8.8 mm drill size
A 8.8 mm metric drill is 0.3465 in (8.800 mm). It is the cut tap, 75% thread drill for M10x1.25.
- Decimal inch
- 0.3465
- Millimeters
- 8.800
- Nearest 1/64
- 11/32" (+0.0027)
- Type
- metric drill
Nearest equivalents in other systems
Speeds and feeds: in mild steel an HSS drill starts at about 990 RPM and 0.0088 in/rev (8.71 IPM); in 6061 aluminum about 2,760 RPM.
8.8 mm drill speeds and feeds by material
Jobber-length twist drill, D = 0.3465 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 | 2,760 | 600 | 6,610 | 0.0079 | 21.8 | 52.2 |
| Brass / free-machining | 150 | 1,650 | 400 | 4,410 | 0.0060 | 9.90 | 26.5 |
| Low-carbon steel (1018) | 90 | 990 | 300 | 3,310 | 0.0088 | 8.71 | 29.1 |
| Alloy steel (4140, annealed) | 70 | 770 | 250 | 2,760 | 0.0096 | 7.39 | 26.5 |
| Stainless 304 | 40 | 440 | 150 | 1,650 | 0.0058 | 2.55 | 9.57 |
| Gray cast iron | 80 | 880 | 250 | 2,760 | 0.0060 | 5.28 | 16.6 |
| Titanium 6Al-4V | 25 | 280 | 100 | 1,100 | 0.0040 | 1.12 | 4.40 |
| Plastics (acetal) | 300 | 3,310 | 500 | 5,510 | 0.0048 | 15.9 | 26.4 |
Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 990 RPM × 0.224 mm/rev = 221 mm/min.
Worked example: 8.8 mm drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.3465 ≈ 990 RPM.
- Feed for a 0.346 in drill in mild steel ≈ 0.0088 in/rev.
- IPM = 990 × 0.0088 = 8.71 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 1.039 in (26.4 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 1.732 in (44 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 2.772 in (70.4 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 8.8 mm drill
- M10x1.25 — cut tap, 75% thread
Nearest drills
- Letter S: 0.3480 in / 8.839 mm (+0.0015 in)
- 11/32": 0.3438 in / 8.731 mm (-0.0027 in)
- 8.9 mm: 0.3504 in / 8.900 mm (+0.0039 in)
- 8.7 mm: 0.3425 in / 8.700 mm (-0.0039 in)
Common questions
- What is a 8.8 mm drill in decimal and mm?
- 0.3465 in, or 8.800 mm; nearest fractional drill: 11/32" (0.3438 in, -0.0027 in); nearest number / letter drill: Letter S (0.3480 in, +0.0015 in).
- What RPM for a 8.8 mm drill in steel?
- In low-carbon steel (1018) an HSS 8.8 mm drill (0.3465 in) runs about 990 RPM at 90 SFM; a carbide drill about 3,310 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a 8.8 mm drill?
- About 0.0088 in/rev in mild steel, 0.0079 in/rev in aluminum and 0.0058 in/rev in 304 stainless. At 990 RPM that is 8.71 IPM in steel (IPM = RPM × IPR).
- What RPM for a 8.8 mm drill in aluminum?
- 2,760 RPM with HSS (250 SFM) or up to 6,610 RPM with carbide (600 SFM), feeding about 0.0079 in/rev.
- What tap uses a 8.8 mm drill?
- M10x1.25 (cut tap, 75% 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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