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Newbie... Relief, secondary, primary edge? Confusion on beginning sharpening

Discussion in 'Maintenance, Tinkering & Embellishment' started by rickcr, Oct 4, 2012.

  1. rickcr


    Sep 5, 2012
    In another thread I was asking about practicing sharpening on some old kitchen knives http://www.bladeforums.com/forums/showthread.php/996573-Newbie-ok-to-practice-sharpening-on-these-knives?p=11350740#post11350740 and lots of good advice there.

    I figured I'd start a more specific topic on 'angles' because I'm curious what I need to be doing in regard to them. For example Murray's Fundamentals of Sharpening video mentions you should always grind down the secondary edge first. Then I found this site http://www.caseyspm.com/Knives.html mentioning "relief" and then a "secondary" and "primary edge."

    I want to learn how to sharpen without guides, but how am going to be able to tell the difference between a 13°, 17°, or 19° angle for the various edges described for (relief, secondary, primary.)

    I'll primarily be practicing with my Mora utility knife (and maybe a bit still with the old cheap kitchen knives.. but per some recommendations in the other post.. this could be a bad idea.. so I might just stick to the mora for now.)

    Currently I only have a 1000/6000 grit waterstone and a cheap old aluminum oxide dual sided stone but don't know the grit. Even the aluminum oxide stone seems too soft for taking away metal from the relief/secondary(?) edges on the kitchen knives so I guess I'll need to get some paper or another coarser grit stone for that. (In a pinch can I just get sandpaper from the hardware store?)

    Maybe I shouldn't worry about the secondary/relief edges is just trying getting a good primary edge?

    Thanks (my wife is laughing at me with all this knife sharpening business... "Should I be worried Rick?")
  2. Jason B.

    Jason B. KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 13, 2007
    Your confusing yourself.

    The sharpened edge is a "V" of two intersecting planes on which you use a abrasive to thin and refine to a point of desired sharpness. It's one angle per side. Once your sharpening has advanced enough to be concerned with relief bevels, micro bevels, and hamaguri grinding methods then you can drive yourself nuts like the rest of us. For now keep it simple.

    A mora is a good learning tool to help you understand the hand movements for freehand. It's a single grind angle though and not something you typically put compound bevels on.

    If you need a cheap coarse stone Home Depot sells a Norton for about $5
  3. Jason B.

    Jason B. KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Jun 13, 2007
    BTW, you won't be able to tell the difference in angle, angle control is more about letting your natural inability to hold a perfect angle work with you and not against you. A freehand edge will be slightly convex, you would need a guide to get you within +/- 1 degree.
  4. Chris "Anagarika"

    Chris "Anagarika"

    Mar 7, 2001
    Murray uses the term differently.

    People here usually says primary bevel and this is referred as secondary edge by Murray.

    I hope I don't confuse it further :p

    BTW: I guess your wife will be glad when the kitchen knife cuts better ;)

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