Table 5a. Standard Tap Dimensions (Ground and Cut Thread) ANSI/ASME B94.9-2008 (R2018) Table 5a. (Continued) Standard Tap Dimensions (Ground and Cut Thread) ANSI/ASME B94.9-2008 (R2018)
Nominal Diameter Range, inch
Nominal Diameter, inch
Nominal Metric Diameter
Tap Dimensions, inch
Machine Screw Size No. and Fractional Sizes
Shank Diameter d 1
Size of Square a
Overall Length L
Thread Length I
Square Length I 2
Blank Design No.
Decimal Equiv. (0.9375) (1.0000) (1.0625) (1.1250) (1.1875) (1.2500) (1.3125) (1.3750) (1.4375) (1.5000) (1.6250) (1.7500) (1.8750) (2.0000)
Over 0.885 0.948 1.010 1.073 1.135 1.198 1.260 1.323 1.358 1.448 1.510 1.635 1.760 1.885
To
mm
inch
M24 M25 M27
0.9449 0.9843 1.0630
3 3 3 3 3 3 3 3 3 3 3 3 3 3
4.91 5.13 5.13 5.44 5.44 5.75 5.75 6.06 6.06 6.38 6.69 7.00 7.31 7.63
2.22 2.50 2.50 2.56 2.56 2.56 2.56 3.00 3.00 3.00 3.19 3.19 3.56 3.56
0.75 0.81 0.88 0.88 1.00 1.00 1.06 1.06 1.13 1.13 1.13 1.25 1.25 1.38
0.760 0.800 0.896 0.896 1.021 1.021 1.108 1.108 1.233 1.233 1.305 1.430 1.519 1.644
0.570 0.600 0.672 0.672 0.766 0.766 0.831 0.831 0.925 0.925 0.979 1.072 1.139
0.948 1.010 1.073 1.135 1.198 1.260 1.323 1.385 1.448 1.510 1.635 1.760 1.885 2.010
15 ⁄ 16
1
1 1 ⁄ 16
…
…
1 1 ⁄ 8
M30
1.1811
1 3 ⁄ 16
…
…
1 1 ⁄ 4
M33
1.2992
1 5 ⁄ 16
…
…
1 3 ⁄ 8
M36
1.4173
1 7 ⁄ 16
…
…
1 1 ⁄ 2 1 5 ⁄ 8 1 3 ⁄ 4 1 7 ⁄ 8
M39 M42
1.5353 1.6535
…
…
2 1.233 Special taps greater than 1.010 inch to 1.510 inch in diameter inclusive, having 14 or more threads per inch or 1.75- mm pitch and finer, and sizes over 1.510 inch in diameter with 10 or more threads per inch or 2.5- mm pitch and finer are made to general dimensions shown in Table 10. For standard ground thread tap limits see Table 20, and Table 21 for inch and Table 16 for metric. For cut thread tap limits see Table 22 and Table 23. Special ground thread tap limits are determined by using the formulas shown in Table 2 for unified inch screw threads and Table 4 for metric M profile screw threads. M48 1.8898 Tap sizes 0.395 inch and smaller have an external center on the thread end (may be removed on bottom taps). Sizes 0.223 inch and smaller have an external center on the shank end. Sizes 0.224 inch through 0.395 inch have truncated partial cone centers on the shank end (of diameter of shank). Sizes greater than 0.395 inch have internal centers on both the thread and shank ends. For standard thread limits and tolerances see Table 17 for unified inch screw threads and Table 19 for metric threads. For runout tolerances of tap elements see Table 14. For number of flutes see Table 11.
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