Creating Delamination Layer for 3D Printed Stacked Prints

Note that this is still a work in progress. Images and steps are still to be added

This might not be a new idea, but I'd remembered that whilst I was printing PETG at 240C, I had horrible delamination problems between layers and had to turn up to 250C to get reliable prints. So considering that we wanted to stack prints, I wondered why not use this to our advantage.

If the bottom layer of the top object is printed at a lower print temperature than the rest of the layers, it would create a layer that would easily delaminate from the layer below it. A delamination interface layer between parts would result in separable parts from a single continuous print without the need of any separating support material or spacing. Furthermore, the parts will have a cleaner bottom layer as they are printed directly onto a flat surface.

Supplies

3D Printer
3D Printer Filament
3D Printer Slicer
Text Editor

Step 1: Creating a Stackable Model

The model should have a completely flat top and bottom with chamfering on edges to help you locate and start a break between layers
Models should avoid having surfaces that concentrate the hotend within a small area. If the hotend is concentrated at a particular area for too long, it can cause the layers to fuse even with a low print temperature.
Ideally the interface between models should consist of perimeters (or using concentric infill) which don't typically concentrate the hotend as much as with rectilinear or line infill.
If a perimeter interface layer can't be achieved, you can create gaps within the model that only result in the use of perimeters when slicing.

Step 2: Preparing a Stacked Model in Cura

Import model into Cura
Go to “Preferences”, “Configure Cura”
Untick “Automatically drop models to the build plate” and close Preferences window:
Right click on model, select “Multiply Selected Model” and enter the number of models you want to add:
After Cura adds the models to the build plate, right click on the build plate and select “Reset All Model Positions” to place all the prints in the center
Once centered, select one of the models in the center and use the left panel to adjust the placement of the model to be on top of the other models. You should use the thickness of the model + any spacing you want to add (this should be the same as layer height or greater)
Example for eu_a4_open.stl: The thickness is 5mm + 0.2mm spacing, Z = 5.2mm
Repeat this process for the number of models you want to be stacked but with the height incrementing based on your model height + spacing
Example for 4 bands: Z = 5.2mm, Z = 10.4mm, Z = 15.6mm
Stack is now ready to be used for printing. You can also export the model to share or reuse for later prints.

Step 3: Option 1: Manually Modifying G-Code for Stacked Layer Using Text Editor

Note that this option requires g-code knowledge for 3D printers, however, it will produce the best result when printing

Note down the layer heights at which the start of the models begin with as your target heights
Example for 4 bands: Z = 5mm, Z = 10mm, Z = 15mm
Slice your stacked model as usual with your slicer and save the g-code to somewhere you can open it
Open the g-code using a text editor
Example software: Notepad++
Within the text editor, search for the letter Z
In Notepad++: go to "Search", "Find...", and type in Z into "Find what :"
Keep searching through next search until you find the number after Z is greater than your target height
Example with 5mm target: The first search value greater than 5mm is Z5.2
Check that the following Z is not less than what you have found. This can be the result of Z lifts in g-code. If the next Z is lower, continue step 5
Example with Z5.2: Next Z search term can not give a Z that has a lower number than Z5.2
Insert "Target Layer" g-code with your desired parameters for S
For inserting "Before Target Layer" g-code, there are two options:
- Place the g-code a set number of lines before. E.g. 500 lines before start of target layer
- Place the g-code a set number of lines before based on the layer time produced in Cura's g-code
Repeat step 5, 6, 7 and 8 for "End of Target Layer" and "After Target Layer"

Step 4: Option 2: Setting Up Cura for Delamination Layer

Once you have a stacked file ready, you can prepare Cura for printing with a delamination layer.
Go to “Extensions”, “Post Processing” and select “Modify G-Code”
In “Post Processing Scripts” window, click add script and select “ChangeAtZ”:
Select the settings as shown below. Z height is based on the height of model + separation distance. Delamination temperature depends on your filament and will need to be found through trial and error. Example based on 5mm model height + 0mm separation
Repeat this process of adding more scripts but setting the “Change Height” value for the rest of the models: Example for 5 models with 5mm model height + 0mm separation. Change Height = 5mm, 10mm, 15mm, 20mm
You may now slice your model normally and the changes will be applied to the g-code after slicing. You may verify the changes by opening the g-code in a text editor and searching for “ChangeAtZ”. The scripts won’t be performed at the exact specified layer but rather at the closest layer above it:

Step 5: Option 3: Setting Up PrusaSlicer for Delamination Layer

Note that this is still a work in progress. Images and steps are still to be added

Step 6: Option 4: Setting Up Delamination Layer With Cura Plugin

Note that this is still a work in progress. Images and steps are still to be added

Step 7: Print Results

Delamination layer tested using a carabiner clip by ZRAFT on Thingiverse: https://www.thingiverse.com/thing:221727

Clip is printed using HIPS plastic with 0mm separation gap between each clip. Normal print temperature was 245C, and was reduced to 210C during delamination layer. The lowSpeed parameter was set to 50% during cooldown and heatup periods when changing temperature.