How a Mechanical Watch Works
ciechanow.skiThis is very, very good. Clear explanation of a mechanical system is hard, but the author made it easy.
Moment of inertia... do they calculate it for those tiny parts, or is it cheaper to just cut and try? The tolerances required must be exceedingly tiny.
I’m sure you can get fairly close at design time but then need to tune it (I think “regulate” is the term of art) to get it just right before sending the watch off.
The interactive animations in this post are neat.