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OPENASTROTRACKER — 3D PRINTABLE ASTROPHOTOGRAPHY TRACKING MOUNT FOR DSLR CAMERAS

A 3D-printed mount that turns with the sky so your camera can photograph galaxies instead of star trails.

by Fabian Uehleke (OpenAstroTech)

FULL CAD BOM FIRMWARE DOCS

ScienceOpen-hardware

Built withESP32Arduino3D printing

difficulty
●●●●○
time
several weekends
license
CC-BY-NC-4.0
repo
repo ACTIVE1,156 stars

WHAT YOU’LL NEED

Videos
3
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COMPAREE VERDICT

OpenAstroTracker solves a real problem: the Earth rotates, so untracked long exposures turn stars into trails. This mount turns your camera in step with the sky, so you can take long exposures that reveal nebulae and galaxies. The project is mature: the hardware repository dates from 2020, the firmware is still being updated, the wiki walks you through shopping, printing, assembly, electronics, firmware and calibration, and there is a real community of builders. The recommended build uses a 2020 aluminium-extrusion base with printed connectors, two NEMA 17 steppers with TMC2209 drivers and an MKS Gen L board; an ESP32 option adds Wi-Fi control. The firmware speaks the Meade LX200 protocol and ships with ASCOM drivers, so planetarium and capture software such as Stellarium or NINA can point the mount (GoTo). The hardest part is not the printing, it is assembly and polar alignment, which newcomers consistently underestimate. One trap: the hardware is licensed CC BY-NC 4.0, so you cannot sell prints or assembled units without the team's permission (they sell official kits themselves). If you already do astrophotography, this is a legitimate path to a tracking GoTo mount; if you are new to both 3D printing and astrophotography, expect to learn two hobbies at once.

GOOD TO KNOW

  • —STL files plus SolidWorks and STEP source files are in the repository; the assembly guides live on the wiki.
  • —Full BOM with part numbers for steppers, bearings, belts, and electronics.
  • —Firmware is MIT licensed and actively maintained; desktop control software available.
  • —Comprehensive wiki at wiki.openastrotech.com with step-by-step build instructions.
  • —Hardware design is CC BY-NC 4.0 — free for personal use, commercial builds require permission.
  • —ASCOM drivers and the OATControl app are in the separate OpenAstroTracker-Desktop repository; the firmware also speaks the Meade LX200 protocol.

Parts to buy

8 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Two 0.9-degree NEMA 17 steppersFind
  • Two TMC2209 driversFind
  • 6001 and 6801 bearingsFind
  • GT2 belt and 16T pulleysFind
  • 2020 aluminium extrusionFind
  • M3/M4 screws and T-nutsFind
  • Quick-release clamp and plateFind
  • Optional LCD keypad and bubble levelFind

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Can I build this?

PrintPrinted parts for your latitude (20 to 50 degrees) and frame option, picked with the project's Printed Parts Chooser; the wiki recommends PLA (stiffer than PETG).
Buytwo 0.9-degree NEMA 17 steppers, two TMC2209 drivers, an MKS Gen L board (or RAMPS + Arduino Mega, or ESP32), 6001 and 6801 bearings, GT2 belt and 16T pulleys, 2020 aluminium extrusion, M3/M4 screws and T-nuts, a quick-release clamp and plate, optional LCD keypad and bubble level
Tools3D printer with 200+ mm bed, Allen keys, screwdrivers, soldering iron for electronics assembly, polar scope or smartphone app for alignment
SkillsIntermediate 3D printing (part orientation and cleanup matter), basic electronics assembly and soldering, patience with mechanical tolerance and polar alignment — the last one is the skill astrophotographers spend years refining
Timeseveral weekends: printing the parts, assembly, wiring and flashing, then calibration and learning polar alignment
Cost$$: the wiki puts an OpenAstroTracker at roughly 150 to 200 dollars, depending on local prices. The parts are standard 3D-printer components (NEMA 17 steppers, drivers, control board, bearings, belts, aluminium extrusion). Official kits are also sold in the project shop.
SafetyMains voltage if you use an AC-DC power supply instead of a 12V brick. Motors have exposed belts and pulleys — keep fingers clear when powered. No unusual hazards beyond standard electronics.

This build involves mains voltage — for adults comfortable with electrical work only.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

OpenAstroTracker - updated

The official project video linked from the README; the wiki covers the build step by step.

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Gallery

Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the wiki cover to cover before ordering anything (The BOM and assembly guide are both here; the wiki is more current than scattered README files)
  2. 2.Download STL files from the repository and check your printer bed size (Some parts are large — confirm they fit your build volume before starting prints)
  3. 3.Order electronics and mechanical parts from the BOM (Stepper motors, belts, and bearings are the long-lead items; generic steppers work but check holding torque specs)
  4. 4.Print and assemble the mechanical structure, then flash firmware (Firmware repository is separate; follow flashing instructions for ESP32 or Arduino depending on your controller choice)

Resources

Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.

