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Sharpmaker Grit Size

Discussion in 'Maintenance, Tinkering & Embellishment' started by singularity35, May 10, 2010.

  1. singularity35


    Mar 1, 2010
    I read somewhere that a sharpmaker's grit size is 15 microns for medium, 6 for fine, and 3 for ultra fine. How do these sizes translate to the number on wet/dry sandpaper? Thanks.
  2. Jason B.

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

    Jun 13, 2007
    Ceramics are odd in that respect, you can't really compare them that way. A 8k water stone, UF ceramic, DMT EEF, and 2k sandpaper are all very close but because of the abrasive shape and hardness they all yield a different finish.
  3. singularity35


    Mar 1, 2010
    I see. thanks.

    PS: which one gives the finest polish?
    Last edited: May 10, 2010
  4. bradefolums


    Aug 29, 2009
    I think polishing gives the finest polish, but I admit I'm newbie, and no, I'm not Polish. :)
  5. Jason B.

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

    Jun 13, 2007
    IMO, abroke-in EEF and worn 2k sandpaper. With the combo of speed and a little lube worn 2k will mirror polish. The DMT show
    best results on hard/wear resistant steels.
  6. singularity35


    Mar 1, 2010
    Thanks for all the info knifenut.
  7. Jenslkl


    May 4, 2010
    I found this somewhere

    Spyderco benchstone grits:

    Med 12-14 u 800-900 grit
    Fine 7-9 u 2000-3000 grit
    UF 3-4 u 4000-6000 grit

    DMT Benchstone Grits:

    XXC 120 u 120 grit
    XC 60 u 220 grit
    C 45 u 325 grit
    F 25 u 600 grit
    XF 9 u 1200 grit
    Ceramic 7 u 2200 grit
    XXF 3 u 8000 grit

    And also, the shape of the rod has something to say
  8. singularity35


    Mar 1, 2010
    Thanks, I saved that for future reference.
  9. basb


    Apr 27, 2010
    Nice find on the spyderco grits.
    Do the UF stones realy give a mirror egde?
  10. unit


    Nov 22, 2009
    I agree. I found this somewhere, and it professes grit sizes etc. but I think in practice it is a little more complicated. As has also been pointed out, the degree of "break-in" for the grinding/polishing media also has an impact.

    Do not underestimate ceramics...I have seen Spyderco UF ceramics produce hair whittling edges.

  11. Jason B.

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

    Jun 13, 2007

    All the items I listed can produce the same results but the finishes and feel of the edge will all be different, the steel being sharpened is also a factor.
  12. singularity35


    Mar 1, 2010
    plus 1 on the steel. At the moment all I have is my SM with medium and fine rods(UF rods and DMT aligner still on the way). However, I can get a really fine polish on my vg-10 E4's edge but I can't get even close to a fine polish on my S30v on my military. Am I right in assuming that this is due to the different steels? or is this also in large part technique related? thanks.
  13. Different steels do make a big difference. S30V is the one that made me begin to understand what 'abrasion resistance' really means. Very tough to sharpen, relative to other steels I've tried (420HC, ATS-34, VG10, D2, 1095 carbon, etc.). To me, 'abrasion resistant' has begun to mean 'polish resistant' ;). You can get it there, but it just takes longer (quite a bit longer). I think a lot of the polish I've attained with S30V has largely been due to a lot of stropping after the fact (with green compound on leather).
  14. singularity35


    Mar 1, 2010
    I see. I can't even strop to save my life. Knife just gets duller no matter what i've tried.
  15. If your knife is getting duller with further attempts at polishing/stropping, I'd think the main issue is either:

    Rounding the edge. If so, it helps immensely to use a decent magnifier (at least 5X - 10X) to closely and frequently inspect the edge as you work. Take a few strokes on the stone or strop, then look to see how it's affected the edge. Look very closely, under bright light and magnification. It also helps to use a flashlight, held at different positions & angles relative to the edge, so you can see if the bevels on each side are meeting completely and sharply at the edge. Until they do, it will be pointless to try moving on to polishing and/or stropping.

