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MMX

A complete path from zero to a working multicolor Klipper setup: files, BOM, hardware assembly, wiring, Happy Hare configuration, calibration, first print and support.

v1.0ActiveFinal release packageKlipper

Start build Printables release Community Builds Discord

4 gatesDocumented gate setup

Type-AServo selector architecture

EBB42Reference wiring board

Happy HareKlipper MMU software

Hardware assembly — from printed parts to finished MMX

This is the build order extracted from the MMX assembly manual. It keeps the mechanical sequence readable while leaving the official manual as the source of truth for drawings, fastener callouts and part orientation details.

Finished MMX — front view — Finished MMX multi-material extruder — front, rear and top views.

Finished MMX — rear view — Finished MMX multi-material extruder — front, rear and top views.

1. Prepare and inspect printed parts

Lay out the left/right ears, diffusers, spacers, gates, idler doors, camshaft, camshaft spacer, standoffs, EBB42 sled, rear/front/bottom/left/right panels, and servo/stepper holder.

Do not start assembly if the filament paths are rough, the idler doors bind, or bearings do not seat correctly.

2. Install heat-set inserts

Press the M3 heat-set inserts into the servo/extruder holder first. Then install the inserts in the MMX left side part and the EBB board sled.

Let the plastic cool before inserting screws. If an insert is crooked, fix it now; alignment gets harder later.

M3 heat-set inserts installed in the servo/extruder holder — Heat-set inserts in the servo/extruder holder (left) and EBB42 sled (right).

M3 heat-set inserts in the EBB42 board sled — Heat-set inserts in the servo/extruder holder (left) and EBB42 sled (right).

3. Prepare gate and idler subassemblies

Install the F695 bearings, BMG gear parts, 6×3 magnets and PTFE pieces. The gate magnet and idler magnet must repel each other.

Magnet orientation matters. If the magnets attract instead of repel, the idler behavior will be wrong.

F695 bearing and BMG gear assembly components laid out — Gate components: F695 bearing with BMG gear (left) and idler door magnet orientation (right).

Idler door with repelling magnet correctly oriented — Gate components: F695 bearing with BMG gear (left) and idler door magnet orientation (right).

4. Install pre-gate sensors

Install the limit switch, 5 mm ball and 6×3 magnet in each gate sensor area. Insert a piece of filament by hand and listen/feel for the switch click before continuing.

Pre-gate limit switch installed and wired in the gate body — Pre-gate sensor: installed and wired (left) and assembly position diagram (right).

Pre-gate sensor assembly diagram showing magnet, ball and switch positions — Pre-gate sensor: installed and wired (left) and assembly position diagram (right).

5. Build the T80 gear assembly

Insert the 20T pulley into the printed T80 gear. Attach the printed flower part using the screws and self-thread it firmly into the pulley.

T80 gear assembly with 20T pulley and printed flower attachment — T80 gear assembly complete with 20T pulley seated.

6. Stack gates on the threaded rods

Screw the threaded rods into the side panel inserts. Place the bearing and gear before lowering each gate onto the rods. Add a spacer, then repeat until all gates are stacked.

All four gates stacked on threaded rods with the side panel — Gate stacking: assembled stack on side panel (left) and rod stacking order diagram (right).

Diagram showing the stacking order on threaded rods — Gate stacking: assembled stack on side panel (left) and rod stacking order diagram (right).

7. Add idler doors and shafts

Insert the 5 mm rod through the extruder gears until it rests in the bearing. Then insert the 3 mm rod through the idler doors. Use loose filament in each gate to align the gear before tightening set screws.

Labeled diagram identifying 3 mm and 5 mm rod positions, pulleys and bearings — Shaft and idler installation: labeled rod diagram (left), completed idler assembly (centre) and idler door fitting (right).

Completed idler assembly with all doors, shafts and gears installed — Shaft and idler installation: labeled rod diagram (left), completed idler assembly (centre) and idler door fitting (right).

8. Mount the servo and stepper plate

Place the servo and stepper plate over the threaded rods. Use two M3 nuts, but do not overtighten yet. Leave enough freedom for alignment.

M3 nuts placed loosely on threaded rods for servo and stepper plate alignment — Servo and stepper plate: M3 nut placement (left) and plate positioned over the gate assembly (right).

Servo and stepper plate positioned over the gate assembly — Servo and stepper plate: M3 nut placement (left) and plate positioned over the gate assembly (right).

9. Install the belt idler, servo and stepper

Install the belt idler frame with its bearings. Mount the MG996 servo and NEMA 17 stepper behind the plate. Do not forget the washers for the stepper adjust screws.

Belt idler frame with bearings installed in the frame recesses — Belt idler frame with bearings fitted (left) and MG996 servo with NEMA 17 stepper mounted (right).

MG996 servo and NEMA 17 stepper mounted on the rear plate — Belt idler frame with bearings fitted (left) and MG996 servo with NEMA 17 stepper mounted (right).

10. Install pulleys and belts

Place the 20T pulley on the stepper shaft and align it with the T80 gear. Install the belt, tension it by moving the stepper, and leave only a small amount of slack.

Belt and pulleys overview showing the drive path — Belt and pulley installation: belt and pulley overview (left), tensioned belt (centre) and T20 pulley detail (right).

Belt tensioned with stepper shifted to adjust slack — Belt and pulley installation: belt and pulley overview (left), tensioned belt (centre) and T20 pulley detail (right).

11. Install LEDs and diffusers

Solder the RGB/RGBW LED wires vertically so the LEDs can slide into position cleanly. Install the semi-transparent diffusers for gate status visibility.

RGBW LED wiring prepared and routed for installation — LED installation: wiring prepared (left), solder connections (centre) and LEDs installed with diffusers (right).

LED wires soldered vertically for clean gate insertion — LED installation: wiring prepared (left), solder connections (centre) and LEDs installed with diffusers (right).

12. Final mechanical inspection

Before wiring/software, manually check that every gate moves, every idler returns, filament slides through each path, belts are aligned, and no printed part rubs where it should not.

MMX filament path showing inbound and exit sides for each gate — Filament path reference — inbound and exit sides of the MMX.