Machinery's Handbook, 31st Edition
2002 CALCULATING THREAD DIMENSIONS round to equivalent values. For standardization the tabulated listing of thread values based on a function of pitch has been established, with thread height used as a reference only All thread calculations are to be performed using a function of pitch ( P ), rounded to 8 decimal places for inch series and as designated for metric series, not a function of thread height ( H ). Thread height is to be used for reference only. See Table 7. P 0.125 P 0.125 H
Basic Major Diameter D bsc, d bsc
60°
0.625 H
H
30°
Basic Pitch Diameter D 2 bsc, d 2 bsc
0.5 p
0.25 H
0.25 P Axis of Screw Thread
Minor Diameter D 1 bsc, d 1 bsc
90°
Fig. 1. Basic Profile of UN and UNF Screw Threads Table 2. Thread Form Data
Constant for Metric Series (7-place)
Constant for Inch Series (8-place)
Reference Values
0.04811252 P 0.05412659 P 0.08660254 P 0.09622504 P 0.10825318 P 0.12990381 P 0.14433757 P 0.16237976 P 0.21650635 P 0.28867513 P 0.32475953 P 0.36084392 P 0.39692831 P 0.43301270 P 0.48713929 P 0.54126588 P 0.57735027 P 0.59539246 P 0.61343466 P 0.61602540 P 0.64951905 P 0.72168783 P 0.79385662 P 0.86602540 P 1.08253175 P 1.19078493 P 1.22686932 P
0.0556 H 0.0625 H 0.1000 H 0.1111 H 0.1250 H 0.1500 H 0.1667 H 0.1875 H 0.2500 H 0.3333 H 0.3750 H 0.4167 H 0.4583 H 0.5000 H 0.5625 H 0.6250 H 0.6667 H 0.6875 H 0.7083 H 0.7113 H 0.7500 H 0.8333 H 0.9167 H 1.0000 H 1.2500 H 1.3750 H 1.4167 H
0.0481125 P 0.0541266 P 0.0866025 P 0.0962250 P 0.1082532 P 0.1299038 P 0.1443376 P 0.1623798 P 0.2165064 P 0.2886751 P 0.3247595 P 0.3608439 P 0.3969283 P 0.4330127 P 0.4871393 P 0.5412659 P 0.5773503 P 0.5953925 P 0.6134347 P 0.6160254 P 0.6495191 P 0.7216878 P 0.7938566 P 0.8660254 P 1.0825318 P 1.1907849 P 1.2268693 P
1 ∕ 1 ∕ 18 H 16 H 10 H 9 H 8 H 20 H 1 ∕ 1 ∕ 16 H 4 H 3 H 8 H 12 H 24 H 1 ∕ 1 ∕ 3 ∕ 16 H 8 H 3 H 16 H 24 H 1 ∕ 6 H 1 ∕ 2 H 5 ∕ 2 ∕ 3 ∕ 5 ∕ 4 H 6 H 12 H 5 ∕ 4 H 8 H 12 H H …
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3 ∕
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11 ∕
9 ∕
11 ∕ 17 ∕
11 ∕
11 ∕
17 ∕
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