What is a 13.1 mm drill in decimal and mm?

0.5158 in, or 13.100 mm; nearest fractional drill: 33/64" (0.5156 in, -0.0001 in); nearest number / letter drill: Letter Z (0.4130 in, -0.1027 in).

What RPM for a 13.1 mm drill in steel?

In low-carbon steel (1018) an HSS 13.1 mm drill (0.5158 in) runs about 670 RPM at 90 SFM; a carbide drill about 2,220 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.

What feed for a 13.1 mm drill?

About 0.0106 in/rev in mild steel, 0.0101 in/rev in aluminum and 0.0086 in/rev in 304 stainless. At 670 RPM that is 7.10 IPM in steel (IPM = RPM × IPR).

What RPM for a 13.1 mm drill in aluminum?

1,850 RPM with HSS (250 SFM) or up to 4,440 RPM with carbide (600 SFM), feeding about 0.0101 in/rev.

What tap uses a 13.1 mm drill?

M14×2.0 (form (roll) tap, 65% thread).

13.1 mm drill size

A 13.1 mm metric drill is 0.5158 in (13.100 mm). It is the form (roll) tap, 65% thread drill for M14×2.0.

Decimal inch: 0.5158
Millimeters: 13.100
Nearest 1/64: 33/64" (+0.0001)
Type: metric drill

Nearest equivalents in other systems

Drills closest to 13.1 mm
System	Drill	Inch	mm	Difference
Fractional	33/64"	0.5156	13.097	-0.0001 in
Number / letter	Letter Z	0.4130	10.490	-0.1027 in

Speeds and feeds: in mild steel an HSS drill starts at about 670 RPM and 0.0106 in/rev (7.10 IPM); in 6061 aluminum about 1,850 RPM.

13.1 mm drill speeds and feeds by material

Jobber-length twist drill, D = 0.5158 in. RPM = 3.82 × SFM ÷ D, rounded to 10. Feed per rev scales with diameter and material; IPM = RPM × IPR.

13.1 mm drilling speeds
Material	HSS SFM	HSS RPM	Carbide SFM	Carbide RPM	Feed (in/rev)	HSS IPM	Carbide IPM
Aluminum (6061)	250	1,850	600	4,440	0.0101	18.7	44.8
Brass / free-machining	150	1,110	400	2,960	0.0083	9.21	24.6
Low-carbon steel (1018)	90	670	300	2,220	0.0106	7.10	23.5
Alloy steel (4140, annealed)	70	520	250	1,850	0.0115	5.98	21.3
Stainless 304	40	300	150	1,110	0.0086	2.58	9.55
Gray cast iron	80	590	250	1,850	0.0086	5.07	15.9
Titanium 6Al-4V	25	190	100	740	0.0050	0.95	3.70
Plastics (acetal)	300	2,220	500	3,700	0.0061	13.5	22.6

Metric: Vc (m/min) = SFM × 0.3048; feed (mm/rev) = in/rev × 25.4. In steel, 670 RPM × 0.269 mm/rev = 180 mm/min.

Worked example: 13.1 mm drill in 1018 steel

HSS drill in low-carbon steel: 90 SFM.
RPM = 3.82 × 90 ÷ 0.5158 ≈ 670 RPM.
Feed for a 0.516 in drill in mild steel ≈ 0.0106 in/rev.
IPM = 670 × 0.0106 = 7.10 IPM.

Peck cycle by hole depth

13.1 mm drill: depth and canned cycle
Depth	Cycle	Peck	Note
3×D = 1.547 in (39.3 mm)	G81 (no peck)	None	Up to 3×D a sharp drill clears chips on its own.
5×D = 2.579 in (65.5 mm)	G73 chip-break	1 × D	Chip-break pecks; full retract if chips pack (soft aluminum, stainless).
8×D = 4.126 in (104.8 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 13.1 mm drill

M14×2.0 — form (roll) tap, 65% thread · tap speeds and feeds

Nearest drills

33/64": 0.5156 in / 13.097 mm (-0.0001 in)
13.0 mm: 0.5118 in / 13.000 mm (-0.0039 in)
13.2 mm: 0.5197 in / 13.200 mm (+0.0039 in)
13.3 mm: 0.5236 in / 13.300 mm (+0.0079 in)

Drill speed calculator, prefilled for 13.1 mm Drill finder: sizes near 13.1 mm Metric drill chart Decimal equivalent chart

Common questions

What is a 13.1 mm drill in decimal and mm?: 0.5158 in, or 13.100 mm; nearest fractional drill: 33/64" (0.5156 in, -0.0001 in); nearest number / letter drill: Letter Z (0.4130 in, -0.1027 in).
What RPM for a 13.1 mm drill in steel?: In low-carbon steel (1018) an HSS 13.1 mm drill (0.5158 in) runs about 670 RPM at 90 SFM; a carbide drill about 2,220 RPM at 300 SFM. RPM = 3.82 × SFM ÷ D.
What feed for a 13.1 mm drill?: About 0.0106 in/rev in mild steel, 0.0101 in/rev in aluminum and 0.0086 in/rev in 304 stainless. At 670 RPM that is 7.10 IPM in steel (IPM = RPM × IPR).
What RPM for a 13.1 mm drill in aluminum?: 1,850 RPM with HSS (250 SFM) or up to 4,440 RPM with carbide (600 SFM), feeding about 0.0101 in/rev.
What tap uses a 13.1 mm drill?: M14×2.0 (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.

Free for machinists & programmers

Put your skills on a free talent profile

Machines, controls, certs and saved calculations in one profile shops can find.

Create free profile

For your shop

Bring shift handoffs to your shop

Stop losing job status between shifts. Every station's notes, counts and issues, handed off cleanly.

See shift handoffs