Table AII-9.--3-Wire Method of Measuring American National Standard Threads
M = D -- (1.5166 X P) = ) 3 X W
.86603
PD -- M +
(3XW)
No. of thds.
per inch
M1 -- M
1
To Check Angle
W1 -- W
1
M Measurement over best size wire.
M1 = Measurement over maximum size wire.
M1 = Measurement over minimum size wire.
D = Ouside Diameter of Thread.
P.D. = Pitch Diameter.
0.57735 X pitch
W = Diamerter Best size wire.
0.90Xpitch
W1 = Diameter maximum size wire.
0.56Xpitch
W1 = Diameter minimum size wire.
Minimum
Maximum
Best Wire Size
Pitch
No. Thds.
Wire Size
Wire Size
Thds. per inch
.57735 x Pitch
per inch
.140000
.250000
.144337
4
.225000
.128300
.124444
.222222
4
.200000
.115470
.112000
.200000
5
.180000
.104969
.101818
.181818
5
.163636
.093333
.096224
.166666
6
.149999
.080000
.082478
.142857
7
.128571
.133333
.074666
.076979
7
.120000
.072168
.07000
.125000
8
.112500
.064149
.062222
.111111
9
.100000
.056000
.100000
.057735
10
.090000
.050909
.052486
.090999
11
.081818
.048695
.050204
.086956
11
.078260
.048112
.046666
.083333
12
.075000
.044411
.043077
13
.076923
.069231
.040000
.041239
.071428
14
.064285
.036084
.035000
.062500
16
.056250
.031111
.032074
.055555
18
.050000
.028000
.050000
.028867
20
.045000
.025454
.026242
.046454
22
.040909
.023333
.024055
.041666
24
.037499
.021538
.022205
.038461
26
.034615
.024383
.022543
.037037
27
.033333
.020000
.03514
28
.032143
.020620
.018666
.019244
30
.033333
.030000
.017500
.018042
.031250
32
.028125
.015555
.016037
.027777
36
.024999
.014000
40
.014433
.025000
.022500
.014727
.013121
.022727
44
.020454
.011666
.020833
.018750
.012027
48
.011547
.011200
.020000
50
.018000
.010000
.010309
.017857
.016071
56
AII-10