BMCU 27-5¶
Product Overview¶
The BMCU 27-5 is the standard version of the Bidirectional Buffer Module, using mechanical micro-switches for filament detection.
Firmware Variants¶
There are two firmware variants for BMCU 27-5:
| Variant | Description |
|---|---|
| 0027 | 4061N's original firmware, perfect Hall effect sub-board, compatible with dual micro-switch sub-board. No special functions such as self-priming. |
| 27 | Stardust's dual micro-switch firmware, perfectly compatible with dual micro-switches, compatible with the original Hall effect. There is a chance to trigger self-priming after photoelectric triggering. |
Firmware Naming Convention¶
Format: [Version]-[Retract Type]
Device Identifier¶
The suffix (A/B/C/D) determines which device the printer recognizes:
- A - Device Identifier A
- B - Device Identifier B
- C - Device Identifier C
- D - Device Identifier D
When you flash the firmware, the device identifier is set at that moment, allowing the printer to distinguish between up to 4 devices.
Retract Types¶
| Type | Description |
|---|---|
| Discontinuation | Retracts until filament is no longer present (for dual micro-switches, retracts to middle micro-switch release point), then reverses and feeds back a little bit |
| Minimum | Retract distance of 12cm, equivalent to original AMSlite retract distance |
| XXcm | Stop after rewinding to XXcm, suitable for different Teflon tube lengths. Note: Due to system response, this unit is not entirely accurate; ruler measurements are for reference only and require manual testing |
Example¶
BMCU_27-5_A_filament return distance 15cm.bin
│ │ │ │
│ │ │ └── Retract Distance: 15cm
│ │ └──── Device Identifier: A
│ └──────── Version: 27-5
└────────────── Product: BMCU
Compatible Printers¶
A1 Series (Tested)¶
- Bambu Lab A1
- Bambu Lab A1 mini
Note for A1 Series: - Requires firmware version 01.07.xx or higher - Before connecting BMCU, go to Printer Settings → AMS Type and set to AMS/AMS2 Pro/AMS HT - Can recognize up to 4 devices and achieve up to 16-color automatic material changing printing
P1 Series (Untested)¶
- Bambu Lab P1P
- Bambu Lab P1S
- Bambu Lab X1C
- Bambu Lab X1E
Note for P1 Series: - Theoretically works but has not been tested yet
Firmware Selection¶
For firmware options, please refer to Firmware Download List.
Microswitch Testing¶
If you are using BMCU 27-5 with micro-switch firmware, you can test if the micro-switch is working properly: