Converting Arcs IJK to R

The Convert IJK Arcs to R function replaces circular interpolation commands G02 / G03 with arc center parameters I, J, or K with equivalent commands using the radius parameter R. This format is often used in manually written NC programs or for simplified geometry representation. NCPlayer supports all 4 possible conversions: Convert IJK INC arcs → IJK ABS, Convert IJK ABS arcs → IJK INC, Convert IJK (Incremental) to R arcs, and Convert IJK (Absolute) to R arcs.

What the function does

• Scans the NC program and finds all G02 / G03 commands with arc center coordinates (I, J, K).
• Determines the current machining plane:
  • G17 — arc center is defined by I, J (Z-axis is perpendicular).
  • G18 — by I, K (Y-axis is perpendicular).
  • G19 — by J, K (X-axis is perpendicular).
• Calculates the arc radius based on:
  • Starting point (current position before the command).
  • Arc end point (X/Y/Z in the command).
  • Arc center coordinates (I, J, K).
• Replaces IJK with the calculated R, preserving arc direction (CW/CCW) and comments.
• Does not change commands with G7x, G8x, G10 or lines that are comments.

Algorithm (short)

1. Read the file line by line, tracking the active machining plane.
2. When a G02 / G03 with IJK is found:
   • Extract the start and end coordinates of the arc.
   • Calculate the radius as the distance from the center to the start point.
3. Remove the I, J, K parameters, add the R parameter with the calculated value.
4. Update the current position to the end of the arc.

Examples

; Before:
G17
N10 G02 X50 Y50 I0  J25 F200
N20 G03 X0  Y0  I-25 J0

; After:
G17
N10 G02 X50 Y50 R25 F200
N20 G03 X0  Y0  R25

When to use

• To simplify geometry and reduce code size.
• When preparing NC programs for machines that do not require IJK and prefer the R parameter.
• For better readability when manually editing G-code.