Getting Started with Tradrack¶

This walks through the initial menuconfig pass for a Tradrack MMU — the screens you’ll see, in the order you’ll see them, and the few choices worth pausing on. Tradrack is deceptively simple: it relies on a single shared gate (entry) sensor and forgoes pre-gate sensors or LED extras, focusing instead on fast, reliable filament handling rather than bling. Other sections cover toolhead calibration and multi‑unit setups. Here the goal is simply to get a Tradrack installed and up and running with Klipper.

Menuconfig Installer¶

From your Happy-Hare checkout/directory:

./install.sh

If this is the very first time you've run ./install.sh, there's no .mmu_config yet, so the installer drops you straight into the interactive menuconfig mode — no separate -i flag needed.

This is the installer's default state: MMU Type is Custom Design, the board is unknown, and the CONFIG WARNINGS / ERRORS panel at the bottom lists exactly that — four things still need a decision. As soon as you pick a real MMU type, most of these clear themselves.

Choosing the MMU type¶

Highlight MMU Type and press Enter. Move down to Tradrack and press Space to select it. Once selected (X) Tradrack, four new options appear indented underneath — Number of gates/lanes, Selector servo type, Project Options and Design attributes — options that only make sense once Happy Hare knows this is a Tradrack. Other settings and options are also enabled based on the MMU design choice.

Enter Number of gates/lanes to match your setup. Tradrack is a modular Type-A MMU design with support for as few or many lanes as you can accommodate in your build. The default is 10, but you can change it to any number from 1 to Happy Hare's maximum of 20.

Next select the Selector servo type. Common options are provided - Feetech FT1117M (default) for people who sourced their servos in the US, the JX PS-1171MG Aliexpress alternate and Not listed if you have a different servo. Servo settings such as min/max pulse widths, etc. are managed using (Top) → Other Settings → Selector servo options later in the menuconfig flow.

Next, review applicable Project Options. If you added an optional Binky encoder, you can select and enable this here.

Back out twice (Esc, Esc) to return to the top menu, and review the warnings panel again. Three of the four warnings are already gone. The one that's left — "Toolhead type is 'other'" — is exactly what it sounds like: Happy Hare still doesn't know your toolhead, and that's covered in a different getting-started page. Don't worry about it here.

Board type¶

Enter Controller Board type. Because you’ve already told the configurator this is a Tradrack, Happy Hare pre‑selects Mellow EASY-BRD v1.x with CANbus — a popular controller choice for Tradrack builds. If your Tradrack runs a different board like an original or RP2040 based EASY-BRD, this is where you’d choose it; default pins for steppers, sensors, and TMC drivers throughout the rest of menuconfig are derived from whatever controller you select here.

MCU connection¶

Esc and back out to the top menu and open MCU connection. Tradrack defaults to USB serial, but if your setup uses CANBus, select CAN instead. The installer attempts to auto‑detect USB serial device IDs and CANBus UUIDs where possible for you to choose from. Unfortunately, if Klipper has previously claimed the CANBus device, UUID's can’t be rediscovered easily unless you remove all references from your klipper Happy Hare configuration and power cycle the printer.

If you’re unsure of the USB serial or CANBus UUID's when migrating to v4, you can check your saved mmu.v3/base/mmu_hardware.cfg configuration or klippy.log for the claimed device entries. The installer will then prompt you for your serial device or CANBus UUID, depending on the option selected.

Existing connection selections/mapping are retained and not overwritten once saved.

The first discovered serial device is selected by default. Press enter to choose a different discovered device.

In this example, we are going to switch to CANBus. Open MCU connection and select CANbus:

A list of discovered CANBus UUIDs is shown. If more than one device is found, select the one that corresponds to your Tradrack controller. If only one device is detected, it will be selected automatically. If no UUIDs are discovered, choose Other / manually entered and enter the correct CANBus UUID manually.

Pins: gear and selector direction¶

Esc and back out to the top menu and open Pins / TMC, then Gear pins. GPIO Pin defaults are set based on your MCU controller board and Tradrack MMU selection. Review all pin settings for Gear and Selector steppers to make sure they are correct for your build. Gear direction especially is the one setting that is impossible to set correctly by default or guessing and depends on how the stepper cable is actually wired. You will validate this later when you buzz the steppers to verify their direction in Stepper direction and homing. This is where you would change the stepper direction if needed.

If the stepper spins the wrong way, you can invert it here without rewiring or hand-editing the configuration. Highlight the Gear dir pin for the stepper and press Enter to open its editor. If that stepper needs reversing, add a ! in front of the pin name — Klipper's standard way of inverting a pin's polarity.

Repeat this for the selector stepper.

Shared Exit Sensor (Gate Sensor)¶

Happy Hare requires one viable gate sensor — either a switch or an encoder. Most Tradrack builds use a single shared exit (gate) sensor to detect filament presence, and this is all Happy Hare needs for a basic setup. If your Tradrack uses a Binky Encoder, you may not have installed this sensor and can disable it by switching the Gate homing endstop to Encoder Movement in the Endstops and Bowden movement menu. Even with a Binky encoder, the gate sensor is still highly recommended, as it reacts much faster and significantly speeds up load and unload operations when set as the Gate homing endstop. This guide assumes you have a gate sensor installed.

Picking a toolhead¶

From the top menu, select Toolhead. This step is optional — if you skip it, Happy Hare falls back to generic Other/Unknown default dimensions, which is a perfectly fine starting point. But if your toolhead (extruder + hotend combo) appears in the list, selecting it gives you real, community‑contributed measurements instead of generic estimates. Here we’ve chosen A4T WWBMG for A4T Dragon Ace to illustrate.

