#41 drill size
A #41 number (wire-gauge) drill is 0.0960 in (2.438 mm). It is the cut tap, 50% thread drill for 4-40.
- Decimal inch
- 0.0960
- Millimeters
- 2.438
- Nearest 1/64
- 3/32" (+0.0023)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
| System | Drill | Inch | mm | Difference |
|---|---|---|---|---|
| Fractional | 3/32" | 0.0938 | 2.381 | -0.0022 in |
| Metric | 2.45 mm | 0.0965 | 2.450 | +0.0005 in |
Speeds and feeds: in mild steel an HSS drill starts at about 3,580 RPM and 0.0023 in/rev (8.23 IPM); in 6061 aluminum about 9,950 RPM.
#41 drill speeds and feeds by material
Jobber-length twist drill, D = 0.0960 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 | 9,950 | 600 | 23,870 | 0.0022 | 21.9 | 52.5 |
| Brass / free-machining | 150 | 5,970 | 400 | 15,920 | 0.0018 | 10.8 | 28.7 |
| Low-carbon steel (1018) | 90 | 3,580 | 300 | 11,940 | 0.0023 | 8.23 | 27.5 |
| Alloy steel (4140, annealed) | 70 | 2,790 | 250 | 9,950 | 0.0023 | 6.42 | 22.9 |
| Stainless 304 | 40 | 1,590 | 150 | 5,970 | 0.0015 | 2.39 | 8.96 |
| Gray cast iron | 80 | 3,180 | 250 | 9,950 | 0.0014 | 4.45 | 13.9 |
| Titanium 6Al-4V | 25 | 990 | 100 | 3,980 | 0.0012 | 1.19 | 4.78 |
| Plastics (acetal) | 300 | 11,940 | 500 | 19,890 | 0.0038 | 45.4 | 75.6 |
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, 3,580 RPM × 0.058 mm/rev = 209 mm/min.
Worked example: #41 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.0960 ≈ 3,580 RPM.
- Feed for a 0.096 in drill in mild steel ≈ 0.0023 in/rev.
- IPM = 3,580 × 0.0023 = 8.23 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.288 in (7.3 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.480 in (12.2 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 0.768 in (19.5 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 #41 drill
- 4-40 — cut tap, 50% thread · tap speeds and feeds
- 2-56 — Helicoil / STI insert (#2-56×1D) · tap speeds and feeds
Nearest drills
- 2.45 mm: 0.0965 in / 2.450 mm (+0.0005 in)
- 2.4 mm: 0.0945 in / 2.400 mm (-0.0015 in)
- #40: 0.0980 in / 2.489 mm (+0.0020 in)
- 3/32": 0.0938 in / 2.381 mm (-0.0022 in)
Common questions
- What is a #41 drill in decimal and mm?
- 0.0960 in, or 2.438 mm; nearest fractional drill: 3/32" (0.0938 in, -0.0022 in); nearest metric drill: 2.45 mm (0.0965 in, +0.0005 in).
- What RPM for a #41 drill in steel?
- In low-carbon steel (1018) an HSS #41 drill (0.0960 in) runs about 3,580 RPM at 90 SFM; a carbide drill about 11,940 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #41 drill?
- About 0.0023 in/rev in mild steel, 0.0022 in/rev in aluminum and 0.0015 in/rev in 304 stainless. At 3,580 RPM that is 8.23 IPM in steel (IPM = RPM × IPR).
- What RPM for a #41 drill in aluminum?
- 9,950 RPM with HSS (250 SFM) or up to 23,870 RPM with carbide (600 SFM), feeding about 0.0022 in/rev.
- What tap uses a #41 drill?
- 4-40 (cut tap, 50% thread); 2-56 (Helicoil / STI insert (#2-56×1D)).
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.
Put your skills on a free talent profile
Machines, controls, certs and saved calculations in one profile shops can find.
Create free profileBring shift handoffs to your shop
Stop losing job status between shifts. Every station's notes, counts and issues, handed off cleanly.
See shift handoffs