Reading G-code for troubleshooting in 3D Printing - Mini Project: Build & Apply

Reading G-code for troubleshooting

📖 Scenario: You are a 3D printing technician who needs to understand G-code commands to troubleshoot printing issues. G-code is a set of instructions that tells the 3D printer how to move, heat, and operate. By reading and interpreting G-code lines, you can find problems like incorrect temperatures or wrong movements.

🎯 Goal: Build a simple step-by-step guide to identify key G-code commands related to movement and temperature. You will create a list of G-code lines, set a temperature threshold, find commands that set temperatures above this threshold, and mark the final command to stop the printer.

📋 What You'll Learn

Create a list of G-code command strings with exact values

Add a temperature threshold variable

Use a loop to find all temperature-setting commands above the threshold

Add a final command to stop the printer

💡 Why This Matters

🌍 Real World

Technicians and hobbyists use G-code reading skills to troubleshoot 3D printer issues like wrong temperatures or movements.

💼 Career

Understanding G-code helps in roles such as 3D printer operator, maintenance technician, and manufacturing engineer.

1

Create the G-code commands list

Create a list called gcode_commands with these exact G-code lines as strings: "G28 ; Home all axes", "M104 S200 ; Set extruder temperature to 200°C", "G1 X50 Y25.3 E22.4 ; Move to X50 Y25.3 while extruding", "M109 S210 ; Wait for extruder temperature to reach 210°C", and "M140 S60 ; Set bed temperature to 60°C".

3D Printing

# Create the list gcode_commands with the specified G-code lines
# Your code here

Hint

Use square brackets to create a list and include each G-code line as a string inside quotes.

2

Set the temperature threshold

Create a variable called temp_threshold and set it to the integer 205. This will help identify temperature commands above this value.

3D Printing

gcode_commands = [
    "G28 ; Home all axes",
    "M104 S200 ; Set extruder temperature to 200°C",
    "G1 X50 Y25.3 E22.4 ; Move to X50 Y25.3 while extruding",
    "M109 S210 ; Wait for extruder temperature to reach 210°C",
    "M140 S60 ; Set bed temperature to 60°C"
]
# Create temp_threshold and set it to 205
# Your code here

Hint

Just assign the number 205 to the variable named temp_threshold.

3

Find temperature commands above the threshold

Create an empty list called high_temp_commands. Use a for loop with the variable command to go through gcode_commands. Inside the loop, check if the command contains "M104" or "M109". If yes, extract the temperature number after S and convert it to an integer. If this temperature is greater than temp_threshold, add the command to high_temp_commands.

3D Printing

gcode_commands = [
    "G28 ; Home all axes",
    "M104 S200 ; Set extruder temperature to 200°C",
    "G1 X50 Y25.3 E22.4 ; Move to X50 Y25.3 while extruding",
    "M109 S210 ; Wait for extruder temperature to reach 210°C",
    "M140 S60 ; Set bed temperature to 60°C"
]
temp_threshold = 205
# Create high_temp_commands list and fill it with commands setting temperature above temp_threshold
# Your code here

Hint

Split the command string by spaces, find the part starting with 'S', convert the number after 'S' to int, then compare with temp_threshold.

4

Add the final stop command

Add the string "M84 ; Disable motors" as the last item in the gcode_commands list to mark the end of the print job.

3D Printing

gcode_commands = [
    "G28 ; Home all axes",
    "M104 S200 ; Set extruder temperature to 200°C",
    "G1 X50 Y25.3 E22.4 ; Move to X50 Y25.3 while extruding",
    "M109 S210 ; Wait for extruder temperature to reach 210°C",
    "M140 S60 ; Set bed temperature to 60°C"
]
temp_threshold = 205
high_temp_commands = []
for command in gcode_commands:
    if "M104" in command or "M109" in command:
        parts = command.split()
        for part in parts:
            if part.startswith("S"):
                temp = int(part[1:])
                if temp > temp_threshold:
                    high_temp_commands.append(command)
# Add the stop command "M84 ; Disable motors" to gcode_commands
# Your code here

Hint

Use the append method on the gcode_commands list to add the stop command.

Practice

1. What does the G-code command G1 X50 Y25 instruct the 3D printer to do?

easy

A. Move the print head to coordinates X=50 and Y=25

B. Set the temperature to 50°C and 25°C

C. Start the print job from layer 50 to 25

D. Pause the printer for 50 seconds and then 25 seconds

Solution

1. Step 1: Understand the G1 command

   The G1 command is used to move the print head to a specific position.

