6.1.1. G71 Rough Turning Cycle and G70 Finishing Cycle
Let's start with G71. This cycle is programmed using two blocks.
Example:
N10 G71 U2 R1
N20 G71 P8 Q9 U0.4 W0
The parameters of the first block are:
U: The depth of cut during the cycle.
R: The retraction height for each completed cut.
The parameters of the second block are:
P: Start block number for the contour.
Q: End block number for the contour.
U: Finishing allowance in the X-axis.
W: Finishing allowance in the Z-axis.
If you load the turning center machine and then open the demo files, there is an example called: Sample3_G70_G71_units.CNC that you can try to see the cycle in action.
The G70 block at the end of the example is the Finishing Cycle. It simply repeats the blocks used in the G71 cycle, but instead of doing rough cuts, it does a contour cut removing the material left from the finishing allowances. Only horizontal cutting operations (internal and external) are supported.
