Reading G-code for troubleshooting in 3D Printing - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding G-code Movement Commands

What does the G-code command G1 X50 Y25.3 F1500 instruct the 3D printer to do?

A Move the print head to X=50, Y=25.3 at a speed of 1500 mm/min

B Set the temperature to 1500°C and move to X=50, Y=25.3

C Pause the print for 1500 seconds at position X=50, Y=25.3

D Home the X and Y axes and set feed rate to 1500

💡 Hint

G1 is a command for controlled movement with specified coordinates and speed.

The G1 command moves the print head to the specified X and Y coordinates at the feed rate given by F. Here, it moves to X=50, Y=25.3 at 1500 mm/min.

📋 Factual

intermediate

Identifying Temperature Commands in G-code

Which G-code command sets the extruder temperature to 210°C?

A G1 S210

B G28 S210

C M106 S210

D M104 S210

💡 Hint

Look for the command that controls temperature settings.

M104 sets the extruder temperature to the value specified by S. Here, S210 means 210°C.

🔍 Analysis

advanced

Troubleshooting Unexpected Retraction Behavior

Given this G-code snippet:

G1 E-2 F1800
G1 X100 Y100 F3000
G1 E0 F1800

What is the purpose of the E-2 command in this context?

A It extrudes 2 mm of filament to start printing

B It retracts the filament by 2 mm to prevent oozing during travel moves

C It sets the extruder temperature to 2°C

D It moves the print head 2 mm backward on the X axis

💡 Hint

Negative E values usually mean filament retraction.

E-2 retracts filament by 2 mm to reduce stringing when the print head moves without printing.

❓ Comparison

advanced

Comparing Homing Commands

Which G-code command homes all axes of the 3D printer?

A M104

B G1

C G28

D M106

💡 Hint

Homing commands reset the position of the printer axes.

G28 homes all axes by moving them to their endstops to establish a reference position.

❓ Reasoning

expert

Diagnosing a Layer Shift from G-code

In a G-code file, you notice this sequence:

G1 X50 Y50 F3000
G1 X150 Y50 F3000
G1 X150 Y150 F3000
G1 X50 Y150 F3000
G92 X0 Y0

What is the effect of the G92 X0 Y0 command here?

A It resets the current position to X=0, Y=0 without moving the print head

B It moves the print head physically to X=0, Y=0

C It pauses the print and waits for user input

D It sets the extruder temperature to 0°C

💡 Hint

G92 changes the printer's idea of its position without moving.

G92 sets the current position to the specified coordinates, effectively resetting the coordinate system origin at the current location.

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