3/4-10 tap drill size
Drill a 21/32" hole (0.6563" / 16.67 mm) for a 3/4-10 UNC tap. That leaves about 72% thread, the standard for general-purpose tapping.
3/4-10 tap drill: 21/32" (0.6563 in / 16.67 mm), 72% thread3/4-10 thread specs
| Series | Unified coarse (UNC) |
|---|---|
| Major diameter | 0.7500" (19.05 mm) |
| Pitch | 10 TPI (2.54 mm) |
| Basic minor diameter | 0.6417" (16.30 mm) |
| Common internal class | 2B |
Every drill that works for 3/4-10
Drills from all four sets that give 50–85% thread, largest first. Lower percentages tap easier; see how much thread you need.
| Drill | Thread | in | mm | Set | Good for |
|---|---|---|---|---|---|
| 43/64" | 60% | 0.6719 | 17.07 | Fractional | hard or tough metals |
| 17.0 mm | 62% | 0.6693 | 17.00 | Metric | hard or tough metals |
| 21/32"standard | 72% | 0.6563 | 16.67 | Fractional | general use |
| 16.5 mm | 77% | 0.6496 | 16.50 | Metric | general use |
| 41/64" | 84% | 0.6406 | 16.27 | Fractional | more torque, more broken taps |
3/4-10 clearance hole
The hole a 3/4-10 screw passes through. Close fit locates parts; free fit is forgiving.
| Fit | Drill | in | mm |
|---|---|---|---|
| Close fit | 49/64" | 0.7656 | 19.45 |
| Free fit | 25/32" | 0.7813 | 19.84 |
3/4-10 counterbore and countersink
For a socket head cap screw to sit flush, and for a flat head socket screw.
| Socket head counterbore | Diameter | Depth |
|---|---|---|
| AMES | 1-3/16" 1.1875" | 0.7500" |
Flat head socket screw: countersink at 82° (inch screws, ASME B18.3) to 1.4380" (36.53 mm) across for a flush head. Metric flat heads use 90°, so don't mix countersinks.
3/4-10 holes in a 3D print
Printed holes usually come out undersize. Model the hole at the drill size plus what your printer loses, then tap or drill to size. Why printed holes shrink.
Print a test hole, measure it with calipers, enter the difference. 0 models the nominal size.
3/4-10 thread repair (Helicoil)
Stripped 3/4-10 thread? Drill out with the STI drill, tap with a 3/4-10 UNC STI tap, and fit a wire thread insert. The drill in your repair kit’s instructions wins over any chart.
| Chart | STI drill | in | mm |
|---|---|---|---|
| AMES | 25/32" | 0.7813 | 19.84 |
| MISUMI | 25/32" | 0.7813 | 19.84 |
Related sizes
Frequently asked questions
What size drill do I use for a 3/4-10 tap?
What metric drill can I use for a 3/4-10 tap?
What size clearance hole for a 3/4-10 screw?
Sources
- Engineers Edge: machinist screw thread tap drill chart (ANSI) checked 2026-10-19
- ETSU: tap, drill & clearance chart checked 2026-10-19
- Albany County Fasteners: clearance hole chart (PDF) checked 2026-10-19
- AMES: counterbore hole dimensions, inch (Machinery's Handbook) checked 2026-10-19
- SC Fastening: flat head socket cap screw spec, ASME B18.3 (PDF) checked 2026-10-19
- Eugene Fastener: flat head socket screw countersink guide checked 2026-10-19
- AMES: Helicoil tap sizes (STI) checked 2026-10-19
- MISUMI: Helicoil tap and drill size chart checked 2026-10-19
Spotted a wrong number? Email contact@clove3d.com and it gets fixed.
% thread = (major − drill) ÷ (1.299 × pitch) × 100. The standard drill comes from published charts and is checked against this formula on every build.