<video src="InShot_20230514_202820016.mp4" controls width="500"></video> Astrophotography has a fundamental problem: the Earth rotates. For long exposures of the night sky, you need a mount that tracks celestial objects as they move across the sky, or your stars become streaks. Commercial equatorial tracking mounts exist, but they're expensive and heavy. The OpenAstroTracker project offers an open-source alternative—a 3D printed equatorial mount with stepper motor control that rivals commercial offerings at a fraction of the cost. There was just one problem with the original design: it requires a flat surface to mount on. A table. In the field. I do most of my astrophotography in remote locations—dark sky sites away from light pollution, often accessible only by hiking. Hauling a table up a mountain isn't practical. ![[20230721_194457.jpg|500]] ## The Redesign My solution was to integrate an RRS MPR-450 cinema rail as both a structural member and a tripod mounting interface. The cinema rail replaces the table entirely, allowing the tracker to mount directly to any Arca-Swiss compatible tripod head. ![[20230311_141721.jpg|500]] ![[20230305_164249.jpg|500]] This wasn't a simple bolt-on modification. The geometry change cascaded through several components: - Motor mount had to be redesigned with shoulder bolts compatible with both the rail and the original "strong mount" option - Electronics enclosure required a complete redesign to accommodate the new geometry - The upside: the new enclosure layout resulted in significantly cleaner cable routing ## Technical Details ![[20230228_190426.jpg|500]]) The build incorporates: - 3D printed structural components in carbon fiber reinforced filament for stiffness and thermal stability - NEMA 17 stepper motors with TMC2209 silent drivers - Raspberry Pi 4 running Astroberry (INDI-based control software) - Automated DSLR control via libgphoto2 for hands-off capture sequences - Dew heater system to prevent condensation on optics during long sessions The RA and DEC axes are individually calibrated (631.3 and 313.2 steps respectively) for precise tracking at my latitude. ## Result A fully portable equatorial tracking mount that fits in a backpack alongside my camera gear. No table required. Dark sky sites that were previously impractical are now fair game. --- Tags: [[3d printing]] [[photography]] [[mechanical design]] [[mechatronics]] [[electronics]]