Thread angle

Diagram of a thread angle

In mechanical engineering, the thread angle of a screw is the included angle between the thread flanks, measured in a plane containing the thread axis. ^[1] This is a defining factor for the shape of a screw thread. Standard values include:

Name	Code	Angle	Profile	Standards
Most V-threads	M	60°		including DIN 13 / ISO, NPT and UTS
Whitworth threads	W	55° [2]		DIN 49301 / BS
British standard pipe thread	G	55°		DIN / BS / EN / ISO 228-1 / ISO 7-1
National Pipe Thread	NPT	60°		ASME B1.20.-1983 Pipe Threads, General Purpose, Inch
Knuckle thread [3] [4] [5] Round thread	Rd	30°	[6]	DIN 405 / DIN 20400
Acme thread [7]		29°		ASME/ANSI B1.5-1988 [8]
Metric trapezoidal threads [1]	Tr	30°		DIN 103
Buttress threads [7]	S	45°		DIN 2781
German buttress threads [7]	S	30°		DIN 513
Square threads [1]	Sq	0° (parallel)		?
Panzergewinde, "steel conduit thread"	Pg	80°		DIN 40430
British Association (BA) thread	BA	47° 30' = 47.5°		BS 93:2008
Löwenherz thread [9]		53° 8' ≈ 53.1°
Bodmer thread [10]		50°
Thury thread [11] [12]		47° 30' = 47.5°

References

• List of DIN standards

Notes

1. Bhandari 2007 , p. 203.
2. BS 84: 1956
3. Knuckle Thread DIN 405
4. Knuckle Thread DIN 20400
5. Bornemann
6. Knuckle thread
7. Bhandari 2007 , p. 204.
8. Machinery's Handbook (1996), pp. 1716.
9. Löwenherz thread
10. Bodmer thread
11. Brooks, Randall C. "Standard Screw Threads for Scientific Instruments. Part 1: Production Techniques and the Filière Suisse." History and Technology, vol 5, 1988, pp. 68.
12. Thury thread

Bibliography

• Bhandari, V B (2007), Design of Machine Elements, Tata McGraw-Hill, ISBN   978-0-07-061141-2 .
• Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L.; Ryffel, Henry H. (1996), Green, Robert E.; McCauley, Christopher J. (eds.), Machinery's Handbook (25th ed.), New York: Industrial Press, ISBN   978-0-8311-2575-2, OCLC   473691581.