Equatorial Sky Tracker

This is a motorized equatorial sky tracker designed for long-exposure astrophotography. The tracker rotates a single polar axis at sidereal rate, allowing a fixed camera to follow the motion of the night sky and eliminate star trailing during extended exposures or timelapse video.

Motion is provided by a stepper motor coupled to a geared reduction consisting of an inline planetary gearbox (100:1) and a large spur gear (12:90). A spring loaded pinion mount maintains gear engagement to minimize backlash.  The polar axis is supported by bearings for smooth rotation. Altitude adjustment is achieved through a thumbturn through a worm gear. 

** - This build is dimensioned for specific components and is not intended to be universally compatible with all parts without modification. 

The geometry, clearances, mounting features, and gear mesh are based on the following specific hardware:

1. Nema 17 Pancake Stepper Motor 1A 17Ncm Bipolar 1.8 Degree

2. Planetary Gearbox Gear Ratio 100:1

3. Small Circular Bubble Levels

4. Stepper Motor Driver TB6600 4A DC9-42V 32 Subdivision

5. (2) Shoulder Bolt 8mm Shoulder Dia 40mm Shoulder Length M6x1

6. 8mm Flange Coupling Connector

7. Cold Shoe Mount Adapter, Aluminum 1/4”-20 Screw Hole 360° Rotation Camera Tripod Mount for GoPro Hero

8. Zeee 3S Lipo Battery 5200mAh 11.1V 80C

9. (6) 608 Bearings

10. (2) Skateboard bearing spacers

11. (4) bearing washers

12. (2) M4x16 w/ nuts (stepper driver mount)

13. (4) M4x12 (planentary gear mount)

14. (4) M3x8 w/ nuts (flange coupling connector)

15. (4) M3x20 w/ nuts (motor spring mount)

16. (4) M3x16 (planetary gear to nema attachment)

17. (4) M2x8 (locking collars & knob for elevation adjustment)