Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 583)

Compound Turning Routines
Chapter 24
24-19
Where : Is :
R__ used to program the retract amount made after each rough facing pass. This
retract amount is an incremental, radius value measured parallel to the Z axis.
Case 1 operations retract at a 45 degree angle to the Z axis and Case 2
operations retract parallel to the Z axis. This does not affect the programmed
value of R, as R is always measured parallel to Z. If no value for R is
programmed then the control uses a value for the retract amount set in AMP by
the system installer.
F: Active feedrate during the routine only (see chapter 17)
S: Spindle speed during the routine only (see chapter 16)
T: Tool number and tool offset to be used during the routine only (see chapter 19)
Important: Any F-, S-, or T-words that are in the set of contour blocks are
ignored when the routine is executed. If programmed in the G74 block
these words replace any previously active modal F-, S-, or T-words for the
remainder of G74 routine operation only. When the G74 routine is
completed the previously active modal F-, S-, and T-words are reactivated.
Figure 24.14
Parameters for G74 Rough Facing
Start point
(I+K)/2 D
Shape after roughing
Shape after roughing
and final pass
Workpiece finished
shape
X
Z
(U+W)/2
R