Greg Koenig from Atomic Delights has a great analysis of the manufacturing process of the Apple Watch based on their Watch Craftsmanship videos.

This walkthrough is a detailed narration of what we see in Apple’s Watch Craftsmanship videos. Of course, we only get to see a mere fraction of the process; I’ve tried to provide plausible explanations for the likely steps taking place between the processes shown on film, but these are assumptions and are included only to provide a more satisfying and complete narration.

Considering the limited amount of detail displayed in these videos, he’s able to extract a lot of information from the various stages of the process. For example:

We see a few shots of the case in a 5 Axis milling setup with custom work holding, milling out the internal features at odd angles. In this shot, our part is flipped yet again and is being presented to the tool so the pocket for the Digital Crown and button can be milled. Machinists should note that Apple isn’t cutting the side button slot with a full-width cutter – the smaller end mill is slower, but produces a far better surface finish by avoiding chip thinning fluctuations.

Great stuff