Table 6. Internal Inch Screw Thread Calculations for 19 ∕ Table 6. (Continued) Internal Inch Screw Thread Calculations for 19 ∕
64 -28 UNS-2B
64 -28 UNS-2B
Characteristic Description
Calculation
Notes
. h P 2 1 08253175 1 08253175 0 02777778 0 030070329 0 030070 n # = = = = . . . .
P is rounded to eight decimal places
Double height of external UN thread 2 h s
For class 2B the value is rounded to three decimal places to obtain the final value; other sizes and classes are expressed in a four place decimal.
. . D D h 2 0 2969 0 030070 0 266830 0 267 min bsc n 1 = − = − = = . .
Minimum internal major diameter ( D 1 min ) Maximum internal minor diameter ( D 1 max ) = minimum internal minor diameter ( D 1 min ) + internal minor diameter tolerance TD 1
D D TD max min 1 1 1 = +
D 1 min is rounded to six decimal places
2
. TD P P 025 040 . = −
1
Internal minor diameter tolerance TD 1
TD 1 is rounded to four decimal places.
. . 0 25 0 02777778 0 40 0 02777778 0 006944 0 000309 0 006635 0 0066 . . . . . . 2 # # − − = =
= =
For Class 2B thread the value is rounded to three decimal places to obtain the final values. Other sizes and classes are expressed to four decimal places
. . D D TD 0 266830 0 006635 0 273465 0 273 max min 1 1 1 = + = + = = . .
Maximum internal minor diameter ( D 1 max )
Minimum internal pitch diameter ( D 2 min ) = basic major diameter ( D bsc ) − twice the external thread addendum ( h b )
D D h min max b 2 1 = −
h b = external thread addendum
. P 0 64951905 0 64951905 0 02777778 0 018042197 0 018042 b # = = = = . . . .
h
h b is rounded to six decimal places
External thread addendum
. . D D h 0 2969 0 018042 0 278858 0 2789 min bsc b 2 = − = − = = . .
Minimum internal pitch diameter ( D 2 min )
D 2 min is rounded to four decimal places
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