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G3 Circular interpolation counterclockwise
Siemens 840D 828D G-code · Mill and lathe
Cuts a counterclockwise arc in the active plane. The arc is set by end point and center (I J K), end point and radius (CR=), or with an opening angle (AR=). A full circle needs the center form.
Format
G3 X Y I J F or G3 X Y CR= F or G3 X Y AR= F or G3 I J AR= F
Addresses
| Address | What it does |
|---|---|
X Y Z | Arc end point |
I J K | Arc center, incremental from the start point by default. I=AC() gives an absolute center. |
CR= | Arc radius. Negative value for an arc greater than 180 degrees. |
AR= | Opening angle of the arc in degrees |
F | Feed rate |
How it works
Modal, G group 1 (motion).
Example program
G17 G90 G54 ; XY PLANE, ABSOLUTE
G0 X30 Y0 Z2 ; START POINT
G1 Z-1 F100 ; FEED TO DEPTH
G3 X0 Y30 I-30 J0 F250 ; CCW QUARTER ARC, CENTER X0 Y0
…
G0 X30 Y0 Z2 ; START POINT
G1 Z-1 F100 ; FEED TO DEPTH
G3 X0 Y30 I-30 J0 F250 ; CCW QUARTER ARC, CENTER X0 Y0
…
The full 6-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- Direction is seen looking from the plus side of the tool axis onto the active plane, so check G17, G18 or G19 first.
- For arcs over 180 degrees with CR= the radius must be negative. A positive value cuts the short arc instead.
Related codes
G3 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Fanuc | Circular interpolation counterclockwise |
| Haas NGC | Circular interpolation counterclockwise |
| Mazak (EIA) | Circular interpolation, counterclockwise |
| Okuma OSP | Circular interpolation counterclockwise |
| Mitsubishi M70 M80 | Circular move counterclockwise |
| Brother Speedio | Circular interpolation counterclockwise |
| Heidenhain TNC (ISO) | Counterclockwise arc, Cartesian |
| Fagor 8055 8065 | Counterclockwise circular interpolation |
| LinuxCNC Tormach | Counterclockwise arc or helix |
| Mach3 Mach4 | Counterclockwise arc |
| Centroid CNC12 Acorn | Counterclockwise arc or helix |
| Hurco WinMax (NC) | Circular or helical move counterclockwise |
| Fadal | Circular interpolation counterclockwise |
| Swiss (Citizen Star) | Circular move counterclockwise |
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