News for hackers. Stuff that matters.
Re:Hand Scraping a Truly Flat Plane (1908) [pdf] by dekhn on Thursday April 16, 2020 @06:10PM (#22894079)
Some of this is covered in One Good Turn: The Natural History of the Screwdriver and the Screw, which I enjoyed more than The Perfectionists. https://www.amazon.com/gp/product/B00CVR143M/

Circa mid-1960s, this defined precision: https://www.amazon.com/Foundations-mechanical-accuracy-Wayne... (at this level of precision, you need a room-within-a-room climate control, because thermal expansion of objects). That leads down the rathole of "jig borers" for making precisely located holes of precise radius and diamond turning machines which are nice for cutting optics.

Re:Hand Scraping a Truly Flat Plane (1908) [pdf] by jbay on Friday April 17, 2020 @02:12AM (#22896665)
Fast-forward to 2016 to see how much the technology has changed:

https://www.nist.gov/news-events/news/2016/09/meet-bob-pmls-...