Grizzly G0791, Owner'S Manual

Page: 73 / 132

Model G0791 (Mfd. Since 9/15)
-71-
Setting Spindle Speed
1. Set Mill FWD/REV switch to desired direction
for milling operations (see Figure 111).
Using the correct spindle speed is important for
safe and satisfactory results, as well as maximiz-
ing tool life.
To set the mill spindle speed for operation, you
will need to: 1) Determine the best spindle speed
for the cutting/drilling task, and 2) use the spindle
speed shift levers to obtain 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 110.
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.
Figure 110. Spindle speed formula for mill/drills.
Spindle Speed
Figure 111. Location of Mill FWD/REV switch.
2. Move spindle speed shift levers, according
to spindle speed chart (see
Figure 112),
to select between 250, 530, 1100, or 2300
RPM.
Figure 112 illustrates spindle speed
set at 250 RPM.
Figure 112. Mill spindle speed controls set for
250 RPM.
530
1100
2300
250
Spindle
Speed
Chart
Spindle Speed
Shift Levers
Mill FWD/REV
Switch