Metal Drill Speeds - DrillBible

DRILL SIZE	STEEL (Low Carbon)	ALUMINUM (All Alloys)	BRASS (Free Cutting)	CAST IRON (Soft/Medium)
1/16"	4800	9600	6400	3800
3/32"	3200	6400	4800	2600
1/8"	2400	4800	3600	1900
5/32"	1900	3800	2900	1500
3/16"	1600	3200	2400	1300
7/32"	1400	2700	2100	1100
1/4"	1200	2400	1800	950
5/16"	950	1900	1450	750
3/8"	800	1600	1200	640
7/16"	685	1370	1030	550
1/2"	600	1200	900	480
5/8"	480	960	720	380
3/4"	400	800	600	320
7/8"	340	685	515	275
1"	300	600	450	240

DRILL SIZE

STEEL
(Low Carbon)

ALUMINUM
(All Alloys)

BRASS
(Free Cutting)

CAST IRON
(Soft/Medium)

1/16"

4800

9600

6400

3800

3/32"

3200

6400

4800

2600

1/8"

2400

4800

3600

1900

5/32"

1900

3800

2900

1500

3/16"

1600

3200

2400

1300

7/32"

1400

2700

2100

1100

1/4"

1200

2400

1800

950

5/16"

950

1900

1450

750

3/8"

800

1600

1200

640

7/16"

685

1370

1030

550

1/2"

600

1200

900

480

5/8"

480

960

720

380

3/4"

400

800

600

320

7/8"

340

685

515

275

300

600

450

240

CRITICAL DRILLING TIPS: • Use cutting oil for steel and cast iron - extends tool life and improves finish | • Aluminum can run dry or with WD-40/kerosene | • Brass machines easily - light oil optional | • Start slow and increase speed gradually | • Peck drill deep holes - retract frequently to clear chips | • Let the drill do the work - don't force it | • For HSS drills - reduce speeds by 25% for harder steels (4140, etc.) | • For carbide drills - can increase speeds by 200-300% | • Keep drill bits sharp - dull bits generate heat and break easier

DRILL BIBLE