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| TAP DRILL INFORMATION | ||||||
|---|---|---|---|---|---|---|
| AMERICAN - Unified Inch Screw Thread | ||||||
| Tap Size | Tap Drill Size | Decimal Equivalent |
* Theo % Thread |
Prob Mean Oversize |
Prob Hole Size |
** Prob % Thread |
| 7/16 - 20 | W | .3860" | 79% | .003" | .3890" | 75% |
| 25/64 | .3906" | 72% | .003" | .3936" | 68% | |
| 1/2 - 13 | 10.5mm | .4134" | 87% | .003" | .4164" | 84% |
| 27/64 | .4219" | 78% | .003" | .4249" | 75% | |
| 7/16 | .4375" | 63% | .003" | .4405" | 60% | |
| 1/2 - 20 | 29/64 | .4531" | 72% | .003" | .4561" | 68% |
| 9/16 - 12 | 15/32 | .4688" | 87% | .003" | .4718" | 84% |
| 12.0mm | .4724" | 72% | .003" | .4874" | 69% | |
| 31/64 | .4844" | 83% | .003" | .4754" | 80% | |
| 9/16 - 18 | 1/2 | .5000" | 87% | .003" | .5030" | 82% |
| 13.0mm | .5118" | 70% | .003" | .5148" | 66% | |
| 31/64 | .5156" | 65% | .003" | .5186" | 61% | |
| 5/8 - 11 | 17/32 | .5313" | 79% | .003" | .5343" | 77% |
| 5/8 - 12 | 35/64 | .5469" | 72% | .003" | .5499" | 69% |
| 5/8 - 18 | 9/16 | .5625" | 87% | .003" | .5655" | 82% |
| 14.5mm | .5709" | 75% | .003" | .5739" | 71% | |
| 37/64 | .5781" | 65% | .003" | .5811" | 61% | |
| 11/16 - 12 | 39/64 | .6094" | 72% | .003" | .6124" | 69% |
| 3/4 - 10 | 41/64 | .6406" | 84% | .003" | .6436" | 82% |
| 16.5mm | .6496" | 77% | .003" | .6526" | 75% | |
| 21/32 | .6563" | 72% | .003" | .6593" | 70% | |
| 3/4 - 12 | 43/64 | .6719" | 72% | .003" | .6749" | 69% |
| 3/4 - 16 | 11/16 | .6875" | 77% | .003" | .6905" | 73% |
| 17.5mm | .6890" | 75% | .003" | .6920" | 71% | |
| 7/8 - 9 | 49/64 | .7656" | 76% | .003" | .7686" | 74% |
| 25/32 | .7813" | 65% | .003" | .7843" | 63% | |
| 7/8 - 14 | 51/64 | .7969" | 84% | .003" | .7999" | 81% |
| 13/16 | .8125" | 67% | .003" | .8155" | 64% | |
| 15/16 - 12 | 55/64 | .8594" | 72% | .003" | .8624" | 69% |
| 15/16 - 20 | 57/64 | .8906" | 72% | .003" | .8936" | 68% |
| 1 - 8 | 22.0mm | .8661" | 82% | .003" | .8691" | 81% |
| 7/8 | .8750" | 77% | .003" | .8780" | 75% | |
| 57/64 | .8906" | 67% | .003" | .8936" | 65% | |
| 1 - 12 | 29/32 | .9063" | 87% | .003" | .9093" | 84% |
| 59/64 | .9219" | 72% | .003" | .9249" | 69% | |
| 1 - 14 | 15/16 | .9375" | 67% | .003" | .9405" | 64% |
| 1-1/8 - 12 | 1-1/32 | 1.0313" | 87% | .003" | 1.0343" | 84% |
| 1-3/64 | 1.0469" | 72% | .003" | 1.0499" | 69% | |
| 1-1/4 - 7 | 1-7/64 | 1.1094" | 76% | .003" | 1.1124" | 74% |
* Based on nominal tap drill diameter.
** Based on .003" probable oversize. To Calculate % of full thread for a given hole 0:
|
| Taper Pipe Thread (NPT) | ||||||
|---|---|---|---|---|---|---|
| Tap Size | Tap Drill Size | Decimal Equivalent |
* Theo % Thread |
Prob Mean Oversize |
Prob Hole Size |
** Prob % Thread |
| 1/4 - 18 | 7/16 | .4375" | N/A | .003" | .4405" | N/A |
| 3/8 - 18 | 9/16 | .5625" | N/A | .003" | .5655" | N/A |
| 1/2 - 14 | 45/64 | .7031" | N/A | .003" | .7061" | N/A |
| 3/4 - 14 | 29/32 | .9063" | N/A | .003" | .9093" | N/A |
The above tap drill information represents probable thread percentages for the standard tap drills stocked at AMEC. Special blade diameters may be required in order to meet a user specific percentage of thread requiremnets. The .003" probable mean oversize hole condition is based on optimum cutting conditions. Probable % of full thread may vary based on less ideal cutting conditions |
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