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3D Printingknowledge~6 mins

Start and end G-code customization in 3D Printing - Full Explanation

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Introduction
When you start or finish a 3D print, the printer needs clear instructions to prepare and finish the job properly. Customizing these instructions helps ensure your printer behaves exactly how you want at the beginning and end of every print.
Explanation
Start G-code
Start G-code is a set of commands that run before the actual printing begins. It prepares the printer by heating the nozzle and bed, moving the print head to the right position, and sometimes cleaning the nozzle. This setup ensures the printer is ready to create a good first layer.
Start G-code sets up the printer to begin printing smoothly and accurately.
End G-code
End G-code runs after the print finishes. It cools down the nozzle and bed, moves the print head away from the finished object, and can turn off motors or fans. This helps protect the print and the printer once the job is done.
End G-code safely finishes the print and prepares the printer for the next use.
Why Customize Start and End G-code
Different printers and materials may need specific commands to work best. Customizing these codes lets you adjust temperatures, movements, and other settings to improve print quality and protect your machine. It also allows adding special actions like nozzle cleaning or pausing for filament changes.
Customization tailors the printer's start and finish actions to your specific needs.
How to Customize
You can edit start and end G-code in your slicing software, which converts 3D models into printer instructions. Most slicers have a section where you can type or paste your custom commands. Testing changes carefully is important to avoid printer errors or damage.
Customization is done by editing G-code in the slicer before printing.
Real World Analogy

Imagine baking a cake: before you start, you preheat the oven and grease the pan to prepare; after baking, you turn off the oven and let the cake cool. Customizing start and end G-code is like adjusting these steps to fit your specific oven and recipe.

Start G-code → Preheating the oven and greasing the pan before baking
End G-code → Turning off the oven and letting the cake cool after baking
Why Customize Start and End G-code → Adjusting oven temperature or baking time for different recipes
How to Customize → Changing the recipe instructions before baking
Diagram
Diagram
┌───────────────┐      ┌───────────────┐      ┌───────────────┐
│   Start G-code│─────▶│   Printing    │─────▶│   End G-code  │
│ (Prepare)     │      │ (Build Object)│      │ (Finish)      │
└───────────────┘      └───────────────┘      └───────────────┘
Flow showing the sequence of start G-code preparing the printer, printing the object, and end G-code finishing the process.
Key Facts
Start G-code → Commands run before printing to prepare the printer.
End G-code → Commands run after printing to safely finish the job.
Customization → Changing start and end G-code to fit specific printer or material needs.
Slicer → Software that converts 3D models into printer instructions including G-code.
Common Confusions
Start and end G-code are the same as regular printing commands.
Start and end G-code are the same as regular printing commands. Start and end G-code are special commands that run only before and after printing, not during the actual print layers.
Customizing G-code is too risky and should be avoided.
Customizing G-code is too risky and should be avoided. Careful customization improves print quality and printer safety; always test changes step-by-step to avoid issues.
Summary
Start G-code prepares the printer before printing begins to ensure a good first layer.
End G-code safely finishes the print by cooling and moving the printer parts away.
Customizing these codes lets you tailor printer behavior for better results and protection.

Practice

(1/5)
1. What is the main purpose of the start G-code in 3D printing?
easy
A. To cool down the printer after printing is finished
B. To pause the print job temporarily
C. To prepare the printer by homing axes and heating before printing
D. To clean the print bed automatically

Solution

  1. Step 1: Understand start G-code role

    Start G-code runs before printing to prepare the printer, such as homing axes and heating.

  2. Step 2: Compare options

    Only To prepare the printer by homing axes and heating before printing describes preparation actions before printing; others describe after or unrelated actions.

  3. Final Answer:

    To prepare the printer by homing axes and heating before printing -> Option C

  4. Quick Check:

    Start G-code = Preparation before print [OK]
Hint: Start G-code sets up printer before printing starts [OK]
Common Mistakes:
  • Confusing start G-code with end G-code
  • Thinking start G-code cools the printer
  • Assuming start G-code pauses printing
2. Which of the following is a correct example of a command you might find in the end G-code?
easy
A. M104 S0 ; Turn off extruder heater
B. G1 Z0.2 F3000 ; Move nozzle close to bed
C. G28 ; Home all axes
D. M109 S200 ; Wait for extruder to reach 200°C

Solution

  1. Step 1: Identify end G-code commands

    End G-code usually turns off heaters and moves the print head safely away.

