Table 3. General Purpose Acme Single-Start Screw Thread Data ANSI/ASME B1.5-1997 (R2014)
Identification
Basic Diameters Classes 2G, 3G, and 4G
Thread Data
Lead Angle λ at Basic Pitch Diameter a Classes 2G, 3G,and 4G
Nominal Sizes (All Classes)
Thickness at Pitch Line, t = P /2 0.03125 0.03571 0.04167 0.04167 0.05000 0.06250 0.08333
Basic Height of Thread, h = P /2 0.03125 0.03571 0.04167 0.04167 0.05000 0.06250 0.08333 0.08333 0.10000 0.10000 0.10000 0.12500 0.12500 0.12500 0.12500 0.16667 0.16667 0.16667 0.25000 0.25000 0.25000 0.25000 0.25000
Basic Width of Flat, F = 0.3707 P
Threads per Inch, a n
Minor Diameter, D 1 = D − 2 h
Pitch Diameter, D 2 = D − h
Stress Area c Class 3G
Shear Area b Class 3G
Major Diameter, D 0.2500
Pitch, P
Deg
Min
16 14 12 12 10
0.2188 0.2768 0.3333 0.3958 0.4500 0.5625 0.6667 0.7917 0.9000 1.0250 1.1500 1.2500 1.3750 1.6250 1.8750 2.0833 2.3333 2.5833 2.7500 3.2500 3.7500 4.2500 4.7500
0.1875 0.2411 0.2917 0.3542 0.4000 0.5000 0.5833 0.7083 0.8000 0.9250 1.0500 1.1250 1.2500 1.5000 1.7500 1.9167 2.1667 2.4167 2.5000 3.0000 3.5000 4.0000 4.5000
0.06250 0.07143 0.08333 0.08333 0.10000 0.12500 0.16667 0.16667 0.20000 0.20000 0.20000 0.25000 0.25000 0.25000 0.25000 0.33333 0.33333 0.33333 0.50000 0.50000 0.50000 0.50000 0.50000
0.0232 0.0265 0.0309 0.0309 0.0371 0.0463 0.0618 0.0618 0.0741 0.0741 0.0741 0.0927 0.0927 0.0927 0.0927 0.1236 0.1236 0.1236 0.1853 0.1853 0.1853 0.1853 0.1853
5 4 4 3 4 4 4 3 4 3 3 3 3 2 2 2 2 2 3 2 2 2 1
12 42 33 50 33 50 33 10 39 19 3 3 3 48 26 55 36 21 19 48 26
0.350 0.451 0.545 0.660 0.749 0.941 1.108 1.339 1.519 1.751 1.983 2.139 2.372 2.837 3.301 3.643 4.110 4.577 4.786 5.73
0.0285 0.0474 0.0699 0.1022 0.1287 0.2043 0.2848 0.4150 0.5354 0.709 0.907 1.059 1.298 1.851 2.501 3.049 3.870 4.788 5.27 7.50
1 ∕ 4
0.3125 0.3750 0.4375 0.5000 0.6250 0.7500 0.8750 1.0000 1.1250 1.2500 1.3750 1.5000 1.7500 2.0000 2.2500 2.5000 2.7500 3.0000 3.5000 4.0000 4.5000 5.0000
5 ∕ 16
3 ∕ 8
7 ∕ 16
1 ∕ 2 5 ∕ 8 3 ∕ 4 7 ∕ 8
8 6 6 5 5 5 4 4 4 4 3 3 3 2 2 2 2 2
0.08333 0.10000 0.10000 0.10000 0.12500 0.12500 0.12500 0.12500 0.16667 0.16667 0.16667 0.25000 0.25000 0.25000 0.25000 0.25000
1
1 1 ∕ 8 1 1 ∕ 4 1 3 ∕ 8 1 1 ∕ 2 1 3 ∕ 4 2 1 ∕ 4 2 1 ∕ 2 2 3 ∕ 4 2
3
3 1 ∕ 2
4
6.67 7.60 8.54
10.12 13.13 16.53
9
4 1 ∕ 2
5
55
a All other dimensions are given in inches. b Per inch length of engagement of the external thread in line with the minor diameter crests of the internal thread. Figures given are the minimum shear area based on max D 1 and min d 2 . c Figures given are the minimum stress area based on the mean of the minimum minor and pitch diameters of the external thread. See formulas for shear area and stress area on page 2056.
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