Model G0678 (Mfd. Since 06/15)
-21-
Setting Spindle
Speed
To select the correct spindle speed (RPM) for your
milling operation, you will need to: 1) Determine
the spindle speed needed for your workpiece, and
2) set the speed dial for the calculated speed.
Calculating Spindle Speed
1. Use the table in Figure 21 to determine the
cutting speed or surface feet per minute
(SFM) required for your workpiece material.
Cutting Speeds for High Speed Steel (HSS)
Cutting Tools
Workpiece Material
Cutting Speed (SFM)
Aluminum & alloys
300
Brass & Bronze
150
Copper
100
Cast Iron, soft
80
Cast Iron, hard
50
Mild Steel
90
Cast Steel
80
Alloy Steel, hard
40
Tool Steel
50
Stainless Steel
60
Titanium
50
Plastics
300-800
Wood
300-500
Note: For carbide cutting tools, double the cutting
speed. These values are a guideline only. Refer to
the MACHINERY'S HANDBOOK for more detailed
information.
Figure 21. Cutting speed table for HSS cutting
tools.
2. Measure the diameter of your cutting tool in
inches.
3. Use the following formula to calculate the
required spindle speed (RPM) for your opera-
tion:
Cutting Speed (FPM) x 12
*
Recommended
Tool Dia. (in inches) x 3.14
=
Spindle
Speed
(RPM)
*
Double if using carbide cutting tool
Setting Spindle Speed
1. Rotate the speed dial all the way to the left,
setting the startup spindle speed close to
zero.
Note: This precaution avoids unexpected
high speed startup of the spindle.
2. Use the direction switch to select the direc-
tion of spindle rotation, turn the spindle
ON,
then rotate the speed dial until the calculated
spindle speed is displayed on the digital read-
out on the control panel (see
Figure 22).
Figure 22. Spindle direction switch, speed dial,
and digital readout.
Digital
Readout
Direction
Switch
Speed
Dial
