Add mixing extruder support

[matyay]

This PR adds support for color mixing extruders. It is a continuation of #3920 with fixed bugs and added features.

It especially adds automatic retraction processing for mixing extruders as it requires special handling to be done correctly.

[binarylefmart]

Hi @matyay, i tested the Branch but when i put the sample macro on my printer.cfg, this kill my mcu communication, have nothing on klippy.log.
Do you have an idea ?

[matyay]

@binarylefmart Hmm, Can you attach your config and klippy.log? When does the communication with MCU breaks? right from the beginning or when you issue some commands?

[binarylefmart]

https://paste.ofcode.org/DkdYWRHdGPKkvVExP2xxix

here is the file,it's weird it is like klipper lost the serial or have wrong script.

[matyay]

@binarylefmart I've pushed a fix. The original mixing extruder code returned a function object in its status. That probably caused the errors in your log:

  File "/usr/lib/python2.7/json/encoder.py", line 184, in default
    raise TypeError(repr(o) + " is not JSON serializable")
TypeError: <function <lambda> at 0x743c2130> is not JSON serializable

[binarylefmart]

always have the same issue, and have one too when i enable the extended g1 line.

[binarylefmart]

[matyay]

@binarylefmart Yeay, try removing the extended_g1 option completely. It shouldn't be there.

[binarylefmart]

When i remove it like i said, have the mcu issue

[KevinOConnor]

Thanks. My high-level feedback at this time is that we need to implement some architectural changes to Klipper's treatment of extruder stepper motors before we can add enhancements in this area. Currently the klipper extruder config section defines the parameters to a hotend, a heater, a temperature sensor, and an extruder stepper motor. I think we need a more clear abstraction so that it is possible to better control "extruder stepper motors". That work should improve future mixing extruder support as it would not require the user to define multiple dummy "extruder" sections.

-Kevin

[KevinOConnor]

FYI, this architectural work also effects #4489, #4082, and #3920.

-Kevin

[ETE-Design]

Thanks. My high-level feedback at this time is that we need to implement some architectural changes to Klipper's treatment of extruder stepper motors before we can add enhancements in this area. Currently the klipper extruder config section defines the parameters to a hotend, a heater, a temperature sensor, and an extruder stepper motor. I think we need a more clear abstraction so that it is possible to better control "extruder stepper motors". That work should improve future mixing extruder support as it would not require the user to define multiple dummy "extruder" sections.

-Kevin

Is this something you will work on in the feature?

[KevinOConnor]

Thanks. I'm not sure what the state of this PR is. If there is still interest in this topic then the PR will need to be updated and a reviewer will need to volunteer to review it ( https://www.klipper3d.org/CONTRIBUTING.html ). Unfortunately, due to time constraints on my side it is unlikely I will be reviewing this PR.

A good place to discuss this PR, get testers, and engage a reviewer is on the Klipper Discourse server ( https://www.klipper3d.org/Contact.html ).

-Kevin

[matyay]

Hi, I'm willing to continue the work on this feature but I'm short on time right now. Besides that I need to do some work on my 3D printer which has the mixing hotend, otherwise I won't be able to test the code.

[ETE-Design]

@matyay Good to hear that your back, and can work on again mabye in a not so far away future... Really would like to have this feature added to Klipper

[KevinOConnor]

FYI, #5143 makes it possible to call SET_EXTRUDER_STEP_DISTANCE on extruder_stepper objects, which may make it possible to implement mixing extruders via extruder_stepper objects.

-Kevin

[github-actions]

Unfortunately a reviewer has not assigned themselves to this GitHub Pull Request and it is therefore being closed. It is a good idea to move further discussion to the Klipper Discourse server. Reviewers can reach out on that forum to let you know if they are interested and when they are available.

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