Horology
I got my first real watch as a gift for my 20th birthday; I had some watches when I was younger but never really appreciated them. This one was a Seiko SUR449, which is a quartz watch with a beautiful green sunburst dial. It was my only watch for over a year, after which I decided that I wanted some more variety and invested in a Timex Expedition (a field watch) and a Casio A158WA. All of these are tools that I use to tell time, but some conversations with people who collect watches during my summer in SF got me interested in mechanical watches more for their engineering than their time-keeping ability. I bought a Seiko 5 from the SNK line, which has an open back which shows some of the complexity inside. This got me more interested, though, and made me really want to better understand what's really inside a watch.
The best way to understand how something works is to work with/on it. I considered buying some broken watches and fixing them, but that would mostly just involve buying replacement parts and fitting them in. To me, watchmaking's complexity is concentrated around design and manufacturing; replacing some gears wouldn't really teach me much about those. I've thought about what I want in a perfect watch for a while. Many people have a 'grail watch,' a piece which they want most but is difficult to get. There are a lot of watches which I like and are nice to look at, but each of those have some shortcomings. I've been thinking for a while about what qualities and designs would make the perfect watch for me.
The obvious step was then to think about making my own watch, from scratch. To understand how I might actually go about this, I read two books: The Theory of Horology and Daniels' Watchmmaking. Actual movement design in terms of gear layout is not very complicated. If I had to explain it in the simplest terms possible, I would say that mechanical watches consist of a spring which is trying to unwind, and an escapement which regulates the spring's unwinding to make sure that it happens slowly and in a periodic fashion. These two components are connected by a bunch of gears - the unwinding spring turns a gear, which drives a few other gears (usually 4, in the simplest of watches) and the last gear is connected to the escapement.
I wanted to design and make my own watch. This meant a custom case, dial, and movement. The case and dial are straightforward; I would CNC or hand mill the case, and I could buy a brass blank to make my own dial. The first watch probably wouldn't have any complications, it would be a plain time watch with hour, minute, and second hands. For the movement, I planned on buying gears and hard to make components like the escapement and barrel/mainspring. I would manufacture