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 (including ISO, NPT and UTS)	M	60°		DIN 13 / ISO ? / ASME/ANSI ?
Whitworth threads	W	55°		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^[2]^[3]^[4] Round thread	Rd	30°	^[5]	DIN 405 / DIN 20400
Acme thread^[6]		29°		ASME/ANSI B1.5-1988^[7]
Metric trapezoidal threads^[1]	Tr	30°		DIN 103
Buttress threads^[6]	S	45°		DIN 2781
German buttress threads^[6]	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^[8]		53° 8' ≈ 53.1°
Bodmer thread^[9]		50°

References

Notes

^ ^a ^b ^c Bhandari 2007, p. 203.
^ Knuckle Thread DIN 405
^ Knuckle Thread DIN 20400
^ Bornemann
^ Knuckle thread
^ ^a ^b ^c Bhandari 2007, p. 204.
^ Machinery's Handbook (1996), pp. 1716.
^ Löwenherz thread
^ Bodmer 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.