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G2 Clockwise arc or helix / Clockwise arc

Centroid CNC12 Acorn G-code · Mill, Lathe

On mills: Clockwise arc or helix

Cuts a clockwise arc in the active plane. Give the end point and either R or I J K. Adding the third axis makes a helix.

Format

Addresses

How it works

Modal, motion group. Stays on until G0, G1 or G3.

Example program

The full 9-line example is in the app. Example is in inch. Check offsets and clearances first.

Watch out for

• A full 360 degree circle must use I J K. R will not work for a full circle.
• I J K are incremental by default. Parameter 2 bit 0 makes them absolute, so check it on a used machine.
• In G18 the arc direction looks reversed. Check the graph before cutting.

On lathes: Clockwise arc

Cuts a clockwise arc in X and Z. Give the end point and R, or I and K to the center. I and R are always radius values.

Format

Addresses

How it works

Modal, motion group.

Example program

The full 9-line example is in the app. Example is in inch. Check offsets and clearances first.

Watch out for

• CNC12 rule: program as if the tool post is at the back and the headstock on the left.
• Concave OD arcs moving toward minus Z are G2. Convex OD arcs moving toward minus Z are G3.

Related codes

G3 · G17 · G117 · G41 · G42

G2 on other controls

The same number can mean something different on another control.