#37 drill size
A #37 number (wire-gauge) drill is 0.1040 in (2.642 mm). It is the cut tap, 75% thread drill for 5-44.
- Decimal inch
- 0.1040
- Millimeters
- 2.642
- Nearest 1/64
- 7/64" (-0.0054)
- Type
- number (wire-gauge) drill
Nearest equivalents in other systems
Speeds and feeds: in mild steel an HSS drill starts at about 3,310 RPM and 0.0025 in/rev (8.28 IPM); in 6061 aluminum about 9,180 RPM.
#37 drill speeds and feeds by material
Jobber-length twist drill, D = 0.1040 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 | 9,180 | 600 | 22,040 | 0.0024 | 22.0 | 52.9 |
| Brass / free-machining | 150 | 5,510 | 400 | 14,690 | 0.0020 | 11.0 | 29.4 |
| Low-carbon steel (1018) | 90 | 3,310 | 300 | 11,020 | 0.0025 | 8.28 | 27.6 |
| Alloy steel (4140, annealed) | 70 | 2,570 | 250 | 9,180 | 0.0025 | 6.43 | 22.9 |
| Stainless 304 | 40 | 1,470 | 150 | 5,510 | 0.0017 | 2.50 | 9.37 |
| Gray cast iron | 80 | 2,940 | 250 | 9,180 | 0.0015 | 4.41 | 13.8 |
| Titanium 6Al-4V | 25 | 920 | 100 | 3,670 | 0.0013 | 1.20 | 4.77 |
| Plastics (acetal) | 300 | 11,020 | 500 | 18,360 | 0.0042 | 46.3 | 77.1 |
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, 3,310 RPM × 0.064 mm/rev = 210 mm/min.
Worked example: #37 drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.1040 ≈ 3,310 RPM.
- Feed for a 0.104 in drill in mild steel ≈ 0.0025 in/rev.
- IPM = 3,310 × 0.0025 = 8.28 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 0.312 in (7.9 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 0.520 in (13.2 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 0.832 in (21.1 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 #37 drill
- 5-44 — cut tap, 75% thread · tap speeds and feeds
- 4-48 — form (roll) tap, 65% thread · tap speeds and feeds
- 3-48 — Helicoil / STI insert (#3-48×1D) · tap speeds and feeds
Nearest drills
- 2.65 mm: 0.1043 in / 2.650 mm (+0.0003 in)
- 2.6 mm: 0.1024 in / 2.600 mm (-0.0016 in)
- 2.7 mm: 0.1063 in / 2.700 mm (+0.0023 in)
- #38: 0.1015 in / 2.578 mm (-0.0025 in)
Common questions
- What is a #37 drill in decimal and mm?
- 0.1040 in, or 2.642 mm; nearest fractional drill: 7/64" (0.1094 in, +0.0054 in); nearest metric drill: 2.65 mm (0.1043 in, +0.0003 in).
- What RPM for a #37 drill in steel?
- In low-carbon steel (1018) an HSS #37 drill (0.1040 in) runs about 3,310 RPM at 90 SFM; a carbide drill about 11,020 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a #37 drill?
- About 0.0025 in/rev in mild steel, 0.0024 in/rev in aluminum and 0.0017 in/rev in 304 stainless. At 3,310 RPM that is 8.28 IPM in steel (IPM = RPM × IPR).
- What RPM for a #37 drill in aluminum?
- 9,180 RPM with HSS (250 SFM) or up to 22,040 RPM with carbide (600 SFM), feeding about 0.0024 in/rev.
- What tap uses a #37 drill?
- 5-44 (cut tap, 75% thread); 4-48 (form (roll) tap, 65% thread); 3-48 (Helicoil / STI insert (#3-48×1D)).
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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