#10 drill size
A #10 number (wire-gauge) drill is 0.1935 in (4.915 mm). It is the cut tap, 50% thread drill for 12-28.
- Decimal inch
- 0.1935
- Millimeters
- 4.915
- Nearest 1/64
- 3/16" (+0.0060)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
| System | Drill | Inch | mm | Difference |
|---|---|---|---|---|
| Fractional | 3/16" | 0.1875 | 4.762 | -0.0060 in |
| Metric | 4.9 mm | 0.1929 | 4.900 | -0.0006 in |
Speeds and feeds: in mild steel an HSS drill starts at about 1,780 RPM and 0.0049 in/rev (8.72 IPM); in 6061 aluminum about 4,940 RPM.
#10 drill speeds and feeds by material
Jobber-length twist drill, D = 0.1935 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 | 4,940 | 600 | 11,840 | 0.0046 | 22.7 | 54.5 |
| Brass / free-machining | 150 | 2,960 | 400 | 7,900 | 0.0040 | 11.8 | 31.6 |
| Low-carbon steel (1018) | 90 | 1,780 | 300 | 5,920 | 0.0049 | 8.72 | 29.0 |
| Alloy steel (4140, annealed) | 70 | 1,380 | 250 | 4,940 | 0.0049 | 6.76 | 24.2 |
| Stainless 304 | 40 | 790 | 150 | 2,960 | 0.0032 | 2.53 | 9.47 |
| Gray cast iron | 80 | 1,580 | 250 | 4,940 | 0.0033 | 5.21 | 16.3 |
| Titanium 6Al-4V | 25 | 490 | 100 | 1,970 | 0.0023 | 1.13 | 4.53 |
| Plastics (acetal) | 300 | 5,920 | 500 | 9,870 | 0.0045 | 26.6 | 44.4 |
Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 1,780 RPM × 0.124 mm/rev = 222 mm/min.
Worked example: #10 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.1935 ≈ 1,780 RPM.
- Feed for a 0.194 in drill in mild steel ≈ 0.0049 in/rev.
- IPM = 1,780 × 0.0049 = 8.72 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.581 in (14.7 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.968 in (24.6 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 1.548 in (39.3 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 #10 drill
- 12-28 — cut tap, 50% thread · tap speeds and feeds
- 10-24 — Helicoil / STI insert (#10-24×1D) · tap speeds and feeds
Nearest drills
- 4.9 mm: 0.1929 in / 4.900 mm (-0.0006 in)
- #11: 0.1910 in / 4.851 mm (-0.0025 in)
- #9: 0.1960 in / 4.978 mm (+0.0025 in)
- 5.0 mm: 0.1968 in / 5.000 mm (+0.0034 in)
Common questions
- What is a #10 drill in decimal and mm?
- 0.1935 in, or 4.915 mm; nearest fractional drill: 3/16" (0.1875 in, -0.0060 in); nearest metric drill: 4.9 mm (0.1929 in, -0.0006 in).
- What RPM for a #10 drill in steel?
- In low-carbon steel (1018) an HSS #10 drill (0.1935 in) runs about 1,780 RPM at 90 SFM; a carbide drill about 5,920 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #10 drill?
- About 0.0049 in/rev in mild steel, 0.0046 in/rev in aluminum and 0.0032 in/rev in 304 stainless. At 1,780 RPM that is 8.72 IPM in steel (IPM = RPM × IPR).
- What RPM for a #10 drill in aluminum?
- 4,940 RPM with HSS (250 SFM) or up to 11,840 RPM with carbide (600 SFM), feeding about 0.0046 in/rev.
- What tap uses a #10 drill?
- 12-28 (cut tap, 50% thread); 10-24 (Helicoil / STI insert (#10-24×1D)).
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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