Model G0762 (Mfd. Since 5/14)
-29-
Using the correct spindle speed is important for
safe and satisfactory results, as well as maximiz-
ing tool life.
To set the spindle speed for your operation, you
will need to: 1) Determine the best spindle speed
for the cutting task, and 2) configure the high/low
range lever for the desired speed range, and 3)
use the variable-speed dial and the RPM digital
readout to set the spindle speed.
Determining Spindle Speed
Many variables affect the optimum spindle speed
to use for any given operation, but the two most
important are the recommended cutting speed
for the workpiece material and the diameter of
the cutting tool, as noted in the formula shown in
Figure 32.
Cutting speed, typically defined in feet per minute
(FPM), is the speed at which the edge of a tool
moves across the material surface.
A recommended cutting speed is an ideal speed
for cutting a type of material in order to produce
the desired finish and optimize tool life.
The books
Machinery’s Handbook or Machine
Shop Practice, and some internet sites, pro-
vide excellent recommendations for which cutting
speeds to use when calculating the spindle speed.
These sources also provide a wealth of additional
information about the variables that affect cutting
speed and they are a good educational resource.
Also, there are a large number of easy-to-use
spindle speed calculators that can be found on
the internet. These sources will help you take into
account the applicable variables in order to deter-
mine the best spindle speed for the operation.
Cutting Speed (FPM) x 12
*
Recommended
Tool Dia. (in inches) x 3.14
=
Spindle
Speed
(RPM)
*
Double if using carbide cutting tool
Figure 32. Spindle speed formula for mill/drills.
Spindle Speed
Setting Spindle Speed
1. Shift high/low range lever (see Figure 33) to
either “
L” (spindle speeds 75–438 RPM) or
“
H” (spindle speeds 438–2500 RPM).
Note: You may need to rotate spindle back
and forth by hand while putting pressure on
the shift lever to allow gears to mesh.
Figure 33. Control panel and spindle speed
controls.
High/Low
Range
Lever
Variable
Speed
Dial
Power
Button
RPM Digital
Readout
2. Rotate variable-speed dial all the way coun-
terclockwise to set spindle speed to lowest
value.
3. Rotate master power switch all the way clock-
wise to enable power.
4. Press POWER button and the correct spindle
direction button for your operation.
5. Watch RPM digital readout and adjust vari-
able-speed dial as needed until desired RPM
is reached.
Summary of Contents for G0762
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