| |
SUGGESTED
HOLE SIZES FOR TAPPING SCREWS
TYPE 1 (or D). F. G and 23 (or T)
|
NOMINAL
DIAMETER & THREADS |
HOLE |
CLOSEST DRILLTO MEAN
HOLE |
Drill
Size |
Drill
Diameter |
Max |
Mean |
Min |
| 2 |
- 56 |
0.078 |
0.076 |
0.074 |
48 |
0.0760 |
| 2 |
- 64 |
-- |
0.077 |
-- |
-- |
-- |
| 3 |
- 48 |
0.090 |
0.087 |
0.084 |
44 |
0.0860 |
| 3 |
- 56 |
-- |
0.089 |
-- |
-- |
-- |
| 4 |
- 40 |
0.100 |
0.097 |
0.094 |
41 |
0.0960 |
| 4 |
- 48 |
-- |
0.100 |
-- |
-- |
-- |
| 5 |
- 40 |
0.011 |
0.110 |
0.107 |
35 |
0.1100 |
| 5 |
- 44 |
-- |
0.112 |
-- |
-- |
-- |
| 6 |
- 32 |
0.123 |
0.119 |
0.115 |
31 |
0.1200 |
| 6 |
- 40 |
-- |
0.124 |
-- |
-- |
-- |
| 8 |
- 32 |
0.150 |
0.460 |
0.141 |
20 |
0.1470 |
| 8 |
- 36 |
-- |
0.148 |
-- |
-- |
-- |
| 10 |
- 24 |
0.170 |
0.165 |
0.160 |
19 |
0.1660 |
| 10 |
- 32 |
0.177 |
0.172 |
0.167 |
11/64 |
0.1719 |
| 12 |
- 24 |
0.198 |
0.192 |
0.186 |
11 |
0.1910 |
| 12 |
- 28 |
-- |
0.196 |
-- |
-- |
-- |
| 1/4 |
- 20 |
0.228 |
0.221 |
0.214 |
2 |
0.2210 |
| 1/4 |
- 28 |
-- |
0.230 |
-- |
-- |
-- |
| 5/16 |
- 18 |
0.289 |
0.281 |
0.273 |
K |
0.2810 |
| 5/16 |
- 24 |
-- |
0.290 |
-- |
-- |
-- |
| 3/8 |
- 16 |
0.349 |
0.339 |
0.329 |
R |
0.3390 |
| 3/8 |
- 24 |
-- |
0.353 |
-- |
-- |
-- |
| 7/16 |
- 14 |
0.409 |
0.397 |
0.385 |
X |
0.3970 |
| 7/16 |
- 20 |
-- |
0.411 |
-- |
-- |
-- |
| 1/2 |
- 13 |
0.471 |
0.457 |
0.443 |
29/64 |
0.4531 |
| 1/2 |
- 20 |
-- |
0.475 |
-- |
-- |
-- |
| FORMULA: MEAN HOLE DIAMETER = 1.015 x basic threadpitch
diameter. Tolerance is ± 3% of mean hole diameter.
Notolerances or drill sizes are given for tapping screws with
finethreads except for #10 size. Fine thread tapping screws
arenot recommended. |
SUGGESTED HOLE SIZES FOR TAPPING SCREWS
TYPE AB, B, BP, BF, AND 25 (or BT)
NOMINALDIAMETER&
THREADS |
HOLE |
CLOSEST DRILLTO MEAN
HOLE |
Drill
Size |
Drill
Diameter |
Max |
Mean |
Min |
| 0 |
- 48 |
0.049 |
0.460 |
0.043 |
56 |
0.0465 |
| 1 |
- 42 |
0.063 |
0.590 |
0.055 |
53 |
0.0595 |
| 2 |
- 32 |
0.077 |
0.720 |
0.067 |
49 |
0.0730 |
| 3 |
- 28 |
0.090 |
0.840 |
0.078 |
45 |
0.0820 |
| 4 |
- 24 |
0.103 |
0.960 |
0.089 |
41 |
0.0960 |
| 5 |
- 20 |
0.114 |
0.107 |
0.100 |
36 |
0.1065 |
| 6 |
- 20 |
0.124 |
0.116 |
0.108 |
32 |
0.1160 |
| 7 |
- 19 |
0.138 |
0.129 |
0.120 |
30 |
0.1285 |
| 8 |
- 18 |
0.148 |
0.138 |
0.128 |
29 |
0.1360 |
| 10 |
- 16 |
0.170 |
0.159 |
0.148 |
21 |
0.1590 |
| 12 |
- 14 |
0.194 |
0.182 |
0.169 |
14 |
0.1820 |
| 1/4 |
- 14 |
0.226 |
0.211 |
0.196 |
4 |
0.2090 |
| 5/16 |
- 12 |
0.289 |
0.270 |
0.251 |
I |
0.2720 |
| 3/8 |
- 12 |
0.356 |
0.333 |
0.310 |
Q |
0.3320 |
| 7/16 |
- 10 |
0.413 |
0.386 |
0.359 |
W |
0.3860 |
| 1/2 |
- 10 |
0.480 |
0.449 |
0.418 |
29/64 |
0.4531 |
| FORMULA: MEAN HOLE DIAMETER = 0.98 x mean of threadmajor
and minor diameters. Tolerance is ± 7% of meanhole
diameter |
LENGTH
TOLERANCES ON TYPES A, AB, BP |
Nominal
Screw Length |
Tolerance on Length |
Up to 1", incl |
±
0.03 |
Over 1" |
±
0.05 |
| |
LENGTH
TOLERANCES ON TYPES B, BF, 25, 1, F, G & 23 |
Nominal
Screw Length |
Tolerance on Length |
Up to 3/4",
incl |
-0.03 |
Over 3/4" TO
1-1/2" incl |
-0.05 |
Over 1 1/2" |
-0.06 |
|
|
