**** This project requires modifications to the system files. Please proceed with caution and follow these instructions carefully and at your own risk. I am not responsible for any damage to your printer. ****

*** Please make a backup of your EMMC before proceeding. At least you should make backups of Macro.cfg, plr.cfg and printer.cfg in directory: /home/sovol/printer_data/config/ 

You should also make a backup copy of filament_switch_sensor.py in directory: /home/sovol/klipper/klippy/extras

Adding FLY LLL Plus filament feeder/buffer to SV08 Max

I wanted to replace the noisy auxiliary feeder/buffer that came with my Sovol SV08 Max. I chose Mellow3d Fly LLL Plus filament buffer. It has a built-in filament runout sensor. It is low-cost; you can also buy it fully assembled or as a kit and print the case in any color you like. I also purchased their FLY MDM, a filament-runout-and-clog sensor. MDM also comes either fully assembled or as a kit. 

If you choose to go with the kit, Mellow3D has assembly videos on its YouTube channel. 

I bought both directly from Mellow3D, though you can buy them from other outlets as well.

FLY LLL Plus: https://3dmellow.com/products/mellow-lll-plus-filament-buffer-for-diy-3d-printers-klipper-rrf-marlin-material-break-detection-automatic-filament-feeding

FLY MDM: https://3dmellow.com/products/mdm?VariantsId=10252

NOTE: Make sure you get FLY LLL Plus and not the cheaper FLY LLL, or LLL AZ. The latter two have a motor that needs to be replaced every 200 hrs of printing and will not work with my setup here.

These units are open source and fully programmable. The full documentation, wiring instructions, and sample codes are provided here:

FLY LLL PLUS: https://mellow.klipper.cn/en/docs/ProductDoc/ExtensionBoard/fly-buffer-plus/

FLY MDM:  https://mellow.klipper.cn/en/docs/ProductDoc/ExtensionBoard/fly-mdm/

Here, I provide one mounting plate for the buffer and two mounting options for the sensor; you can choose either. They both function the same just a different look!

In order to use the FLY buffer, we need first to DELETE the Sovol Auxiliary Feeder. Here are the steps:

1- Comment out the [include buffer_stepper.cfg] in printer.cfg

2- We need to comment out any reference to the functions related to the Feeder. These Macros are called/referenced in three files: Macros.cfg, plr.cfg, and filament_switch_sensor.py. I've included the three files here with appropriate sections commented out. These are OEM-provided files that came with my SV08 Max.

*** Use them at your own risk.***

*** Rename your original files before copying these files over. That way you have a backup to revert to if things don't work right ***

*** Please note: any future firmware upgrade will, in all likelihood, replace these files.***

Macro.cfg and plr.cfg should replace the ones with the same name in:

/home/sovol/printer_data/config/

filament_switch_sensor.py should replace the file with the same name in:

/home/sovol/klipper/klippy/extras/

3- Now, Sovol's auxiliary buffer can be safely disconnected. 

 FLY buffer is a 24DCV device like Sovol's buffer. So we can use the same wires. Either cut the connector and use black and red wires to power the FLY buffer, or you can make your own connector using a female Molex Micro-fit MX3.0-2x2P connector. https://a.co/d/0h5bVF9H

On the other end, you would need a female JST-XH 2.54mm connector. https://a.co/d/0cCYa5Lv

Alternatively, you can bring the 24DCV from either the printer's power supply or other available pins on the MCU.

If you don't need any other functionality and just want a passive filament buffer, that's it! You're done.

If you want to have a filament runout sensor as well, you need another wire to go from FLY buffer to the printer's MCU. 

I connected this white wire to the PB2 connector on the MCU. Please refer to the MCU pinout diagrams included in the "other files" tab of the download section. 

Please note: By drawing power from the MCU, I created a common ground between the printer and the buffer. Therefore, I could just connect the signal to PB2 by itself. However, if you use an external power supply to power the buffer, you would also need to connect the buffer's ground to GND on the PB2 connector.

