11/16" drill size
A 11/16" fractional drill is 0.6875 in (17.463 mm). It is the cut tap, 75% thread drill for 3/4-16.
- Decimal inch
- 0.6875
- Millimeters
- 17.463
- Nearest 1/64
- 11/16" (+0.0000)
- Type
- fractional drill
Nearest equivalents in other systems
Speeds and feeds: in mild steel an HSS drill starts at about 500 RPM and 0.0113 in/rev (5.65 IPM); in 6061 aluminum about 1,390 RPM.
11/16" drill speeds and feeds by material
Jobber-length twist drill, D = 0.6875 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 | 1,390 | 600 | 3,330 | 0.0107 | 14.9 | 35.6 |
| Brass / free-machining | 150 | 830 | 400 | 2,220 | 0.0088 | 7.30 | 19.5 |
| Low-carbon steel (1018) | 90 | 500 | 300 | 1,670 | 0.0113 | 5.65 | 18.9 |
| Alloy steel (4140, annealed) | 70 | 390 | 250 | 1,390 | 0.0119 | 4.64 | 16.5 |
| Stainless 304 | 40 | 220 | 150 | 830 | 0.0093 | 2.05 | 7.72 |
| Gray cast iron | 80 | 440 | 250 | 1,390 | 0.0096 | 4.22 | 13.3 |
| Titanium 6Al-4V | 25 | 140 | 100 | 560 | 0.0054 | 0.76 | 3.02 |
| Plastics (acetal) | 300 | 1,670 | 500 | 2,780 | 0.0068 | 11.4 | 18.9 |
Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 500 RPM × 0.287 mm/rev = 144 mm/min.
Worked example: 11/16" drill in 1018 steel
- HSS drill in low-carbon steel: 90 SFM.
- RPM = 3.82 × 90 ÷ 0.6875 ≈ 500 RPM.
- Feed for a 0.688 in drill in mild steel ≈ 0.0113 in/rev.
- IPM = 500 × 0.0113 = 5.65 IPM.
Peck cycle by hole depth
| Depth | Cycle | Peck | Note |
|---|---|---|---|
| 3×D = 2.063 in (52.4 mm) | G81 (no peck) | None | Up to 3×D a sharp drill clears chips on its own. |
| 5×D = 3.438 in (87.3 mm) | G73 chip-break | 1 × D | Chip-break pecks; full retract if chips pack (soft aluminum, stainless). |
| 8×D = 5.500 in (139.7 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 11/16" drill
- 3/4-16 — cut tap, 75% thread · tap speeds and feeds
- 3/4-10 — cut tap, 50% thread · tap speeds and feeds
Nearest drills
- 17.5 mm: 0.6890 in / 17.500 mm (+0.0015 in)
- 17.25 mm: 0.6791 in / 17.250 mm (-0.0084 in)
- 17.75 mm: 0.6988 in / 17.750 mm (+0.0113 in)
- 43/64": 0.6719 in / 17.066 mm (-0.0156 in)
Common questions
- What is a 11/16" drill in decimal and mm?
- 0.6875 in, or 17.463 mm; nearest number / letter drill: Letter Z (0.4130 in, -0.2745 in); nearest metric drill: 17.5 mm (0.6890 in, +0.0015 in).
- What RPM for a 11/16" drill in steel?
- In low-carbon steel (1018) an HSS 11/16" drill (0.6875 in) runs about 500 RPM at 90 SFM; a carbide drill about 1,670 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
- What feed for a 11/16" drill?
- About 0.0113 in/rev in mild steel, 0.0107 in/rev in aluminum and 0.0093 in/rev in 304 stainless. At 500 RPM that is 5.65 IPM in steel (IPM = RPM × IPR).
- What RPM for a 11/16" drill in aluminum?
- 1,390 RPM with HSS (250 SFM) or up to 3,330 RPM with carbide (600 SFM), feeding about 0.0107 in/rev.
- What tap uses a 11/16" drill?
- 3/4-16 (cut tap, 75% thread); 3/4-10 (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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