Esc to backout to the top menu and select Toolhead sensors/settings. This is where you can enable other features such as Toolhead cutter, toolhead and extruder entry sensors if fitted. The community-contributed measurements for Extruder entrance to nozzle and Residual filament, under Toolhead dimensions, can be reviewed and tuned if necessary. For A4T WWBMG for A4T Dragon Ace, the values are88 and 36.5.

The other two distances Happy Hare can use (Toolhead sensor to nozzle & Extruder sensor to entry) only appear when you have enabled the sensors and remain hidden when disabled.

This is a shortcut, not a substitute: even with community-sourced toolhead measurements, it's useful to learn how to measure and calibrate your own eventually, since small build variations and mods add up. But it's a genuinely good starting point. If your exact combo isn't listed, select Other/Unknown and follow the manual calibration MMU_CALIBRATE_TOOLHEAD process.

MMU Features / Additions¶

Optional Tradrack features can be enabled or disabled based on your Tradrack build here. Tradrack is a deceptively simple, modular design with a basic set of out-of-the-box features. Popular community contributed extensions like Sync-feedback buffers (sensors) such as Annex Belay or more recent analog Proportional Sync Feedback sensors, Encoder, etc. can be enabled here.

Validating Hardware setup & initial calibration¶

The Hardware Validation checklist covers the MCU, selector variants, encoder and the movement/homing model in more detail. The guide below calls out the Tradrack specific hardware and initial calibration needed.

Selector servo¶

Tradrack includes a 3D printed servo tool to help orientate the servo arm correctly on the shaft before securing. With the servo removed (not unplugged) and arm unattached, set the servo angle to 0 (MMU_SERVO ANGLE=0), power down and use the tool to position and secure the servo arm in the correct position trying not to move the servo as you do. Install the servo, and power up so you can validate servo angles.

1. Disable steppers (MMU_MOTORS_OFF).
2. Move the servo to the up position (MMU_SERVO POS=up).
3. Line up the selector with a gate until you can insert a short piece of filament though the gate and into the selector.
4. Issue the following commands to validate the servo angles and expected results:

Servo angles can be adjusted dynamically using MMU_SERVO ANGLE=<angle>. To save the angle into the mmu/mmu_vars.cfg persistent state file, issue MMU_SERVO POS=<position> SAVE=1 when you are happy with the angles e.g. MMU_SERVO POS=up SAVE=1.

Stepper direction and homing¶

• Buzz the gear stepper to identify the correct stepper moves (MMU_TEST_BUZZ_MOTOR MOTOR=gear). Power down and swap the stepper cables over or update gear stepper pin settings in menuconfig if the incorrect stepper moves - whichever is easiest.
• Disable the steppers (MMU_MOTORS_OFF) and move the selector away from the homing end stop.
• Buzz the selector stepper to identify it's direction. It should initially move to the right when you issue MMU_TEST_BUZZ_MOTOR MOTOR=selector. If it moves to the left, update and invert the selector stepper dir pin in menuconfig (e.g. add or remove the !) in front of the pin.
• Once the steppers are moving in the correct direction, issue MMU_HOME to home Tradrack. The selector should move to the homing endstop (on the left) and home the MMU.

Selector calibration¶

Issue MMU_CALIBRATE_SELECTOR AUTO=1 to calibrate the selector and inter-gate spacing. Depending on your build and homing end-stop offset, if the gate spacing isn't CAD perfect or tightly butted up against each other, you "may" need to manually calibrate the selector position and offsets for each gate - refer to MMU_CALIBRATE_SELECTOR for details.

Shared exit sensor¶

When filament isn't present, the mmu_shared_exit sensor should report as Open. Insert a short piece of filament into gate 0 after homing (MMU_HOME) until it triggers the Tradrack gate sensor. If it's working correctly, mmu_shared_exit should report as Triggered and Open when removed.

Use the foldoc/GettingStarted-Tradrack.mdlowing command to verify or use the Mainsail/Fluid sensor status.

MMU_SENSORS

mmu_shared_exit       --> Open

Checking Basic Operation¶

That's it, you should now be able to load and unload filament using your Tradrack MMU. The bowden length will be automatically calibrated the first time you attempt to load filament (autocal_bowden_length: 1 setting) using collision based homing by default, extruder sensors, or compression / proportional sync feedback sensors if defined and set as the extruder homing endstop in menuconfig.

Outside of a print, confirm the basics work end to end (if using ASB/ASA, preheat the extruder to an appropriate temperature as the default minimum preheat temperature is 210°C).

Issue the following commands to validate the basic load/unload operation:

MMU_SELECT GATE=0
MMU_LOAD
MMU_UNLOAD

Each command should complete without error — no pauses, no "not calibrated" warnings you weren't expecting. If something goes wrong here, it's much easier to diagnose now than mid-print; see Operation: Debugging Problems if any of it doesn't behave as expected.

What Next?¶

• Gear Rotation Distance Calibration - It's worthwhile manually calibrating the gear stepper rotation distance to fine tune out-of-the-box defaults as BMG extruder gear manufacturing tolerances do matter, affecting accuracy. As the Tradrack uses a single BMG gear for all gates, it only needs to be calibrated once.
• Tip Forming and Purge to get your Tradrack ready for printing
• Install KlipperScreen (Happy Hare edition) if you want a touchscreen front end, or drive everything from Mainsail / Fluidd — either works, and both are covered.
• From here, explore the rest of this site's Features section one page at a time as you actually need them — Spoolman integration, Toolhead cutter, Blobifier, Shared NFC/RFID reader, EndlessSpool, and the rest. Trying to absorb all of it before your first print is the fastest way to feel overwhelmed by an MMU that, day to day, mostly just works.