What is a 37/64" drill in decimal and mm?

0.5781 in, or 14.684 mm; nearest number / letter drill: Letter Z (0.4130 in, -0.1651 in); nearest metric drill: 14.75 mm (0.5807 in, +0.0026 in).

What RPM for a 37/64" drill in steel?

In low-carbon steel (1018) an HSS 37/64" drill (0.5781 in) runs about 590 RPM at 90 SFM; a carbide drill about 1,980 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a 37/64" drill?

About 0.0108 in/rev in mild steel, 0.0103 in/rev in aluminum and 0.0088 in/rev in 304 stainless. At 590 RPM that is 6.37 IPM in steel (IPM = RPM × IPR).

What RPM for a 37/64" drill in aluminum?

1,650 RPM with HSS (250 SFM) or up to 3,960 RPM with carbide (600 SFM), feeding about 0.0103 in/rev.

What tap uses a 37/64" drill?

5/8-18 (cut tap, 75% thread); 5/8-24 (cut tap, 75% thread); 5/8-11 (form (roll) tap, 65% thread).

37/64" drill size

A 37/64" fractional drill is 0.5781 in (14.684 mm). It is the cut tap, 75% thread drill for 5/8-18.

Decimal inch: 0.5781
Millimeters: 14.684
Nearest 1/64: 37/64" (+0.0000)
Type: fractional drill

Nearest equivalents in other systems

Drills closest to 37/64"
System	Drill	Inch	mm	Difference
Number / letter	Letter Z	0.4130	10.490	-0.1651 in
Metric	14.75 mm	0.5807	14.750	+0.0026 in

Speeds and feeds: in mild steel an HSS drill starts at about 590 RPM and 0.0108 in/rev (6.37 IPM); in 6061 aluminum about 1,650 RPM.

37/64" drill speeds and feeds by material

Jobber-length twist drill, D = 0.5781 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

37/64" drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	1,650	600	3,960	0.0103	17.0	40.8
Brass / free-machining	150	990	400	2,640	0.0085	8.42	22.4
Low-carbon steel (1018)	90	590	300	1,980	0.0108	6.37	21.4
Alloy steel (4140, annealed)	70	460	250	1,650	0.0117	5.38	19.3
Stainless 304	40	260	150	990	0.0088	2.29	8.71
Gray cast iron	80	530	250	1,650	0.0090	4.77	14.8
Titanium 6Al-4V	25	170	100	660	0.0052	0.88	3.43
Plastics (acetal)	300	1,980	500	3,300	0.0063	12.5	20.8

Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 590 RPM × 0.274 mm/rev = 162 mm/min.

Worked example: 37/64" drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.5781 ≈ 590 RPM.
Feed for a 0.578 in drill in mild steel ≈ 0.0108 in/rev.
IPM = 590 × 0.0108 = 6.37 IPM.

Peck cycle by hole depth

37/64" drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 1.734 in (44.1 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 2.891 in (73.4 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 4.625 in (117.5 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 37/64" drill

5/8-18 — cut tap, 75% thread · tap speeds and feeds
5/8-24 — cut tap, 75% thread
5/8-11 — form (roll) tap, 65% thread · tap speeds and feeds

Nearest drills

14.75 mm: 0.5807 in / 14.750 mm (+0.0026 in)
14.5 mm: 0.5709 in / 14.500 mm (-0.0073 in)
15.0 mm: 0.5906 in / 15.000 mm (+0.0124 in)
9/16": 0.5625 in / 14.288 mm (-0.0156 in)

Drill speed calculator, prefilled for 37/64"Drill finder: sizes near 37/64"Fractional drill chart Decimal equivalent chart

Common questions

What is a 37/64" drill in decimal and mm?: 0.5781 in, or 14.684 mm; nearest number / letter drill: Letter Z (0.4130 in, -0.1651 in); nearest metric drill: 14.75 mm (0.5807 in, +0.0026 in).
What RPM for a 37/64" drill in steel?: In low-carbon steel (1018) an HSS 37/64" drill (0.5781 in) runs about 590 RPM at 90 SFM; a carbide drill about 1,980 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a 37/64" drill?: About 0.0108 in/rev in mild steel, 0.0103 in/rev in aluminum and 0.0088 in/rev in 304 stainless. At 590 RPM that is 6.37 IPM in steel (IPM = RPM × IPR).
What RPM for a 37/64" drill in aluminum?: 1,650 RPM with HSS (250 SFM) or up to 3,960 RPM with carbide (600 SFM), feeding about 0.0103 in/rev.
What tap uses a 37/64" drill?: 5/8-18 (cut tap, 75% thread); 5/8-24 (cut tap, 75% thread); 5/8-11 (form (roll) tap, 65% 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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