This kind of content is great, thanks for the post. If you're into this kind of thing I recommend by Moore. Really interesting ideas of how one measures and guarantees accuracy in machining. I think this is the book the guy in the video got all his pictures from and he basically described ideas from that book.

Nice.

I have a set of 'slip gauges' that i keep because they're cool. Never used them for anything. They were a 'hangover' from a defunct Quality Management System (IS0 9001, the IMTE requirements). If you have a set of these you can in-house calibrate any measuring instrument in the factory, no outside service needed.