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Model G0758 (Mfd. Since 2/14)
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 operation, you will
need to: 1) Determine the best spindle speed for
the cutting/drilling task, and 2) adjust the gear box
knob and variable-speed knob to produce deter-
mined 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 29.
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 29. Formula for determining best spindle
speed.
Spindle Speed
Removing Tooling
Tools Needed Qty
Spindle Pin ........................................................ 1
Wrench 8mm ..................................................... 1
Brass Hammer .................................................. 1
To remove tooling:
1. DISCONNECT MACHINE FROM POWER!
2. Remove drawbar cap and secure spindle
with spindle pin. Unthread drawbar from tool-
ing one full rotation.
Note: Do not fully unthread tooling from
drawbar or the drawbar and tool threads
could be damaged in the next step.
3. Tap top of drawbar with brass hammer to
unseat taper.
4. Hold onto tooling with one hand and fully
unthread drawbar.