    Lack of burr formation. During sharpening, most steels will form a burr at the edge when the bevels finally come together. Sometimes it's obvious (you can feel it with your fingertip/nail). You can also wipe the edge with a damp tissue/paper towel. If a burr is there, it'll 'snag' the fibers of the tissue and you'll see them dangling from the blade edge at the burr locations. Other times, it may take some very close inspection under bright light & magnification. A few steels may not necessarily produce a noticeable burr (I've noticed this in particular with S30V, more than once, and also with D2), in which case it's all the more important to closely inspect the edge as you go, to see that the bevels meet cleanly and completely along the full length of the cutting edge.

    If it were me, I'd put my focus and energy into making sure these issues are eliminated or resolved before worrying about polishing the edge. Only then would I move on to stropping. And when doing that, keep the angle low and your pressure light. And inspect, inspect, inspect frequently as you go.
  16. singularity35


    Mar 1, 2010
    Thank you obssessed. I have a loupe but I think the magnification is not high enough because I can only see the sides of the bevel, I can't really see with it if the edges have met. How much does a good loupe cost? and what magnification is ideal? the one I got from ebay says 30X21 but it's from China.
    Last edited: May 14, 2010
  17. I'm guessing, based upon your loupe description, that you probably have enough magnification (30X ?). In fact, if yours is like most other loupes I've seen, I'm assuming you have to put the loupe VERY CLOSE to the edge of your blade, to be in focus. Sometimes, at very close range, it's difficult to adequately illuminate the subject under inspection, because the loupe is just too close (it's blocking the light). You might be better off using a magnifier that allows you to focus from slightly further away (at least an inch or two), so you can still keep a bright light shining on the edge.

    Having a bright light source is really important. Under good, bright light, if you rotate the blade edge back and forth (toward you and then away from you) while using the magnifier, there will be moments where the light will be BRIGHTLY reflected off of the bevels. If the edge is slightly rounded, or if the bevels haven't completely come together at a sharp edge, you'll see a secondary bright reflection from that portion. Ideally, if your bevels are nice and flat, and meet cleanly and sharply at the edge, it'll almost seem like the edge 'disappears' as you rotate the blade past the bevel (and it's bright reflection) and look at the edge straight on. Then, as you continue to rotate the blade towards the other side, at some point, the bevel on that side will once again BRIGHTLY reflect the light into your eyes.

    Imagine if you held two very thin, rectangular mirrors with the edge of one held firmly against the edge of the other to form a 'V'. If there were a bright light shining on the mirrors, at some point, as you view each mirror from different positions, that light would be brightly reflected off of each mirror into your eyes. But when you look directly at the seam between the two mirrors, there's virtually no reflected light. That's what you're shooting for, as far as what you'd want to see when inspecting a very clean, sharp edge.

    I hope this helps. I know it's pretty long-winded, but hopefully it gives you a clearer picture of what you should see when you inspect your edge.

    Good luck.

    Edited to add:
    I was still curious about the magnifier you're using. Did a Google search for 30 X 21 magnifier, and found this:

    Is that what you've got? If so, it appears to be only 3X magnification (the '30 X 21' appears to be the unit's dimensions in millimeters). If this is what you've got, it may still be worth using something with a bit more magnification (5X or more). And again, I can't over-emphasize the importance of a good BRIGHT light source (the built-in lights on most of these pocket magnifiers are usually pretty dim). Use a 60W or brighter lamp, or under direct sunlight.
    Last edited: May 14, 2010
  18. singularity35


    Mar 1, 2010
  19. How close to your edge do you have to put this magnifier to be in focus?

    Whether it's 3X or 30X, I'm still thinking you'd benefit with more BRIGHT light during inspection. If your light source is bright enough, it should be relatively easy to see where the light is reflecting off of your bevels, even without magnification. Under good light, a rounded edge or secondary bevel (like a microbevel) will appear as a thin 'thread' of light along the length of the cutting edge.

    For reference/comparison, this is what I've been using most of the time. It's a simple, cheap 2" x 4" rectangular 2X magnifier with an inset 6X circular magnifier. The 6X is just enough for me to get a decent look at my edge:


    I do my sharpening (with my Lansky) next to a window during daylight hours. I also use a fairly bright LED flashlight (MagLite 2AA LED) to shine on my edge if I want a little more light.
    Last edited: May 14, 2010
  20. singularity35


    Mar 1, 2010
    I have tried it in direct sunlight and under bright worklamps. I have to have it about 1.5 to 2 inches away to focus properly. I guess i will be taking a knife to the jeweler's so that I can make a comparison.

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