Hi horza，
Thank you again for reaching out proactively before release. This is vital to keeping our community safe and respectful. We truly appreciate the exploration you’ve done on the U1 and your willingness to share the details with us.
Community sharing
We welcome developers like you sharing discoveries in the community, and you’re free to post your project on the official forum.
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We want every user who experiments with firmware to do so only after fully understanding the terms, the risks, and the warranty implications.
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If you plan to continue developing your toolkit, we strongly recommend placing the following notices at the top of both your GitHub repo and your forum thread:
About our open-source plan
As previously stated in the U1 Kickstarter FAQ, we will publish the open-source portions of the U1 firmware by the end of March 2026.
At that time, most U1 Kickstarter backers will have received their machines, and we welcome users with ideas and skills to submit changes and engage in technical discussions that contribute to the U1 project.
What firmware does Snapmaker U1 use, and is it open source?
Snapmaker U1 runs Klipper firmware with Moonraker for API management. Both components have been modified by Snapmaker and will be released under an open-source license before March 2026. We also use the unmodified Fluidd web client, which can be open-sourced at any time.
We’re still in a rapid-iteration phase and need additional time to prepare the open-source environment so users can modify the code and run it correctly on U1. Once that work is finished, we’ll publish the code as promised.
Snapmaker has benefited greatly from open-source projects such as OrcaSlicer and Klipper, and we remain committed to complying with open-source licenses and giving back to the community.
To help you and any other developers planning to experiment with firmware customization, please fully understand the possible implications.
We spoke with our firmware team and compiled the key points below (which you need to fully understand before modifying U1 code/configurations):
Functionality & Performance Risks of Third-Party Firmware
Since Snapmaker cannot verify or test third-party firmware, we cannot guarantee that all official U1 features will work properly under third-party firmware. Snapmaker is not responsible for any damage or risks resulting from such modifications.
System-resource & Stability Risks
a) CPU load – excessive usage can trigger communication errors and cause prints to abort unexpectedly.
b) Memory load – too many background services may exhaust RAM and trigger OOM (Out-of-Memory) crashes.
c) Storage space – every partition has a fixed size; overfilling them can lead to unpredictable failures.
Functionality that may be affected, including (but not limited to):
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Toolhead swapping
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Multi-toolhead offset calibration
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Auto-load / auto-unload filament
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Thermal-runaway protection
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Online (cloud) control
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Local or OTA firmware-update flow from the touchscreen
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Safety-critical logic executed during printing
Hardware Damage or Safety Hazards
If third-party firmware modifications result in functional abnormalities, machine damage, or potential safety hazards (such as fire), these situations fall outside Snapmaker’s responsibility. This is especially the case after official firmware updates, where older modifications may behave unpredictably or become incompatible.
Privacy & Data Risk
Third-party firmware may pose risks of leakage of print files, network data, and personal privacy.
High-Risk Modifications – Strongly Discouraged
The following actions carry extremely high risk and may cause the U1 to fail to boot, making it impossible to recover firmware via the screen/USB drive:
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Altering the bootloader or kernel command-line
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Editing boot-configuration files
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Modifying system partition sizes or names
U1 Terms of Use — Brief Reminder
To make the rules crystal-clear for anyone building or using third-party firmware, the key passages from the U1 Terms of Use are quoted below:
(3) Snapmaker Software and Firmware
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You acknowledge and agree that Snapmaker Luban, Snapmaker Orca software, and product firmware incorporate customized developments based on open-source projects (including, but not limited to, Orca Slicer, Klipper, and others). Such open-source content is governed by their respective open-source license agreements.
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The use of open-source software must strictly comply with the applicable license terms. License texts are included with each software package; please read them carefully.
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You may modify the corresponding code in compliance with the relevant open-source licenses. Please note: While installing custom firmware does not automatically void the product warranty, any damage caused by or attributable to the installation or use of custom firmware is not covered under the warranty. Snapmaker shall not be liable for any software or hardware failures, data loss, or other damages arising from user modifications to the firmware.
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Except for the open-source components mentioned above, this Software (including but not limited to Snapmaker firmware, GUI, system management services, camera services, remote connection services, update services, and product information management services) constitutes the proprietary property of Snapmaker. We grant you a personal, non-exclusive, non-transferable license to use such proprietary software on Snapmaker devices. Regarding this proprietary software, you agree not to:
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Copy, modify, create derivative works from, decompile, reverse engineer, or disassemble the Software, or attempt to derive the source code therefrom;
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Sell, rent, lease, sublicense, or distribute our Software without authorization;
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Remove, obscure, or alter any copyright, trademark, or other proprietary rights notices contained in the Software;
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Circumvent any technical protection measures contained in the Software.
Thanks again for your contributions and for checking in with us.
Best regards
Snapmaker Community Team
I only flashed it, but didn’t try printing because my printer is still open to allow easy access to SoC
