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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

difficulty
●●●●○
time
several weekends
license
CC-BY-NC-SA-4.0
repo
repo ACTIVE1,123 stars

WHAT YOU’LL NEED

  • 3D printer + filament — printable parts — files are in the repo
  • Electronic parts — full list with part numbers in the repo BOM
  • Dev board / microcontroller — runs the project firmware

Partner

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Videos
3

COMPAREE VERDICT

OpenAstroTracker solves a real problem: Earth rotates, so untracked long exposures turn stars into trails. This mount rotates your camera in sync with the sky, letting you take multi-minute exposures that reveal nebulae and galaxies invisible to the naked eye. The design is mature — the repository has been active since 2019, the wiki is thorough, and there is a real community of builders who post their results. You will print around 50 parts, then add steppers, bearings, timing belts, and an ESP32 or Arduino-based controller. The hardest part is not the printing — it is the mechanical assembly and polar alignment, which astrophotography newcomers consistently underestimate. If your mount is not precisely aligned with Earth's axis, tracking drifts and stars blur. The firmware supports GoTo slewing and works with ASCOM, so you can use desktop planetarium software to point the mount at targets. One trap: the non-commercial licence means you cannot sell prints or assembled units without reaching out to the team. For someone who already does astrophotography and wants precise tracking without spending four figures on a commercial mount, this is a legitimate path. For someone new to both 3D printing and astrophotography, expect to learn two hobbies at once.

NOT IN THE REPO

  • —STL files, Fusion 360 source files, and assembly guide are in the repository.
  • —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-SA 4.0 — free for personal use, commercial builds require permission.
  • —ASCOM driver for integration with professional astronomy software is included.

Can I build this?

PrintApproximately 50 STL files for the mechanical structure, designed for PLA or PETG on a standard FDM printer
BuyNEMA 17 stepper motors, GT2 timing belts and pulleys, 608 bearings, linear rails, ESP32 or Arduino Mega, stepper drivers, power supply, ballhead or camera adapter
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
TimePrint time is 60-80 hours spread across days; assembly is two full weekends if everything fits; add another weekend for polar alignment and firmware setup
Cost$$ — motors and electronics dominate, around 150-250 depending on suppliers and whether you already have a power supply and stepper drivers
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.

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Videos

OpenAstroTracker Build Guide

Official project video walkthrough; there are multiple community build videos on YouTube that show real assembly sessions

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.

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KNOWN ISSUES

  • The non-commercial licence (CC BY-NC-SA) blocks selling assembled units or prints — if you want to make a batch for a club or sell kits, contact the project first.
  • 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.
  • Stepper motor specs vary; underpowered motors will skip steps under load, especially if you mount a telephoto lens or small telescope.
  • Backlash in the drive train shows up as star elongation — belt tension and gear mesh need attention during assembly, not as an afterthought.
  • 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?

The design supports small refractors and guide scopes — the wiki lists weight limits per version. Heavier scopes need the beefier V4 variant with reinforced mounts.

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

Phone apps like Polar Finder work, but a polar scope gives better precision. Either way, you will iterate alignment over multiple nights as you learn what good enough looks like.

What camera works best with this?

Any DSLR or mirrorless with a standard tripod mount. Full-frame sensors give you more sky, but the mount does not care — weight and balance matter more than sensor size.

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?

MangoJH23d ago

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

CompareeTEAM19d 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.

CompareeTEAM1mo agoedited

Practical notes from our verification: The hardware repository is the mechanical design; firmware lives in a separate repo under the same organisation. The wiki is far more useful than the README for actual building — it has current BOMs, assembly photos, and version-specific notes. The non-commercial licence surprised us because the project feels fully open, but it blocks selling prints or kits without reaching out to the team first. 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 project has been continuously active since 2019, with regular firmware updates and community contributions.

Fabian Uehleke (OpenAstroTech)

OpenAstroTracker was designed by Fabian Uehleke, an astrophotographer in Germany, who wanted publicly available 3D-printable astrophotography gear so the hobby would not start at 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 and several hardware variants for different payload weights. 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

Star the project on GitHub

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  • Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
  • 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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