FarmLoop Stage 2 assembly, Bambu H2C

Read through the entire guide before you start. Have every part from the kit laid out where you can reach it, and make sure the printer is powered off and unplugged before opening anything.

Approximate time: 40-55 minutes. (The H2C skips the side-panel routing step, so it’s slightly faster than the H2S and H2D.)

Board version matters

• V2.1 boards use a Y-cable to connect to the actuators.
• V3.1 boards use the orange connector.

Check which board version shipped with your kit before wiring. The two are not interchangeable.

Prerequisites

• Bambu Lab H2C with latest firmware installed
• FarmLoop Stage 2 kit (door-opener parts, bender ×2, wire harness, PCB holder, scraper, tilted feet, lid lifter, screws)
• Printed parts from Makerworld
• FarmLoop Pro App subscription, sign up at app.3d-farmers.com
• A clean, flat work surface large enough to lay every part out
• ~40-55 minutes uninterrupted

Before you start

• Power off and unplug the printer.
• During operation, never reach into the printer while a bender is active — the actuator exerts significant force.
• Before installing a bender, make sure the build plate is raised above the bender position. Remove it first if it’s below.
• Parts are designed to fit smoothly. If a component needs excessive force, stop and check orientation.
• Door sensors break easily — do not apply force near them when fitting the benders.
• Route all cables away from moving parts.

1. Assemble the door opener

1. Press the button into the designated hole in the lid.
2. Fix the button using the rubber ring and metal ring.
3. Attach both wires to the button terminals.

4. Slide the actuator into the bottom part until it is fully seated.
5. Align the lid with the base and press them together until they click/lock into place.

2. Set up the benders (×2 — repeat for each)

1. Slide each actuator into its bender bracket until fully inserted.
2. Check that the actuator is facing the correct direction — the cable must sit in the designated gap.
3. Attach one hook to each actuator and tighten the screws firmly so the hook does not move.

4. Press the endstop switch into the slot in the left floor part.

Tip

Repeat steps 1-3 for the second bender. Step 4 (the endstop) is on the left floor part only.

3. Prepare the 3D printer

3.1 Remove the lid

Remove the printer’s lid and set it aside — you’ll re-fit it at the end.

3.2 Attach the scraper on top of the print head

H2C-specific

The H2C is the simplest of the three H-printers for this step — the scraper attaches directly on top of the print head without removing screws or covers.

Attach the scraper on top of the print head.

3.3 Replace the original feet with tilted feet

Remove every original foot and replace each one with a tilted foot, screwing it in firmly.

3.4 Swap the door hinge

1. Remove the bottom two screws from the original door hinge.
2. Position the new door hinge in the same place.
3. Reinsert the same two screws to secure it.

3.5 Place the lid lifter

Place the lid lifter into its designated slot. Check the label on the lifter so you fit the correct one for the H2C.

3.6 Route the wire harness into the print room

Insert the wire harness into the print room through the designated opening.

3.7 Attach the benders to the print room

Attach one bender to each side of the print room. Check the direction of the hook before pressing it into place.

Door sensors are fragile

Do not apply force near the door sensors while fitting the benders — they break easily.

3.8 Thread the wire harness through the bottom parts

Thread the wire harness through all bottom parts in order, following the intended routing path.

3.9 Connect the actuators to the harness

Connect each actuator to its corresponding connector on the wire harness. The Y-cable (V2.1) or orange connector (V3.1) sits between actuator and harness — match it to your board version.

3.10 Screw down the bottom parts

Align the bottom parts with the screw holes on the printer floor and screw them down firmly.

3.11 Side-panel routing — skipped on H2C

H2C-specific

The H2C does not need the side-panel wire-harness routing step that the H2S and H2D have. The wire harness routes directly without removing or sliding through the side panel.

Continue straight to the next step.

3.12 Verify free movement of the print head

Adjust the wire harness so it lies flat and tight against the side of the printer. Then manually move the print head to all corners and confirm it moves freely without pulling or snagging the harness.

3.13 Secure the wire harness

Secure the wire harness to the printer frame using tape at regular intervals and zip ties at stress points (where the harness flexes or could snag).

3.14 Install the PCB holder

1. Remove the top screw from the back panel.
2. Position the PCB holder against the panel.
3. Reinsert the same screw through the holder to fix it in place.

3.15 Install the door opener

Slide the door opener into the slot at the bottom front of the printer until it sits flush.

3.16 Connect all cables

Connect every cable. Attach cable clips where needed and press each cable firmly into its clip so nothing dangles or works loose.

3.17 Attach the door opener to the door handle

Attach the door opener to the door handle.

3.18 Re-fit the lid + clip the bed

1. Place the lid onto the lid lifter.
2. Clip the bed using the clips on both sides.

✅ Done!

Next step

Continue the Start here flow at step 3 (firmware update) once your hardware is mounted.

For door-button controls, OTA mode, MQTT setup, and the LED-signal reference, see the sections below — the firmware behaviour is identical to the P / X series.

Operation

Door-button controls

The DOOR BUTTON is the manual-control button on the automatic door console. Its function depends on the current system state:

System state	Action	Result
Idle	Short tap	Door control (open/close toggle)
Idle	Long press (3+ seconds)	Enter test mode
Any state	5 quick taps within 3 seconds	Enter OTA configuration mode
Reset after safety-check failed	Single tap	Recovers from SAFETY_FAILED state. Homes bender, closes door, returns to initial state.

