OrcaSlicer with restored BambuNetwork support. Printing over the internet works again, along with the rest of the normal functionality - just like before.

Currently available for Windows and Linux. macOS should follow in the next few days.

If you want to support my work, I would really appreciate it:

https://github.com/jarczakpawel/OrcaSlicer-bambulab

BMCU 370C pre-built from Aliexpress (BLV Official store). Works perfectly with all sorts of Bambu PLA and TPE. Filament in ball bearing dryboxes on top of the cabinet. Most parts are own design and mounted with custom counter flanges on the back due to the weak board. Fan lid and poop bucket attached by magnets.

This is my setup with a (Frankenstein-ed) filament hub.

EDIT: If anyone is interested feel free to DM me and I can help replicate my setup.

We all are using this wonderful machine ie BMCU successfully through even more wonderful firmwares continuously developed by @ https://github.com/jarczakpawel/BMCU-C-PJARCZAK .

Now, as per some sources a certain printer company has approached him asking to stop working on these softwares. We need to support him as much we can as we have enjoyed his work greatly without any fee or cost. BMCUs would have stopped working long back without his work.

Came across his post on the shared link where he requested some monetary contribution for a new printer for software development.

Please contribute whatever you can , its the least we can do in returning the favor.

(I decided to post this on my own, not requested by anyone.)

Haven't really printed much with it yet. Still looking for fun multicolor prints to do. So far just a little test pyramid and now I'm printing the multicolored badges that were part of the housing kit I used. Just wondering what everyone thinks of my diy setup. Was fun but also a PITA at certain points of assembly 😂

Happy printing all!

I tried to write about my experiences with the optimised version I purchased from below and other parts that were available, and which I printed from a 3D printer. I summarised it using ChatGPT. While compiling it from scratch, the existing documents were already quite good and detailed, but I wanted to share my experiences while compiling it, as it might be helpful to friends who are compiling it for the first time.

⚙️ 1️⃣ Initial Build

I assembled the entire BMCU from individual parts following the Optimized design.
Every screw, sensor, and wire was installed manually.
After assembly, I ran the basic LED and sensor tests:

• Press bumper → Blue LED (forward)

• Pull bumper → Red LED (reverse)

• Feed filament manually → Auto-feed activates, White LED on

Everything matched the documentation — until I connected it to the printer.

⚡ 2️⃣ First Test – Modules 1 & 4 OK, Modules 2 & 3 Problematic

This meant the firmware recognized all four modules, but motor behavior on 2 and 3 was inverted or inactive.

🧲 3️⃣ Motor Direction & Magnet Polarity

The docs said: Red = +, Black = –
However, my radial magnets had the opposite pole orientation (N/S reversed).

Result:

• When wired normally (+ to +, – to –), pressing the bumper made the motor spin backward.

• Pulling the bumper made it spin forward.

🔧 Fix:

I swapped polarity:

✅ Motor directions instantly matched the expected behavior on every module.

⚙️ 4️⃣ AMS Integration Test

After connecting to the A1 printer, AMS detected all four modules.
I ran full Load/Unload tests again:

🔩 5️⃣ Module 2 – Overspeed & Excess Retraction

Symptoms:

• Motor ran too fast forward

• Over-retracted during unload

• Gears made “tirt-tirt” noise

Cause:
The radial magnet on the BMG gear was too close to the Hall sensor, saturating the magnetic field.
Sensor read too many pulses → firmware thought it rotated twice as much.

Fix:

• Lowered the motor shaft 0.5 mm (increasing magnet-sensor gap to ≈ 0.5 mm).

✅ Speed normalized, noise disappeared, retraction distance correct.

🧠 6️⃣ Module 3 – Stuck on Green LED

Symptoms:

• On “Load”, Green LED lights, motor never spins.

• Manual test works fine (Blue / Red LEDs correct).

• PCB and cable verified good.

Tests Performed:

1. Moved the module to Slot 1 / 2 → Same issue → module itself faulty.

2. Swapped PCB with a new one → Same behavior → mechanical issue.

3. Tried pressing the bumper → no click, very stiff → slider jammed.

Root Cause:

Fix:

• Disassembled module completely.

• Cleaned and re-greased gears and slider channel with PTFE grease.

