A replica of The Prague Astronomical Clock--- Orloj, featuring a manually interactive decorative centerpiece.

Dial diameter: 250 mm; thickness approximately 50 mm.

About the clock body:

The clock operates on a 24-hour cycle and lacks minute hands. The golden hand points to Roman numerals 1–12, indicating modern time—solar time.

On the central dial, three golden rings represent the Tropic of Cancer, the Equator, and the Tropic of Capricorn, while sky blue denotes daytime and darker shades signify nighttime. On the eastern (left) side of the horizon are inscribed “aurora” (Latin for dawn) and “ortus” (rising), whereas the western (right) side bears “occasus” (sunset) and “crepusculum” (twilight).

The outer ring displays Old Czech time, showing how sunset times vary throughout the year in 24-hour increments—from as early as 4:00 PM in winter to as late as 8:16 PM in summer.

A movable disk is the ecliptic plate, completing one rotation every 23 hours and 56 minutes—sidereal time.

The golden sun travels along the ecliptic, thus indicating its position relative to the zodiac, while seasonally shifting between the Tropic of Cancer, the Equator, and the Tropic of Capricorn.

The moon depicts its orbital motion and lunar phases.

Model replication details:

The manual mechanism allows coordinated movement of the golden hand and the ecliptic disk, enabling adjustment of the sun’s position.

The golden hand and the ecliptic disk each complete roughly 30 cycles (the main body rotates about 365–366 times per year), but due to weight and friction—especially after suspension—they do not operate perfectly smoothly.

The outer ring representing Old Czech time can be manually shifted so that the 24-hour mark aligns with the modern time range of 4:00 PM to 8:00 PM.

Non‑3D‑printed components required include:

1. One 608 bearing and one 6806 bearing
2. Eight M2×10 screws
3. One M3×20 screw
4. Three M3×12 or longer screws
5. One M2.5×6–10 screw
6. Three M2×6 screws

Assembly instructions:

All screws used as “axles” should not be tightened excessively.

First slide the slider beneath the sun into place, then secure it with screws.