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G90 Absolute positioning / OD and ID turning cycle
Haas NGC G-code · Mill, Lathe
On mills: Absolute positioning
Axis positions are read as distances from the active work zero.
Format
G90
How it works
Modal, group 03. Default mode.
Example program
G90 G54 G00 X1. Y1. (MOVE TO X1 Y1 FROM PART ZERO)
X2. (NOW AT X2 FROM PART ZERO)
Y0. (NOW AT X2 Y0 FROM PART ZERO)
X2. (NOW AT X2 FROM PART ZERO)
Y0. (NOW AT X2 Y0 FROM PART ZERO)
Example is in inch. Check offsets and clearances first.
Watch out for
- Put G90 in every safe start line. A G91 left active from a G28 line is a common crash.
On lathes: OD and ID turning cycle
Turns one pass: feed in Z, feed out in X, rapid back to start. Add more X values on the next lines for more passes. I adds a taper.
Format
G90 X Z [U] [W] [I] F
Addresses
| Address | What it does |
|---|---|
X | Diameter of the pass |
Z | End of the pass in Z |
U W | Incremental target |
I | Taper, radius, added to X at the target |
F | Feed rate |
How it works
Modal, group 01. Cancel with G00 or another group 01 code.
Example program
T0101 (OD ROUGH TOOL)
G99 G96 S500 M03 (CSS 500 SFM)
G00 G54 X2.1 Z.1 M08 (START POINT)
G90 X1.9 Z-1. F.012 (PASS 1)
…
G99 G96 S500 M03 (CSS 500 SFM)
G00 G54 X2.1 Z.1 M08 (START POINT)
G90 X1.9 Z-1. F.012 (PASS 1)
…
The full 7-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- The tool rapids back to the start point after each pass. Start clear of the stock.
- I is a radius value. A negative I tapers smaller toward the start on an OD.
Related codes
G90 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Fanuc | Absolute programming |
| Mazak (EIA) | Absolute programming |
| Okuma OSP | Absolute programming |
| Mitsubishi M70 M80 | Absolute programming |
| Brother Speedio | Absolute programming |
| Siemens 840D 828D | Absolute dimensions |
| Heidenhain TNC (ISO) | Absolute dimensions |
| Fagor 8055 8065 | Absolute programming |
| LinuxCNC Tormach | Absolute distance mode |
| Mach3 Mach4 | Absolute mode |
| Centroid CNC12 Acorn | Absolute positioning |
| Hurco WinMax (NC) | Absolute mode |
| Fadal | Absolute positioning |
| Swiss (Citizen Star) | OD turning cycle |
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