Start and end G-code customization in 3D Printing - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of start G-code in 3D printing?

Start G-code prepares the 3D printer before printing begins. It usually heats the nozzle and bed, homes the axes, and primes the extruder to ensure smooth printing.

beginner

What does end G-code typically do after a print finishes?

End G-code cools down the printer by turning off heaters, moves the print head away from the finished object, and may disable motors to prevent strain.

intermediate

Why customize start and end G-code instead of using defaults?

Customizing allows better control over printer behavior, improves print quality, and adapts to specific printer models or materials.

beginner

Give an example of a common command in start G-code.

A common command is G28, which homes all axes to set the printer's starting position.

intermediate

What could happen if end G-code does not turn off the heaters?

The printer could overheat, wasting energy and potentially damaging the printer or causing safety hazards.

What is the main role of start G-code in 3D printing?

A Prepare the printer before printing

B Cool down the printer after printing

C Pause the print mid-way

D Change filament color automatically

Start G-code prepares the printer by heating and homing before printing begins.

Which G-code command is commonly used to home all axes?

A G1

B M104

C G28

D M140

G28 homes all axes to the printer's starting position.

What is a typical action in end G-code?

A Load filament

B Move print head to home position

C Start heating the nozzle

D Turn off heaters and motors

End G-code usually turns off heaters and motors to safely finish the print.

Why might you customize your start G-code?

A To improve print quality and adapt to your printer

B To make prints take longer

C To disable safety features

D To skip heating the bed

Customizing start G-code helps improve print quality and fits your specific printer setup.

What risk exists if end G-code does not turn off the printer's heaters?

A Print will finish faster

B Printer may overheat and cause damage

C Filament will change color

D Printer will automatically restart

Leaving heaters on can cause overheating and damage or safety hazards.

Explain the main functions of start and end G-code in 3D printing.

Think about what the printer needs before and after printing.

Why is it important to customize start and end G-code for your specific 3D printer?

Consider differences between printers and materials.

Practice

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