Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 578)

Using Pocket Milling Cycles
Chapter 22
22-6
Figure 22.2
Rectangular Pocket Enlarging Using G88.1
Q
Plunge Position
(X, Y)
EXISTING POCKET
Q
D
D
D
H+TR
Important: The tool should be positioned near the center of the original
pocket prior to the G88.1 block. The Z coordinate of this position
determines the initial Z level or top of the pocket. This is the pre-cycle
position of the tool. The pre-cycle position must be at some depth other
than the cycles programmed final depth or an error is generated.
From the pre-cycle position, the control simultaneously raises the tool by
the clearance amount (AMP selectable, refer to system installers literature)
while moving it to the longest side of the original pocket. This move is
always along the -X or --Y axis depending on whether the rectangular
pocket is longer along the X or Y axis (shorter axis move is the first
move). This position is the plunge- position, the position where the plunge
to the programmed depth takes place.
Important: If the original pocket has rounded or chamfered corners,
excess material may be in the corners that may have to be cleaned out
before attempting to enlarge the original pocket, since the G88.1 cycle
does not compensate for rounded or chamfered corners.