#9 drill size
A #9 number (wire-gauge) drill is 0.1960 in (4.978 mm). It is the cut tap, 50% thread drill for 12-32.
- Decimal inch
- 0.1960
- Millimeters
- 4.978
- Nearest 1/64
- 13/64" (-0.0071)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
Speeds and feeds: in mild steel an HSS drill starts at about 1,750 RPM and 0.0050 in/rev (8.75 IPM); in 6061 aluminum about 4,870 RPM.
#9 drill speeds and feeds by material
Jobber-length twist drill, D = 0.1960 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 | 4,870 | 600 | 11,690 | 0.0046 | 22.4 | 53.8 |
| Brass / free-machining | 150 | 2,920 | 400 | 7,800 | 0.0040 | 11.7 | 31.2 |
| Low-carbon steel (1018) | 90 | 1,750 | 300 | 5,850 | 0.0050 | 8.75 | 29.3 |
| Alloy steel (4140, annealed) | 70 | 1,360 | 250 | 4,870 | 0.0050 | 6.80 | 24.4 |
| Stainless 304 | 40 | 780 | 150 | 2,920 | 0.0033 | 2.57 | 9.64 |
| Gray cast iron | 80 | 1,560 | 250 | 4,870 | 0.0033 | 5.15 | 16.1 |
| Titanium 6Al-4V | 25 | 490 | 100 | 1,950 | 0.0024 | 1.18 | 4.68 |
| Plastics (acetal) | 300 | 5,850 | 500 | 9,740 | 0.0044 | 25.7 | 42.9 |
Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 1,750 RPM × 0.127 mm/rev = 222 mm/min.
Worked example: #9 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.1960 ≈ 1,750 RPM.
- Feed for a 0.196 in drill in mild steel ≈ 0.0050 in/rev.
- IPM = 1,750 × 0.0050 = 8.75 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.588 in (14.9 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.980 in (24.9 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 1.568 in (39.8 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 #9 drill
- 12-32 — cut tap, 50% thread
Nearest drills
- 5.0 mm: 0.1968 in / 5.000 mm (+0.0008 in)
- #10: 0.1935 in / 4.915 mm (-0.0025 in)
- #8: 0.1990 in / 5.055 mm (+0.0030 in)
- 4.9 mm: 0.1929 in / 4.900 mm (-0.0031 in)
Common questions
- What is a #9 drill in decimal and mm?
- 0.1960 in, or 4.978 mm; nearest fractional drill: 13/64" (0.2031 in, +0.0071 in); nearest metric drill: 5.0 mm (0.1968 in, +0.0008 in).
- What RPM for a #9 drill in steel?
- In low-carbon steel (1018) an HSS #9 drill (0.1960 in) runs about 1,750 RPM at 90 SFM; a carbide drill about 5,850 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #9 drill?
- About 0.0050 in/rev in mild steel, 0.0046 in/rev in aluminum and 0.0033 in/rev in 304 stainless. At 1,750 RPM that is 8.75 IPM in steel (IPM = RPM × IPR).
- What RPM for a #9 drill in aluminum?
- 4,870 RPM with HSS (250 SFM) or up to 11,690 RPM with carbide (600 SFM), feeding about 0.0046 in/rev.
- What tap uses a #9 drill?
- 12-32 (cut tap, 50% 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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