UPDATE:

2023-09-15: Now you can use BAFS (Direct Drive) with Marlin or Klipper.

• Marlin: [https://github.com/yonitjio/openbafs-marlin](https://github.com/yonitjio/openbafs-marlin)
• Klipper: [https://github.com/yonitjio/openbafs-klipper](https://github.com/yonitjio/openbafs-klipper)

BAFS is a kind of multi material unit for 3d printer. It's very basic, don't expect fancy stuff. It only do one thing: switching filament.

Features:

1. Modular design, i.e. you decide how many ports you want, print accordingly.
2. Only 1 pwm port needed from the printer
3. Redundant design, if one of the motor port stop working, most likely it won't affect the other.
4. Cheap, it uses commonly available parts.
5. Easy to print, for the most parts, you might not need to print with support at all.

BAFS is a great and affordable way to learn and understand how multi filament / multi material 3d printing works.

Be aware this design has the same problems/challenges as similar design using single nozzle and y-splitter: jams, clogging, color bleeds, etc.

Most printers don't have many servo ports, to solve this, I use one PWM port from the printer to generate PWM pulse that signal which port to use to external module. I use Arduino, stepper motor shield and custom board.

Non printed parts:

• Servos (I use MG996R)
• A Stepper motor (for direct drive printers)
• M5 rod, stainless is preferable.
• M5 to M5 coupler
• M3 bolts and nuts
• M4 bolts
• Long M4 bolts and nuts
• Bearings 625zz, 623zz, u604zz
• Extruder gears
• Grease
• PC4-M6

Electronic parts:

• Arduino
• Protoshield for Arduino
• Stepdown module
• Power Supply
• Connectors
• Wires

These parts are only for the switch, you still need at least a y-splitter. Use whichever work for you. You can search it on thingiverse, printables, etc. I use my own: [https://www.printables.com/model/469032-curved-4-to-1-bowdenptfe-tube-joinersplitter](https://www.printables.com/model/469032-curved-4-to-1-bowdenptfe-tube-joinersplitter) 

Extrusion System

Initially BAFS was designed for bowden system, but since I changed my printer to direct drive, I also update BAFS to support direct drive.

With bowden extrusion system, BAFS also acts as the extruder, it uses the printer's stepper motor.

For printers with direct drive extrusion system, it acts as a feeder. It needs additional stepper motor.

Each version requires different firmware. Other than the stepper motor and firmware, everything else is the same.

Firmware

To use BAFS you need firmware support, unfortunately, currently there's no official firmware support.

You can use my fork the printer firmware:

• Marlin: [https://github.com/yonitjio/openbafs-marlin](https://github.com/yonitjio/openbafs-marlin)
• Klipper: [https://github.com/yonitjio/openbafs-klipper](https://github.com/yonitjio/openbafs-klipper) 

For the Arduino, you can get it here:

[https://github.com/yonitjio/openbafs](https://github.com/yonitjio/openbafs)

Electronics

To build the electronics you need to have at least basic skills about arduino and electronics. It requires soldering and making wires with connectors.

It is pretty straight forward. Nothing fancy here. You just need to connect the servos, stepper motor and the printer to Arduino.

There are plenty tutorials about using servos and stepper motor with Arduino.

Adjust the codes according to your setup.

Notes:

Even though it's modular, it's better to plan ahead to minimize costs, for example if you plan to use 4 filaments but want to start with 2 first, it's better to prepare the shaft and bolts for 4 filaments from the start. This is because the you need longer shaft and bolts for more ports for the filaments.

I will try to inform updates here, but most likely updates will be on github and buymecoffee first, please check there for any updates and/or tips and tricks for BAFS.

DISCLAIMER: This is an experimental project. It may or may not work. Use it at your own risk.

Additionals:

Water Dragon: [https://www.thingiverse.com/thing:2376420](https://www.thingiverse.com/thing:2376420)

The Thinker Multi Color: [https://www.printables.com/model/195144-the-thinker-multicolor-support-free-remix-for-mmu-/comments/858285](https://www.printables.com/model/195144-the-thinker-multicolor-support-free-remix-for-mmu-/comments/858285) 

Cat fridge magnet: [https://www.printables.com/model/340674-cat-fridge-magnet-v1](https://www.printables.com/model/340674-cat-fridge-magnet-v1)

Gyroscope Keychain: [https://www.printables.com/model/542103-print-in-place-gyroscope-fidget-toy-keychain](https://www.printables.com/model/542103-print-in-place-gyroscope-fidget-toy-keychain) 

Snowman: [https://www.printables.com/model/333725-cute-happy-lil-snowman/comments](https://www.printables.com/model/333725-cute-happy-lil-snowman/comments)