Manual G-code modifications in 3D Printing - Mini Project: Build & Apply

Manual G-code Modifications for 3D Printing

📖 Scenario: You have a 3D printer and a G-code file that controls how your printer makes a small object. Sometimes, you need to change the G-code manually to fix small issues or customize the print.For example, you want to change the print speed or add a pause at a certain layer.

🎯 Goal: You will learn how to open a G-code file, find specific commands, and manually edit them to change print speed and add a pause command.

📋 What You'll Learn

Open a G-code file as plain text

Identify lines that control print speed

Modify the speed value in those lines

Add a pause command at a specific layer

💡 Why This Matters

🌍 Real World

3D printing often requires tweaking G-code manually to fix print issues or customize behavior without re-slicing the model.

💼 Career

Understanding manual G-code editing helps technicians and makers troubleshoot prints and optimize printer performance.

1

Load the G-code file content

Create a variable called gcode_lines that contains the following lines exactly as a list of strings:
";Start G-code",
"G1 F1500",
"G1 X50 Y25.3 E22.4",
";Layer 1",
"G1 F1200",
"G1 X60 Y30 E25"

3D Printing

# Create the variable gcode_lines with the exact lines given
# Your code here

Need a hint?

Use a list of strings with the exact lines given, including the semicolons and spaces.

2

Set the new print speed

Create a variable called new_speed and set it to the integer 1800 to represent the new print speed in mm/min.

3D Printing

gcode_lines = [
    ";Start G-code",
    "G1 F1500",
    "G1 X50 Y25.3 E22.4",
    ";Layer 1",
    "G1 F1200",
    "G1 X60 Y30 E25"
]
# Set the new_speed variable to 1800
# Your code here

Need a hint?

Just assign the number 1800 to the variable new_speed.

3

Modify print speed commands in G-code

Use a for loop with the variable index to go through gcode_lines. If a line starts with "G1 F", replace that line with "G1 F" followed by the value of new_speed as a string.

3D Printing

gcode_lines = [
    ";Start G-code",
    "G1 F1500",
    "G1 X50 Y25.3 E22.4",
    ";Layer 1",
    "G1 F1200",
    "G1 X60 Y30 E25"
]
new_speed = 1800
# Loop through gcode_lines by index and replace lines starting with 'G1 F' with 'G1 F' + new_speed
# Your code here

Need a hint?

Use range(len(gcode_lines)) to get indexes and startswith("G1 F") to check lines.

4

Add a pause command after layer 1 comment

Find the index of the line ";Layer 1" in gcode_lines. Insert a new line "M0 ; Pause for user" immediately after it.

3D Printing

gcode_lines = [
    ";Start G-code",
    "G1 F1500",
    "G1 X50 Y25.3 E22.4",
    ";Layer 1",
    "G1 F1200",
    "G1 X60 Y30 E25"
]
new_speed = 1800
for index in range(len(gcode_lines)):
    if gcode_lines[index].startswith("G1 F"):
        gcode_lines[index] = f"G1 F{new_speed}"
# Insert 'M0 ; Pause for user' after the line ';Layer 1'
# Your code here

Need a hint?

Use the index() method to find the line and insert() to add the pause command.