Spindle Speed - Grizzly G0949G Owner's Manual

Spindle Speed

Using the correct spindle speed is important for
getting safe and satisfactory results, as well as
maximizing 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 lathe
controls to produce the required 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
workpiece, as noted in the formula shown below.
*
Recommended
Cutting Speed (FPM) x 12
Dia. of Cut (in inches) x 3.14
*
Double if using carbide cutting tool
Figure 60. Spindle speed formula for lathes.
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.
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Setting Spindle Speed
Selecting one of the two spindle speed ranges is
performed by positioning the spindle speed range
lever (see Figure 61) to Low (L) or High (H) range.
The spindle speed dial is then used to determine
the precise spindle speed within the selected
Spindle
speed range.
Speed
=
(RPM)
Note: To maximize spindle torque, always use low
range RPM speeds for heavier cuts. If required
spindle speed exceeds 515 RPM (low range
maximum) it is acceptable to use higher RPM
range with lighter cuts.
Follow along with this example for setting the
spindle speed for the Model G0949G to gain a
better understanding of the task:
To set spindle speed to 150 RPM:
1.
2.
3.
4.
Spindle Speed
Digital Readout
Spindle Speed
Range Lever
Figure 61. Spindle range and speed levers.
To avoid damaging gears, ALWAYS make
sure the spindle is completely stopped
BEFORE moving the spindle speed lever.
Move FWD/REV switch to "0".
Move spindle speed range lever to Low (L)
position (see Figure 61).
Move FWD/REV switch to FWD, and press
the START button.
Adjust spindle speed dial until spindle speed
digital readout shows 150 RPM.
Model G0949G (Mfd. Since 01/22)
Spindle Speed Dial
FWD/REV
Switch