7/16-14 tap drill size
Use a U drill (0.3680 in) for a 7/16-14 cutting tap at 75% thread.
| Tap type | Drill | Decimal (in) |
|---|---|---|
| Cutting tap, 75% thread | U | 0.3680 |
| Cutting tap, 50% thread (hard material) | 25/64" | 0.3906 |
| Roll / form tap, 65% thread | 13/32 | 0.4063 |
| Helicoil / STI insert (7/16-14×1D) | 29/64" | 0.4531 |
- Pitch
- 1.8143 mm (14 TPI)
- Major Ø
- 0.4375
- Pitch Ø
- 0.3911
- Minor Ø
- 0.3499
7/16-14 tapping speeds and feeds
Feed = pitch (0.0714 in per rev). Starting points for a general-purpose HSS cut tap:
- Aluminum 6061 / 7075: 610 RPM · 43.6 IPM
- Free-machining / mild steel: 170 RPM · 12.1 IPM
- 304 / 316 stainless: 90 RPM · 6.43 IPM
7/16-14 tap speeds and feeds: all materials, form taps and G84 code · U drill size and speeds
Common questions
- What size drill for a 7/16-14 tap?
- Use a U drill (0.3680 in) for a 7/16-14 cutting tap at 75% thread.
- What drill for a 7/16-14 roll (form) tap?
- About 0.4059 in; the nearest standard drill is 13/32. Check your tap maker's table.
- What drill for a 7/16-14 Helicoil?
- Drill 29/64" (0.4531 in), then tap with the 7/16-14 STI tap.
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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