Perhaps the most ingenious part of the Antikythera Mechanism is a rather small unassuming gear pair. But despite its simplicity, the K1/K2 gears very closely model the eccentricity of the moon’s orbit.

Developing a mathematical model for determining eclipses decades in the future, that could be used to design a mechanical model for such a task.

While no fragments remain, researchers agree that a planetarium was once mounted on the B1 drive wheel of the Antikythera Mechanism. Here we explore what is likely to have been present

One point of potential confusion when considering astronomical gearing are the various types of lunar months. How they are defined and how long they are is all explained here.

A traditional algorithm for identifying complex gear ratios, such as for astronomical gearing. But not always as simple as it seems to use in practice…

With the benefit of modern computing, usually a more straightforward approach to identifying gear trains for irrational ratios.

Bevel gears present a challenge to a manual machinist due to the non-constant tooth pitch. However, there are some neat tricks in order to get them very close to the true involute profile.

Ultimately culminating in a pile of moving gears makes designing and building orreries to be a bit of a daunting task, but when taken step by step it is not so difficult to design your own.

Correcting for the Equation of Time had a brief lifetime in horology, but it is in interesting subject especially once we consider mechanical methods to replicate it.