Drill Speed is measured by the rate at which the outside diameter of the tool moves in relation to the work piece. This speed is known as Surface Feet Per Minute (SFM) and is shown in the table below. The formula used to convert SFM to Revolutions Per Minute (RPM) is:


The speeds shown in this table are a generalization and it is recommended that the user start at the lower end of the range and build up to the maximum after trial indicates this is possible.

Material	Hardness Rc	Speed SFM	Speed RPM
Steel
Mild Steel		300
Plain Carbon		300
Alloyed	<30	260
Alloyed (Hardened & Tempered)	30-38	215
Alloyed (Hardened & Tempered)	38-45	170
Cast Iron
Cast Iron		300
Titanium
Alloys (Annealed)		130
Alloys (Treated), Inconel		60
Aluminum – Magnesium
Aluminium		600
Magnesium		600
Plastique
Graphite Composite		210
Epoxy Fibre		210
Acrylic		160

Recommended Feeds For Drilling

Drill Diameter	Feed (Inch/Revolution)
1/16 – 3/32 1/8 – 5/32 3/16 – 7/32 1/4 – 5/16 3/8 – 7/16 1/2 – 9/16 5/8 – 3/4 7/8 – 1"	.001 – .003 .002 – .005 .003 – .006 .004 – .008 .005 – .010 .007 – .012 .010 – .015 .015 – .020