Openness: Mostly open (4.2 of 5)
Walled gardenOpen

FLSUN is the printer brand of Zhengzhou Chaokuo Electronic Technology, a Chinese company founded in 2015. Since 2017 it has made only delta printers, built for speed: the open-frame T1 series, the enclosed S1 and the large V400 Max all run Klipper. They suit people who print tall parts or want fast prints and are willing to tune a delta.

Founded: 2015 · Headquarters: Zhengzhou, Henan, China · Ownership: Brand of Zhengzhou Chaokuo Electronic Technology Co., Ltd., privately held · Website: flsun3d.com

Fairly free to use as you like: Klipper with a local web interface, OrcaSlicer support and a deep spare-parts catalogue. The firmware source came late, as one-time uploads.

Firmware and custom firmware
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The S and T series run Klipper, which Tom's Hardware found close to stock on the S1. FLSUN uploaded the Klipper and Moonraker code for the S1, S1 Pro, T1, T1 Pro, T1 Max and T1E to GitHub in August 2025, more than a year after the S1 shipped, as one-time uploads rather than maintained repositories. [3][4][9]
Local control and integrations
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The S1 and T1 series run Klipper with a stock Mainsail interface on the local network, with no account; FLSUN put the printers' Klipper and Moonraker code on GitHub in 2025, and other software can use Moonraker's documented API. FLSUN's app and web platform add remote control and fleet management. [9][10][4][11][15]
Third-party filament, slicers and parts
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Any filament works, and OrcaSlicer ships profiles for the S1, T1 and V400 next to FLSUN's own OrcaSlicer-based slicer (published under the AGPL). The S1 takes a standard removable V6-type nozzle, but effectors and hotend kits are FLSUN delta parts. [14][6][9]
Repairs and spare parts
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FLSUN's US shop lists over 100 spare parts for the S, T and V400 series, down to motherboards, effectors, parallel arms, screens, motors and belts. We found no published CAD for the current printers. [12]
Data and privacy
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Printing over Klipper needs no account. FLSUN's app does, and its privacy policy describes collecting device data, location signals and usage, without saying where the data is stored. [13]
From SimplyPrint Our own experience working with FLSUN. It isn't part of the rating.
  • When an FLSUN owner had a problem with SimplyPrint, one of FLSUN's developers spent over an hour in our live chat with our developers, working it out together.
Pros
  • Fast delta printers that suit tall parts.
  • Klipper with a Mainsail web interface on your own network, no account needed.
  • Large spare-parts catalogue, down to boards, arms and effectors.
  • OrcaSlicer has FLSUN profiles, so you are not tied to FLSUN's slicer.
Cons
  • Firmware source arrived late and as one-time uploads, not maintained repositories.
  • Reviewers found the S1 needed slicer tuning for accurate prints and measured the T1 Pro louder than advertised.
  • Tom's Hardware did not recommend the S1 for beginners.
  • The privacy policy does not say where app data is stored.
Track record
  • August 2025: FLSUN published the Klipper and Moonraker code for the S1, S1 Pro, T1, T1 Pro, T1 Max and T1E as separate GitHub repositories, uploaded between 8 and 21 August 2025. [4][5]
  • May 2024: FLSUN published the source of FlsunSlicer, its OrcaSlicer-based slicer, on GitHub under the AGPL-3.0. [6]
  • October 2022: FLSUN published the Klipper and Moonraker builds for the V400's Speeder Pad on GitHub under the GPL-3.0. [7][8]
  • March 2021: FLSUN launched the Super Racer (SR), the delta that it says first brought it wide attention. [1]
  • 2017: FLSUN says it dropped over 90% of its product lines to build only delta printers, and that its revenue fell by 80% as a result. [1]
Researched from 15 sources, last checked October 18, 2026. Show sources
  1. About us - FLSUN flsun3d.com
  2. About us - FLSUN US store us.store.flsun3d.com
  3. Flsun3d repositories - GitHub github.com
  4. Flsun3d/T1-max: klipper and moonraker of T1 max github.com
  5. Flsun3d/S1: klipper and moonraker of S1 github.com
  6. Flsun3d/FlsunSlicer github.com
  7. Flsun3d/klipper_fs github.com
  8. Flsun3d/moonraker_fs github.com
  9. FLSun S1 Review - Tom's Hardware tomshardware.com
  10. FLSun T1 Pro 3D Printer Review: Is Speed Still the Most Important Feature? - 3DPrint.com 3dprint.com
  11. Flsun World (app and platform) - FLSUN flsun3d.com
  12. Accessories - FLSUN US store us.store.flsun3d.com
  13. Privacy Policy - FLSUN flsun3d.com
  14. OrcaSlicer FLSun printer profiles - GitHub github.com
  15. moonraker.readthedocs.io