You need a section like below in your printer.cfg:

### FLY MDM =================================
[filament_switch_sensor FLY_filament_sensor]
pause_on_runout: FALSE
switch_pin: ^PB2   # Please replace with the actual pin you are using
runout_gcode:
    M117 Filament runout detected, printing paused
    RESPOND MSG=“Filament runout detected, printing paused”
    PAUSE
insert_gcode:
    M117 Filament inserted
    RESPOND MSG=“Filament inserted”
event_delay: 2.0    # Event trigger delay (seconds)
pause_delay: 2.0     # Pause command delay (seconds)
### FLY MDM =================================

***OPTIONAL***

Adding FLY_MDM filament runout and clog sensor

There are 2 ways for MDM to be added to the SV08 Max:

Method 1:

FLY_MDM can be connected to FLY_LLL_Plus using a cable which is terminated at the MDM side with a 4-pin JST-XH 2.54mm and at the buffer side with a 6-pin JST-XH 2.54mm connector, as seen in the figure below:

With this setup, the connection from LLL Plus to the printer stays the same as above. This means that while the MDM issues the trigger for filament runout and/or filament clog, these signals are passed to the buffer, which, in turn, issues the "filament runout" signal to the printer, as in the example above, to PB2. 

The printer.cfg code block stays the same as above.

Method 2:

FLY_MDM can connect directly to the printer,  bypassing FLY_LLL. For this configuration, you must not have the FLY_LLL runout signal sent to PB2 (the white wire to PB2 in the example above should be disconnected). The buffer would act as a passive buffer/feeder. Instead, the FLY_MDM sends distinct signals to the printer, one for filament runout and the other for clog (or filament entanglement). Here is the connection cable that you need: On the MDM side, you will have a 4-pin JST-XH 2.54mm connector, and on the printer's side, you will have (2) 3-pin JST-XH 2.54mm connectors, as shown below:

You need the following code section in your printer.cfg:

### FLY MDM =================================
[filament_switch_sensor FLY_filament_sensor]
pause_on_runout: FALSE # we will pause with runout_gcode
switch_pin: ^PB2   # Please replace with the actual pin you are using
runout_gcode:
    M117 Filament runout detected, printing paused
    M118 Filament runout detected, printing paused
    PAUSE
insert_gcode:
    M117 Filament inserted
    M118 Filament inserted
event_delay: 1.0    # Event trigger delay (seconds)
pause_delay: 0.5     # Pause command delay (seconds)

[filament_motion_sensor FLY_motion_sensor]
switch_pin: PE7       # Replace with the pin you are using, connected to the filament clog detection pin.
detection_length: 3.5 # Minimum distance to trigger a state change on the switch_pin.
extruder: extruder
The extruder associated with this sensor.
This parameter must be provided.
pause_on_runout:
runout_gcode:
    M117 Filament Clog
    M118 Filament Clog
    PAUSE
event_delay: 3.0
pause_delay: 1.0
FLY MDM =================================

The detection_length: 3.5 is from the official MDM manual. The distance from the MDM module to the extruder greatly influences this value. You need to experiment with this value and determine the best for your setup.

Tip: On my printer the optimal detection_length is 12.5mm.

Any detection_length <= 10mm  often gives me false clogging trigger.

---

BOM:

• 4 Threaded inserts, M3X4mm(H)

• 4 M3x8mm screws

• Molex Micro-fit MX3.0-2x2P conector. https://a.co/d/0h5bVF9H

• JST-XH 2.54mm connector. https://a.co/d/0cCYa5Lv

**** This project requires modifications to the system files. Please proceed with caution. Though it worked for me, there's no guarantee it will work for you. I am not responsible for any damage to your printer. ****

You can check out my other models at:

https://www.printables.com/@Toy_Maker_3184077/models

Your “likes” and “boosts” are appreciated.

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A great thank you to @3DPrintDemon for figuring out the unpublished pins on the MCU and Extra_MCU.