Multiple Extrusion

Smoothie can handle up to 3 extruders (6 defined axes is the maximum the memory can handle).

To add extruders, simply add Extruder (controlling the extruder motor) and TemperatureControl (controlling the hotend) modules to the configuration file for each new extruder.

The default build of Smoothie only supports 2 extruders (5 axes). If you need 3 extruders, you need to compile with make AXIS=6.

Hardware Requirements

For each extruder, you will need:

  • One temperature input for the hotend. Smoothieboard has 4 thermistor inputs, allowing for one heated bed and three hotends, or four hotends and no bed. Additional hotends can be added using thermocouple external boards connected to the SPI port.

  • One MOSFET output: Smoothieboard has 6 MOSFET outputs that can be used for hotends. External MOSFETs or SSRs can be wired to any free GPIO pin for additional outputs.

  • One stepper motor driver: Smoothieboard has 5 drivers, with 3 needed for 3-dimensional movement. Additional drivers can be wired using free GPIO pins.

Assuming a heated bed is used, two extruders can be driven with the on-board Smoothieboard. For three extruders, one external stepper motor driver is needed, and so on.

Configuration

The default configuration is for a single extruder. To set up a second one, use the “module generation” syntax as seen in the TemperatureControl and Switch modules.

Extruder Module Configuration

Here is an example configuration for two extruders:

# Extruder module configuration
extruder.hotend.enable                          true
extruder.hotend.steps_per_mm                    140
extruder.hotend.default_feed_rate               600
extruder.hotend.acceleration                    500
extruder.hotend.max_speed                       50
extruder.hotend.step_pin                        2.3
extruder.hotend.dir_pin                         0.22
extruder.hotend.en_pin                          0.21
delta_current                                   1.5

# Second extruder module configuration
extruder.hotend2.enable                         true
extruder.hotend2.steps_per_mm                   140
extruder.hotend2.default_feed_rate              600
extruder.hotend2.acceleration                   500
extruder.hotend2.max_speed                      50
extruder.hotend2.step_pin                       2.8
extruder.hotend2.dir_pin                        2.13
extruder.hotend2.en_pin                         4.29
epsilon_current                                 1.5

Replace your current extruder configuration with this in the config file.

Temperature Control Configuration

Also, configure an additional TemperatureControl module for the hotend.

Example configuration for two hotends:

# Temperature control configuration
temperature_control.hotend.enable            true
temperature_control.hotend.thermistor_pin    0.23
temperature_control.hotend.heater_pin        2.7
temperature_control.hotend.thermistor        EPCOS100K
temperature_control.hotend.set_m_code        104
temperature_control.hotend.set_and_wait_m_code 109
temperature_control.hotend.designator        T0

# Second hotend configuration
temperature_control.hotend2.enable            true
temperature_control.hotend2.thermistor_pin    0.25
temperature_control.hotend2.heater_pin        1.23
temperature_control.hotend2.thermistor        EPCOS100K
temperature_control.hotend2.set_m_code        104
temperature_control.hotend2.set_and_wait_m_code 109
temperature_control.hotend2.designator        T1
Do not copy/paste the examples without understanding and adapting them to your specific setup. Tip: For two extruders going into one hotend, set up two extruder modules and one temperature control module. Ensure the temperature control is named differently from the extruder modules.

Wiring

The first extruder is wired to M4, the second to M5.

For more extruders, external stepper motor drivers are needed. Refer to the 3D printer guide for more information.