to 6" , TPI 40 to 2.5
Dia Inch | BSW | BSF | BSB | Type of Thread Gauges used | ||||
1/8 | 40 | - | 26 | Thread Plug Gauges. | Plain plugs to check tapped holes/ minor diameter |
Thread Ring Gauges. |
Check Plug Gauges to Check New Rings. |
Wear Check Plug Gauges to Check / Calibrate used Rings. |
3/16 | 24 | 32 | 26 | |||||
* 7/32 | - | 28 | * | |||||
1/4 | 20 | 26 | 26 | |||||
5/16 | 18 | 22 | 26 | |||||
3/8 | 16 | 20 | 26 | |||||
7/16 | 14 | 18 | 26 | |||||
1/2 | 12 | 16 | 26 | |||||
*9/16 | 12 | 16 | 26 | |||||
5/8 | 11 | 14 | 26 | |||||
*11/16 | 11 | 14 | * | |||||
3/4 | 10 | 12 | 26 | |||||
7/8 | 9 | 11 | 26 | |||||
1 | 8 | 10 | 26 | |||||
1.1/8 | 7 | 9 | 26 | |||||
1.1/4 | 7 | 9 | 26 | |||||
*1.3/8 | - | 8 | 26 | |||||
.1/2 | (6) | (8) | 26 | |||||
1.3/4 | (5) | (7) | 26 | |||||
2 | (4.5) | (7) | 26 | |||||
2.1/4 | (4) | (6) | * | |||||
2.1/2 | (4) | (6) | * | |||||
2.3/4 | (3.5) | (6) | * | |||||
3 | (3.5) | (5) | * | |||||
*3.1/4 | (3.25) | (5) | * | |||||
3.1/2 | (3.25) | (4.5) | * | |||||
*3.3/4 | (3) | (4.5) | * | |||||
4 | (3) | (4.5) | * | |||||
4.1/2 | (2.875) | (4) | * | |||||
5 | (2.75) | - | * | |||||
5.1/2 | (2.625) | - | * | |||||
6 | (2.5) | - | * |
Tolerance Class
Internal Threads -Plug | External Threads - Rings |
Medium Class | Medium Class |
Normal Class | Free Class |
Close Class | Close Class |