ANSI Thread Limits
Metric Size Taps - Ground Thread (USCTI Table 337)
Standard Pitch Diameter Limits (Inches)
Major Diameter (Inches)
Nom- inal Size
Pitch
Basic Pitch Diam.
D3 Limits D4 Limits D5 Limits
D6 Limits
D7 Limits
D8 Limits D9 Limits
Basic Min. Max.
mm mm
Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max.
1.6 0.35 0.062992 0.0641 0.0651 0.054042 0.0550 0.0556 – – 0.078740 0.0801 0.0811 0.068511 0.0695 0.0701 – – 2.5 0.45 0.098425 0.0999 0.1009 0.086918 0.0879 0.0885 – – 2.0 0.4
– – – –
– – – – – – –
– – – – – – –
– – – – – – – – –
– – – – – – – – –
– – – – – – – – – – –
– – – – – – – – – – –
– – – – – – – – – – – – – –
– – – – – – – – – – – – – –
– – – – – – – – – – – – – – –
3.0 0.5 3.5 0.6 4.0 0.7 5.0 0.8 6.0 1.0
0.118110 0.1198 0.1208 0.105324 0.1063 0.1069 – –
0.137795 0.1397 0.1407 0.122452 – 0.157480 0.1597 0.1613 0.139580 – 0.196850 0.1994 0.2010 0.176393 – 0.236220 0.2395 0.2411 0.210648 –
– 0.1237 0.1245 – – 0.1408 0.1416 – – 0.1776 0.1784 –
– – – – – – – – – –
– – 0.2122 0.2132 – – – 0.2843 0.2855 –
8.0 1.25 0.314960 0.3189 0.3214 0.282995 – 0.393700 0.3985 0.4010 0.355343 – 12 1.75 0.472440 0.4780 0.4805 0.427690 – 10 1.5
– – – – – – – – – – – – – – – –
– – – – – – – –
– 0.3572 0.3584 – – 0.4295 0.4307 –
14 2.0 16 2.0 20 2.5 24 3.0 30 3.5 36 4.0
0.551180 0.5575 0.5600 0.500037 – 0.629920 0.6363 0.6388 0.578777 – 0.787400 0.7954 0.7979 0.723471 – 0.944880 0.9544 0.9583 0.868165 – 1.181100 1.1922 1.1961 1.091599 – 1.417320 1.4300 1.4339 1.315034 –
– – – – – –
– – – – – –
– 0.5020 0.5036 – – 0.5807 0.5823 – – 0.7254 0.7270 –
– – –
– – –
– 0.8706 0.8722 –
– –
– –
– 1.0942 1.0962 – 1.3176 1.3196
LEAD TOLERANCE A maximum lead deviation of ±0.013 mm within any two threads not farther apart than 25 mm is permitted. ANGLE TOLERANCE Pitch (mm) Deviation in Half Angle Over 0.25 to 2.5 Incl. ± 30’ Over 2.5 to 4 Incl. ± 25’ Over 4 to 6 Incl. ± 20” FORMULA Min. Major Dia. = Basic + W Max. Pitch Dia. = Basic + Y Max. Major Dia. = Min. + X Min. Pitch Dia. = Max. - Z For Values of W, Y & Z, See Table 341
In all cases, the tap major and pitch diameter inch conversions have been rounded upwards to the next ten thousandth of an inch. Basic values agree with B1 Report—ISO Metric Screw Threads, Table 9B.
OH Tap Limits
Threading Technical
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