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From Very Sharp To Dull Quickly. Rolled Edge ?

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  • #55206
    Hogdog
    Participant
    • Topics: 1
    • Replies: 18

    I’ve been using WE for quite some time and have always had this issue. I can get a very sharp edge going up to my super fine ceramics or 3000 diamond stones. I strop with leather  5.0 and 3.5 microns. But with little use it loses its keen edge quickly mainly cutting thin cardboard. Even if I only go to 1000 grit finished with a strop I still have the issue. I’ve also tried stropping at up to 2 degrees higher and lower to see if that will correct but with no discernible change. It seems to me that the burr is not quite fully removed causing it to roll. I’ve tried going from 17* to 20* angles and different micro bevels with no changes. I seem to notice it worse on my EDC blades both leathermans one is a S30V which is the worst of the two and the other is 420HC. I can quickly regain my edge with just a few light strokes on my Spyderco Sharpmaker fine ceramic rods. I can even get a decent edge back with a few stropping strokes on my Levi covered thigh (don’t try this at home). My kitchen knives seem to hold up well but I do use a steel often probably hiding the issue.
    I’m mainly a lurker and rarely post. I appreciate the wisdom I’ve learned reading many posts but I’ve never seen this issue discussed, however with the vast amount of posts maybe I’ve missed it. Any help is much appreciated.

    #55207
    MarcH
    Moderator
    • Topics: 62
    • Replies: 2202

    Are you using a lighted magnified visual aid like a jeweler’s loupe.  Or maybe a USB Microscope .

    Being able to see your sharpening results are invaluable.

    I’d suggest you simplify the issue.  Only sharpen to 1000 grit,  to start.  Visually inspect your sharpening progress and finished edges to be sure the apex is true, exposed and there are no remnants of any burr.  That the knife is sharpened well and properly to begin with.

    I suggest you use an alternating side, left-right-left-right,  edge leading stroke, down and against the knife edge, as your final sharpening strokes to end each grit, you use.

    Drop the extra fine stones and the strops.  Don’t do any touch ups with the Sharpmaker or even your pants leg.

    Use that knife as usual.  When it looses it’s sharpness, visually inspect the knife edge.  This should let you see exactly what you’re dealing with.  Inspect the entire length of the edge and both sides.

    Now, with just that one knife, alone, add the sharpening steps back, only one extra step at a time.  Finer stones, then stropping.  Use the knife till it needs sharpening, again.  (No touchups with ceramic rods).  By isolating the indivual steps and adding them back systematically, one at a time, and visually inspecting the edge each time, you should be able to see how and where your edge failure is.

    Stropping can add to or take away from your sharpness results.  It’s a sharpening skill unto itself.  Like sharpening, stropping takes practice, too.  It’s suggested that you strop the knife edge at 1º to 2º less an angle than the sharpened bevel angle.  That is if you sharpened at 20º, then strop at 18º-19º.  This is to prevent rounding over the sharpened edge by stropping.  Applied stropping pressure effects the results.  The idea is to coordinate your angle reduction to coincide with your applied stropping pressure.  (Start with 2º)

    The S30V is a really tough steel, but brittle.  I’d expect it to stand up well to use.  Cardboard and paper are two of the toughest substrates to cut with a knife.  I’d expect the S30V steel to wear off, or chip off, not roll the edge.

    Marc
    (MarcH's Rack-Its)

    #55208
    Hogdog
    Participant
    • Topics: 1
    • Replies: 18

    Thank you MarcH. I appreciate your advise and will try to reverse engineer  my process. As a side note I use a very light touch with my stropping and the increase in edge sharpness is always impressive to me. Also I do use a loupe and I don’t see any remnants of a burr after sharpening however I  haven’t looked at the edge after the loss of performance   That I will also certainly do.

    #55209
    MarcH
    Moderator
    • Topics: 62
    • Replies: 2202

    Be aware that edge trailing sharpening strokes may result in a very thin yet very sharp knife edge.  Sometimes it’s an elongated wire edge.  It starts out incredibly sharp but lacks durability and stability and may fail before not too long.  Stropping or a ceramic rod may easily restore sharpness to a failed wire edge.

    Marc
    (MarcH's Rack-Its)

    #55210
    Hogdog
    Participant
    • Topics: 1
    • Replies: 18

    Thanks again MarkH excellent point. I do use trailing edge strokes and an elongated edge makes perfect sense. Should I use edge leading for my final diamond grit?  I’m aware of the safety hazards using edge leading.

    #55211
    MarcH
    Moderator
    • Topics: 62
    • Replies: 2202

    I suggest you use an alternating side, left-right-left-right, edge leading stroke, that is, down and against the knife edge, as your final sharpening strokes to end each and every grit you use.

    Marc
    (MarcH's Rack-Its)

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