Machinery's Handbook, 31st Edition
Alternate Stub Acme Screw Threads 2073 Table 13. American National Standard Stub Acme Screw Thread Form— Basic Dimensions ANSI/ASME B1.8-1988 (R2016)
Width of Flat
Total Height of Thread, 0.3 P + 1 ∕ 2 allowance b
Crest of InternalThread
Height of Thread (Basic), 0.3 P 0.01875 0.02143 0.02500 0.03000 0.03333 0.03750 0.04285 0.05000 0.06000 0.07500 0.08571 0.10000 0.12000 0.15000 0.20000 0.22500 0.30000
Thread Thickness (Basic), P /2 0.03125 0.03571 0.04167 0.05000 0.05556 0.06250 0.07143
Root of Internal Thread, 0.4224 P − 0.259 × allowance b
Thds. per Inch a n
Pitch, P = 1/ n 0.06250 0.07143 0.08333 0.10000 0.11111 0.12500 0.14286 0.16667 0.20000 0.25000 0.28571 0.33333 0.40000 0.50000 0.66667 0.75000 1.00000
(Basic), 0.4224 P 0.0264 0.0302 0.0352 0.0422 0.0469 0.0528 0.0603 0.0704 0.0845 0.1056 0.1207 0.1408 0.1690 0.2112 0.2816 0.3168 0.4224
16 14 12 10
0.0238 0.0264 0.0300 0.0400 0.0433 0.0475 0.0529 0.0600 0.0700 0.0850 0.0957 0.1100 0.1300 0.1600 0.2100 0.2350 0.3100
0.0238 0.0276 0.0326 0.0370 0.0417 0.0476 0.0551 0.0652 0.0793 0.1004 0.1155 0.1356 0.1638 0.2060 0.2764 0.3116 0.4172
9 8 7 6 5 4
0.08333 0.10000 0.12500 0.14286 0.16667 0.20000 0.25000 0.33333 0.37500 0.50000
3 1 ∕ 2
3
2 1 ∕ 2
2
1 1 ∕ 2 1 1 ∕ 3
1
a All other dimensions in inches. See Fig. 1, page 2055. 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 ANSI/ASME B1.8-1988 (R2016) D = Basic Major Diameter and Nominal Size in Inches
D 2 = Basic Pitch Diameter = D − 0.3 P D 1 = Basic Minor Diameter = D − 0.6 P
No.
External Threads (Screws)
1 Major Dia., Max = D . 2 Major Dia., Min. = D minus 0.05 P .
3 Pitch Dia., Max. = D 2 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. = D 1 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. = D 2 = D − 0.3 P 10 Pitch Dia., Max. = Pitch Dia., Min. (Formula 9) plus Class 2G tolerance from Table 5. 11 Minor Dia., Min. = D 1 = D − 0.6 P 12 Minor Dia., Max = Minor Dia., Min. (Formula 11) plus 0.05 P .
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