G Code for Milling a Straight Line: Syntax and Example

To mill a straight line in G code, use G01 for linear interpolation with specified coordinates. For example, G01 X10 Y0 F100 moves the tool in a straight line to X=10, Y=0 at feed rate 100.

Syntax

The basic G code command to mill a straight line is G01, which tells the machine to move in a straight line at a controlled feed rate.

• G01: Linear interpolation (straight line move)
• X, Y, Z: Target coordinates for the move
• F: Feed rate (speed of the tool movement)

Example: G01 X20 Y10 F150 moves the tool straight to X=20, Y=10 at feed rate 150.

gcode

G01 X10 Y0 F100

Example

This example shows a simple G code program that mills a straight line from the current position to X=50, Y=0 at a feed rate of 200 mm/min.

gcode

G21 ; Set units to millimeters
G90 ; Use absolute positioning
G00 X0 Y0 ; Rapid move to start point
G01 X50 Y0 F200 ; Mill straight line to X=50, Y=0
M30 ; End of program

Output

The CNC machine moves rapidly to X0 Y0, then mills a straight line to X50 Y0 at feed rate 200 mm/min, then stops.

Common Pitfalls

Common mistakes when milling a straight line include:

• Forgetting to set the feed rate (F), which can cause the machine to move too fast or not move at all.
• Using G00 instead of G01 for cutting moves; G00 is rapid positioning and does not cut.
• Not setting the correct coordinate mode (G90 for absolute or G91 for incremental), leading to unexpected tool paths.

Wrong: G00 X50 Y0 (moves fast, no cutting)
Right: G01 X50 Y0 F150 (cuts a straight line)

gcode

G00 X50 Y0 ; Incorrect for cutting
G01 X50 Y0 F150 ; Correct for cutting

Quick Reference

Command	Description
G00	Rapid move (no cutting)
G01	Linear interpolation (cutting straight line)
X, Y, Z	Target coordinates
F	Feed rate (speed)
G90	Absolute positioning mode
G91	Incremental positioning mode

Key Takeaways

Use G01 with X, Y coordinates and feed rate F to mill a straight line.

Always set the correct positioning mode with G90 or G91 before moves.

Never use G00 for cutting moves; it is for rapid positioning only.

Specify feed rate F to control the cutting speed.

Start with a safe rapid move (G00) to the start point before cutting.