Threads and Threading - Sportpilot.info

1844 ALTERNATIVE STUB ACME SCREW THREADS
Table 13. American National Standard Stub Acme Screw Thread Form — Basic
Dimensions ASME/ANSI B1.8-1988 (R2001)
Thds.
per
Inch a
n
Pitch,
P = 1/n
Machinery's Handbook 27th Edition
Height of
Thread
(Basic),
0.3P
Total
Height of
Thread,
0.3P + 1 ⁄ 2
allowance b
Thread
Thickness
(Basic),
P/2
Crest of
InternalThread
(Basic),
0.4224P
Width of Flat
Root of Internal
Thread,
0.4224P −0.259
×allowance b
16 0.06250 0.01875 0.0238 0.03125 0.0264 0.0238
14 0.07143 0.02143 0.0264 0.03571 0.0302 0.0276
12 0.08333 0.02500 0.0300 0.04167 0.0352 0.0326
10 0.10000 0.03000 0.0400 0.05000 0.0422 0.0370
9 0.11111 0.03333 0.0433 0.05556 0.0469 0.0417
8 0.12500 0.03750 0.0475 0.06250 0.0528 0.0476
7 0.14286 0.04285 0.0529 0.07143 0.0603 0.0551
6 0.16667 0.05000 0.0600 0.08333 0.0704 0.0652
5 0.20000 0.06000 0.0700 0.10000 0.0845 0.0793
4 0.25000 0.07500 0.0850 0.12500 0.1056 0.1004
31 ⁄ 2 0.28571 0.08571 0.0957 0.14286 0.1207 0.1155
3 0.33333 0.10000 0.1100 0.16667 0.1408 0.1356
21 ⁄ 2 0.40000 0.12000 0.1300 0.20000 0.1690 0.1638
2 0.50000 0.15000 0.1600 0.25000 0.2112 0.2060
11 ⁄ 2 0.66667 0.20000 0.2100 0.33333 0.2816 0.2764
11 ⁄ 3 0.75000 0.22500 0.2350 0.37500 0.3168 0.3116
1 1.00000 0.30000 0.3100 0.50000 0.4224 0.4172
a All other dimensions in inches. See Fig. 1, page 1826.
b Allowance is 0.020 inch for 10 or less threads per inch and 0.010 inch for more than 10 threads per
inch.
Table 14a. American National Standard Stub Acme Single-Start Screw Threads —
Formulas for Determining Diameters ASME/ANSI B1.8-1988 (R2001)
D = Basic Major Diameter and Nominal Size in Inches
D2 = Basic Pitch Diameter = D − 0.3P
D1 = Basic Minor Diameter = D − 0.6P
No. External Threads (Screws)
1 Major Dia., Max = D.
2 Major Dia., Min. = D minus 0.05P.
3 Pitch Dia., Max. = D2 minus allowance from the appropriate Class 2G column, Table 4.
4 Pitch Dia., Min. = Pitch Dia., Max. (Formula 3) minus Class 2G tolerance from Table 5.
5 Minor Dia., Max. = D1 minus 0.020 for 10 threads per inch and coarser and 0.010 for finer
pitches.
6 Minor Dia., Min. = Minor Dia., Max. (Formula 5) minus Class 2G pitch diameter tolerance
from Table 5.
Internal Threads (Nuts)
7 Major Dia., Min. = D plus 0.020 for 10 threads per inch and coarser and 0.010 for finer
pitches.
8 Major Dia., Max.= Major Dia., Min. (Formula 7) plus Class 2G pitch diameter tolerance
from Table 5.
9 Pitch Dia., Min. = D2 = D − 0.3P
10 Pitch Dia., Max. = Pitch Dia., Min. (Formula 9) plus Class 2G tolerance from Table 5.
11 Minor Dia., Min. = D1 = D − 0.6P
12 Minor Dia., Max = Minor Dia., Min. (Formula 11) plus 0.05P.
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