Scientists Have Unlocked the Secrets of the Ancient 'Antikythera Mechanism'

Chris from Clickspring has done an amazing amount of work recreating the tools and methods the Greeks would have used, I'm fairly certain he's got all the right answers.

https://hackaday.com/2020/12/12/hackers-discovery-changes-un...

I made gears for 5 years of my life, and they are a pain, but the ancient gears didn't push metallurgy to the limit, expecting decades of continuous service... they had a lot more leeway. Even so, there were a lot of very skilled craftsmen who put in an enormous amount of time building these things, probably in a small shop.