#49 drill size
A #49 number (wire-gauge) drill is 0.0730 in (1.854 mm). It is the cut tap, 50% thread drill for 2-56.
- Decimal inch
- 0.0730
- Millimeters
- 1.854
- Nearest 1/64
- 5/64" (-0.0051)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
| System | Drill | Inch | mm | Difference |
|---|---|---|---|---|
| Fractional | 5/64" | 0.0781 | 1.984 | +0.0051 in |
| Metric | 1.85 mm | 0.0728 | 1.850 | -0.0002 in |
Speeds and feeds: in mild steel an HSS drill starts at about 4,710 RPM and 0.0017 in/rev (8.01 IPM); in 6061 aluminum about 13,080 RPM.
#49 drill speeds and feeds by material
Jobber-length twist drill, D = 0.0730 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 | 13,080 | 600 | 31,390 | 0.0017 | 22.2 | 53.4 |
| Brass / free-machining | 150 | 7,850 | 400 | 20,930 | 0.0014 | 11.0 | 29.3 |
| Low-carbon steel (1018) | 90 | 4,710 | 300 | 15,700 | 0.0017 | 8.01 | 26.7 |
| Alloy steel (4140, annealed) | 70 | 3,660 | 250 | 13,080 | 0.0017 | 6.22 | 22.2 |
| Stainless 304 | 40 | 2,090 | 150 | 7,850 | 0.0012 | 2.51 | 9.42 |
| Gray cast iron | 80 | 4,190 | 250 | 13,080 | 0.0011 | 4.61 | 14.4 |
| Titanium 6Al-4V | 25 | 1,310 | 100 | 5,230 | 0.0009 | 1.18 | 4.71 |
| Plastics (acetal) | 300 | 15,700 | 500 | 26,160 | 0.0029 | 45.5 | 75.9 |
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, 4,710 RPM × 0.043 mm/rev = 203 mm/min.
Worked example: #49 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.0730 ≈ 4,710 RPM.
- Feed for a 0.073 in drill in mild steel ≈ 0.0017 in/rev.
- IPM = 4,710 × 0.0017 = 8.01 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.219 in (5.6 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.365 in (9.3 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 0.584 in (14.8 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 #49 drill
- 2-56 — cut tap, 50% thread · tap speeds and feeds
- 0-80 — Helicoil / STI insert (#0-80×1D) · tap speeds and feeds
Nearest drills
- 1.85 mm: 0.0728 in / 1.850 mm (-0.0002 in)
- 1.9 mm: 0.0748 in / 1.900 mm (+0.0018 in)
- 1.8 mm: 0.0709 in / 1.800 mm (-0.0021 in)
- #50: 0.0700 in / 1.778 mm (-0.0030 in)
Common questions
- What is a #49 drill in decimal and mm?
- 0.0730 in, or 1.854 mm; nearest fractional drill: 5/64" (0.0781 in, +0.0051 in); nearest metric drill: 1.85 mm (0.0728 in, -0.0002 in).
- What RPM for a #49 drill in steel?
- In low-carbon steel (1018) an HSS #49 drill (0.0730 in) runs about 4,710 RPM at 90 SFM; a carbide drill about 15,700 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #49 drill?
- About 0.0017 in/rev in mild steel, 0.0017 in/rev in aluminum and 0.0012 in/rev in 304 stainless. At 4,710 RPM that is 8.01 IPM in steel (IPM = RPM × IPR).
- What RPM for a #49 drill in aluminum?
- 13,080 RPM with HSS (250 SFM) or up to 31,390 RPM with carbide (600 SFM), feeding about 0.0017 in/rev.
- What tap uses a #49 drill?
- 2-56 (cut tap, 50% thread); 0-80 (Helicoil / STI insert (#0-80×1D)).
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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