Tired of using a single color for your 3D printing? The use of this dual extruder upgrade makes these models more colorful.

The extruder is one of the most important components of a 3D printer, which directly affects the quality and complexity of 3D printing. The idea behind the dual extruder system is to allow 3D printers to print objects with two color schemes. Before delving into the details of the dual extruder upgrade, let's take a look at the working principle of the 3D printing extruder.

The extruder consists of two parts:

Cold end: The cold end is composed of a stepper motor, a gear device, a spring idler that fixes the filament, and a PTFE tube that guides the filament into the hot end.

Hot end: The hot end is the part where the filament is melted and extruded from the nozzle. In the Bowden 3D printer extruder system, the filament feed tube directly inserts the filament into the thermal break through the radiator. Then the molten filament is ejected from the nozzle.

The following paragraphs will guide us how to upgrade a single extruder system to a double Bowden extruder system by adding an extruder motor and filament mixing hot end. The modification will allow us to use two filaments and print unique objects using a two-color scheme.

Related: Turn your cheap 3D printer into a manufacturer's dream

You need to modify the following components.

The upgrade requires the following modifications to the hardware, electronic equipment, firmware, and slicer program.

You can use the models provided on Thingiverse to print additional spool holders according to the frame specifications of the 3D printer, or you can buy universal spool holders online. The assembly of the spool support is quite simple, and the support needs to be screwed to the frame where the spool is installed or bolted. One trick to keep two spools working effectively is to place them parallel to mirror each other.

The extruder assembly is connected to the stepper motor and installed on the top of the frame using the extruder mounting bracket. Thingiverse provides some great stand designs for different 3D printers, which can also be customized according to requirements. The extruder motor components should be similar to the default extruder, and the positioning on the frame is also similar.

The default hot end of the 3D printer will be replaced by The BIGTREETECH Mixed Color 2 Into 1 hot end. This component requires a hot-end mounting bracket, which can be downloaded from here. The fan is screwed on the hot end, and the thermistor wire is connected from the hot end to the controller board. Then connect the PTFE tube from the extruder to the hot end.

Since we need a controller with five stepper motor drivers, if the default board has only four stepper motor driver slots, we will replace our existing board with BIGTREETECH SKR Pro v1.2. The wiring of the extruder stepper motor assembly will be connected to the control board in the fifth slot. If you are not familiar with how to set up the controller board, we will introduce it in detail in the future.

Marlin is the most compatible firmware for 3D printers and supports multiple controller boards. The firmware configuration is quite simple. You only need to make the following changes to the Marlin firmware configuration.h file. You can simply open these files using Visual Studio Code and make the following changes:

Check whether the directions of the two extruders are the same:

Check the current and micro steps of the extruder:

After the firmware is updated, we can perform PID auto-tuning on the new hot end. This can be done through the console, or if the 3D printer has an LCD interface, there is a PID auto-tuning option where you can set the value of the desired temperature and the number of cycles of PID tuning.

The slicer software we will use for the modified printer is Cura, but the upgraded version is compatible with all slicing software, only minor changes to the settings are required. In Cura, we just need to go to settings and add a 3D printer. After adding the printer, go to the machine settings and enter all the values ​​of the printer size. Change the number of extruders to two, and then configure each extruder individually. Finally, import the two-color model from Thingiverse and start printing with the upgraded 3D printer.

The dual extruder upgrade is a detailed modification that requires an intermediate understanding of the use of 3D printers. This is a great learning experience for users who are interested in upgrading a 3D printer and are willing to spend some time adjusting the printer settings.

Using a 3D printer can sometimes be difficult. Let's take a look at some basic FDM 3D printer settings you will encounter while enjoying this hobby.

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