-19-
Longitudinal Handwheel
The longitudinal handwheel moves the carriage left or
right along the bed. Use this control when setting up
the machine for facing or turning.
Cross Slide Handwheel
The cross slide handwheel moves the top slide toward
and away from the work. Turning the dial clockwise
moves the slide toward the workpiece. Adjust the
graduated scale by holding the handwheel with one
hand and turning the dial with the other.
Compound Slide Handwheel
The compound slide handwheel controls the position
of the cutting tool relative to the workpiece. The
compound is adjustable for any angle within its range.
The combo inch/metric graduated scale is engraved
into a rotatable barrel. Angle adjustment is secured
by cap screws on the base of the compound.
Spindle Speed
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.
2. Con
fi
gure the lathe controls to produce the
required spindle speed.
Figure 45. Carriage Controls.
Longitudinal
Handwheel
Cross Slide
Handwheel
Compound Slide
Handwheel
Determining Spindle Speed
Many variables affect the optimum spindle speed
to use for any given operations, 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 :
RPM =
D
CSx
4
RPM = Spindle speed, revolution per minute.
CS = Cutting speed in surface feet per minute ( SFM )
D = Diameter of workpiece
EXAMPLE :
If the cutting speed is 40 for a certain alloy steel and
the workpiece is 2 inches in diameter,
fi
nd the rpm as
follows :
RPM = = 80
After calculating the RPM, use the nearest or next
lower speed on the lathe and set the spindle speed.
Cutting speed, typically de
fi
ned 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
fi
nish 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.
All of these sources will help you take into account all
the applicable variables in order to determine the best
spindle speed for the operation.
Setting Spindle Speed
1. Make sure the spindle is turned OFF and it has
come to a complete stop.
2. Use the chart in Figure 46 to determine the
available spindle speed range closest to your
calculated spindle speed.
SPEEDS
LEVER
RPM
LOW
20 – 40
HIGH
400 - 2500
Figure 46. Spindle speed range chart.
Manual Feed
You can manually move the cutting tool around
the lathe for facing or turning operations using the
handwheels shown in Figure 45 and described below.
