Extruder module

Extruders are used to push plastic filament thru a hotend, to achieve the awesome feat of 3D Printing.

This module controls the motor that pushes the filament, it does not take care of the hotend itself, which is the job of TemperatureControl.

The most important parameter to get your extruder module to work properly, is extruder.module-name.steps_per_mm.

You can create as many Extruder modules as you want, as long as you give them different module names. You can name those modules whatever you want ( as long as you stick to only alphanumerical characters ).

Configuration

All options

All of the options currently supported by the Extruder module : 

Steps per millimeter

The number of steps on the stepper motor drivers smoothie needs to generate if it wants to move the filament 1 millimeter.

This value depends on your stepper motor, the microstepping on your stepper motor drivers, the gear reduction ratio on the extruder assembly if any and the diameter of your hobbed pulley/bolt.

A very good guide on how to find this value can be found here : http://reprap.org/wiki/Triffid_Hunter%27s_Calibration_Guide#E_steps

extruder.hotend.steps_per_mm                        140

Filament diameter

This is an optional parameter for those who want to use volumetric extrusion, but are too lazy to do their own math. ;) Simply enter the machine's filament diameter here and set your slicer's filament diameter to 1.128379mm ( 2*sqrt(1/pi) ) and enjoy portable gcode! Further explanation can be found in Triffid_Hunter's guide, linked above.

extruder.hotend.filament_diameter                   3.0

The filament diameter can also be saved at run time with this M code

and saved with M500.

Firmware Retract

G10/G11 will cause the filament to retract and unretract, this option can be set in most current slicers.

The amounts of extrusion and speed can be set with the following M codes

or can be set in config with the following settings…

extruder.hotend.retract_length                  3               # retract length in mm
extruder.hotend.retract_feedrate                45              # retract feedrate in mm/sec
extruder.hotend.retract_recover_length          0               # additional length for recover
extruder.hotend.retract_recover_feedrate        8               # recover feedrate in mm/sec (should be less than retract feedrate)
extruder.hotend.retract_zlift_length            0               # zlift on retract in mm, 0 disables
extruder.hotend.retract_zlift_feedrate          6000            # zlift feedrate in mm/min (Note mm/min NOT mm/sec)

These can be set differently for each extruder defined.

Pins

As all stepper motors, the extruder stepper motor needs 3 pins to be controlled : step, direction and enable (Pin Reference):

1st Extruder (delta)

extruder.hotend.step_pin                     2.3
extruder.hotend.dir_pin                      0.22
extruder.hotend.en_pin                       0.21

2nd Extruder (epsilon)

extruder.hotend2.step_pin                     2.8
extruder.hotend2.dir_pin                     2.13
extruder.hotend2.en_pin                      4.29

Advanced pin configuration

You can have a pin's output inverted by adding a "!" after this pin's number in the config line, example :

my_pin_name                      19!

There are other modifiers for pins :

Current

On boards which feature current control of the stepper motor drivers ( Smoothieboard or 4pi ), you have to set that value for the extruder too.

This is handled by the Currentcontrol module, but usually, the line for the configuration of a given stepper motor is written along with it's pins, for clarity.

delta_current                                1.5

Set the value to the exact value your stepper motor is rated for ( or less, for less noise, but less torque ).

Setting the current to a value higher than the recommended one causes overheating, and skipped steps.

G-code

Here are the G-code commands currently supported by the Extruder module : 

• G0/G1 : Move to the given coordinates. The F parameter defines speed and is remembered by subsequent commands ( specified in millimetres/minute ) (command is modal)
• G10 : Do firmware extruder retract
• G11 : Do firmware extruder un-retract
• G90 : Absolute mode ( default ) : passed coordinates will be considered absolute (command is modal)
• G91 : Relative mode : passed coordinates will be considered relative to the current point (command is modal )
• G92 : Set current position to specified coordinates
• M17 : Turn the active stepper motor driver's off
• M18 : Turn the active stepper motor driver's on
• M82 : Set absolute mode for extruder only
• M83 : Set relative mode for extruder only
• M84 : Turn the active stepper motor driver's on
• M92 : Set this axis' steps per millimetre. For example M92 E100 to set for the currently active Extruder, and M92 E100 P2 to set for the second extruder.
• M114 : Displays XYZ position, as well as the E position of the currently active Extruder
• M200 : Set E units for volumetric extrusion - D<filament diameter> set to 0 to disable volumetric extrusion, for example : M200 D3.0 to set for the currently active Extruder, and M200 D3.0 P3 to set for the third Extruder.
• M203 : Set maximum rate for axis, set E for Extruder axis or V for volumetric extrusion limit, for example : M203 V10 will limit extrusion moves to no faster than 10mm^3/s. M203 V0 disables.
• M204 : Set acceleration in mm/sec^2, E<nnn> sets extruder only move acceleration, for example : M204 E500. P selects the extruder, uses the currently active extruder if omitted.
• M207 : Set retract length S[positive mm] F[feedrate mm/min] Z[additional zlift/hop] Q[zlift feedrate mm/min], for example : M207 S4 F30 Z1
• M208 : Set retract recover length S[positive mm surplus to the M207 S*] F[feedrate mm/min], for example : M208 S0 F8
• M221 : S<flow rate factor in percent> : Set flow rate factor override percentage for current extruder
• M500 : Save volatile settings to an override file
• M503 : Display volatile settings