3/64" drill size
A 3/64" fractional drill is 0.0469 in (1.191 mm). It is the cut tap, 75% thread drill for 0-80.
- Decimal inch
- 0.0469
- Millimeters
- 1.191
- Nearest 1/64
- 3/64" (+0.0000)
- Type
- fractional drill
Nearest equivalents in other systems
| System | Drill | Inch | mm | Difference |
|---|---|---|---|---|
| Number / letter | #56 | 0.0465 | 1.181 | -0.0004 in |
| Metric | 1.2 mm | 0.0472 | 1.200 | +0.0004 in |
Speeds and feeds: in mild steel an HSS drill starts at about 7,330 RPM and 0.0011 in/rev (8.06 IPM); in 6061 aluminum about 20,370 RPM.
3/64" drill speeds and feeds by material
Jobber-length twist drill, D = 0.0469 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.
| Material | HSS SFM | HSS RPM | Carbide SFM | Carbide RPM | Feed (in/rev) | HSS IPM | Carbide IPM |
|---|---|---|---|---|---|---|---|
| Aluminum (6061) | 250 | 20,370 | 600 | 48,890 | 0.0011 | 22.4 | 53.8 |
| Brass / free-machining | 150 | 12,220 | 400 | 32,590 | 0.0009 | 11.0 | 29.3 |
| Low-carbon steel (1018) | 90 | 7,330 | 300 | 24,450 | 0.0011 | 8.06 | 26.9 |
| Alloy steel (4140, annealed) | 70 | 5,700 | 250 | 20,370 | 0.0011 | 6.27 | 22.4 |
| Stainless 304 | 40 | 3,260 | 150 | 12,220 | 0.0008 | 2.61 | 9.78 |
| Gray cast iron | 80 | 6,520 | 250 | 20,370 | 0.0007 | 4.56 | 14.3 |
| Titanium 6Al-4V | 25 | 2,040 | 100 | 8,150 | 0.0006 | 1.22 | 4.89 |
| Plastics (acetal) | 300 | 24,450 | 500 | 40,740 | 0.0019 | 46.5 | 77.4 |
Small drills: the computed RPM is above most spindles. Run at your spindle's maximum and keep the feed per rev; feed drops in proportion.
Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 7,330 RPM × 0.028 mm/rev = 205 mm/min.
Worked example: 3/64" drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.0469 ≈ 7,330 RPM.
- Feed for a 0.047 in drill in mild steel ≈ 0.0011 in/rev.
- IPM = 7,330 × 0.0011 = 8.06 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.141 in (3.6 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.234 in (6 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 0.375 in (9.5 mm) | G83 full retract | 0.5-1 × D, shrinking with depth | Retract to clear chips; reduce feed ~10-20% past 5×D. |
Taps that use a 3/64" drill
- 0-80 — cut tap, 75% thread · tap speeds and feeds
Nearest drills
- 1.2 mm: 0.0472 in / 1.200 mm (+0.0004 in)
- #56: 0.0465 in / 1.181 mm (-0.0004 in)
- 1.15 mm: 0.0453 in / 1.150 mm (-0.0016 in)
- 1.25 mm: 0.0492 in / 1.250 mm (+0.0023 in)
Common questions
- What is a 3/64" drill in decimal and mm?
- 0.0469 in, or 1.191 mm; nearest number / letter drill: #56 (0.0465 in, -0.0004 in); nearest metric drill: 1.2 mm (0.0472 in, +0.0004 in).
- What RPM for a 3/64" drill in steel?
- In low-carbon steel (1018) an HSS 3/64" drill (0.0469 in) runs about 7,330 RPM at 90 SFM; a carbide drill about 24,450 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a 3/64" drill?
- About 0.0011 in/rev in mild steel, 0.0011 in/rev in aluminum and 0.0008 in/rev in 304 stainless. At 7,330 RPM that is 8.06 IPM in steel (IPM = RPM × IPR).
- What RPM for a 3/64" drill in aluminum?
- 20,370 RPM with HSS (250 SFM) or up to 48,890 RPM with carbide (600 SFM), feeding about 0.0011 in/rev.
- What tap uses a 3/64" drill?
- 0-80 (cut tap, 75% thread).
Nearby drill sizes
Sources
- Machinery's Handbook, 31st ed., Speeds and Feeds for Drilling, Reaming and Threading (Tables 17-23) — HSS and carbide drilling SFM (rounded).
- RedLine Tools (Productivity Inc.) catalog p. 340, Cobalt & HSS Drills Speeds & Feeds — feed per rev by drill diameter and material (middle of the catalog range).
- ASME B94.11M twist drills: number (#1-#80) and letter (A-Z) drill sizes; drill size reference.
Material feed multipliers (aluminum 1.3×, brass 1.1×, 4140 0.85×, stainless and titanium 0.7× the mild-steel feed) are JobLine estimates. Peck guidance is JobLine shop practice. Use your drill maker's data first.
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