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
. . d d Td 0 4989 0 006508 0 492392 0 4924 min max = − = − = = . .
Minimum external major diameter ( d min ) Maximum external pitch diameter ( d 2 max ) = maximum external major diameter ( d max ) − twice the external thread addendum ( h as )
d min is rounded to four decimal places
h 2
d
d max # = −
h as = external thread addendum
2
max
as
. 2 064951905 2 0 64951905 2 0 64951905 0 03571429 0 02319711 0023197 as as as # = = = = = . . . . . h h P h
P
2 h as is rounded to six decimal places
External thread addendum
. h 2 0 4989 0 23197 . as = −
d d
# = −
Maximum external pitch diameter ( d 2 max ) Minimum external pitch diameter ( d 2 min ) = maximum external pitch diameter ( d 2 max ) − external pitch diameter tolerance (Td 2 ) Minimum external pitch diameter ( d 2 min ) Maximum external UNR minor diameter ( d 3 max ) = maximum external major diameter ( d max ) − double height of external UNR thread 2 h s
d 2 max is rounded to four decimal places
2
max max
. 0 475703 0 4757 . =
=
Td 2 = external pitch diameter tolerance (see previous Td 2 calculation in this table)
d d Td min max 2 2 2 = −
. . d d Td 0 4757 0 003668 0 472032 0 4720 min max 2 2 2 = − = − = = . .
d 2 min is rounded to four decimal places
h 2
d d max 3
max # = −
h s = external UNR thread height,
s
. h P 2 1 19078493 1 19078493 0 03571429 0042528 s # = = = . . .
External UNR thread height (2 h s )
2 h s rounded to six decimal places
. h 2 0 4989 0 042528 . s −
d d
max # = − =
Maximum external UNR minor diameter ( d 3 max )
d 3 max is rounded to four decimal places
3
max
. 0 456372 0 4564 . =
=
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