#43 drill size
A #43 number (wire-gauge) drill is 0.0890 in (2.261 mm). It is the cut tap, 75% thread drill for 4-40.
- Decimal inch
- 0.0890
- Millimeters
- 2.261
- Nearest 1/64
- 3/32" (-0.0048)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
| System | Drill | Inch | mm | Difference |
|---|---|---|---|---|
| Fractional | 3/32" | 0.0938 | 2.381 | +0.0047 in |
| Metric | 2.25 mm | 0.0886 | 2.250 | -0.0004 in |
Speeds and feeds: in mild steel an HSS drill starts at about 3,860 RPM and 0.0021 in/rev (8.11 IPM); in 6061 aluminum about 10,730 RPM.
#43 drill speeds and feeds by material
Jobber-length twist drill, D = 0.0890 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 | 10,730 | 600 | 25,750 | 0.0020 | 21.5 | 51.5 |
| Brass / free-machining | 150 | 6,440 | 400 | 17,170 | 0.0017 | 10.9 | 29.2 |
| Low-carbon steel (1018) | 90 | 3,860 | 300 | 12,880 | 0.0021 | 8.11 | 27.1 |
| Alloy steel (4140, annealed) | 70 | 3,000 | 250 | 10,730 | 0.0021 | 6.30 | 22.5 |
| Stainless 304 | 40 | 1,720 | 150 | 6,440 | 0.0014 | 2.41 | 9.02 |
| Gray cast iron | 80 | 3,430 | 250 | 10,730 | 0.0013 | 4.46 | 13.9 |
| Titanium 6Al-4V | 25 | 1,070 | 100 | 4,290 | 0.0011 | 1.18 | 4.72 |
| Plastics (acetal) | 300 | 12,880 | 500 | 21,460 | 0.0036 | 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, 3,860 RPM × 0.053 mm/rev = 206 mm/min.
Worked example: #43 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.0890 ≈ 3,860 RPM.
- Feed for a 0.089 in drill in mild steel ≈ 0.0021 in/rev.
- IPM = 3,860 × 0.0021 = 8.11 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.267 in (6.8 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.445 in (11.3 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 0.712 in (18.1 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 #43 drill
- 4-40 — cut tap, 75% thread · tap speeds and feeds
- 3-48 — form (roll) tap, 65% thread · tap speeds and feeds
- 3-56 — form (roll) tap, 65% thread · tap speeds and feeds
- 1-64 — Helicoil / STI insert (#1-64×1D) · tap speeds and feeds
Nearest drills
- 2.25 mm: 0.0886 in / 2.250 mm (-0.0004 in)
- 2.3 mm: 0.0906 in / 2.300 mm (+0.0015 in)
- 2.2 mm: 0.0866 in / 2.200 mm (-0.0024 in)
- #44: 0.0860 in / 2.184 mm (-0.0030 in)
Common questions
- What is a #43 drill in decimal and mm?
- 0.0890 in, or 2.261 mm; nearest fractional drill: 3/32" (0.0938 in, +0.0047 in); nearest metric drill: 2.25 mm (0.0886 in, -0.0004 in).
- What RPM for a #43 drill in steel?
- In low-carbon steel (1018) an HSS #43 drill (0.0890 in) runs about 3,860 RPM at 90 SFM; a carbide drill about 12,880 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #43 drill?
- About 0.0021 in/rev in mild steel, 0.0020 in/rev in aluminum and 0.0014 in/rev in 304 stainless. At 3,860 RPM that is 8.11 IPM in steel (IPM = RPM × IPR).
- What RPM for a #43 drill in aluminum?
- 10,730 RPM with HSS (250 SFM) or up to 25,750 RPM with carbide (600 SFM), feeding about 0.0020 in/rev.
- What tap uses a #43 drill?
- 4-40 (cut tap, 75% thread); 3-48 (form (roll) tap, 65% thread); 3-56 (form (roll) tap, 65% thread); 1-64 (Helicoil / STI insert (#1-64×1D)).
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