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For Machines Mfg. Since 8/09 SB1024/SB1025/SB1026
-37-
OPERATION
Setting Spindle Speed
Setting Spindle Speed Range
Setting the spindle speed range involves
engaging and disengaging a spindle spline that
uses gearing to increase or decrease the range of
spindle speeds.
The procedures to set the speed range for the
Model SB1024 and Model SB1025/SB1026 differ
slightly. Use the appropriate section on the
following pages for the mill when selecting the
speed range.
Note: Regardless of the model of the mill, you
MUST properly perform the Meshing Spindle
& Spindle Clutch procedure as instructed on
Page 40 when using the high spindle speed
range.
To avoid damage to the spindle, gears, or
cutting tools:
s 3PINDLEROTATIONMUSTBETURNED/&&AND
the spindle must be at a complete stop
BEFORE you change the spindle speed
range.
s 4HEMILLISDESIGNEDTO/.,9OPERATEWITH
the spindle speed range selector in either
the high or low position. To avoid damaging
the moving parts inside the headstock,
never start spindle rotation without the
range selector detent pin firmly seated in
either the high or low position.
s 7HENCHANGINGTHESPINDLESPEEDRANGE
and the direction of spindle rotation
reverses, you will need to either change
the cutting tool to match the direction of
spindle rotation or use the spindle direction
switch to compensate for the reversal.
Using the correct spindle speed is important
for 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 mill
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 cutting tool, as noted in Figure 31:
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, provide
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 all applicable variables to determine
the best spindle speed for the operation.
Cutting Speed (FPM) x 12
*Recommended
Tool Dia. (in inches) x 3.14
= SpindleSpeed (RPM)
*Double if using carbide cutting tool
Figure 31. Spindle speed formula for milling.