2. Step 2: Interpret the coordinates

   X50 and Y25 mean move the print head to X=50 units and Y=25 units on the print bed.

3. Final Answer:

   Move the print head to coordinates X=50 and Y=25 -> Option A

4. Quick Check:

   G1 moves print head = Move to X=50 Y=25 [OK]

Hint: G1 moves print head to given coordinates [OK]

Common Mistakes:

• Confusing G1 with temperature commands
• Thinking G1 pauses the printer
• Assuming G1 controls print speed only

2. Which of the following is the correct syntax to set the extruder temperature to 210°C in G-code?

easy

A. G1 T210

B. G28 S210

C. M104 S210

D. M109 X210

Solution

1. Step 1: Identify the temperature command

   M104 is the G-code command used to set the extruder temperature without waiting.

2. Step 2: Check the syntax

   S210 means set temperature to 210°C. So, M104 S210 sets extruder temperature to 210°C.

3. Final Answer:

   M104 S210 -> Option C

4. Quick Check:

   M104 sets temp with S value = M104 S210 [OK]

Hint: M104 sets extruder temp; S is temperature value [OK]

Common Mistakes:

• Using G28 which is for homing axes
• Confusing M109 which waits for temp
• Using wrong letter like X or T for temperature

3. Given this G-code snippet:

G28
M104 S200
G1 X100 Y100 E10 F1500
M109 S200

What does the command G1 X100 Y100 E10 F1500 do?

medium

A. Homes all axes and waits for temperature 200°C

B. Moves the print head to X=100, Y=100 while extruding 10 units of filament at speed 1500

C. Sets the extruder temperature to 100°C and moves at speed 1500

D. Pauses the print for 10 seconds at position X=100, Y=100

Solution

1. Step 1: Understand the G1 command with parameters

   G1 moves the print head. X100 Y100 sets position. E10 means extrude 10 units of filament. F1500 sets movement speed.

2. Step 2: Combine all parts

   The command moves the head to X=100, Y=100 while pushing 10 units of filament out at speed 1500 mm/min.

3. Final Answer:

   Moves the print head to X=100, Y=100 while extruding 10 units of filament at speed 1500 -> Option B

4. Quick Check:

   G1 with X,Y,E,F moves and extrudes at speed [OK]

Hint: G1 with E extrudes filament while moving [OK]

Common Mistakes:

• Thinking E means temperature
• Confusing F as filament amount
• Assuming G1 only moves without extruding

4. You see this G-code line causing a print error:
M104 S-10
What is the problem and how to fix it?

medium

A. Temperature cannot be negative; change S-10 to a positive value like S210

B. M104 cannot be used for temperature; replace with G1 command

C. The command is missing a wait; add M109 before M104

D. S-10 means wait 10 seconds; replace with S10 to fix

Solution

1. Step 1: Identify invalid temperature value

   Temperature values must be positive. S-10 is invalid because temperature cannot be negative.

2. Step 2: Correct the temperature value

   Change S-10 to a valid positive temperature like S210 to fix the error.

3. Final Answer:

   Temperature cannot be negative; change S-10 to a positive value like S210 -> Option A

4. Quick Check:

   Temperature must be positive = fix S-10 to S210 [OK]

Hint: Temperature values must be positive numbers [OK]

Common Mistakes:

• Thinking negative temperature means wait time
• Confusing M104 with movement commands
• Adding wrong commands instead of fixing value

5. You want to troubleshoot a print where the filament is not extruding properly. Which G-code command should you check first to verify the extrusion amount?

hard

A. M109 commands waiting for temperature

B. M104 commands setting temperature

C. G28 commands for homing axes

D. G1 commands with the E parameter

Solution

1. Step 1: Identify extrusion control in G-code

   The E parameter in G1 commands controls how much filament is pushed out (extruded).

2. Step 2: Focus on G1 commands with E values

   Checking these commands helps verify if the printer is instructed to extrude filament properly.

3. Final Answer:

   G1 commands with the E parameter -> Option D

4. Quick Check:

   Extrusion controlled by G1 E values = check G1 E commands [OK]

Hint: Extrusion amount is set by E in G1 commands [OK]

Common Mistakes:

• Checking temperature commands instead of extrusion
• Confusing homing commands with extrusion
• Assuming M109 controls extrusion amount