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Diamond vs. Choseras – – shaving sharp?

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  • 05/08/2013 at 12:00 am #11360
    Josh
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    Hey guys… I don’t understand why I can get a knife edge shaving sharp off of my 200 grit diamond stones but not off of the 800 grit Choseras… Have any of you had this experience? What’s the lowest grit you can go with Choseras and still get a shaving sharp edge?

    05/08/2013 at 5:59 am #11366
    Ken Buzbee
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    I’ve not found that, Josh. Mine will shave fine after the 400s. It’s not the smooth shave I get after the 12k, of course, but it’s perfectly serviceable. Can you see anything under magnification that would give you a clue? Is this one specific knife or a general trend? How much “stone prep” (soaking, rubbing together etc ) are you doing? How much pressure? I find I drop to almost no pressure for the last dozen strokes at each grit.

    Ken

    05/08/2013 at 4:59 pm #11374
    Jende Industries
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    The reason, IMO (regardless of Verhoeven), is that t he diamonds create a “false positive” due to the rather deep scratches in the edge of the edge, which are deep enough to cause the edge to cut hairs in what is basically a serrated edge, but the overall bevel is still too thick.

    A good illustration of what I mean is this:

    You can see the overall “bevel” is thick, but the areas within the serrations where the actual thin blade is exposed would be your deeper scratches from the diamonds. It catches the hairs and cuts them.

    When you hit the Choseras and Shaptons, the edge is more homogenous, the scratches are not as deep, the serrations aren’t as sharp – and more importantly, the edge of the edge is still too wide to cleanly sever a hair.

    Compare the tops of the two pics of the 200 WEPS and the 800 Chosera and the 1K Shapton (which is equivalent to the 800 Chosera):

    200 WEPS Diamond:

    800 Chosera:

    1K Shapton Pro:

    05/08/2013 at 9:30 pm #11376
    Ken Buzbee
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    I see what you are saying, Tom, and it makes sense but wouldn’t the Choseras then continue to refine the edge to the point it would shave? In other words, is this simply a case of more strokes are needed to get to this level with this stone? Something folks may not typically do if they know they are going further (finer grits)?

    Ken

    05/08/2013 at 11:59 pm #11377
    Jende Industries
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    • Topics: 14
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    With good technique, the 800 Chosera refines the edge to a point to where you should be able to shave arm hairs with the slightest of pressure, but not enough for shaving your face. There isn’t enough polish effect of the 800 Chosera to squeeze out an actual shaving edge, either – for that you’d need a different type of stone, one that has more polishing effect and less concentration/softer abrasive – and that’s an entirely different topic.

    As for what is happening between the Chosera 800 and the 200 WEPS diamond, there has been some disagreement in what exactly is happening.

    CBW refers to the Verhoeven, where the edge is a point that is fine enough to cut hairs, but the surface of the bevels are not smooth enough and impede the cutting process.

    I think the edge of the edge is not able to be to a fine enough point to cleanly sever hairs at 800 because the abrasive keeps “cutting through” the edge, keeping it, in this case, too thick. Not until you reach higher refinements will the edge become thin enough.

    The more I mull this over, these arguments seem similar in what they are saying, and I think it is more a matter of perspective. The real fact here is that the diamonds cut much differently.

    05/09/2013 at 4:03 am #11380
    Ken Buzbee
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    • Topics: 14
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    The real fact here is that the diamonds cut much differently.

    They definitely do. I still find even 400 Choseras leave a shaving edge. And yes, I’m talking scraping off arm hair, not tree topping or face shaving 😉

    Ken

    05/09/2013 at 9:57 am #11385
    Josh
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    • Topics: 89
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    I’ve not found that, Josh. Mine will shave fine after the 400s. It’s not the smooth shave I get after the 12k, of course, but it’s perfectly serviceable. Can you see anything under magnification that would give you a clue? Is this one specific knife or a general trend? How much “stone prep” (soaking, rubbing together etc ) are you doing? How much pressure? I find I drop to almost no pressure for the last dozen strokes at each grit.

    Ken

    That is very interesting… I must be doing something wrong. I haven’t checked it under my USB scope yet, I will have to do that soon to see what is going on at the edge. I haven’t really checked into it much on different knives, it was mainly my Para 2 in cts-20cp. I will advise after I can look into it more… I did let the stones soak for 10-15 minutes, and then lapped them on each other creating a slurry, then I sharpened with this slurry. For the final passes I use only the weight of the stone after I clean off the stone surface completely of all swarf and just keep it damp.

    The reason, IMO (regardless of Verhoeven), is that t he diamonds create a “false positive” due to the rather deep scratches in the edge of the edge, which are deep enough to cause the edge to cut hairs in what is basically a serrated edge, but the overall bevel is still too thick.

    You can see the overall “bevel” is thick, but the areas within the serrations where the actual thin blade is exposed would be your deeper scratches from the diamonds. It catches the hairs and cuts them.

    When you hit the Choseras and Shaptons, the edge is more homogenous, the scratches are not as deep, the serrations aren’t as sharp – and more importantly, the edge of the edge is still too wide to cleanly sever a hair.

    Compare the tops of the two pics of the 200 WEPS and the 800 Chosera and the 1K Shapton (which is equivalent to the 800 Chosera):

    I understand the theory Tom, and agree to an extent, but I would have to see some direct photos straight on the edge to give more validity to this theory. 😉 If it is still cutting hairs then the edge must be still “thin enough” at certain points in either the peaks or valleys of the edge of the edge. So how does it get this thin on a courser grit? I see in your pics where the diamonds seem to leave deeper scratches sure… but this is to be expected 🙂

    05/09/2013 at 11:19 am #11387
    Ken Buzbee
    Participant
    • Topics: 14
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    I’ll be interested to hear what you see under magnification, Josh.

    Process sounds good. How many stokes are you giving it? Following what stone?

    20CP on that knife is pretty wear resistant.

    Ken

    05/27/2013 at 11:32 pm #11790
    Josh
    Participant
    • Topics: 89
    • Replies: 1672

    Took some microscope pics today… I got it shaving pretty well actually, must have been doing something wrong before as I couldn’t get it to shave at all hardly. Now it shaves pretty well, but still nowhere as good as my 1k diamonds which I can actually get to treetop arm hairs sometimes. It just seems like the 1k diamond stones produce a “keener” edge, what are your experiences when comparing the two?

    I started on the choseras with a slurry from rubbing the two stones together to flatten them out, then I cleaned off the slurry and only used some water. For the last step I wiped the surface of the stones clean and just left the semi-dry stone to remove the burr while only trying to use the weight of the stone itself.

    1k Diamond stones

    800 Choseras(reversed direction)

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