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Need advice please.

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This topic contains 3 replies, has 4 voices, and was last updated by  MarcH 05/07/2018 at 12:19 pm.

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  • #46213

    sam
    Participant
    • Topics: 5
    • Replies: 3

    I go though the whole process starting the 100 grit all the way though the 1500 and the 1600 ceramics I tape on the 2500 grit sand paper then last, I strop with the 5 micron the 3 then switch to the kangaroo with the .25 micron and finish with the .1 micron and blade will barely cut phone book paper. It wont shave and doesn’t seem sharp at all. What am I doing wrong?

    #46216

    tcmeyer
    Participant
    • Topics: 30
    • Replies: 1512

    Hi Sam:  It’s likely that you’re not reaching the apex somewhere along the line.  This is one of the key points new users have to learn.  If you don’t have a good loupe or a USB microscope, then the only real option you have to ensure that you’re actually stoning the very edge is by feeling for a burr on the edge.  Reaching the apex is an absolute key to producing a sharp edge.  This may require a slight change in technique if you’ve been using the alternating stroke method shown in Clay’s videos.  Instead, work one side at a time.

    As an example, tonight I was sharpening an IKEA 7″ Santoku.  It had been heavily used and “touched up” with a steel.  It looked awful, but I could see the factory grind (17 dps) so I set up for that angle on both sides and started with my 400 grit.  If I didn’t have my USB ‘scope, I would have stoned the left side (I’m left-handed) continuously, until I had produced a full-length burr that I could feel with my fingertips on the right side.  Having done so, I would then stone the right side for some nominal number of strokes (for a 7″ kitchen knife, I use about thirty strokes per side) until the burr had rolled over and could now be felt with my fingertips on the left side.  If the bevel width on the left side was obviously wider than the right side, I’d continue to work the right side until the bevels matched in width.

    Some people continue to use the burr as an indicator for all subsequent grits, but I know that all of my stones hit the same angle within less than 0.1 degrees of error, so I just continue from grit to grit, knowing that all the subsequent stones will be close enough to work the apex, where all the sharp magic happens.  I do finish each grit with three or four alternating strokes to remove any burrs which might obstruct the smooth movement of the stones along the bevels.

    The sequence I used was 400, 600, 800, 1000, 1500, then 6 and 3 micron films.  I wasn’t looking for a mirror finish, so there are a number of scratches from early grits showing through, but I know they don’t detract from the sharpness.  It slices telephone book paper easily, but the paper in my phone book will only slice in the long direction.  Apparently, the paper machine produces an interlocking of the paper pulp fibers in the cross-direction.  The fibers will tear before they’ll slice.  Even a fresh scalpel blade won’t slice through it.

    Hope this helps… Good luck.

     

    Tom

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    #46221

    Organic
    Participant
    • Topics: 16
    • Replies: 498

    Tom’s advice is spot on. If you don’t reach the apex during the sharpening process, then the knife will not be sharp not matter how many different grits you use. A sharpie or similar marker can be used to color in the bevels and can also help you see if you have reached the apex, but this is most reliable when used in conjunction with a magnifying device.

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    #46226

    MarcH
    Moderator
    • Topics: 45
    • Replies: 1063

    Sam that is a very common experience you had and a normal part of the learning curve.  I experienced the same issue, when I was just learning. I still verify I’m reaching the apex with each and every knife I sharpen as a regular part of my sharpening routine/technique.

    Following up the individual side scrubbing motion to draw the burr, as Tom suggested, with alternating side stone strokes, left side – right side – left side – right side helps to insure you’ve reached the apex, and to even out the bevel.  I pull a small square piece of newspaper, held by the corners, down onto the sharpened edge of the clamped knife to test for sharpness after each grit.  This helps me to determine the edge is getting sharper following each grit in the progression, by how much easier the newspaper cuts.

    Marc
    (MarcH's Rack-It)

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