Recommended Drilling Speeds

Drilling speeds in RPM, adapted for Grizzly 12-speed drill press (G7943 / G7944)

Drill Bit Material
Type Diameter
Softwood
Hardwood
Acrylic
Brass
Aluminum
Steel
Twist 1/16" to 3/16"
3050
3050
2180
3050
3050
3050
1/4" to 3/8"
3050
1510
2180
1160
2180
980
7/16" to 5/8"
1510
980
1510
980
1510
540
11/16" to 1"
980
540
 
380
980
380
Spade 1/4" to 1/2"
2180
1510
 
 
 
 
5/8" to 1"
1650
1510
 
 
 
 
1-1/8 to 1-1/2
1510
1510
 
 
 
 
Brad Point 1/8"
1650
1160
1510
 
 
 
1/4"
1650
980
1510
 
 
 
3/8"
1650
980
1510
 
 
 
1/2"
1650
980
980
 
 
 
5/8"
1650
540
980
 
 
 
3/4"
1510
540
980
 
 
 
7/8"
1160
260
540
 
 
 
1"
980
260
260
 
 
 
Forstner 1/4" to 3/8"
2180
540
 
 
 
 
1/2" to 5/8"
2180
540
260
 
 
 
3/4" to 1"
1510
540
260
 
 
 
1-1/8" to 1-1/4"
1510
260
260
 
 
 
1-3/8 to 2"
540
260
 
 
 
 
Circle Cutter 1-1/2" to 3"
540
260
260
 
 
 
3-1/4" to 8"
260
260
260
 
 
 
Countersink 2-flute
1510
1510
 
 
 
 
5-flute
980
980
980
260
260
260

Many thanks to the Woodworker's Club of Houston


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© 2003 by Christopher M. Albrecht