Threading Checklist

1 What’s the Application 3 Select Tooling

A) Internal or External F) External

B) Type of thread form G) Internal

C) Material being machined

b f Thread Angle Helix Angle I 2 I 1

ExternalInternald
Thread1
Thread
f

h z h d

1 I2 I 1

Depth of Thread See pages C238 – C242

2 Machine Set-Up 4 Check Helix Angle

D) LH or RH thread form Note: The 1.5°

E) Machine Set-Up Calculation of thread helix angle for a given thread

Right Hand Thread / Right Hand ToolingHelix angle - Tan-1 u =Lead of the Thread
Pitch/Effective Diameter x π
Helix Angle Calculation (mm)
OutsidePitchPitch
Diameter11,251,51,752233445566
mmHelix Angles (Degrees and Minutes) es and Minutes)
53° - 38'4° - 33'5° - 27'------
63° - 2'3° - 48'4° - 33'5° - 18'6° - 33'----
82° - 17'2° - 51'3° - 25'3° - 59'4° - 33'6° - 49'---
101° - 49'2° - 16'2° - 44'3° - 11'3° - 39'5° - 27'---
121° - 31'1° - 54'2° - 17'2° - 39'3° - 2'4° - 33'---
See page C248 141° - 18'1° - 38'1° - 57'2° - 17'2° - 36'3° - 54'---
161° - 8'1° - 42'1° - 42'2° - 0'2° - 17'3° - 25'---
181° - 1'1° - 16'1° - 31'1° - 46'2° - 2'3° - 2'4° - 3'--
2055´ See page C2501° - 8'1° - 22'1° - 36'1° - 49'2° - 44'3° - 39'--
2544´55´1° - 6'1° - 16'1° - 28'2° - 11'2° - 55'--
3036´46´55´1° - 4'1° - 13'1° - 49'2° - 26'3° - 2'3° - 39'
3531´39´47´55´1° - 3'1° - 33'2° - 5'2° - 36'3° - 8'
4027´34´41´48´55´-1° - 49'2° - 17'2° - 44'
4524´30´36´43´48´1° - 13'1° - 37'2° - 2'2° - 26'
50---38´44´1° - 6'1° - 28'1° - 49'2° - 11'
60----36´55´1° - 13'1° - 31'1° - 49'
70--23´-31´47´1° - 3'1° - 18'1° - 34'
80-----41´55´1° - 8'1° - 22'
90---21´24´36´48´1° - 1'1° - 13'
100--17´19´-33´-55´1° - 6'