Digital technologies/3D printing/3D printing- Intermediate/Dual Extrusion

Dual colour prints refer to a technique that can print multiple colours on one model using one nozzle head. This is achieved by switching the filament during the printing process. Dual extrusion refers to printing a model with 2 nozzles to extrude two different filaments. This will allow for mixing colours, gradients, or patterns. It can also print models using two different materials for different parts of the object for complex geometries that would otherwise be difficult to achieve.

Dual colour prints are achievable using the Ultimaker 2+ printers.  In order to change the colour during the print, a script is added to the g-code telling the printer to stop the print at a certain instance. This is done during the slicing process in Cura.

1. Click on “Extensions” in the top menu bar.
2. Select “Post-processing” -> “Modify g-code”.
3. Click on “Add a script”
4. Select “Pause at height”

At this point, there will be many different settings to modify. First, determine if you would like to pause at a height value (mm) or at a layer number. Choosing a layer number would be a simpler option in ensuring that the print ends when a full layer is completed. The layer number can be seen in the “Preview” mode on Cura. The model can then be sliced like normal. Once the print stops, the material can be changed (ask the staff) to complete the print in a different colour.

Dual extrusion prints are possible using the Ultimaker 3 or Raise printers in MakersSpace. To do so with the Ultimaker, two separate 3D models are needed. If they are part of the same model, they will be merged together in Cura. Ensure that the printer selected is Ultimaker 3. The printer can be added using “Add printer” button.  Open both models in Cura and set the print core and the materials. This can be done through the printing options beside the printer selection. Both print cores should be set at AA .4. The material is set to PLA by default but it can be changed to the material of our choice. There is no need to change the colour of the filament on Cura as it will be determined by the filament that is loaded in the printers. By default, both models will be set to print with core 1. To change the print core, select the model then select per model settings and print model with print core 2. After the print core, merge the two models together. Select both models by holding shift while left clicking on both parts. Both models should thenm be highlighted in blue. Then, right click and select “Merge Models”. The two models will then become a single model. At which point, you can adjust the printer settings like a regular single extrusion print. If you would like to customize the settings for one print core, the printer settings need to be assigned in custom model.