Threads and Threading - Sportpilot.info

Machinery's Handbook 27th Edition
Table 3. General Purpose Acme Single-Start Screw Thread Data ASME/ANSI B1.5-1988
Identification Basic Diameters Thread Data
Nominal
Sizes
(All
Classes)
Threads
per
Inch, a
n
Classes 2G, 3G, and 4G
Pitch,
P
Thickness
at Pitch
Line,
t = P/2
Basic
Height of
Thread,
h = P/2
Basic
Width of
Flat,
F = 0.3707P
Lead Angle λ at Basic
Pitch Diametera Classes 2G, 3G,and 4G
Shear
Areab Class 3G
Stress
Areac Major Pitch Minor
Diameter, Diameter, Diameter,
D D2 = D − h D1 = D − 2h Deg Min
Class 3G
1
⁄4 16 0.2500 0.2188 0.1875 0.06250 0.03125 0.03125 0.0232 5 12 0.350 0.0285
5
⁄16 14 0.3125 0.2768 0.2411 0.07143 0.03571 0.03571 0.0265 4 42 0.451 0.0474
3
⁄8 12 0.3750 0.3333 0.2917 0.08333 0.04167 0.04167 0.0309 4 33 0.545 0.0699
7
⁄16 12 0.4375 0.3958 0.3542 0.08333 0.04167 0.04167 0.0309 3 50 0.660 0.1022
1
⁄2 10 0.5000 0.4500 0.4000 0.10000 0.05000 0.05000 0.0371 4 3 0.749 0.1287
5
⁄8 8 0.6250 0.5625 0.5000 0.12500 0.06250 0.06250 0.0463 4 3 0.941 0.2043
3
⁄4 6 0.7500 0.6667 0.5833 0.16667 0.08333 0.08333 0.0618 4 33 1.108 0.2848
7
⁄8 6 0.8750 0.7917 0.7083 0.16667 0.08333 0.08333 0.0618 3 50 1.339 0.4150
1 5 1.0000 0.9000 0.8000 0.20000 0.10000 0.10000 0.0741 4 3 1.519 0.5354
11 ⁄ 8 5 1.1250 1.0250 0.9250 0.20000 0.10000 0.10000 0.0741 3 33 1.751 0.709
11 ⁄ 4 5 1.2500 1.1500 1.0500 0.20000 0.10000 0.10000 0.0741 3 10 1.983 0.907
13 ⁄ 8 4 1.3750 1.2500 1.1250 0.25000 0.12500 0.12500 0.0927 3 39 2.139 1.059
11 ⁄ 2 4 1.5000 1.3750 1.2500 0.25000 0.12500 0.12500 0.0927 3 19 2.372 1.298
13 ⁄ 4 4 1.7500 1.6250 1.5000 0.25000 0.12500 0.12500 0.0927 2 48 2.837 1.851
2 4 2.0000 1.8750 1.7500 0.25000 0.12500 0.12500 0.0927 2 26 3.301 2.501
21 ⁄ 4 3 2.2500 2.0833 1.9167 0.33333 0.16667 0.16667 0.1236 2 55 3.643 3.049
21 ⁄ 2 3 2.5000 2.3333 2.1667 0.33333 0.16667 0.16667 0.1236 2 36 4.110 3.870
23 ⁄ 4 3 2.7500 2.5833 2.4167 0.33333 0.16667 0.16667 0.1236 2 21 4.577 4.788
3 2 3.0000 2.7500 2.5000 0.50000 0.25000 0.25000 0.1853 3 19 4.786 5.27
31 ⁄ 2 2 3.5000 3.2500 3.0000 0.50000 0.25000 0.25000 0.1853 2 48 5.73 7.50
4 2 4.0000 3.7500 3.5000 0.50000 0.25000 0.25000 0.1853 2 26 6.67 10.12
41 ⁄ 2 2 4.5000 4.2500 4.0000 0.50000 0.25000 0.25000 0.1853 2 9 7.60 13.13
5 2 5.0000 4.7500 4.5000 0.50000 0.25000 0.25000 0.1853 1 55 8.54 16.53
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 1827.
Copyright 2004, Industrial Press, Inc., New York, NY
ACME SCREW THREADS 1831