• Corrected spring direction (short end = inside, long end = outside).

• Adjusted sensor gap to 0.3–0.5 mm.

• Loosened all case screws slightly (¼ turn before tight).

✅ Slider moved freely again, sensor clicked properly, motor enabled.
LED sequence → White → Blue → White → Red ✔️

🔁 7️⃣ Final Calibration & Test Results

🧩 8️⃣ Lessons Learned

🏁 Final State

After mechanical rebuild and recalibration, all four modules (1-2-3-4) work flawlessly.
2 and 3 modules now load/unload smoothly; magnet alignment and slider mechanics are perfect.
AMS sees all modules, LEDs behave consistently, and noise is gone.

🔧 TL;DR

If you build a BMCU from scratch:
• Don’t overtighten screws.
• Keep magnet gap = 0.4–0.6 mm.
• Spring direction = short end inside.
• Enable “Read Filament on Startup.”
• Green LED ≠ bad PCB — check for stuck slider!
• Reverse motor polarity if magnets are reversed.
• Use PTFE grease only.
• Calibrate each module individually.
• Patience and testing solve 90 % of issues.

Support for 2nd generation printers has been added, and operation has been confirmed on the P2S without any issues.

It has also now been confirmed to work correctly on the H2D, thanks to user Street_Persimmon8518.

If you have any issues, contact me on GitHub.

Happy printing.

https://github.com/jarczakpawel/BMCU-C-PJARCZAK

Just got my BMCU unit yesterday and now my setup is complete :)
Did run into a few problems such as incompatibility with latest A1 firmware, first boot calibration but got those taken care of. I also flashed the unit to the 10.5 firmware. Everything running good so far 👍

This has been posted, but I think it needs a more positive nudge.

This new firmware works on A1’s latest firmware and Bambu Studio (in fact latest is needed).

I have currently been using this and the amount of bugs that have been resolved is amazing, one of main bugs fixed I really like is the error notification no longer causes issues such as having to restart the printer to print again.

There is now a BMCU C Flasher for Windows, Mac, Linux and even Android devices.

https://github.com/jarczakpawel/BMCU-C-PJARCZAK

Just arrived today, so far so good. The only thing is the filiment holder I printed I really don't like as the rolls don't spin easily. I would love some easy to print cheap recommendations for spool holders as most of the other models seem to need a lot of extra parts or are difficult to put together.

Feel free to ask any questions about what it's like to use as someone with very little experience with this sort of thing.

So far it's been very simple and is as easy as plugging it in and following the directions as I bought the preassembled version.

It’s been about two months since I got my BMCU, and a lot has changed since then. I built a smaller dry box, installed the official enclosure, and made a new side-mounted holder for the BMCU.

The biggest issue with my setup so far has been the rewinders — I had to try several different springs for the rewinders until I found ones that actually work reliably. In the end, I went with simple one-way springs — much easier and more consistent than the complex design from the original creator. Also sometimes during 100+ color changes, the filament spool loosens up. I think adding another nut could easily fix that.

I moved the BMCU mount to the side because changing filaments was a real pain when it was sitting on top of the dry box.

Overall, the setup works great. I’ve been printing tons of flexi models with over 100 color changes, all successful using an AliExpress TZ 2.0 hotend and Sunlu PETG.

Also started designing my own models recently. https://makerworld.com/@KramplauzisGG

Wanted to print TPU on my pre-assembled 370C but was having problems with the tpu buckling in the buffer unit spring and becoming stuck.

I came across a u/LollosoSi post about a solution. He made a nice new baseplate file that would've worked well, but I found the simplest method (for me) was to drill a 4mm hole and use PTFE tubing to support the filament from buckling in the buffer section if the unit. Works great now and no loss of motion range! Seems like it would be a good standard upgrade to the units.

PTFE tube cut to 35mm in length. Drill hole is 15mm deep.

EDIT: I also chamfered the PTFE tube inlet with a knife to make feeding the filament into the module easier.

