#58 drill size
A #58 number (wire-gauge) drill is 0.0420 in (1.067 mm).
- Decimal inch
- 0.0420
- Millimeters
- 1.067
- Nearest 1/64
- 3/64" (-0.0049)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
| System | Drill | Inch | mm | Difference |
|---|---|---|---|---|
| Fractional | 3/64" | 0.0469 | 1.191 | +0.0049 in |
| Metric | 1.05 mm | 0.0413 | 1.050 | -0.0007 in |
Speeds and feeds: in mild steel an HSS drill starts at about 8,190 RPM and 0.0010 in/rev (8.19 IPM); in 6061 aluminum about 22,740 RPM.
#58 drill speeds and feeds by material
Jobber-length twist drill, D = 0.0420 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 | 22,740 | 600 | 54,570 | 0.0010 | 22.7 | 54.6 |
| Brass / free-machining | 150 | 13,640 | 400 | 36,380 | 0.0008 | 10.9 | 29.1 |
| Low-carbon steel (1018) | 90 | 8,190 | 300 | 27,280 | 0.0010 | 8.19 | 27.3 |
| Alloy steel (4140, annealed) | 70 | 6,370 | 250 | 22,740 | 0.0010 | 6.37 | 22.7 |
| Stainless 304 | 40 | 3,640 | 150 | 13,640 | 0.0007 | 2.55 | 9.55 |
| Gray cast iron | 80 | 7,280 | 250 | 22,740 | 0.0006 | 4.37 | 13.6 |
| Titanium 6Al-4V | 25 | 2,270 | 100 | 9,090 | 0.0005 | 1.14 | 4.55 |
| Plastics (acetal) | 300 | 27,280 | 500 | 45,470 | 0.0017 | 46.4 | 77.3 |
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, 8,190 RPM × 0.025 mm/rev = 208 mm/min.
Worked example: #58 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.0420 ≈ 8,190 RPM.
- Feed for a 0.042 in drill in mild steel ≈ 0.0010 in/rev.
- IPM = 8,190 × 0.0010 = 8.19 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.126 in (3.2 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.210 in (5.3 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 0.336 in (8.5 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 #58 drill
No standard UNC, UNF or metric tap in our tables calls for a #58 drill. Use it for clearance, pilot or reamer prep holes.
Nearest drills
- 1.05 mm: 0.0413 in / 1.050 mm (-0.0007 in)
- #59: 0.0410 in / 1.041 mm (-0.0010 in)
- #57: 0.0430 in / 1.092 mm (+0.0010 in)
- 1.1 mm: 0.0433 in / 1.100 mm (+0.0013 in)
Common questions
- What is a #58 drill in decimal and mm?
- 0.0420 in, or 1.067 mm; nearest fractional drill: 3/64" (0.0469 in, +0.0049 in); nearest metric drill: 1.05 mm (0.0413 in, -0.0007 in).
- What RPM for a #58 drill in steel?
- In low-carbon steel (1018) an HSS #58 drill (0.0420 in) runs about 8,190 RPM at 90 SFM; a carbide drill about 27,280 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #58 drill?
- About 0.0010 in/rev in mild steel, 0.0010 in/rev in aluminum and 0.0007 in/rev in 304 stainless. At 8,190 RPM that is 8.19 IPM in steel (IPM = RPM × IPR).
- What RPM for a #58 drill in aluminum?
- 22,740 RPM with HSS (250 SFM) or up to 54,570 RPM with carbide (600 SFM), feeding about 0.0010 in/rev.
- What size is a #58 drill?
- 0.0420 in / 1.067 mm. The nearest other drills are 1.05 mm (0.0413 in), #59 (0.0410 in), #57 (0.0430 in).
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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