G77 Back Bore Canned Cycle (Group 09)
F Feedrate in inches (or mm) per minute I Shift value along the X-axis before retracting, if Q is not specified J Shift value along the Y-axis before retracting, if Q is not specified L Number of holes to bore if G91 (Incremental Mode) is used Q The shift value, always incremental R Position of the R plane (position above the part) X X-axis location of hole Y Y-axis location of hole Z Position of the Z-axis at the bottom of hole
In addition to boring the hole, this cycle shifts the X and/or Y axis prior to and after cutting in order to clear the tool while entering and exiting the part (see G76 for an example of a shift move). Setting 27 determines the shift direction. If Q is not specified, optional I and J values are used to determine shift direction and distance.
G77 Back Bore Canned Cycle