3/4-10 tap drill size
Use a 21/32" drill (0.6562 in) for a 3/4-10 cutting tap at 75% thread.
| Tap type | Drill | Decimal (in) |
|---|---|---|
| Cutting tap, 75% thread | 21/32" | 0.6562 |
| Cutting tap, 50% thread (hard material) | 11/16" | 0.6875 |
| Roll / form tap, 65% thread | 45/64 | 0.7031 |
| Helicoil / STI insert (3/4-10×1D) | 49/64" | 0.7656 |
- Pitch
- 2.54 mm (10 TPI)
- Major Ø
- 0.7500
- Pitch Ø
- 0.6850
- Minor Ø
- 0.6273
Common questions
- What size drill for a 3/4-10 tap?
- Use a 21/32" drill (0.6562 in) for a 3/4-10 cutting tap at 75% thread.
- What drill for a 3/4-10 roll (form) tap?
- About 0.7058 in; the nearest standard drill is 45/64. Check your tap maker's table.
- What drill for a 3/4-10 Helicoil?
- Drill 49/64" (0.7656 in), then tap with the 3/4-10 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.