Tool Edge Micrographs

Discussion in 'Woodturning Discussion Forum' started by Jeff Gilfor, Jul 22, 2014.

  1. Jeff Gilfor

    Jeff Gilfor

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    So, I "borrowed" a microscope from work (they'll never miss it).

    Took an inexpoensive HSS SRG, and sharpened in various ways. Here are the micrographs:

    Dry grinder, 80 grit CBN wheel: 80 Grit CBN-r25.jpg
    Dry grinder 180 grit CBN wheels: 180 Grit CBN-r25.jpg
    Tormek immediately after leveling stone (no grading): Tormek Fresh Stone-r25.jpg
    Tormek after rough grading and honing the flute: Tormek Rough Graded Honed Flute-r25.jpg
    Tormek after fine grading and honing the flute: Tormek Fine Graded Honed Flute-r25.jpg No, I did NOT switch these photos. Weird huh?

    More photos in next post. I hit the 5 photo maximum.
     
  2. Jeff Gilfor

    Jeff Gilfor

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    Here are the photos with my new 280 grit Tormek CBN wheel:

    Tormek CBN Honed Flute-r25.jpg

    and here is a blue light photo to show the edge detail:
    Tormek CBN Edge Detail-r25.jpg

    I expected the CBN wheel to be a bit rough when I first started using it. Based upon my experiences with CBN wheels on the dry grinder, it seems like there is a several month break-in period, during which the CBN grades up quite a bit.

    So, what do you think? Cool photos huh?
    Still have the microscope. Any request photos?
    Sorry, I cannot do AO wheels, I no longer own any.
     
  3. hockenbery

    hockenbery AAW Advisor Staff Member

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    Jeff,
    Cool photos!
    The tormek get closest to what I would call a razor blade edge.
    The edge I would want for hand carving.

    The question is what do they mean with regard to woodturning?
    I have heard several experts say the seratted edge from a 60 grit wheel cuts wood really well.
    Suggesting the CBN 80 would be best with regards to serrated edge.
     
  4. robo hippy

    robo hippy

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    When looking at the first set of pictures from the CBN wheels, I thought they looked pretty rough, and I was wondering how 'new' they were. They do smooth out a LOT as they break in. Probably the same with your 280 grit wheel. Break in depends on how much you use them.

    robo hippy
     
  5. hu lowery

    hu lowery

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    interesting

    Jeff,

    Any chance of getting a picture of a new shaving or medical grade razor blade and/or a razor knife blade? Just curious how they compare to these images.

    Were those first images deburred or were we looking at the burr?

    Trying to figure out what we are seeing. Very interesting regardless and your time and effort are much appreciated!

    Hu
     
  6. W Jack Young

    W Jack Young

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    just a thought how bout a pic of a new razor blade
    or a shave the hair of your arm sharp knife
    just for comparison;)

    hu beat me to the post button
     
    Last edited: Jul 22, 2014
  7. odie

    odie

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    Interesting photos, Jeff.....and, thanks for investing the effort in showing us.


    Question: With the honed edges, are you just taking off the burr from inside the flute, or are you honing both sides? I'm one who hones both sides, and there is a noticeable secondary bevel on the edge of the grind, with the first honing. The secondary bevel increases in size with subsequent rehonings, until a regrind is necessary.

    ooc
     
    Last edited: Jul 22, 2014
  8. john lucas

    john lucas

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    Thanks for the photos Jeff. What magnification did you use so I might have some comparison if i ever get my project done.
    I spent quite a while sharpening my newer carving tools on the tormek and I don't feel they are as sharp as using some of my ceramic stones. I feel there is a gap between the grit of the stone graded fine and the polishing with the green compound on the strop. When I sharpen using the ceramic stone it seems to polish the steel better than the tormek stone. I do polish the tools after the ceramic on the green compound strop on the tormek. Of course I've never been able to see the edge magnified over 20 times but there is a noticeable less striation on the ceramic stone vs the Tormek.
     
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

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    John, there are now several stones available for the Tormek. You might want to look at their ceramic stone for carving tools. Honing on the Tormek is something that, if not done correctly, will ruin a good edge. Many Tormek user get obsessed with putting a mirror finish on bevels -- It can be done --- at the expense of a sharp edge. The proper way to hone is to just remove the wire edge which means feather light pressure and just a couple seconds of honing. The bevel should have a smooth gray color and not be polish to a mirror finish.

    They also have a black stone for shaping tools.
     
