From the course: G-Code Programming for CNC Foundations

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Absolute and incremental commands: G90 and G91

Absolute and incremental commands: G90 and G91 - G-Code Tutorial

From the course: G-Code Programming for CNC Foundations

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Absolute and incremental commands: G90 and G91

- [Instructor] CNC machines can operate in two modes. The first mode is called absolute positioning, and it's called using the G90 command. Once you call a G90 mode, this mode will stay active until you call a G91 command. The G90 command tells the machine that the G code positions that we send in our program will be absolute values with the respect to the current work offset. This is like the game of Battleship. Every position on the table has an exact location in the absolute coordinate system. Now if we switch over to incremental, using the G91 command, it's completely the opposite. When I give a G91 command and I give an X value, it's going to move some value in X, so if I say X 10 inches, it's going to move 10 inches in X from wherever it happens to be. It doesn't really care where it is exactly on the table. It's just going to move 10 inches in X. Same thing in Y. If you go to a G91 command, Y 5.0, It's going to move five inches from wherever it happens to be. Now the absolute…

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