G71 Rough Turning Cycle and G70 Finishing Cycle Lets start with G71. This cycle is programmed by 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_unit.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.

G76 Threading Cycle Threads can be done externally or internally with this two-block threading canned cycle. Here is a brief

explanation of the cycle and its parameters.

The parameters of the first block are:

P: This parameter is composed of three values that control the thread behavior.

In the example above we have P010060. Let's take the numbers apart.

01: Number of spring cuts. This means, when done with the thread cuts, that the machine can be

programmed to take a number of extra cuts at the same depth to smooth the final thread.

00: Run out angle. The angle used to leave the thread.

60: Infeed angle. The angle used when entering the thread.

Q : Depth of each normal cut. This value is given in hundreds so the Q500 above means 0.5.

R: Depth of last or finish cut.

The parameters of the second block are:

X: End value in the X-axis.

Z: End value in the Z-axis.

P: Thread depth (radial value).

Q: Depth of first cut.

F: Thread pitch.

Note! The CNCSimulator Pro simplifies the threading process by ignoring some of the parameters, as for

the simulation, it is not important to take every parameter literary. The important parameters for the

simulator are the following:

The Q parameter in the first block tells the simulator how much to take for each cut.

The X and Z values of the second block tells the simulator where to end the thread.

The F parameter of the second block tells the simulator the pitch of the thread.

There is an example among the demo programs called Sample4_G76_Threading_unit.cnc that you can

run to see the cycle in action.