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ANSI Taps Fraction-Size Tolerances Per ASME B94.9
Manufacturing Reference Data | Mechanical Tolerances
ANSI Taps Fraction-Size Per ASME B94.9
- All dimensions are given in inches.
- Lead Tolerance: Plus or minus 0.003 inch max. per inch of thread.
- Angle Tolerance: Plus or minus 35 min. in half angle or 53 min. in full angle for 4 1⁄2 to 5 1⁄2 thds. per in.; 40 min. half angle and 60 min. full angle for 6 to 9 thds.; 45 min. half angle and 68 min. full angle for 10 to 28 thds.; 60 min. half angle and 90 min. full angle for 30 to 64 thds. per in.
ANSI Standard Fraction-Size Taps — Cut Thread Limits Per ASME B94.9
|
Tap Size
|
Threads per Inch
|
Major Diameter
|
Pitch Diameter
|
||||||
|---|---|---|---|---|---|---|---|---|---|
|
NC UNC
|
NF UNF
|
NS UNS
|
Basic
|
Min.
|
Max.
|
Basic
|
Min.
|
Max.
|
|
|
1/8
|
…
|
…
|
40
|
0.1250
|
0.1266
|
0.1286
|
0.1088
|
0.1090
|
0.1105
|
|
5⁄32
|
…
|
…
|
32
|
0.1563
|
0.1585
|
0.1605
|
0.1360
|
0.1365
|
0.1380
|
|
3⁄16
|
…
|
…
|
24
|
0.1875
|
0.1903
|
0.1923
|
0.1604
|
0.1609
|
0.1624
|
|
3⁄16
|
…
|
…
|
32
|
0.1875
|
0.1897
|
0.1917
|
0.1672
|
0.1677
|
0.1692
|
|
1⁄4
|
20
|
…
|
…
|
0.2500
|
0.2532
|
0.2557
|
0.2175
|
0.2180
|
0.2200
|
|
1⁄4
|
…
|
28
|
…
|
0.2500
|
0.2524
|
0.2549
|
0.2268
|
0.2273
|
0.2288
|
|
5⁄16
|
18
|
…
|
…
|
0.3125
|
0.3160
|
0.3185
|
0.2764
|
0.2769
|
0.2789
|
|
5⁄16
|
…
|
24
|
…
|
0.3125
|
0.3153
|
0.3178
|
0.2854
|
0.2859
|
0.2874
|
|
3⁄8
|
16
|
…
|
…
|
0.3750
|
0.3789
|
0.3814
|
0.3344
|
0.3349
|
0.3369
|
|
3⁄8
|
…
|
24
|
…
|
0.3750
|
0.3778
|
0.3803
|
0.3479
|
0.3484
|
0.3499
|
|
7⁄16
|
14
|
…
|
…
|
0.4375
|
0.4419
|
0.4449
|
0.3911
|
0.3916
|
0.3941
|
|
7⁄16
|
…
|
20
|
…
|
0.4375
|
0.4407
|
0.4437
|
0.4050
|
0.4055
|
0.4075
|
|
1⁄2
|
13
|
…
|
…
|
0.5000
|
0.5047
|
0.5077
|
0.4500
|
0.4505
|
0.4530
|
|
1⁄2
|
…
|
20
|
…
|
0.5000
|
0.5032
|
0.5062
|
0.4675
|
0.4680
|
0.4700
|
|
9⁄16
|
12
|
…
|
…
|
0.5625
|
0.5675
|
0.5705
|
0.5084
|
0.5089
|
0.5114
|
|
9⁄16
|
…
|
18
|
…
|
0.5625
|
0.5660
|
0.5690
|
0.5264
|
0.5269
|
0.5289
|
|
5⁄8
|
11
|
…
|
…
|
0.6250
|
0.6304
|
0.6334
|
0.5660
|
0.5665
|
0.5690
|
|
5⁄8
|
…
|
18
|
…
|
0.6250
|
0.6285
|
0.6315
|
0.5889
|
0.5894
|
0.5914
|
|
3⁄4
|
10
|
…
|
…
|
0.7500
|
0.7559
|
0.7599
|
0.6850
|
0.6855
|
0.6885
|
|
3⁄4
|
…
|
16
|
…
|
0.7500
|
0.7539
|
0.7579
|
0.7094
|
0.7099
|
0.7124
|
|
7⁄8
|
9
|
…
|
…
|
0.8750
|
0.8820
|
0.8860
|
0.8028
|
0.8038
|
0.8068
|
|
7⁄8
|
…
|
14
|
…
|
0.8750
|
0.8799
|
0.8839
|
0.8286
|
0.8296
|
0.8321
|
|
1
|
8
|
…
|
…
|
1.0000
|
1.0078
|
1.0118
|
0.9188
|
0.9198
|
0.9228
|
|
1
|
…
|
12
|
…
|
1.0000
|
1.0055
|
1.0095
|
0.9459
|
0.9469
|
0.9494
|
|
1
|
…
|
…
|
14
|
1.0000
|
1.0049
|
1.0089
|
0.9536
|
0.9546
|
0.9571
|
|
1 1⁄8
|
7
|
…
|
…
|
1.1250
|
1.1337
|
1.1382
|
1.0322
|
1.0332
|
1.0367
|
|
1 1⁄8
|
…
|
12
|
…
|
1.1250
|
1.1305
|
1.1350
|
1.0709
|
1.0719
|
1.0749
|
|
1 1⁄4
|
7
|
…
|
…
|
1.2500
|
1.2587
|
1.2632
|
1.1572
|
1.1582
|
1.1617
|
|
1 1⁄4
|
…
|
12
|
…
|
1.2500
|
1.2555
|
1.2600
|
1.1959
|
1.1969
|
1.1999
|
|
1 3⁄8
|
6
|
…
|
…
|
1.3750
|
1.3850
|
1.3895
|
1.2667
|
1.2677
|
1.2712
|
|
1 3⁄8
|
…
|
12
|
…
|
1.3750
|
1.3805
|
1.3850
|
1.3209
|
1.3219
|
1.3249
|
|
1 1⁄2
|
6
|
…
|
…
|
1.5000
|
1.5100
|
1.5145
|
1.3917
|
1.3927
|
1.3962
|
|
1 1⁄2
|
…
|
12
|
…
|
1.5000
|
1.5055
|
1.5100
|
1.4459
|
1.4469
|
1.4499
|
|
1 3⁄4
|
5
|
…
|
…
|
1.7500
|
1.7602
|
1.7657
|
1.6201
|
1.6216
|
1.6256
|
|
2
|
4 1⁄2
|
…
|
…
|
2.0000
|
2.0111
|
2.0166
|
1.8557
|
1.8572
|
1.8612
|
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