If the printer offers an AMS update with the BMCU connected, do not update the AMS firmware, as the BMCU will stop working and you will have to manually re-upload the BMCU firmware.

Firmware A1/A1 mini 01.07 tested and supported. Functionality with newer firmware cannot be guaranteed. BMCU Firmware https://drive.google.com/drive/folders/1hdiSyvxWcIvtZG92uE7YCp_mhSPL9PZN BMCU 370C is an open-source alternative to Bambu AMS lite, which enables multi-color and multi-material printing on Bambu Lab printers. The 370C variant utilizes a Hall buffer and is designed for stable, gentle, and quiet feeding of material. This version is assembled and includes a connection cable. Simply plug it into the printer and print. When connecting, it is important to turn off the printer, plug in the BMCU, and then turn the printer back on.

Main Benefits

• Bidirectional buffering and smoother feeding – reduces the risk of filament damage/jamming and supports "long retraction after cutting" during material changes.
• Active feeding (370 motors) for reliable filament switching even with longer material paths.
• 4-filament system – a simple solution for printing with up to 4 materials/colors. (Expansion beyond 4 filaments is currently not supported.)
• Open-source firmware and hardware with community documentation (CH32 series control MCU).

Compatibility

• Bambu Lab A1 and A1 mini – fully supported.
• P1S / P1P – experimental support (requires custom integration; functionality without warranty).
• X1 series – "possible, but unverified".

What to Expect During Assembly

BMCU 370C in this variant is already assembled and just needs to be connected to the printer. This is a community solution without RFID spool recognition.

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Key Features

• 4 independent filament paths for multi-color/MMU printing.
• Hall buffer (370C version): quieter operation and higher resistance to "backpressure" in the hub.
• Bidirectional buffering and long retraction after filament cutting.
• Active feeding with 370 motors.
• Open-source design, MCU CH32, without RFID reader.
• Compatible with 1,75 mm filaments (PLA/PETG etc.; according to printer recommendations).

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Technical Parameters

Parameter	Value
Number of filaments	4 (no expansion beyond 4)
Version	370C (Hall buffer)
Feeding principle	Active feeding + bidirectional buffer
Control electronics	MCU CH32 (open-source firmware)
Compatibility	Bambu Lab A1, A1 mini; P1S/P1P (experimental); X1 (unverified)
Supported materials	1,75 mm filament (according to printer specifications)
Extra functions	"Long retraction when cut in filament"
Sets	A–D (varying levels of kit completeness)
Requirements	3D printed parts, basic soldering and calibration

Note: When used with the P1 series, this is experimental support without guarantee of full compatibility or manufacturer support.

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Who is the BMCU 370C for

• Bambu A1/A1 mini users who want an affordable alternative to AMS lite.
• Printers who prefer DIY and open solutions and want flexibility (e.g., connection to dryers/dryboxes and external filament routing).

Package Contents

• BMCU 370C assembled, PTFE tube, connection cable.

Do you have questions about kit selection, printing parts, or setup? We are happy to advise before and after purchase.

Key Features:

• Open alternative to AMS lite for Bambu Lab A1/A1 mini.
• Hall buffer (370C) with bidirectional buffering – quieter and gentler operation.
• 4 channels for multi-color and multi-material printing.
• Active feeding with 370 motors for stable material swaps.
• Community firmware/hardware (MCU CH32), no RFID – simple configuration.
• Experimental support for P1S/P1P – integration possibility, no guarantee of full compatibility.