Sharp 1840TC-FC Instruction Manual And Parts List page 54

4.4 SELECTION OF SPINDLE SPEEDS
Select the appropriate spindle speed for working from cutting speed chart
on the headstock, there are 3 steps in the range of spindle speeds.
CAUTION : DO NOT MOVE SPEED SELECT HANDLE DURING THE
SPINDLE RUNNING
1.Stop spindle running.
2.In order to obtain the desired spindle speeds,place the lever at the proper
position , be sure not shift the lever when the spindle is running.
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