Hand Scraping a Surface Plate to Sub 5 Micron / A - Grade Flatness

Hello and welcome, in this video I'm showing you how I handscraped my steel surface plate to a flatness of less than 5 microns (0,2 thou). It ended up beeing somewhere inbetween 3 and 4 microns of flatness. That's 0,003-0,004mm. So not that much. All scraping was done by hand. Roughing with a 30mm/25mm carbide blade with 140mm radius. Finer scraping was done with a 25mm carbide blade and 90mm radius, final scraping was done with 60mm radius. For scraping basics check out ‪@StefanGotteswinter‬ 's channel, he has awesome basic videos about scraping. My ghetto carbide grinder is also inspired by him.    • Scraping basics - Scraping flat - Part 1   MUSIC: The Gentlemen - DivKid Snowy Peaks pt I - Chris Haugen Snowy Peaks pt II - Chris Haugen Pink Horizon - Chris Haugen Soft Feeling - Cheel Sunday Rain - Cheel Sunset Dream - Cheel Blue Dream - Cheel Lazy Walk - Cheel Smokey Eye - Cheel Campfire Song - Chris Haugen Blue Creek Trail - Dan Lebowitz 00:00-02:55 Intro 02:56-20:50 Rough scraping 20:51-22:37 Carbide grinding 22:38-30:12 Fine scraping 30:13-34:45 Measurement method 34:46-40:55 Metrology theory 40:56-44:45 Measurements and results 44:46-47:02 Bonus