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Hand Scraped Finish?

Discussion in 'Maintenance, Tinkering & Embellishment' started by BaneLordTartarus, Aug 8, 2018.

  1. BaneLordTartarus


    Feb 17, 2013
    I stumbled across an old educational video, detailing a machining process called metal scraping. Using a surface plate, some Prussian Blue, and a series of tools resembling chisels, the machinist could achieve a completely flat surface. The process was also used aesthetically to create an effect called "frosting". It produces a really interesting surface patern.

    I was wondering if anyone knew of such a finish being used for a knife.
  2. Wowbagger


    Sep 20, 2015
    I assume you mean on the blade ?
    The finish you mentioned is done on cast iron surfaces etc but I would think a decent knife blade would be nearly as hard as the tools used to cut the cast iron so probably not practical for a finish on a knife blade.
    It might look cool on a handle.
    I have never used these scrapers but have read about the process in my old machinist magazines.
  3. David Martin

    David Martin Gold Member Gold Member

    Apr 7, 2008
    To me that finish would be used as a quick cover up so flaws could not be detected as easily as on a mirror finish. DM
  4. eKretz


    Aug 30, 2009
    No, scraping is a precision finishing method. It is used to create flatness in the near millionths of an inch range. Grinding machines can only do so well, and this is what is used post-grinding to dial in near perfect flatness. It's used for precision mating fits and alignment. It's a very involved and labor intensive process, and isn't simple, nor easy. At precision of this level, even the touch of your hand can cause enough thermal expansion to ruin a fit.

    Frosting is different - it's used on sliding surfaces after precision scraping to create tiny troughs that hold lubricant, so that the fits on these precision surfaces don't glue themselves together or run dry.

    This is a large and involved subject for those who aren't familiar with machining and precision fits - if you want to know more, Google will help you.
    Getting older likes this.
  5. eKretz


    Aug 30, 2009
    Oh, and yes you could use it as a decorative finish on a knife blade easily enough. Modern scrapers are tipped with tungsten carbide, which can fairly easily cut hardened steel. Making it look nice would take some practice though - I'd suggest starting on some scrap.

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