Grizzly G9249 - Manual (Page 36)

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g9249 12" x 37" Belt drive gap Bed lathe
Spindle Speed
to set the correct spindle speed for your opera-
tion, you will need to: 1) determine the spindle
speed needed for your workpiece, and 2) config-
ure the belts and gears for the calculated spindle
speed.
calculating the correct Spindle RPM
1. use the table in figure 48 to determine the
recommended cutting speed for the workpiece
material.
Recommended Cutting Speeds
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Note: These values are based on HSS cutting
tools. For carbide cutting tools, double the aver-
age speed. These values are a guideline only.
Refer to the MACHINERY’S HANDBOOK for
more detailed information.
figure 48. Cutting speed table.
2. determine the final diameter, in inches, for
the cut you are about to take.
Note: For this step, you will need to aver-
age out the diameters or work with the finish
diameter for your calculations.
3. use the following formula to determine the
correct spindle speed (rpM) for your opera-
tion:
Cutting Speed (SFM) x 4
Diameter of Cut
Spindle Speed =
configuring the V-Belts and Back
Gear
there are twelve spindle speeds are available
by properly positioning the motor V-belt, spindle
V-belt, and back gears.
To configure the V-belts:
1. disConneCt lAthe FroM poWer!
2. refer to the chart in figure 49 and find
the value closest to your calculated spindle
speed.
Note: This chart is also on the front of the
headstock. The "Direct" speeds are with
the back gear disengaged. Instructions for
engaging the back gear are on
Page 35.
6 & ' (
/min.
A
B & ' (
DIRECT
BACK GEAR
1200 900 655
550 410 300
220 165 120
100 75 50
7
B
figure 49. spindle speed configuration chart.