KNOWN ISSUES

  • The non-commercial licence (CC BY-NC 4.0) blocks selling assembled units or prints — if you want to make a batch for a club or sell kits, contact the project first (they also sell official kits).
  • Polar alignment is a separate skill that the mount cannot fix for you — even a perfectly built tracker is useless if the polar axis is off by a degree.
  • Print tolerances matter — if holes are too tight or shafts too loose, you will spend hours filing or reprinting before anything moves smoothly.
  • Use the steppers from the shopping list: 0.9-degree NEMA 17 motors (2 A recommended, unless you run on batteries) with TMC2209 drivers.
  • Stick to the recommended NEMA 17 steppers with TMC2209 drivers: the old geared 28BYJ-48 option adds backlash and periodic error, and the wiki advises against it for lenses much over 100 mm. Tension the GT2 belts properly during assembly.
  • The repository has multiple hardware versions; make sure all your STLs and assembly instructions match the same version to avoid parts that do not fit together.

Can I mount a telescope on this or is it DSLR only?

It is designed mainly for cameras (DSLR or mirrorless) with lenses. The wiki recommends NEMA 17 steppers with TMC2209 drivers for anything beyond short lenses, and a guider for focal lengths above about 150 mm. Small telescopes are possible, but balance and weight matter; for heavier payloads the team has a separate, larger mount (OpenAstroMount).

Do I need a polar scope or can I align with a phone app?

Neither is strictly required: the firmware includes polar-alignment helper routines, the wiki has a polar alignment guide, and the AutoPA add-on can automate it with plate solving. Expect to practise over several nights.

What camera works best with this?

Most builders use a DSLR or mirrorless camera on a quick-release clamp and plate. Weight and balance matter more than the camera model; with ESP32 builds you can also control the mount from a phone over Wi-Fi.

How much post-processing do astrophotos need after tracking?

Tracking gets you clean stars, but pulling out faint nebulae still needs stacking multiple exposures and stretching in software like PixInsight or Siril. The mount is half the workflow, not the whole thing.

Community builds

No community builds yet — be the first, we feature the best ones.

Discussion3

FROM THE COMPAREE TEAM

Over 1,100 stars on the repository and a detailed wiki written by people who have actually built this — what would you photograph first if your camera could track for five minutes straight?

MangoJH2mo ago

Can I use a raspberry pi 4b for this? Also I have stepper motors from a previous prusa i3mk3s. Are these suitable?

CompareeTEAM2mo ago

Two different answers. The Pi 4B: not as the controller. The firmware builds for AVR Mega2560, RAMPS, MKS Gen L v1/v2/v2.1 and ESP32, so there is no Raspberry Pi target and the Pi cannot drive the steppers. Where a Pi 4B is genuinely useful is as the host sitting next to the mount: run Astroberry/INDI on it, plug the OAT in over USB and control everything from a browser on your network, with your camera on the same Pi. You may need the CH340 USB driver before the connection comes up. On Windows there are ASCOM drivers and OATControl instead. The MK3S motors: yes, with one config change. They are NEMA17 bipolar 4-wire, 1.8 degree, so 200 steps per revolution. OAT's defaults assume 0.9 degree motors, so set RA_STEPPER_SPR and DEC_STEPPER_SPR to 200 instead of 400 in your local config. You do lose half the full-step resolution, which is why 0.9 degree is the default; run TMC2209s in UART mode and the 256x microstepping used for tracking gets most of it back. Use the X or Y motors rather than the extruder one, since the extruder motor usually has a gear pressed onto its shaft. They are rated around 1 A, comfortably inside what a TMC2209 handles, so just set the current rating in the config to match.

CompareeTEAM2mo agoedited

Practical notes from our verification: the hardware repository is the mechanical design; firmware lives in a separate repo (OpenAstroTracker-Firmware) under the same organisation. The README sends you to the wiki for all the guides, and it also links an active Discord and subreddit — use those, the wiki is far more useful than the README for actual building. The licence is non-commercial (CC BY-NC 4.0), which surprised us because the project feels fully open: it does not allow selling prints or kits without permission from the team. Polar alignment is the single thing that trips up new builders more than any mechanical issue — the mount can be perfect and the photos still fail if the axis is off. The hardware repo was created in 2020, and while its last commit was in February 2025, the firmware repo was still being updated in September 2026. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Fabian Uehleke (OpenAstroTech)

OpenAstroTracker was designed by astrophotographer Fabian Uehleke to give people an affordable way into astrophotography with 3D-printable gear, instead of starting with the price of a commercial tracking mount. He published the design openly and it grew into OpenAstroTech, a collaborative project with a team maintaining the firmware, desktop software and several mounts. If you build one, the best way to support the work is through the project shop or the developers directly; Fabian is on Instagram as @fabianuehleke.

GitHub Web

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  • Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
  • Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
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