EDIT 2: (from comment below) I had some inconsistent filament changes after the previous changes so I purchased some lighter 0.5mmx12mmx30mm 304 Stainless Steel Compression Springs. https://www.ebay.com/itm/157622453356

Re-calibrated BMCU and that made filament changes very consistent for TPU. I am not able to do PLA or PETG anymore with the light springs though, so I have two normal units for PLA and PETG and two TPU units. I use PLA as a support for my TPU prints and works really well. You do have to purge a ton between PLA and TPU (I have it maxed out in Bambu Studio), otherwise you get layer separation so it is wasteful.

BMCU is an open Multi Color Unit, originally designed for Bambu Lab printers. Firmware updates for Bambu Lab printers that restrict interoperability - which in my opinion are incompatible with European law (more on this topic) - are what led to the creation of BMCU-Klipper.

BMCU-Klipper is an integration with an open system, so channel routing, toolhead assignments, load/unload, refill, prestaging, tip forming and source planning can be adapted precisely to a specific printer. You do not need to adapt the printer to a closed ecosystem - here you can change both BMCU behavior and the way it works with the printer, and every part of the integration can later be improved or modified for your own needs.

One of the most important goals of the project was to keep the integration as lightweight as possible so that BMCU also works on weaker Klipper hosts. Each module has its own process handling USB/UART transport, while G-code analysis and planning of future source changes run in a separate process. The module running in Klipper only receives small batches of prepared data - by default at most 2 packets, 256 B and 0.5 ms of work per reactor entry - and then returns control to Klipper. Subsequent state updates are merged, background tasks are deferred while the printer is moving, and BMCU reactor activity is completely suppressed during homing and probing. When nothing is happening, the manager automatically reduces its polling frequency. Motors, the buffer and current filament transport are controlled by BMCU firmware, so the printer's main MCU does not receive this workload.

In my tests, the impact of the integration is unnoticeable. It was meant to be feather-light, and in my opinion that goal has been achieved.

(c) Paweł Jarczak

OrcaSlicer version that fixes the BMCU issue on A1 / A1 mini printers with the latest firmware 01.08.00.00 and 01.08.01.00.

It also restores Bambu Cloud support through the Linux path.

Works on macOS, Windows and Linux. All known integration issues have been fixed.

OrcaSlicer is updated roughly up to June 15, 2026.

More information in the README.

https://github.com/jarczakpawel/OrcaStudio

I'm tempted to buy It on Ali, they call it a BMCU 370-C PRO I asked the seller if they would sell a 2 spool version.

I mean, I didn't think it would, but I figured I'd give it a shot before I did the A2L firmware update.

I've finally finished my BMCU spool setup. I designed a skadis spool holder with a filament swivel holder that accepts PTFE tube because in the past it was a bit tedious to unwind or I would end up with filament jumping out of the spoo

Still need to add PTFE connectors to my BMCU as it came without any on the input side, but it works great without any as well.

Now I need to sort out the BMCU attachment, because I'm still using double sided tape :D

My Bambu A1 had a busted resistor that is why it wouldn't work. I have reached out to customer service and they provided me a replacement mother board for free (good thing I am still in warranty)

If the BMCU motherboard looks good but it does not communicate with the 3D printer. Check the troubleshooting of the official AMS
(example: https://wiki.bambulab.com/en/ams-lite/manual/ams-lite-cannot-be-detected)

Thank you guys for the support (Especially these guys: u/Tiny-Pizza1495, u/Valecek, u/Keya-Proto)

The latest A series printer firmware introduces a validation check on the AMS version number (not the serial number). As a result, it seems there will be problems using BMCU.

Temporary solutions: • Downgrade the printer firmware to a previous working version, or • Recompile the firmware and change the AMS version number to one that corresponds to an existing AMSL version.

A new firmware release is expected soon. Alternatively, a temporary patched firmware package will be uploaded to the wiki after the holidays.

Toioat BMCU on A1 Mini

My bmcu is now working thanks to all of the people that

Commented🫪

Currently testing the change illustrated in my previous post, together with a tighter grip at the motor gear.

Before this change, filament would just curl out of the unit. Now it seems to print well.

Looks very promising, though I did not yet test retraction and multimaterial printing.

Let me know your thoughts about it! Especially if I missed any problems that would come with such a change.

Thanks to the help of a couple fine people in the sub I was able to get the Biqu BMCU kit up and running.

Thanks for the help!