Arco Unleashed — Quick Start

From a stock Phrozen Arco to Debian Bookworm · kernel 6.18 · Klipper v0.13, without opening the printer: it flashes its own eMMC from a USB stick.

Five steps, about 30 minutes — or an hour if you also take the backup the installer offers. Much of that is the printer working while you wait, not you typing. Every screen of the install is pictured in the MANUAL; the full reference is the README.

This is the short path: five steps where the MANUAL has ten. Each heading names the MANUAL step it corresponds to, so you can switch between the two documents at any point.

⚠️ Your risk, and probably your warranty. Replacing the factory OS and firmware will very likely void your Phrozen warranty, and you do it entirely at your own risk — no guarantee of any kind, and nobody here is liable for a printer that ends up damaged or unusable.

ℹ️ Not affiliated with Phrozen. Arco Unleashed is an independent, community-made project — not endorsed, supported or distributed by Phrozen. Do not ask Phrozen for support on a printer running it. Phrozen and Arco are their trademarks, used only to say which machine this fits. No Phrozen proprietary software is bundled, hosted or mirrored here. Phrozen’s parts come from the zip you supply, or from Phrozen’s own public repository — and from the repository only after you confirm.

Before you begin

You need: the printer on your network · a PC with an SSH client (PuTTY on Windows) · one empty, freshly formatted FAT32 stick — ≥ 8 GB if you will take the backup, 4 GB is enough without it · 2.0 mm and 2.5 mm hex keys for Step 3. Plug the stick straight into the printer, never through a USB hub.

Optional: Phrozen’s Arco_FW_V*.zip, which you download from Phrozen. Bring it only if the printer will have no internet during setup, or if you want PhrozenGo, their cloud app. Otherwise the printer offers to fetch the display module from Phrozen’s own public repository, once you confirm.

Three things are irreversible, so decide now:

Phrozen’s gateway — what the display talks to, and where the AMS work mode lives — exists only on your printer, and the flash erases it. The installer saves it for you and refuses to write if it cannot.
The eMMC is overwritten in place. If you may ever want to return to stock, take the backup the installer offers as menu item 2, and take it before you flash. Phrozen do not publish a stock image for download, although their support has supplied one on request. And once Unleashed is installed, a backup can only ever capture Unleashed.
Once the write begins there is no undo. If it fails, recovery means opening the printer and taking the eMMC module out (MANUAL, Appendix A).

Start from an empty stick. The tools find their inputs by pattern (Arco-Unleashed*.img.gz, Arco_FW_V*.zip) and take the first match. So an old firmware zip or a (1) re-download left on the stick can win silently, and install something you did not intend.

Taking the eMMC out instead? Then the installer never runs, and the installer is what rescues the gateway and images the old system. Do both yourself first, while the printer is still running Phrozen’s original system — the commands are in MANUAL › FAQ.

Fill the stick

Extract Arco-Unleashed-USB.zip to the top level of the stick. That supplies the image, its checksums, the self-flash tool and the guides. Then add Phrozen’s firmware zip if you want it:

On the stick	From
`Arco-Unleashed_bookworm_6.18.30.img.gz` + `.sha256` + `.rawsize`	the release zip
`unleashed-selfflash.tar.gz` + `prepare_unleashed_self_flash.sh`	the release zip
`Arco_FW_V*.zip`	you download it from Phrozen
`arco-phrozen-ams.tar.gz`	collected for you while flashing — by hand only if you pull the eMMC

WiFi — the printer must be online afterwards, because Step 3 runs over SSH. Pick one:

Nothing to do (default). The flasher copies the network this printer is already using, region setting included.
A wifi-seed.txt you create — plain text, no quotes, and a 2.4 GHz network (the Arco has no 5 GHz radio). Set COUNTRY to your two-letter region, or the printer may not join:
```
SSID=YourNetworkName
PSK=YourWiFiPassword
COUNTRY=US
```
A no_wifi.txt — leaves WiFi empty on purpose, and the printer raises its own setup hotspot on first boot so you can pick the network from your phone.

Done when: the release zip rows are on the stick, plus the firmware zip if you want it — and no older image or firmware zip is left on it.

Step 1 — Flash · MANUAL Step 2

Put the filled stick back in the printer and SSH in as mks / makerbase. The address is the printer’s IP — look it up on your router or on the Phrozen display, because unleashed.local only exists after the flash:

sh ~/printer_data/gcodes/USB/prepare_unleashed_self_flash.sh

It unpacks the flasher fresh from the stick and asks whether to start it. Answer y, give your password, and a menu opens — 1 check only, 2 back up first, 3 install, 4 cancel something already armed. Choose 3.

Type yes to the disclaimer, then the target device to confirm. Reboot the printer. The display shows a progress bar and the words DO NOT POWER OFF; when it is done the printer restarts by itself.

🚪 If something goes wrong before the write starts — missing image, checksum mismatch, a hang — pull the stick and power-cycle. With no image on the stick the flasher stands down and your existing system boots normally.

The flasher stays armed, which is how you retry: put a good image back and power-cycle. But if you stop here and keep using the old system, disarm the flasher — otherwise the next boot with that stick in overwrites the eMMC without asking:
sudo bash ~/selfflash/install-unleashed.sh --disarm
🔌 A checksum mismatch is usually the stick, not the download. Take it off any USB hub and plug it straight into the printer, then copy the image again. If you see CRC or I/O errors, the stick itself is failing or is one this printer cannot drive — use another, preferably a plain USB 2.0 one.

Done when: the printer has rebooted itself and the progress bar is gone.

