Issue adding 3rd extruder

Controllers Smoothie
1

I’m adding a third extruder to my printer. I am currently using all five built-in motor controllers so I’ve added an external motor control board as per the documentation. I added the following section to my config file as per the docs to enable the third extruder, but after I add this and reboot the Smoothieboard no longer boots up or responds. It gets stuck somewhere near initialization. I must be doing something wrong. Any suggestions?

Thanks.

-larry

  1. Third extruder module configuration

extruder.hotend3.enable true # Whether to activate the extruder module at all. All configuration is ignored if false
extruder.hotend3.steps_per_mm 293 # Steps per mm for extruder stepper
extruder.hotend3.default_feed_rate 200 # Default rate ( mm/minute ) for moves where only the extruder moves
extruder.hotend3.acceleration 100 # Acceleration for the stepper motor, as of 0.6, arbitrary ratio
extruder.hotend3.max_speed 50 # mm/s

extruder.hotend3.step_pin 1.31 # Pin for extruder step signal was 2.8
extruder.hotend3.dir_pin 1.30 # Pin for extruder dir signal was 2.13
extruder.hotend3.en_pin 1.22 # Pin for extruder enable signal was 4.29

extruder.hotend3.x_offset 0 # x offset from origin in mm
extruder.hotend3.y_offset 0 # y offset from origin in mm
extruder.hotend3.z_offset 0 # z offset from origin in mm

zeta_current 1.5 # Third extruder stepper motor current

Imported from wikidot

2

Ok I figured out the problem. In the firmware MAX_ROBOT_ACTUATORS is set to 5. Adding a 3rd extruder makes the total number of actuators 6, thus causing an error.

I’m testing a recompile with it changed to 6. Dunno if it will work.

The documentation should really be changed to say that the total number of motors cannot currently exceed 5 without changing the firmware.

3

FYI the documentation on adding multiple extruders should probably be updated/fixed. Currently it says this:

“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 ).”

(look at the smoothieware dot org slash extruder page)

That is incorrect. With the current firmware you can only have a total of 5 motors without making changes to the firmware itself. I am currently testing whether you can simply change MAX_ROBOT_ACTUATORS in the firmware and recompile without adding side-effects, but at a minimum I’m sure it is eating up more memory. I’m sure there is a hard memory limit to the number of actuators regardless. It would be better to know exactly how many you can add and having a clear process to make that firmware change when you need to.