Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 590)

Compounding Turning Routines
Chapter 24
24-26
Figure 24.21
Tool Motion in Case 2 G74
Cutting feed
Rapid feed
Start point
R
8
5
D
8
8
8
2
1
6 3
7
4
In Figure 24.21, these tool paths are made:
1. The tool is moved from the start point to the first contour point at
feedrate F. This move must generate motion in both the X and Z
axes.
2. The control generates a rough cut towards the spindle face, parallel to
the workpiece contour, and offset by the finish allowance amount and
the final pass amount (if any). This rough cut continues until the Z
axis value has decreased an amount D as programmed in the G74
block.
3. A rough cut is made parallel to the X axis, at a feedrate F, to a point
that intersects with the workpiece contour path minus the finish
allowance and final pass allowance (if any).
4. A rough cut is made away form the spindle face, parallel to the
workpiece contour, and offset by the finish allowance amount and the
final pass amount (if any). This rough cut continues, at a feedrate F,
until the Z axis value has increased an amount D as programmed in
the G74 block.
5. The tool is retracted from this point, on the Z axis only, a distance R
as programmed in the G74 block (or the default distance R set in
AMP) at a feedrate F (see Figure 24.21).