#26 drill size
A #26 number (wire-gauge) drill is 0.1470 in (3.734 mm). It is the cut tap, 50% thread drill for 8-36.
- Decimal inch
- 0.1470
- Millimeters
- 3.734
- Nearest 1/64
- 9/64" (+0.0064)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
Speeds and feeds: in mild steel an HSS drill starts at about 2,340 RPM and 0.0036 in/rev (8.42 IPM); in 6061 aluminum about 6,500 RPM.
#26 drill speeds and feeds by material
Jobber-length twist drill, D = 0.1470 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 | 6,500 | 600 | 15,590 | 0.0034 | 22.1 | 53.0 |
| Brass / free-machining | 150 | 3,900 | 400 | 10,390 | 0.0029 | 11.3 | 30.1 |
| Low-carbon steel (1018) | 90 | 2,340 | 300 | 7,800 | 0.0036 | 8.42 | 28.1 |
| Alloy steel (4140, annealed) | 70 | 1,820 | 250 | 6,500 | 0.0036 | 6.55 | 23.4 |
| Stainless 304 | 40 | 1,040 | 150 | 3,900 | 0.0024 | 2.50 | 9.36 |
| Gray cast iron | 80 | 2,080 | 250 | 6,500 | 0.0023 | 4.78 | 14.9 |
| Titanium 6Al-4V | 25 | 650 | 100 | 2,600 | 0.0018 | 1.17 | 4.68 |
| Plastics (acetal) | 300 | 7,800 | 500 | 12,990 | 0.0048 | 37.4 | 62.4 |
Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 2,340 RPM × 0.091 mm/rev = 214 mm/min.
Worked example: #26 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.1470 ≈ 2,340 RPM.
- Feed for a 0.147 in drill in mild steel ≈ 0.0036 in/rev.
- IPM = 2,340 × 0.0036 = 8.42 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.441 in (11.2 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.735 in (18.7 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 1.176 in (29.9 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 #26 drill
- 8-36 — cut tap, 50% thread · tap speeds and feeds
Nearest drills
- 3.7 mm: 0.1457 in / 3.700 mm (-0.0013 in)
- #25: 0.1495 in / 3.797 mm (+0.0025 in)
- 3.8 mm: 0.1496 in / 3.800 mm (+0.0026 in)
- #27: 0.1440 in / 3.658 mm (-0.0030 in)
Common questions
- What is a #26 drill in decimal and mm?
- 0.1470 in, or 3.734 mm; nearest fractional drill: 9/64" (0.1406 in, -0.0064 in); nearest metric drill: 3.7 mm (0.1457 in, -0.0013 in).
- What RPM for a #26 drill in steel?
- In low-carbon steel (1018) an HSS #26 drill (0.1470 in) runs about 2,340 RPM at 90 SFM; a carbide drill about 7,800 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #26 drill?
- About 0.0036 in/rev in mild steel, 0.0034 in/rev in aluminum and 0.0024 in/rev in 304 stainless. At 2,340 RPM that is 8.42 IPM in steel (IPM = RPM × IPR).
- What RPM for a #26 drill in aluminum?
- 6,500 RPM with HSS (250 SFM) or up to 15,590 RPM with carbide (600 SFM), feeding about 0.0034 in/rev.
- What tap uses a #26 drill?
- 8-36 (cut tap, 50% thread).
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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