Start and end G-code customization in 3D Printing - Step-by-Step Execution

Concept Flow - Start and end G-code customization

Printer powers on

↓

Start G-code runs

↓

Print job executes

↓

End G-code runs

↓

Printer finishes and cools down

The printer runs start G-code before printing to prepare, then prints, then runs end G-code to finish and cool down.

Execution Sample

3D Printing

; Start G-code example
G28 ; Home all axes
G1 Z5 F5000 ; Lift nozzle
; End G-code example
M104 S0 ; Turn off nozzle heater
M140 S0 ; Turn off bed heater
G28 X0 Y0 ; Home X and Y axes

This code homes the printer and lifts the nozzle before printing, then turns off heaters and homes axes after printing.

Analysis Table

Step	G-code Command	Action	Printer State Change	Notes
1	G28	Home all axes	X=0, Y=0, Z=0	Start G-code: prepares printer position
2	G1 Z5 F5000	Lift nozzle 5mm	Z=5	Prevents nozzle from scratching bed
3	Print job runs	Print layers	Nozzle moves, extrudes filament	Main printing process
4	M104 S0	Turn off nozzle heater	Nozzle temp=0	End G-code: cool down nozzle
5	M140 S0	Turn off bed heater	Bed temp=0	End G-code: cool down bed
6	G28 X0 Y0	Home X and Y axes	X=0, Y=0	End G-code: park head
7	End	Print finished	Motors off, cool	Printer ready for next job

💡 All start and end commands executed, print job complete

State Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	Final
X position	unknown	0	0	varies	varies	varies	0	0
Y position	unknown	0	0	varies	varies	varies	0	0
Z position	unknown	0	5	varies	varies	varies	varies	varies
Nozzle temperature	off	off	off	printing temp	0	0	0	0
Bed temperature	off	off	off	printing temp	printing temp	0	0	0

Key Insights - 3 Insights

Why do we home all axes at the start (G28)?

Homing sets the printer's position to a known point (0,0,0). This ensures the printer knows where the nozzle is before printing, as shown in step 1 of the execution_table.

Why lift the nozzle before printing (G1 Z5)?

Lifting the nozzle prevents it from scratching the print bed or existing prints. This is shown in step 2 where Z moves to 5mm before printing starts.

Why turn off heaters at the end (M104 S0 and M140 S0)?

Turning off heaters cools the printer safely after printing, preventing damage or burns. Steps 4 and 5 in the execution_table show these commands.

Visual Quiz - 3 Questions

Look at the execution_table, what is the Z position after step 2?

A 5 mm

B 0 mm

C Unknown

D 10 mm

💡 Hint

Check the 'Printer State Change' column for step 2 in the execution_table.

At which step does the printer turn off the bed heater?

A Step 3

B Step 5

C Step 6

D Step 4

💡 Hint

Look for 'M140 S0' command in the execution_table.

If the start G-code did not include G28, what would likely happen?

A Printer would home axes anyway automatically

B Printer would skip heating

C Nozzle position might be unknown, causing print errors

D Print would finish immediately

💡 Hint

Refer to the key_moments about homing axes and step 1 in the execution_table.

Concept Snapshot

Start and end G-code run before and after printing.
Start G-code prepares printer (home axes, lift nozzle).
End G-code cools down (turn off heaters, home axes).
Customizing these codes controls printer setup and finish.
Proper start/end codes prevent print errors and damage.

Full Transcript

Start and end G-code customization controls what commands the 3D printer runs before and after a print job. The start G-code usually homes all axes to set the printer's position to zero, then lifts the nozzle to avoid scratching the bed. After the print job runs, the end G-code turns off the nozzle and bed heaters to cool down the printer and homes the X and Y axes to park the print head. This sequence ensures the printer is ready and safe before printing and properly finishes after printing. Missing or incorrect start/end G-code can cause print failures or damage. The execution table shows each step with commands and printer state changes, helping visualize the process. Variables like nozzle position and temperature change step-by-step. Key moments explain why homing and heating commands are important. The visual quiz tests understanding of these steps and their effects. Overall, customizing start and end G-code lets users control printer behavior for better prints and safety.