Stub ACME Thread ANSI/ASME B1.8-1977

The ACME thread was developed as a compromise, to offer better strength than a V-form while overcoming the problems with the square thread form.
The flank angle is 29°.

Nominal
Diameter
Diameter
Inch
Diameter
mm
Tapping Drill Size
mm
TPI Pitch
mm
1/4" - 16 STUB ACME 0.250 6.350 5.398 16 1.588
5/16" - 14 STUB ACME 0.312 7.938 6.123 14 1.814
3/8" - 12 STUB ACME 0.375 9.525 8.255 12 2.117
7/16" - 12 STUB ACME 0.437 11.112 9.843 12 2.117
1/2" - 10 STUB ACME 0.500 12.700 11.176 10 2.540
5/8" - 8 STUB ACME 0.625 15.875 13.970 8 3.175
3/4" - 6 STUB ACME 0.750 19.050 16.510 12 2.117
7/8" - 6 STUB ACME 0.875 22.225 19.685 6 4.233
1" - 5 STUB ACME 1.000 25.400 22.352 5 5.080
1 1/8" - 5 STUB ACME 1.125 28.575 25.527 5 5.080
1 1/4" - 5 STUB ACME 1.250 31.750 28.702 5 5.080
1 3/8" - 4 STUB ACME 1.375 34.925 31.115 4 6.350
1 1/2" - 4 STUB ACME 1.500 38.100 34.290 4 6.350
1 3/4" - 4 STUB ACME 1.750 44.450 40.640 4 6.350
2" - 4 STUB ACME 2.000 50.800 46.990 4 6.350
2 1/4" - 3 STUB ACME 2.250 57.150 52.070 3 8.467
2 1/2" - 3 STUB ACME 2.500 63.500 58.420 3 8.467
2 3/4" - 3 STUB ACME 2.750 69.850 64.770 3 8.467
3" - 2 STUB ACME 3.000 76.200 68.580 2 12.700
3 1/2" - 2 STUB ACME 3.500 88.900 81.280 2 12.700
4" - 2 STUB ACME 4.000 101.600 93.980 2 12.700
4 1/2" - 2 STUB ACME 4.500 114.300 106.680 2 12.700
5" - 2 STUB ACME 5.000 127.000 119.380 2 12.700