Industrial Catalog
Metric Forming Taps Percentage of Thread
75%Thread
65%Thread
60%Thread
70%Thread
Tap Size
Pitch
Theoretical Hole Size
Nearest Drill Size
Theoretical Hole Size
Nearest Drill Size
Theoretical Hole Size
Nearest Drill Size
Theoretical Hole Size
Nearest Drill Size
2 2 3 3 4 4 5 5 6 6 8 8
56 64 48 56 40 48 40 44 32 40 32 36 24 32 24 28 20 28 18 24 16 24 14 20 13 20 12 18
.0769 .0780 .0884 .0899 .0993 .1014 .1123 .1134 .1221 .1253 .1481 .1498 .1688 .1741 .1948 .1978 .2245 .2318 .2842 .2912 .3431 .3537 .4011 .4120 .4608 .4745 .5200 .5342
1.95 5/64 2.25
.0774 .0785 .0890 .0904 .1000 .1020 .1130 .1141 .1230 .1260 .1490 .1507 .1700 .1750 .1960 .1989 .2260 .2329 .2861 .2927 .3452 .3552 .4035 .4137 .4634 .4762 .5229 .5361
1.95
.0781 .0791 .0898 .0911 .1010 .1028 .1140 .1150 .1242 .1270 .1502 .1517 .1716 .1762 .1976 .2002 .2279 .2342 .2879 .2941 .3474 .3566 .4059 .4154 .4660 .4779 .5257 .5380
5/64
.0787 .0796 .0905 .0917 .1018 .1035 .1148 .1157 .1252 .1278 .1512 .1526 .1729 .1772 .1989 .2014 .2295 .2354 .2898 .2955 .3495 .3580 .4084 .4171 .4686 .4796 .5285 .5398
47 2.0 2.3 2.3 38 2.6 2.9
47 43 39 38 33
2.0 43 2.3 39 2.6 33 2.9 3.2 25 24
43 2.5 38 34 33 3.1 1/8
2.9 3.1 3.2 3.8 18
1/8
3.25
3.75
3.8 24
Metric Forming Taps Percentage of Thread
25
10 10 12 12
11/64
11/64
17 10
= 9 8
16
5.0
8 7 1
5.0 5.7 7.2 7.4
8 1 A
1/4 1/4
5.9
15/64
5/16 5/16
7.25
7.3
L
M
7.5 8.9
8.75
S
3/8 3/8
11/32
9.0
9.0
T
7/16 7/16
Y
13/32
Z
10.5
1/2 1/2
15/32
12.0
9/16 9/16
17/32
13.5
FORMULA FOR TAP / DRILL SIZES FOR DECIMAL / INCH TAPS:
HOLE SIZE = Basic Tap O.D. - (
) .0068 x % of Thread* Threads per Inch
) For example: To determine drill size for a 1/4-20 thread forming tap at 65% of thread: .250 - = .2279 *Use whole number for % of thread... for 65%, use 65 (not .65). .0068 x 65 20 (
FORMULA FOR TAP / DRILL SIZES FOR METRIC TAPS:
HOLE SIZE (mm) = Basic Tap O.D. (mm) - (
)
% of Thread x mm Pitch 147.06
*Use whole number for % of thread... for 65%, use 65 (not .65).
17
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