Besly Cutting Tools, Inc
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Besly Drill Selector for Maxx-Taps Fractional Sizes |
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|---|---|---|---|---|
| Tap Size | UNJC or UNJF Aerospace Thread | UNC-UNF Unified Threads | ||
| Product Minor Dia. (MAX UNJ)* |
Recommended Drill Size | Product Minor Dia. (MAX 3B)* |
Recommended Drill Size | |
| 1/4-20 | .2121 | No. 5 (.2055) | .2067 | 13/64 (.2031) |
| 1/4-28 | .2229 | 7/32 (.2187) | .2190 | No. 3 (.2130) |
| 5/16-18 | .2690 | 6.7mm (.2638) | .2630 | F (.2570) |
| 5/16-24 | .2799 | 7.0mm (.2756) | .2754 | 6.8mm (.2677) |
| 3/8-16 | .3251 | 8.1mm (.3189) | .3182 | 5/16 (.3125) |
| 3/8-24 | .3418 | 8.5mm (.3346) | .3372 | O (.3320) |
| 7/16-14 | .3795 | 3/8 (.3750) | .3717 | U (.3680) |
| 7/16-20 | .3970 | 10mm (.3937) | .3916 | 9.90mm (.3898) |
| 1/2-13 | .4368 | 11mm (.4331) | .4284 | 10.80mm (.4252) |
| 1/2-20 | .4591 | 29/64 (.4531) | .4537 | 11.40mm (.4488) |
| * Select a drill that will produce a minor diameter as large as possible. It should not exceed the maximum product minor diameter for the class being tapped. | ||||