Industrial Catalog

Metric Percentage of Thread

Probable Percentage of Full Thread Produced in Tapped Hole Using Stock Sizes of Drill

Metric Tap Size (mm)

Decimal Equiv. Tap Drill (in.)

Theoretical % of Tap Drill (in.)

Probable Mean Oversize (in.)

Probable Hole Size (in.)

Metric Tap Size (mm)

Decimal Equiv. Tap Drill (in.)

Theoretical % of Tap Drill (in.)

Probable Mean Oversize (in.)

Probable Hole Size (in.)

Probable % of Thread

Probable % of Thread

Tap Drill Drill (mm or in.)

Tap Drill Drill (mm or in.)

A

.2340 .2362 .2380 .2638 .2656 .2660 .2677 .3307 .3320 .3346 .4016 .4040 .4062 .4688 .4724 .5469 .5512 .6875 .6890 .8125 .8268 .8281

81 77 74 80 77 77 74 82 80 77 79 76 74 81 77 81 77 78 77 86 76 76 83 77 75 74

.0038 .0038 .0038 .0041 .0041 .0041 .0041 .0044 .0044 .0044 .0047 .0047 .0047 .0048 .0048 .0049 .0049 .0050 .0052 .0052 .0054 .0054 .0071 .0071 .0072

.2378 .2400 .2418 .2679 .2697 .2701 .2718 .3351 .3364 .3390 .4063 .4087 .4109 .4736 .4772 .5518 .5561 .6925 .6942 .8177 .8322 .8335

74 70 66 74 71 70 68 76 75 71 75 71 69 76 72 76 72 74 73 82 73 73 80 73 70

1.20 1.25 1/16 1.60

.0472 .0492 .0625 .0630 .0635 .0807 .0810 .0820 .0980 .0984 .0995 .1130 .1142 .1160 .1260 .1285 .1299 .1457 .1470 .1495 .1654 .1660 .1935 .1960 .1969 .1990

88 77 79 77 74 77 76 71 79 77 73 81 77 71 88 81 77 82 79 72 77 75 84 79 77 73

.0014 .0014 .0015 .0017 .0017 .0019 .0019 .0019 .0023 .0023 .0023 .0026 .0026 .0026 .0029 .0029 .0029 .0032 .0032 .0032 .0032 .0032 .0038 .0038 .0038 .0038

.0486 .0506 .0640 .0647 .0652 .0826 .0829 .0839 .1003 .1007 .1018 .1156 .1168 .1186 .1289 .1314 .1328 .1489 .1502 .1527 .1686 .1692 .1973 .1998 .2006 .2028

80 69 72 69 66 69 67 63 70 68 64 72 68 63 80 73 69 74 70 64 69 68 76 71 70 65

1.6 x 0.35

7 x 1.00

6.00

B

6.70

2 x 0.40

17/64

52

8 x 1.25

H

2.05

6.80 8.40

2.5 x 0.45

46 45 40

10 x 1.50

Q

8.50

3 x 0.50

2.50

10.20

39 33

12 x 1.75

Y

13/32 15/32 12.00 35/64 14.00 11/16 17.50 13/16 21.00 53/64 1-1/32 25.50 1-3/64

3.5 x 0.60

2.90

32

14 x 2.00

3.20

4 x 0.70

30

16 x 2.00

3.30 3.70

20 x 2.50

4.5 x 0.75

26 25

24 x 3.00

4.20

5 x 0.80

19 10

1.0312 1.0433 1.0469 1.2656

1.0383 1.0504 1.0541

30 x 3.50

9

Metric Percentage of Thread 6 x 1.00

5.00

36 x 4.00

1-17/64

REAMING RECOMMENDED

8

TAP DRILL SIZE FORMULAE

–

=

Major Diameter of Thread

Drilled Hole Size

.01299 x Amt. of percentage of full thread Number of threads per inch

Note: Select nearest commercial stock drill.

Percentage of Full Thread for Other Drill Sizes

Major Diameter of Thread - Selected Drill Diameter .01299 ( )

=

No. of Threads per Inch

Percentage of Full Thread

16