TAP DRILL SIZES FOR THREADED INSERTS (HELICOIL)
STEEL, PLASTIC, MAGNESIUM
| TAP SIZE |
TAP DRILL SIZE |
DECIMAL EQUIV. OF TAP DRILL (INCHES) |
| 4-40 | # 31 | .1200 |
| 5-40 | # 29 | .13600 |
| 6-32 | # 25 | .1495 |
| 6-40 | # 25 | .1495 |
| 8-32 | # 16 | .1770 |
| 10-24 | #5 | .2055 |
| 10-32 | 13/64 | .2031 |
| 12-24 | # 1 | .2280 |
| 1/4-20 | 17/64 | .2656 |
| 1/4-28 | 17/64 | .2656 |
| 5/16-18 | Q | .3320 |
| 5/16-24 | Q | .3320 |
| 3/8-16 | X | .3970 |
| 3/8-24 | 25/64 | .3906 |
| 7/16-14 | 15/32 | .4687 |
| 7/16-20 | 29/64 | .4531 |
| 1/2-13 | 17/32 | .5312 |
| 1/2-20 | 33/64 | .5156 |
ALUMINUM
| TAP SIZE |
TAP DRILL SIZE |
DECIMAL EQUIV. OF TAP DRILL (INCHES) |
| 4-40 | # 31 | .1200 |
| 5-40 | # 30 | .1285 |
| 6-32 | # 25 | .1495 |
| 6-40 | # 26 | .1470 |
| 8-32 | # 17 | .1730 |
| 10-24 | 13/64 | .2031 |
| 10-32 | #7 | .2010 |
| 12-24 | # 2 | .2210 |
| 1/4-20 | 17/64 | .2656 |
| 1/4-28 | G | .2610 |
| 5/16-18 | Q | .3320 |
| 5/16-24 | 21/64 | .3281 |
| 3/8-16 | X | .3970 |
| 3/8-24 | 25/64 | .3906 |
| 7/16-14 | 29/64 | .4531 |
| 7/16-20 | 29/64 | .4531 |
| 1/2-13 | 33/64 | .5156 |
| 1/2-20 | 33/64 | .5156 |
| TO BUY BY CHECK |