Step 2 — First boot · MANUAL Step 3

On this first boot the printer installs Phrozen’s firmware and the rescued gateway files on its own, restarts once more, and then settles on a “Notice — Error occurred” screen.

That error is expected and is not a fault. Klipper cannot start until Step 3 flashes the MCUs, so the display has nothing to recover to — restarting or power-cycling will not clear it. Do not set anything up on the display, and do not skip ahead. Wait for that screen to settle — a settled screen is how you know the automatic restarts have finished.

🛑 Do not power-cycle until it is finished. Allow up to five minutes per stage. The display is drawn once per stage and then simply stays put, so an unchanged screen is not a hung printer — it is the normal picture. Cutting power in the middle does not speed anything up: it throws away the stage that was running and starts it again. Worse, a stage interrupted while it writes can leave the install half-done.

If you used no_wifi.txt, this is where the Arco-Unleashed-Setup hotspot appears — the full WiFi scan happens first, so give it time.

Done when: the display sits on the settled “Error occurred” screen and the printer answers on your network. Remove the stick.

Printer never appears? Put a wifi-seed.txt (as in the stick preparation) on the stick and power-cycle. Until Phrozen’s firmware is installed, the printer re-reads the stick on every power-cycle. It applies the file once, then renames it .applied so you can see it was picked up. Each seed is used once, and it is the contents that count. To try again, the details must actually differ — a corrected password, say. Writing out the identical file changes nothing, so if the details were right and it still did not join, use the setup portal instead.

Step 3 — Flash the MCUs · the one step that is not optional · MANUAL Step 5

The host runs Klipper v0.13; your MCUs still carry the factory firmware and cannot talk to it. SSH in (mks / makerbase) and open the menu:

unleashed

Take 1 — Flash MCUs. Only two chips are actually flashed: the F407 main board and the toolhead F103. Klipper’s Linux host MCU is not a chip at all — it is a process on the host that reports CPU temperature. Take a — All three and everything is done in one pass. The F407 goes over USB with no buttons. The toolhead F103 needs a one-time hands-on step. Remove the front cover (unplug its fan) and undo the four screws of the back cover. Then, with the printer running and the script waiting at its prompt: hold BOOT → tap RESET while holding it → let go of BOOT → press ENTER. There is no countdown: the chip reads BOOT the instant RESET comes back up, and afterwards stays in its bootloader until something resets it again.

The teardown is pictured step by step in the MANUAL. Power the printer off and unplug it before the covers come off; the flash itself then needs it switched on again.

When the flash finishes, switch the printer fully off for about 10 seconds and back on. A reboot is not enough. Klipper is deliberately left stopped until you switch the printer off and on, so nothing works in between — that is normal, not a failed flash.

Done when: after that power-cycle, Mainsail at http://unleashed.local/ comes up ready with no MCU error, and the display’s error popup is gone.

Step 4 — Calibrate, then save it · MANUAL Step 7

Bed mesh, PID, input shaper and purge position are measured per machine and the image ships none — another printer’s numbers are worthless. Easiest is the display’s factory-reset auto-calibration, which runs input shaper, bed mesh and purge position back to back and returns to the home screen by itself. It does not do PID: run PID_BED and PID_NOZZLE from Mainsail afterwards, then SAVE_CONFIG. There is no z-offset step — the Arco probes with a load cell.

Decline the “print test” the display offers. Not because the file is bad — this kit replaces both built-in test prints with its own. It is Phrozen’s factory-reset print flow on the display that is untested and used to stall here. Want the test print? Start FDM_TEST.gcode from Mainsail instead; that route is verified. Or go straight to your own first print in Step 5.

Then save what you just measured: setup menu → 2 — Save / restore SETTINGS. Also copy it to a USB stick — the local copy lives on the very eMMC it is protecting.

Done when: calibration is back at the home screen, SAVE_CONFIG has restarted Klipper after the PID runs, and your backup is on a stick.

Step 5 — Print · MANUAL Step 9

OrcaSlicer already ships the official Phrozen Arco profile, so no fork is needed. To also get the kit’s AMS auto-mode, import one of the two profiles from this project’s orca/ folder. OrcaSlicer runs on your PC and the kit lives on the printer, so fetch them first — from GitHub (Download raw file), or with WinSCP from ~/arco-unleashed/orca/ on the printer. Then use File → Import → Import Configs…. (Unleashed) loads your saved bed mesh at print start; (Unleashed, adaptive mesh) probes the print area each time instead. Or paste the start G-code from the README into your own profile.

Own an AMS? There is nothing to switch on. Plug it in and print. The printer detects the unit and sets its own flag within seconds, so T1–T15 and the right print mode appear on their own.

Two things you can set, both in one dialog — run AMS_SETUP in the Mainsail console: which slot serves which tool (for when the colours went in in a different order than you sliced), and refeed, which lets a single-colour print carry on from another slot when one runs out. The MANUAL has both in full.

Attach or remove the AMS whenever you like; Orca then picks single-colour, multicolour or auto-refill by itself, decided at print start.

Done when: a sliced file prints.

You’re done

Mainsail is on http://unleashed.local/ (:81 works too) and Fluidd on http://unleashed.local:8808/ — the same ports your Arco used before, and the printer’s IP works for both if your network blocks mDNS. The theme is applied, the AMS is detected automatically, PhrozenGo is on. Klipper is not pinned: it tracks master and updates normally, and the guards on klipper.service re-apply this project’s changes before every start, so an update repairs itself.

Everything else is optional and lives in the setup menu. If something ever breaks, run Emergency repair from it — one action, no diagnosis needed.

For remote access, prefer Tailscale or WireGuard over PhrozenGo’s cloud.