Rockwell Automation 8520 9/Series CNC Lathe - Manual (Page 657)

Drilling Cycles
Chapter 26
26-31
When using Method II, remember:
the generated move is a single linear move and executes at
The format for the G87 back boring cycle is:
G87X__Z__ I__J__K__ R__F__L__;
Q__
Where : Is :
X specifies location of the hole.
Z defines the Z point level. The Z point level in this case is the top of the
hole that is being cut by the back boring operation.
Q or I,
J, K
defines the tool shift amount.
R defines the position beyond the hole bottom so the tool can safely shift.
F defines the cutting feedrate.
L defines the number of times the drilling cycle is repeated.
Important: This cycle requires an existing hole through which the back
boring tool can be safely lowered prior to the back boring operation.
(G87): Back Boring Cycle