How to print in 3D on several colors or materials with only one extruder?

Many users of 3D printing with FDM technology have asked this question at some point.

Most desktop FDM 3D printers have only one extruder, so the user "loses" the option of combining several filaments; for example when printing complex parts using one construction filament and one support filament or in case the part requires to integrate several colors.

Image 1: 3D printed vase with Fillamentum and Mosaic Palette filaments. Source: Fillamentum.

To solve this problem, there are several solutions depending on the user's needs and the complexity of the part. In this article we will explain two of them:

• Using a laminating software.
• Using an external device.

Using a laminating software

The simplest method is to use the Lamination Software to generate .gcode files ready for the user to change the printer filament at the right time. In this way, pieces of various colours or materials can be printed.

In this case, multi-colour printing will be limited to full layers. That is, each isolated layer will be a single color (there will not be two colors per layer). It is very important to take these limitations into account when designing the piece.
To use this method, it is recommended to use Ultimaker Cura, one of the most popular free software nowadays; although it is possible to perform the process with other laminating software without problems.

1. To begin, you must import the chosen design into Ultimaker Cura.
2. Once opened, you must adjust the parameters according to the material to be used in the printing of the piece.
3. At this point, you must find out at what height or in what layer you want to change the color/material.
4. Once this information is obtained, go to Extensions>Post Processing>ModifyGcode and press Add Command Sequence>Pause at height.
5. In the pop-up window you must choose pause by layer or by mm. Depending on the design chosen, it will be more convenient to use one command or the other. In any case, the number we include in the box will correspond to the layer or height at which the change of filament will be made.
   
   The term Park Print Head X/Y refers to the coordinates to which the Hotend should be directed at the time of the break. It is recommended to use the coordinates 0/0 (Home) to facilitate the filament change.
   
   In addition, the retraction parameters, retraction speed and Extrude Amount must be set. The first two will depend on the material used, while for the last one, it is recommended to set about 5 cm; which will correspond to the amount of filament to be extruded after changing the filament, before resuming printing.

Image 2: Cure interface. Source: Ultimaker Cura.

This method would not be viable for printing a complex part that requires support material (ABS + PVA). If different materials are to be used, the degree of adhesion between them must be taken into account. If the adhesion is not sufficient, the part will separate sooner or later in the bonding layers between materials.

Using an external device

The laminator software method has certain limitations and requires user participation during the printing process to change material; it is not an automatic process.

To solve this problem, Mosaic Manufacturing has developed a device that allows printing with up to 4 different colors or materials: Mosaic Palette. In this case, it is possible to include up to 4 different colours or materials in the same layer.

Mosaic Palette bases its operation on the combination of up to 8 strands in one continuously. 

To facilitate the operation and usability of Mosaic Palette 3 and Mosaic Palette 3 Pro, Mosaic Manufacturing has developed its own laminating software in parallel: Canvas.

By importing a design into Canvas, areas of different colours/materials can be easily and intuitively marked and differentiated, just like colouring. In this software, you can also create the profiles of the different materials you want to use.

Mosaic Palette 3 and Mosaic Palette 3 Pro recognize and calculate the quantity of each filament of each colour/material that needs to be used in each layer.

How does it work?

To carry out the printing process, Mosaic Palette 3 have four filament inputs, and Mosaic Palette 3 Pro have eight filament inputs (each with its own extruder and filament sensor).

Once the filament is fed into each extruder, it is directed to the cutting system, which consists of a rotary cutter that cuts the filament into the exact length required according to the Canvas lamination program.

After the filament is cut, the material is joined to the one to be continued thanks to the Splice Core, a resistance that joins the materials.

Image 3: Junction between two filaments. Source: Mosaic.

When the filament pieces are joined, they pass through a cooling zone and go through the Scroll Wheel, an adjustment wheel that ensures a correct diameter along the whole filament.

What materials can you use?

Mosaic Palette 3 and Mosaic Palette 3 Pro can use the same material in up to 8 different colours, but they also allow different combinations of materials.

The following table shows some of the possible material combinations and their degree of difficulty. In some cases it is indicated that the combination of materials is "Experimental"; this means that it cannot always be carried out successfully, but that there are users who have successfully printed projects with these materials.

In addition, Mosaic makes available a great deal of information and resources in the support area of its website.

Among these resources, you can find recommended configurations for joining different material strands, complete material compatibility charts, or resolution of the most common problems.

Always keep in mind that the optimal print configuration is different for each printer, so the values Mosaic shares are only a guide. If you have a good printing configuration with a particular media, it is recommended that you use this configuration if you combine strands of this media.

Mosaic Palette also has a space on the Thingiverse platform, where it periodically uploads designs adapted to the use of various colours/materials with Mosaic Palette.

Image 5: Design suitable for free download. Source: Thingiverse.

Both for the final results and for the free service and resources offered, Mosaic Palette 3 and Mosaic Palette 3 Pro are a very interesting option for those users who want to print with several colors or experiment with 3D printing of several materials with their single extruder FDM 3D printers.