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Configuration

After installing Happy Hare firmware, there are some configurations you need to go through before printing in multimaterial.

Filament Sensors

Required Sensors

To use the 3MS, you'll need a filament sensor somewhere between your Y-splitter and printer extruder.

There are two options for this sensor:

Assuming you already have one installed, you can configure it in mmu_hardware.cfg.

Locate the [mmu_sensors] section near the bottom of mmu_hardware.cfg.

Extruder/Toolhead Sensors

To configure an extruder entry sensor (a sensor right before your extruder), set your extruder_switch_pin:

Don't know where to find a sensor?

If you don't know where to find a good sensor for your printer, here are a few tips:

Don't know your sensor pin?

If you don't know your sensor pin, and it's already configured with Klipper, locate your sensor configuration (usually filament_switch_sensor) and note the sensor_pin.

mmu_hardware.cfg
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[mmu_sensors]
...
extruder_switch_pin: <SOME PIN>

To configure your toolhead sensor (a sensor right after your extruder), set your toolhead_switch_pin the same way as you set your extruder_switch_pin.

Shared Gate Sensor

Moving backwards from the extruder, the next possible sensor you may have installed is a shared gate sensor. This goes right after the Y-splitter.

If you have a gate sensor installed, set your gate_switch_pin:

mmu_hardware.cfg
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[mmu_sensors]
...
gate_switch_pin: <SOME PIN>

Pre/Post Gate Sensors (Optional)

If you have a filament sensor before or after each of your 3MS filament units, configure a pre_ or post_gate sensor.

Pre-Gate

Pre-gate sensors go before each of your filament units. Configure each of these:

mmu_hardware.cfg
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[mmu_sensors]
pre_gate_switch_pin_0: <SOME PIN>
pre_gate_switch_pin_1: <SOME PIN>
pre_gate_switch_pin_2: <SOME PIN>
pre_gate_switch_pin_3: <SOME PIN>

Post-Gear

Post-gear sensors go after each of your filament units. Configure each of these:

mmu_hardware.cfg
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[mmu_sensors]
...
post_gear_switch_pin_0: <SOME PIN>
post_gear_switch_pin_1: <SOME PIN>
post_gear_switch_pin_2: <SOME PIN>
post_gear_switch_pin_3: <SOME PIN>

Existing Sensors

Before moving on, ensure all your existing filament_switch_sensor and filament_motion_sensor sections are commented out or deleted. Leaving this enabled will lead to unintended issues later on.

Endstops

There are two main endstops you need to setup in Happy Hare firmware for loading and unloading of filament.

Gate Homing Endstop

When homing filament (checking if it is present), you have three options for the sensor to be used:

  • mmu_gate Use the shared gate sensor after the Y-splitter
  • mmu_gear Use the individual post-gate sensors.
  • extruder Use the extruder entry sensor.

Select one of the three options in gate_homing_endstop, located in mmu_parameters.cfg.

Extruder Homing Endstop

Happy Hare also needs a reference sensor inside the toolhead. You have two main options for this:

  • extruder Use the extruder entry sensor.
  • none Don't home inside the extruder.

Select one of those options in extruder_homing_endstop in mmu_parameters.cfg.

Advanced Options

Happy Hare does support three additional advanced options for this endstop:

  • filament_compression Use a sync-feedback sensor like TurtleNeck as a homing endstop
  • collision Use StallGuard on the printer's extruder.
  • mmu_gear_touch Use StallGuard on the 3MS's extruder.

Note that since I don't use these options, I won't be able to help much with these options.

Distances

There are many key distances to set up in Happy Hare firmware. All the distance parameters are located in mmu_parameters.cfg.

Homing Distance

Firstly, configure the maximum distance Happy Hare should attempt to load filament to the homing sensor, before "giving up" and deciding that the spool is empty. This should usually be ~150% the distance from your filament parking position to the sensor.

Note

If you use post-gear endstops (mmu_gear), this uses the gate_preload_homing_max parameter.

This parameter is called gate_homing_max.

Eject Distance

Finally, if you want to switch out which filament is in a filament unit, edit your gate_final_eject_distance. This should be the distance from your parking position to your filament unit gears, plus a small margin.

Speeds

There are many different speeds you can configure with Happy Hare firmware.

These are located in the speeds section of mmu_parameters.cfg (near the top).

Homing Speed

"Homing" is when the HH moves the filament into your extruder entry sensor to ensure they are present. You can adjust the speed at which this happens by editing the gear_homing_speed parameter.

First Load Speeds

Happy Hare allows for slowing down the initial load to deal with additional drag from the filament spool. To adjust this speed, adjust gear_from_spool_speed.

Load/Unload Speeds

To adjust your load/unload speeds during a toolchange, adjust the gear_from_buffer_speed parameter.

Toolhead Distances

There are many key distances to setup in Happy Hare firmware, this time for the measurements of your toolhead. Again, all these parameters are located in mmu_parameters.cfg.

There are three main ways to get any of the following distances:

  • Find configs available online for your toolhead
  • Use CAD models of your toolhead
  • Measure (approximate) yourself with a piece of filament and calipers

Homing Max

toolhead_homing_max is the maximum distance from the gate endstop to your extruder endstop HH will attempt to load filament.

This parameter is only relevant if you use both an extruder entry sensor and a shared gate sensor

Internal Dimensions

There are three main parameters to measure inside your toolhead.

  • toolhead_extruder_to_nozzle

    This is the distance between your extruder gears and the nozzle. If you don't have access to CAD of your printer's toolhead, you can follow the below procedure to approximate it.

    1. Preheat your nozzle to printing temperatures.
    2. Press a piece of filament up against the entrance to your extruder gears.
    3. Using KlipperScreen/Mainsail/Fluidd controls, load the filament in until it barely starts oozing out of the nozzle. Note the total distance traveled. This is your approximate toolhead_extruder_to_nozzle

  • toolhead_sensor_to_nozzle

    This parameter is only relevant if you have a toolhead sensor.

    This is the distance between your toolhead sensor and nozzle. An easy way to approximate this is:

    1. Preheat your nozzle to printing temperatures.
    2. Press a piece of filament up against the entrance to your extruder gears.
    3. Using KlipperScreen/Mainsail/Fluidd controls, load the filament in until it triggers the toolhead sensor. Note the total distance traveled. Set toolhead_sensor_to_nozzle to toolhead_extruder_to_nozzle - <MEASURED DISTANCE>

  • toolhead_entry_to_extruder

    This parameter is only relevant if you have an extruder entry sensor.

    This is the distance between your extruder entry sensor and extruder gears. To approximate this:

    1. Take a scrap of filament and slowly push it into your toolhead until the extruder entry sensor triggers.
    2. Brace a marker against the top of your toolhead and mark the filament.
    3. Push filament further in until it hits the extruder gears.
    4. Put another mark on the filament.
    5. Remove the filament and measure the distance between the two marks. This is your toolhead_entry_to_extruder value.

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