  10. Jeff Gilfor

    Jeff Gilfor

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    Thanks for the comments all. I posted those first set of photos quickly, because I promised and wanted to get the thread going. This weekend, I will spend some more time to provide better and more photos. I will include those sharpened using my Sorby EdgePro (belt sharpener), and will include some fresh scalpel blad pix for comparison. I will also attempt to photo the edges head-on to show the burr, if there is one. It is a bit tricky, as I have to adjust the depth of field and focus just right. The digital output loses some quality over binocular vision through the eyepieces.

    This is 200 times magnification. I have capability to use white and near UV blue light to light the subject matter.
     
  11. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Jeff, when I sharpen a skew on my Tormek after the edge is sharp, I flip the tool from one side to the other using progressively lighter pressure to try to prevent any roll over at the edge. As a last step, I lightly hone both edges for a second or two on each side -- but it does take a few seconds to get the angle set just right on the honing wheel to make sure that I am not honing away the edge, which can easily happen. I use a Sharpie to paint the bevel to facilitate fine tuning the jig setting. Most of my skews have a 35° included angle.
     
  12. Jeff Gilfor

    Jeff Gilfor

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    Thanks Bill. I do something like that as well, but didn't want to "muddy the waters" on these initial photos. I did not hone the cutting edge, just the flute side. I wanted to knock off any burr, so that the edge itself could be seen more clearly. This weekend, I'll do a more thorough set of photos, including honed edges.

    My CBN wheels are rather new and, perhaps haven't settled down yet. When moving the shop from up north, my grinder was dropped, damaging both my original, and already broken in wheels. These are the replacements. They are only about a month or two old. I tried using the damaged CBN wheels for some time, but got too annoyed at avoiding the scars to continue that way any longer.
     
  13. Dennis J Gooding

    Dennis J Gooding

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    The term "200 times magnification" is meaningless here, because we have no way to account for the scale factor of the camera, the effects of reducing file size for transmission and the characteristics of the display. Do you have any way to determine the actual dimensions of the individual pictures? An interesting experiment, nevertheless!

    Dennis
     
  14. john lucas

    john lucas

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    I was wanting to know what magnification he used so when I do my tests I can use something similar so we have some sort of comparison. I realize we don't have a standard but we have to start somewhere.
     
  15. Bill Boehme

    Bill Boehme Administrator Staff Member

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    It will be different for every monitor. Some monitors have a resolution in the neighborhood of 70 pixels per inch while others might be 110 pixels per inch. However the scale factor from the camera, resizing software, and monitor basically have no effect on the structure revealed by the microscope itself. It may look larger or smaller than what is seen by looking directly through the microscope, but the size effects of everything downstream of the microscope doesn't add any further detail to the image. The thing that is most important is that all of the images were made at the same magnification so that we can compare apples to apples without the need to know precisely what an inch on your screen translates to on the actual object. It is a comparative study so that we can see the resulting edge from different kinds of sharpening tools. If a millimeter would fit in the picture, that might give you an idea of what 200X magnification means, but it doesn't otherwise add anything. We had a scanning electron microscope at work and we often looked at magnifications of 50,000X. The fact that an inch would be almost a mile was far more abstract than simply using the photomicrograph for its intended purpose of performing failure analyses.
     
  16. Jeff Gilfor

    Jeff Gilfor

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    I almost didn't want to answer that question about magnification, because I KNEW it was very relative to a variety of things.

    When taking the photos, I used the "200x" objective lens. In this type of microscope, the actual magnification is dependent upon several factors, including focus and distance of object from lens.

    This is starting to become a bit more of a science experiment than I had originally expected but, okay, I'm up for the challenge. I will repeat the photos this weekend, plus will add some size reference to the images (I'll figure something out), and will add the other photos I was planning.

    I wish there was a way for me to place ALL the photos, arranged side by side, in one post. The 5 photos per post limit is going to make this somewhat confusing to read. Any moderators out there have an idea?
     
  17. odie

    odie

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    Jeff.......just a note to let you know your taking the time and effort to do this is appreciated.

    ooc
     
  18. john lucas

    john lucas

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    group photo

    I hope I kept them all in order wish they would print larger on this screen
    sharpening-group.jpg
     
  19. Gretch Flo

    Gretch Flo

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    Thanks

    Ditto what Odie said, Gretch
     
  20. Mark Wollschlager

    Mark Wollschlager

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    A further refinement of the study

    How about showing the same edge after 20 seconds of cutting some basic maple at the same RPM.
    Then at 1 minute. Or different type of wood after a set time.
    It would be interesting to see how much, or how little the starting edge quality matters after use.
     

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