GcodeGoblin

GcodeGoblin is a small python script for post-processing G-Code.

For 3d printing, this allows for various hacks, like skipping entire layers (with ...CUT commands), or repeating layers with alternate settings (with ...COPY commands).

It provides the following post-processing commands:

• ; START_COPY: <buffer-name>: Starts to copy the following lines into a named buffer
• ; STOP_COPY: End of the copying
• ; PASTE: <buffer-name>: Pastes the named buffer here
• ; PRINT_BUFFER: <buffer-name>: Prints the buffer content to stdout
• ; REMOVE_EXTRUSION: <buffer-name>: Removes extrusion from buffer
• ; STOP_EXTRUDE:: Removes extrusion from all following G1, G2, G3 commands
• ; START_EXTRUDE:: Leaves G1, G2, G3 commands alone
• ; START_CUT: Suppresses the following lines
• ; STOP_CUT: prints the following lines.

Note that the semicolon (;) indicates that the following characters are G-Code comments.

Files

The tool works on both .3mf files as generated by the Bambu and Orca slicer (it recaclucates the required checksum file also), and it also works on plain .gcode files.

Integration notes

As of September 2024, the Others -> Post-processing scripts feature in Bambu and Orca slicer appears not to work.

Example

;; filename: example.gcode
G1
; START_COPY: A
G2
; STOP_COPY
G3
; START_CUT
G4
; STOP_CUT
G5
; PASTE: A

running python gcodegoblin.py example.gcode should yield

;; filename: example.fixed.gcode
G1
; START_COPY: A
; starting to copy into buffer A
G2
; STOP_COPY: A
; stopping copy into buffer A
G3
; START_CUT
; CUT START
; CUT STOPPED
G5
; PASTE: A
; pasting from buffer A into output:
G2
; END OF PASTE BUFFER

Remove Extrusion command

The remove extrusion command changes the extrusion commands into movement commands. It does that by looking for movement commands (G1, G2, G3) and removing removing any E1.23 components.

This makes the hotend into a heat bonding device and allows the bonding of thin membranes that are flush to the top surface of a 3d printed plastic piece.

Real world example

In 3d printer slicer (Prusa, Orca, Bambu, maybe others), you can right click on the + on the top end of the Z-Axis slider to get a little menu that allows you to add custom G-Code, like the ; START_COPY: A etc. This will be put into the G-Code that is generated next time you slice it.

The workflow is:

1. Load Model
2. Slice Model
3. Insert G-Code with the right-click
4. Slice Model again
5. Export G-Code with Export plate sliced file or similar option
6. Run GcodeGoblin on the generated file
7. Print the generated file

Generally, repeating a previous layer with a lower flow rate allows solid bonding of membranes.