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Free hand sharpening or use gadget.

Discussion in 'Maintenance, Tinkering & Embellishment' started by Houlahound, Jul 8, 2019.

  1. tiguy7

    tiguy7 Gold Member Gold Member

    Jun 25, 2008
    They got it right the second time. Not my picture. 523FD3FF-E5F8-4C23-8E2B-FE8E5FA81404.jpeg
     
  2. David Martin

    David Martin Gold Member Gold Member

    Apr 7, 2008
    Someone will have to translate their writing for me. DM
     
  3. David Martin

    David Martin Gold Member Gold Member

    Apr 7, 2008
    @HeavyHanded , I was also not apprised about the 2 degree variation that CATRA endorses. So, I'm trying to catch up on my reading. I would not doubt there are some freehand sharpeners in this forum that can produces edges with 1 degree variations.
    I would think this amount of error is easily within tolerance levels of many of these gadgets. So, now we begin to see the playing field very equal. DM
     
  4. bucketstove

    bucketstove

    Sep 23, 2014
    Hi,
    Basically too much trust/confidence in a very strict tolerances machine (tester) that turned out to be incorrectly assembled. Problem was detected with lesser machine but ignored (confirmation bias).
    hand-polishing was also used .
    Quotes below
    https://en.wikipedia.org/wiki/Hubble_Space_Telescope#Flawed_mirror
    its mirror needed to be polished to an accuracy of 10 nanometers (0.4 microinches, 0.01micron), or about 1/65 of the wavelength of red light.
    Although it was probably the most precisely figured optical mirror ever made, smooth to about 10 nm (0.01 micron, 0.4 μin), at the perimeter it was too flat by about 2,200 nanometers (2.2 micrometers; 87 microinches).
    [​IMG]
    The Allen Commission found that a reflective null corrector, a testing device used to achieve a properly shaped non-spherical mirror, had been incorrectly assembled—one lens was out of position by 1.3 mm (0.051 in).
    A few final tests, using the conventional null correctors, correctly reported spherical aberration. But these results were dismissed, thus missing the opportunity to catch the error, because the reflective null corrector was considered more accurate.
    Instead, the fact that the mirror had been ground so precisely to the wrong shape led to the design of new optical components with exactly the same error but in the opposite sense, to be added to the telescope at the servicing mission, effectively acting as "spectacles" to correct the spherical aberration.



    Hubble - Construction, The Hubble Mirror, Blurred Vision, Hubbles Contact Lens
    Finally, highly skilled opticians using manually controlled tools and delicate hand-polishing techniques removed an additional 0.03 of an inch ( 762 micron ) from the mirror's surface

    Hubble Space Telescope Optics System | NASA
    [​IMG]
     
  5. bucketstove

    bucketstove

    Sep 23, 2014
    Hi
    Guided freehand, seriously :)
    Its just a bit of tape/cardboard for easier visualization
    Why should sharpening require more precision than actual cutting?
    For looks , crisp lines and mirror polish and all that
    bladeforums.com/threads/angle-guide-for-honing-rod.1661832/#post-19006978
    [​IMG]
     
    kreisler likes this.
  6. Craig James

    Craig James

    32
    Oct 30, 2018
    I freehand sharpen. I have a DMT coarse and some unbranded rubbishy 2000/6000 combo.

    I normally just use the DMT and my edges can pop arm hair. It’s learning an understanding of how to effectively remove the wire edge that has really improved my technique.

    I’ve never been able to achieve whittling or tree topping edges.

    Although through practise and better equipment I may eventually get to this stage the scientist in me understands that a guided system will always produce a finer end product than just my eyes and hands can produce
     
  7. lonestar1979

    lonestar1979

    Mar 2, 2014
    Wicked edge and edge pro produce excellent edges,but for my uses theyre unnecessary and too expensive.I still prefer slightly convex edges off the stones,and think theyre more durable.Sharpmaker is amazing,for light touchups,and i use it ,but in combination with stones is amazing.I just use few swipes on SM ,and thats usually enough,when edge gets dull,use the stone and work up the burr.
     
  8. mb>

    mb> Gold Member Gold Member

    Sep 24, 2014
    The hardest part of learning to sharpen for me was translating written descriptions into practice. It would have gone SO much faster with a mentor, in person. Like others have experienced, at some point I learned that I wasn’t dealing with burr removal correctly, and things really improved after that.

    I almost bought a system once, but forced myself to learn freehand instead. I’m glad I did. I never wanted to be tied to a large tool when I could have a small portable stone.

    Kudos to Michael Christy and his YouTube videos for showing what’s possible in terms of consistent freehand hair whittling results. I don’t bother going that far, but it helped inspire me on the path.
     
    David Martin likes this.
  9. HeavyHanded

    HeavyHanded

    Jun 4, 2010
    Personally I don't think my widget even has a full degree of variation as long as the stones are flat. I always use a microbevel to finish when sharpening with it, and mostly use it with diamond plates.

    The CATRA is a single pass, edge-ready unit.

    Still thinking of ways to accurately introduce a bit of variation in my guide that doesn't involve hard stops on the rod (that doesn't work well, at all).
     
    David Martin likes this.
  10. redw0lf

    redw0lf

    27
    Jun 27, 2019
    I made a strop to sharpen my 3v edc. Thought it would be a nightmare, but after some time, the blade feels great. And stropping is calming.
     
  11. David Martin

    David Martin Gold Member Gold Member

    Apr 7, 2008
    Exactly, for 500$ I could do a lot of other things. But for some that have challenges with eye / hand coordination this is the only way they can obtain a sharp edge. Still, I'm glad someone built these gadgets. Many come some wobble. They could have a
    1*-2* angle of error, depending on pressure and other factors. This causes me to move to the middle ground, thinking that freehand and gadget sharpening are close to each other from an accuracy stand point. DM
     
  12. Twindog

    Twindog Gold Member Gold Member

    Apr 6, 2004
    There is going to be a large variance in the edge angles and sharpness of knives sharpened freehand. Skilled, well-practiced people will get fairly consistent angles and keen edges. Few to no others will match the edges of someone truly skilled.

    My dad taught me how to sharpen when I was about 12: It was easy peasy. Squirt some oil on a cheap stone, move the blade in circles on the stone until it was sharp. There was no instruction on angles, burrs, reprofiling, microbevels or anything else. And I would get my knife sharp enough to do everyday things.

    The guided systems are about getting an optimal edge, with clean, even bevels and a super keen apex. With knowledge, you can learn to leave no burr and refine the edge with a strop. You can get a killer edge. A pro-level edge. I could never get that nice an edge as a kid, but I didn't need to.

    As an adult who uses various knives every day, I appreciate a killer edge. I can freehand well; but at my skill level, I can get a better edge with my Wicked Edge and a collection of stones and strops.
     
  13. tiguy7

    tiguy7 Gold Member Gold Member

    Jun 25, 2008
    I have gotten picture perfect edges with Razor Edge and Buck jigs, but the set up time and other complications allow me to live with a less than picture perfect edge. Hand holding cannot compete with mechanical devices for precision (reproducible) results. Most of my cutting applications are not critical like sectioning a tumor with a microtome or parting the floating silk scarf with a Samurai sword.
    I can get very useful edges by hand sharpening, and they are not hard to do. I hate to use a lovingly sharpened EDC for breaking up cardboard boxes, but my Ti boxcutter with a bimetal blade solves that problem.
    If I had enough pockets, I would probably carry a specific knife for every job. The light in the tunnel: I am acquiring new knives faster than I can wear out the edges on the old ones.
    They’re coming to take me away Ha Ha, straight to the Clinging Vine Home for the Crazed.
     

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