In Chapter 35, various lathe cycles were the main subject, normally used for turning and boring. In this section, a similar look will aim at one more of the multiple repetitive cycles, this time used for various threading applications.

In the earlier stages of CNC development, the simple G92 threading cycle was a direct result of the computerized technology of its time. The computer technology has been rapidly advancing and many great new features have been offered to CNC programmers. These new features simplify the program development. One of the major additions is another lathe cycle, used for threading - a multiple repetitive threading cycle G76. This cycle is considered a complex cycle - not because it is difficult to use (on the contrary) but because it has some powerful internal features.

To fully appreciate the impact of G76 threading cycle, compare it with the original G32 threading method, and even the G92 cycle just described. While a program using the G32 method requires four or even five blocks of program for each threading pass, and the G92 cycle requires one block for each threading pass, the G76 cycle will do any single thread in one block of program code (two blocks are required for some controls). With the G76 cycle, any number of threading passes will still occupy only a very small portion of the program, making editing on the machine (if necessary) very easy and fast.

There are two programming...