美制外螺纹常用规格极限尺寸表.pdf

美制外螺纹（2A）常用规格极限尺寸表（粗牙）

公称尺寸和螺纹系大径极限中径极限螺胚直径
小径max
每英寸牙数列代号最小最大最小最大最小最大
8-320.15710.16310.13990.14280.1248
3.583.61
(0.164-32)3.99034.14273.55353.62713.1699
10-240.18180.18900.15860.16190.1379
4.074.10
(0.190-24)4.61774.80064.02844.11233.5027
12-240.20780.21500.18450.18790.1639
4.724.75
(0.216-24)5.27815.46104.68634.77274.1631
1/4-200.24080.24890.21270.21640.1876
5.455.48
(0.250-20)6.11636.32215.40265.49664.7650
5/16-180.30260.31130.27120.27520.2431
6.946.98
(0.3175-18)7.68607.90706.88856.99016.1747
3/8-160.36430.37370.32870.33310.2970
8.408.44
(0.375-16)9.25329.49208.34908.46077.5438
7/16-140.42580.43610.38500.38970.3485
UNC9.839.87
(0.4375-14)10.815311.07699.77909.89848.8519
1/2-130.48760.49850.44350.44850.4041
11.3411.38
(0.50-13)12.385012.661911.264911.391910.2641
9/16-120.54950.56090.50160.50680.4587
12.8012.84
(0.5625-12)13.957314.246912.740612.872711.6510
5/8-110.61130.62340.55890.56440.5119
14.2714.32
(0.625-11)15.527015.834414.196114.335813.0023
3/4-100.73530.74820.67730.68320.6255
17.2817.33
(0.750-10)18.676619.004317.203417.353315.8877
7/8-90.85920.87310.79460.80090.7368
20.2720.32
(0.875-9)21.823722.176720.182820.342918.7147
1"-80.98300.99800.91000.91680.8446
23.2223.27
(1.000-8)24.968225.349223.114023.286721.4528

1.螺胚直径指滚丝前的尺寸，数值为依经验公式计算而得，在实践中需验证。
2.标记示例：10-24UNC-2A(或0.190-24UNC-2A)、3/8-16UNC-2A(或0.375-16UNC-2A)
（注：表中上行斜体数值单位为英寸，下行为毫米）

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美制外螺纹（2A）常用规格极限尺寸表（细牙）

公称尺寸和螺纹系大径极限中径极限螺胚直径
小径max
每英寸牙数列代号最小最大最小最大最小最大
8-360.15770.16320.14240.14520.1291
3.653.67
(0.164-36)4.00564.14533.61703.68813.2791
10-320.18310.18910.16580.16880.1508
4.244.27
(0.190-32)4.65074.80314.21134.28753.8303
12-280.20850.21500.18860.19180.1712
4.824.85
(0.216-28)5.29595.46104.79044.87174.3485
1/4-280.24250.24900.22250.22580.2052
5.695.71
(0.250-28)6.15956.32465.65155.73535.2121
5/16-240.30420.31140.28060.28430.2603
7.177.20
(0.3175-24)7.72677.90967.12727.22126.6116
3/8-240.36670.37390.34300.34680.3228
8.758.78
(0.375-24)9.31429.49718.71228.80878.1991
7/16-200.42810.43620.39950.