Full Main Dial for 2025 Heliochronometer Sundial - Southern Hemisphere Version

Change History

Update (24-10-25):   The teeth on the main dial gear were re-aligned to better register with the noon mark. The original design was off by 1.25 degrees.  Note that this has no impact on the reading accuracy of the dial itself since that is primarily determined by the alignment of the minute dial.  The new file is named: Clock_Hybrid_Gard_Main_Dial_Gear_v2.stl

The original 2025 heliochronometer sundial reads time between 5:30AM & 6:30PM.  This is due to the crescent main dial which limits the mechanical movement of the alidade.  The original design is available here: Super Accurate Heliochronometer Sundial - 2025 - Southern Hemisphere Version by 3DMason | Download free STL model | Printables.com

Note: This design is only compatible in the SOUTHERN HEMISPHERE.  A NORTHERN HEMISPHERE version can be downloaded here:  Full Main Dial for 2025 Heliochronometer Sundial by 3DMason | Download free STL model | Printables.com

This new main dial design provides a complete 24 hour movement by incorporating the following modifications:

1. A full circle main dial with 24 hour markings;
2. A full Outer Ring Gear: i.e.  
   • 144 inner teeth vs. original 94;
   • 144mm Pitch Dia. (same)
3. Additional (2nd) Planetary Gear: 
   • 69 teeth;
   • 69m Pitch Dia.
4. Upgraded Dial/Latitude Crescent Support with extra arm.

Modifications 3 & 4 are optional, but will add to the overall rigidity of the sundial assembly when using the new full circle main dial.

Refer to the original design for assembly, setup & use:  Super Accurate Heliochronometer Sundial - 2025 - Southern Hemisphere Version by 3DMason | Download free STL model | Printables.com