Table 3. External Inch Screw Thread Calculations for 1 ∕ Table 3. (Continued) External Inch Screw Thread Calculations for 1 ∕
2 -28 UNEF-2A
2 -28 UNEF-2A
Characteristic Description
Calculation
Notes
Maximum external UN minor diameter ( d 1max ) = maximum external major diameter ( d max ) − double height of external UN thread 2 h s
For UN threads, 2 h s = 2 h n
h 2
d d max 1
max # = −
s
. h P 2 1 08253175 1 08253175 0 03571429 0 03866185 0038662 s # = = = = . . . .
Double height of external UN thread 2 h s
2 h s is rounded to six decimal places
. h 2 0 4989 0 038662 0 460238 0 4602 . . . max # = − = − s = =
d d max 1
Maximum external UN minor diameter ( d 1 max )
d 1 max is rounded to four decimal places
Table 4. Internal Inch Screw Thread Calculations for 1 ∕
2 -28 UNEF-2B
Characteristic Description
Calculation
Notes
. 2 1 05 05000 .
d
d bsc is rounded to four decimal places
Basic major diameter, d bsc
bsc = = =
P is rounded to eight decimal places
Pitch, P
. . P 28 = 1 = 0 035714285714 0 03571429 =
Minimum internal minor diameter ( D 1 min ) = basic major diameter ( D bsc ) − double height of external UN thread 2 h n
D D h 2 min bsc n 1 = −
2 h n is the double height of external UN thread
. h P 2 1 08253175 1 08253175 0 03571429 0 03866185 0 038662 n # = = = = . . . . . . D D h 2 0 5000 0 038662 0 461338 0 461 min bsc n 1 # = − = − = = . .
Double height of external UN thread 2 h s
2 h n is rounded to six decimal places
For class 2B the value is rounded to three decimal places to obtain the final values
Minimum internal major diameter ( D 1 min )
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