OTA mode (firmware updates + setup)

OTA (Over-The-Air) mode is the FarmBoard’s built-in web config page. It’s the entry point for two things:

• Firmware updates — drop in a new .bin file when we ship one
• Initial setup of the optional MQTT printer connection — see the next section

You don’t need OTA mode for everyday operation. The board runs whatever’s already saved in its permanent storage. Only enter OTA when you’re updating firmware or changing connection details.

Entering OTA mode: tap the DOOR BUTTON five times quickly within 3 seconds. Each tap must be shorter than 0.8 seconds. The LED switches to fast 4 Hz blinking to confirm.

Connecting to the OTA page:

1. On your phone or laptop, join the Wi-Fi network FarmLoop (password: 3D-Farmers).
2. Open http://farmloop.local (or http://192.168.4.1 if your device doesn’t resolve .local names).

OTA page sections:

• Firmware Update — pick a .bin file, click upload. The board reboots automatically when done.
• Printer Connection — Wi-Fi credentials, printer IP, LAN access code, serial number. Optional — covered in the next section.
• Save Printer Config — writes the current values to permanent storage.
• Clear Connection Details — wipes Wi-Fi and printer data. The board runs in standalone mode after reboot.
• Exit OTA Mode — reboot into normal operation. Or wait 5 minutes; the board reboots automatically on timeout.

5-minute OTA timeout

The FarmLoop Wi-Fi access point shuts down 5 minutes after you enter OTA mode, even if you haven’t saved your config. Save partway through if you’re hunting for printer credentials so you don’t lose your work.

Optional: MQTT printer connection

MQTT is optional. The FarmLoop system works fine without it — the FarmBoard runs purely off the limit-switch and door-button gestures.

When MQTT is enabled, the FarmBoard knows the printer’s state in real time and can react to it automatically. It removes one timing-sensitive manual step at end of print, and adds a safety net: the FarmBoard can send a STOP to the printer if something goes wrong mid-cycle.

What changes with MQTT enabled

Step	Without MQTT	With MQTT
Door close at print start	Long tap + short tap (or 4-tap reset)	4-tap reset (start-gcode)
Door open + fan at last layer	Manual long press (4-6 s)	Automatic
Start bending	Triple tap	Triple tap
Safety check	Double tap	Double tap
Final door close	Long press	Long press

So MQTT removes one timing-sensitive manual step (the long press at end of print) and makes the cycle more forgiving.

Benefits

• Door + fan trigger exactly at the last layer — no timers, no missed presses.
• Safety stop: the FarmBoard can send a STOP to the printer if a safety check fails.

What you need

Enter OTA mode (5 taps on the DOOR BUTTON → join the FarmLoop Wi-Fi with password 3D-Farmers → open http://farmloop.local), then in the Printer Connection card fill in:

• Wi-Fi SSID + password — the network your printer is on
• Printer IP — printer Settings → Wi-Fi
• LAN access code — printer Settings → Network → LAN Mode (8 digits)
• Serial number — printer Settings → Device

Click Save Printer Config, then Exit OTA Mode.

After reboot, the LED tells you what happened:

• 5 slow blinks = Wi-Fi connected ✅
• 10 fast blinks = MQTT connected to printer ✅
• 2 long blinks = Wi-Fi failed (check SSID + password)
• 4 long blinks = MQTT failed (check printer IP, LAN access code, and that LAN Mode is enabled on the printer)

The “Enable MQTT auto-trigger” checkbox in the Printer Connection card switches the auto-behaviour on or off without removing your printer details.

Common questions

Is anything sent to the cloud? No — MQTT runs on your local network only. Nothing leaves your home Wi-Fi.

What if Wi-Fi drops mid-print? The FarmBoard falls back to manual mode automatically. When the network returns, the MQTT connection re-establishes itself.

Do I need MQTT? No, it’s optional. If your printer isn’t on Wi-Fi, or you’d rather skip network setup, mechanical mode (the default) works fine.

Non-Bambu printer? MQTT integration is Bambu-Lab-specific. For Klipper / Marlin / non-Bambu printers, use mechanical mode and plan the end-of-print long press manually.

LED signals

After the board boots, the LED shows a sequence indicating connection status.

Successful startup sequence: 3 quick blinks → 5 slow blinks → 10 fast blinks. If you see all three patterns, the board is fully connected to the printer.

During OTA mode: the LED blinks rapidly at 4 Hz continuously until you exit or the timeout is reached.

LED pattern	Meaning	Action needed
3 quick blinks	Boot successful	None, normal
5 slow blinks	Wi-Fi connected	None, good
10 fast blinks	MQTT printer connected	None, fully operational
2 long blinks	Wi-Fi connection failed	Check SSID and password in OTA
4 long blinks	MQTT connection failed	Check printer IP and access code

Support

• Email: support@3d-farmers.com
• Skool community: skool.com/3dfarmers
• Community (Pro members): log in at app.3d-farmers.com to access the Discord invitation

If your kit arrived damaged, email us with photos and your order number before opening anything further.