Arco Unleashed v1.2.3 (Bookworm 6.18.30)
Latest build — 2026-08-27 (v1.2.3). Five things an owner will notice.
(1) One command, and it asks what you want. The flasher used to be four flags that differ by one
word, one of which cannot be undone. Now sh prepare_unleashed_self_flash.sh unpacks the tool from the
stick and offers to start it, and what opens is a menu: check (changes nothing), back up,
install, cancel something already armed. Choosing from a list is not a confirmation — install
still asks for yes and for the target device typed out in full. The flags all still work, and where
there is no terminal to ask on the bare command still means inspect, change nothing.
(2) The install no longer refuses because of a step you did not take. Phrozen's gateway —
phrozen_master and ~/hdlDat, what the display talks to and where the AMS work mode lives — exists
only on the running original printer and is in no download. The flasher used to check for it and stop.
It now collects it itself, at the last moment it still can, verifies what it collected, and keeps
the refusal only for when that genuinely fails. An archive already on your stick is never overwritten.
By hand it now matters on one road only: writing the eMMC in a PC, where nothing of ours ever runs.
(3) A backup too large for one file is no longer invisible. A backup that crosses FAT32's 4 GiB
ceiling is written as .001, .002 — and until now the restore menu could not see it, because it
looked for a file under the plain name that a split set does not have. Worse on the way home: going
back to Buster reported "no usable image on this stick" while the parts lay on it. Both menus now
recognise either shape and show the part count beside the entry.
(4) Five features that shipped without documentation. AMS_SETUP — one dialog for which slot serves
which tool and the refeed switch — had never been written down anywhere, nor had AMS_SLOTS,
AMS_REFEED, ARCO_FILA_EMPTY or Z_TILT_LEVEL. The chamber light and the AMS refeed are named as
what they are: real toggle switches in Mainsail, not just macros, and the light follows the display.
(5) The documents were audited, and some of them were wrong. A channel switch told you to restart
Klipper; the guard that follows the channel runs on Moonraker, and the script has known that since
August. Troubleshooting sent you to a setup-menu entry a that does not exist. A callout described a
feature that had been removed. Counts had drifted — seven guards where there are thirteen, five Klipper
extras where seven are installed. Alongside that, 146 sentences were rewritten for being correct but
harder to read than they needed to be, each one checked afterwards so that no rewrite quietly dropped a
condition or a warning.
Also: Phrozen do not publish a stock image for download, but their support has supplied one on
request — the flat "there is no stock image" was wrong in six places. And a spare eMMC module alone is
not a way back: the MCU firmware sits on the chips and has to go back to v0.11 as well.
Arco Unleashed — Full Image (pre-built, flash & run)
A complete Debian Bookworm + Klipper v0.13 image for the Phrozen Arco. Includes the Klipper
stack, the arco-unleashed kit (setup menu, AMS auto-mode, Mainsail theme) and the Arco configuration.
No proprietary Phrozen software is included — you supply Phrozen's official Arco_FW_V*.zip
yourself, or let the printer fetch the display module from Phrozen's own public repository once you
confirm.
📦 What to download
| Asset | You need it for |
|---|---|
Arco-Unleashed-USB.zip |
everything — the image, its checksums, the self-flash tool and all guides. |
Arco-Reflash-to-Buster-USB.zip |
only if you ever want to go back to stock Phrozen Buster. |
Two downloads, and most people need only the first. The image lives inside Arco-Unleashed-USB.zip
together with its .sha256 and .rawsize, so there is one thing to fetch and nothing to mismatch —
and collect_data_arco.sh is in there too, at the top level, for the one case that still needs it.
Flashing it
Extract Arco-Unleashed-USB.zip onto the root of a FAT32 stick — plugged straight into the
printer, never through a hub. Phrozen's Arco_FW_V*.zip is optional: bring it only if the printer will
have no internet during setup, or if you want PhrozenGo. Then SSH in as mks and:
cd ~/printer_data/gcodes/USB
sh prepare_unleashed_self_flash.shIt unpacks the flasher — replacing whatever was in ~/selfflash, so the version that runs is always the
one on this stick — and asks whether to start it. Answer y, give your password, and take 3 —
Install. Type yes to the disclaimer and then the target device in full. Leave the stick in: the
display shows check → write → verify, and write and verify both say DO NOT POWER OFF, and both mean
it. The printer restarts by itself.
There is one hands-on step afterwards, and it is not optional: flashing the MCUs, which needs two
buttons pressed inside the toolhead. The MANUAL pictures every screen of it.
Going back
Take the backup the installer offers as menu item 2 before you flash — it images the whole eMMC
onto your stick, no teardown. Phrozen publish no stock image for download, though their support has
supplied one on request; a copy you take yourself is this printer, with your calibration, available
the moment you want it. Note that the eMMC is only half the machine: a return to stock also needs both
MCUs flashed back to v0.11, which the setup menu's going back to Buster does in the right order.
Documentation: MANUAL ·
QUICKSTART ·
README
Arco Unleashed is an independent, community-made project. It is not endorsed, supported or distributed
by Phrozen, and Phrozen cannot be asked for support on a printer running it. Use at your own risk — this
will very likely void your warranty.