9/16-12 tap drill size
Use a 31/64 drill (0.4844 in) for a 9/16-12 cutting tap at 75% thread.
| Tap type | Drill | Decimal (in) |
|---|---|---|
| Cutting tap, 75% thread | 31/64 | 0.4844 |
| Cutting tap, 50% thread (hard material) | 33/64 | 0.5156 |
| Roll / form tap, 65% thread | 17/32 | 0.5313 |
- Pitch
- 2.1167 mm (12 TPI)
- Major Ø
- 0.5625
- Pitch Ø
- 0.5084
- Minor Ø
- 0.4723
9/16-12 tapping speeds and feeds
Feed = pitch (0.0833 in per rev). Starting points for a general-purpose HSS cut tap:
- Aluminum 6061 / 7075: 480 RPM · 40.0 IPM
- Free-machining / mild steel: 140 RPM · 11.7 IPM
- 304 / 316 stainless: 70 RPM · 5.83 IPM
9/16-12 tap speeds and feeds: all materials, form taps and G84 code · 31/64 drill size and speeds
Common questions
- What size drill for a 9/16-12 tap?
- Use a 31/64 drill (0.4844 in) for a 9/16-12 cutting tap at 75% thread.
- What drill for a 9/16-12 roll (form) tap?
- About 0.5257 in; the nearest standard drill is 17/32. Check your tap maker's table.
Other UNC sizes
Drill sizes from Machinery's Handbook and ASME B1.1/B1.13M; roll tap sizes from the form-tap formula. Tap and insert makers' tables are authoritative.
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