  2. Step 2: Analyze options

    M104 S0 ; Turn off extruder heater turns off the extruder heater, which is typical for end G-code. G28 ; Home all axes homes axes (start), C moves nozzle close (start), D waits for heat (start).

  3. Final Answer:

    M104 S0 ; Turn off extruder heater -> Option A

  4. Quick Check:

    End G-code = Turn off heaters [OK]
Hint: End G-code usually turns off heaters [OK]
Common Mistakes:
  • Choosing commands that heat or home axes as end G-code
  • Confusing waiting commands with end commands
  • Selecting movement commands that prepare printing
3. Given this start G-code snippet:
G28 ; Home all axes
M140 S60 ; Set bed temperature
M190 S60 ; Wait for bed temperature
M104 S200 ; Set extruder temperature
M109 S200 ; Wait for extruder temperature
G1 Z0.2 F3000 ; Move nozzle close to bed

What will the printer do first when starting a print?
medium
A. Home all axes
B. Heat the extruder to 200°C
C. Move nozzle close to bed
D. Wait for bed temperature to reach 60°C

Solution

  1. Step 1: Read the G-code commands in order

    The first command is G28, which homes all axes.

  2. Step 2: Understand command sequence

    Printer homes axes first, then sets and waits for bed and extruder temperatures, then moves nozzle.

  3. Final Answer:

    Home all axes -> Option A

  4. Quick Check:

    First command = G28 = Home axes [OK]
Hint: G28 always homes axes first in start G-code [OK]
Common Mistakes:
  • Assuming heating happens before homing
  • Confusing wait commands with first action
  • Thinking nozzle moves before homing
4. You added this line to your end G-code:
M104 S0
But the extruder heater does not turn off after printing. What is the likely problem?
medium
A. The command needs a G28 before it to work
B. The printer firmware does not support M104
C. The command should be M140 S0 to turn off the extruder
D. The command is correct but placed before the print finishes

Solution

  1. Step 1: Understand M104 S0 function

    This command turns off the extruder heater.

  2. Step 2: Check command placement

    If placed before print ends, heater stays on during printing. It must be after printing finishes.

  3. Final Answer:

    The command is correct but placed before the print finishes -> Option D

  4. Quick Check:

    Heater off command must run after print ends [OK]
Hint: Place heater-off commands after printing completes [OK]
Common Mistakes:
  • Using bed heater command instead of extruder heater
  • Assuming firmware lacks support without checking
  • Thinking homing is needed before heater off
5. You want to customize your start G-code to include a line that wipes the nozzle before printing. Which of these sequences correctly adds this action after homing and heating?
hard
A. G28 ; Home axes G1 E10 F300 ; Extrude filament to wipe M104 S200 ; Heat extruder G1 X10 Y10 ; Move to wipe position
B. G28 ; Home axes M104 S200 ; Heat extruder G1 X10 Y10 ; Move to wipe position G1 E10 F300 ; Extrude filament to wipe
C. G1 X10 Y10 ; Move to wipe position G28 ; Home axes M104 S200 ; Heat extruder G1 E10 F300 ; Extrude filament to wipe
D. M104 S200 ; Heat extruder G28 ; Home axes G1 E10 F300 ; Extrude filament to wipe G1 X10 Y10 ; Move to wipe position

Solution

  1. Step 1: Identify correct order of start G-code actions

    Start G-code should home axes first, then heat extruder, then move to wipe position and extrude filament.

  2. Step 2: Analyze options for correct sequence

    G28 ; Home axes M104 S200 ; Heat extruder G1 X10 Y10 ; Move to wipe position G1 E10 F300 ; Extrude filament to wipe follows this order: home, heat, move, extrude. Others mix heating and homing or move before heating.

  3. Final Answer:

    G28 ; Home axes M104 S200 ; Heat extruder G1 X10 Y10 ; Move to wipe position G1 E10 F300 ; Extrude filament to wipe -> Option B

  4. Quick Check:

    Home -> Heat -> Move -> Extrude = G28 ; Home axes M104 S200 ; Heat extruder G1 X10 Y10 ; Move to wipe position G1 E10 F300 ; Extrude filament to wipe [OK]
Hint: Home first, heat second, then wipe nozzle [OK]
Common Mistakes:
  • Moving nozzle before heating extruder
  • Extruding filament before heating
  • Heating after homing but before moving