Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 587)

Compound Turning Routines
Chapter 24
24-23
Figure 24.18
Tool Retraction in Case 1 G74
R
45 °
45 °
R
Z
X
4. Rapid traverse back along the X and Z axes to the coordinate that the
last rough cut started from (in step 2).
5. Move parallel to the Z axis, at a feedrate F, a distance D as
programmed in the G74 block.
Steps 2 - 5 continue to repeat until the operation is aborted or the rough
contour shape is completed. The rough contour shape is completed when
the thickness of the remaining material to be removed from the workpiece
is equal to the sum of the finishing allowance (U+W)/2 and the final pass
allowance (I+K)/2. If no final pass is to be made skip to step 7.
6. The final pass is made at the feedrate programmed in your contour
block including any rapid moves (if no feedrate is programmed in the
contour blocks the control uses the F-word programmed in the G74
block). Only the amount of material specified with the final pass
allowance (I+K)/2 is cut. This cut is made parallel to the exact
contour of the final workpiece, it is not a roughing pass. After this
cut is complete, the only remaining material on the workpiece contour
is the finish amount (if any) programmed with U and W.
7. The control returns the cutting tool, at a rapid feedrate, to the start
point of the cycle.