CNC Machinist Calculator UltraG91 Incremental programming
Fanuc G-code · Mill
Axis values are distances from the current position. Used for G28 returns, repeated patterns and subprograms that step along.
Format
G91
How it works
Modal, group 03.
Example program
G91 G28 Z0. (Z HOME, INCREMENTAL)
G90 (BACK TO ABSOLUTE)
G91 G01 X.5 F20. (STEP .5 IN X)
G90 (ABSOLUTE AGAIN)
G90 (BACK TO ABSOLUTE)
G91 G01 X.5 F20. (STEP .5 IN X)
G90 (ABSOLUTE AGAIN)
Example is in inch. Check offsets and clearances first.
Watch out for
- Forgetting to switch back to G90 is a classic crash. Put G90 on the next line.
- In canned cycles under G91, R is the distance from the start point and Z is the distance from R.
Related codes
G91 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Haas NGC | Incremental positioning |
| Mazak (EIA) | Incremental programming |
| Okuma OSP | Incremental programming |
| Mitsubishi M70 M80 | Incremental programming |
| Brother Speedio | Incremental programming |
| Siemens 840D 828D | Incremental dimensions |
| Heidenhain TNC (ISO) | Incremental dimensions |
| Fagor 8055 8065 | Incremental programming |
| LinuxCNC Tormach | Incremental distance mode |
| Mach3 Mach4 | Incremental mode |
| Centroid CNC12 Acorn | Incremental positioning |
| Hurco WinMax (NC) | Incremental mode |
| Fadal | Incremental positioning |
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