Hand scraping is done, but for ultimate flat you need to lap three plates not hand scrape. Hand scrapping is not as flat - but the average is close enough and the imperfections are needed anyway for oil so hand scraping is used for bearing surfaces.

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ggm 6 days ago | parent [-]

New Scientist published a reminiscence of somebody in the relatively modern era doing the 3 plate dance. I wish I could find it online. They said it was tedious work.

Maudsleys 3 plates are in the London science museum along with Whitworths screw, and some of Marc Brunels stuff. Same room as the meccano differential analyser and the harmonic calculator for tide charts and Babbage bits.

Edit: found it - https://archive.is/iyCzB

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hug 6 days ago | parent [-]

It's a straight edge, not a bed, but this is a fun watch: https://www.youtube.com/watch?v=pq47yXFmj24

	▲	ggm 6 days ago \| parent [-]
		Much the same process, in one less dimension. And it looks time consuming but I bet immensely satisfying.