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Thread: Weight On a String sharpness test

  1. #11
    Customized Birnando's Avatar
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    An interesting idea!
    I would have wanted something to tell me when I was at "shave ready" so bad when I first started honing.

    I never did find anything though, except 2 things.
    One was the TPT, which to me is the best method for assessing while honing. The thing, of course, was to calibrate it. Gain experience if you will
    The second was the arm hair test. That too, took quite a while to get the right feel for, but now it is of value to me, and tells me what I want to know.

    I'm looking forward to see if this concept gets to a usable level and how you find the consistency of it!
    As the others have noted, I'm not sure this can be used to assess the smoothness, but we'll see when you get it done what you find
    Good luck!
    Last edited by Birnando; 05-01-2011 at 01:43 PM.
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    Um, all of them, any of them that have been in front of me over all these years....


  2. #12
    Senior Member blabbermouth JimmyHAD's Avatar
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    I'm not sure of how a strand of monofilament is constructed but IIRC a human hair is segmented if you look at it microscopically. A couple of years ago someone figured out that if you hold the strand of hair with the root outboard the edge is more apt to catch between segments and cut the hair more easily than if it is held with the root inbound. In that case the hair's segments will slide over the edge. Cutting hanging hair, monofilament, dental floss ..... there is a vid wih Mastro Livi cutting up a feather ..... is all well and good but in the final analysis the question is always "how does it shave."
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  3. #13
    Senior Member northpaw's Avatar
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    I tried a few strand-cutting designs and got some to work pretty well, but I eventually gave up on them. Even though fairly consistent results can be achieved, you get more (and more useful) feedback from your tactile senses, like how the razor feels on a hone, or 'stickiness' on the thumb pad test. Other than shaving, those are about all you need, and they're quick 'n easy.

    Fun to mess around with, though.

  4. #14
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    Quote Originally Posted by Mike Blue View Post
    ...
    As long as the string made perpendicular contact with the edge and did not slide laterally the string will not cut. Blade edges are most efficient when they move laterally through the material. A slicing motion if you will.

    If you have the opportunity to see the Catral device in action, it slices, it does not only push through the material being cut.
    If you mean this machine here:
    Sharpness tester

    The web page says this:
    The test utilises the constant cut depth method in which the blade is pushed normally without longitudinal travel into the test media The cutting force is recorded as a measure of the sharpness, which means the lower the force the sharper the blade. The test media is either 8 mm square or with a 3 mm wide side bead silicon rubber which is bent around a 20 mm former and the cut is made into the outer periphery of this bend. This causes the rubber to open up the cut as the blade penetrates, thereby reducing the point of contact of rubber and blade to the tip of the edge only.
    It looks like they are saying there is no slicing motion involved.

    I wonder how much that machine costs to buy AND operate. That silicon test media can't be cheap.

    On the other hand, this design costs close to zero to build and close to zero to operate. One inch or less of string per test. Much better suited for hobbyist use.
    And if properly calibrated, I would argue that it is every bit as accurate as the high dollar one.

    I suppose it is better suited for knife sharpening or bevel setting on a razor rather than polishing the edge. I intend to find out. Might take me a while, I will have to find me a razor to restore.

    I also agree that honemeisters have no need of it, it is more for beginners' use.

  5. #15
    The Great & Powerful Oz onimaru55's Avatar
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    Quote Originally Posted by JimmyHAD View Post
    I'm not sure of how a strand of monofilament is constructed but IIRC a human hair is segmented if you look at it microscopically. A couple of years ago someone figured out that if you hold the strand of hair with the root outboard the edge is more apt to catch between segments and cut the hair more easily than if it is held with the root inbound. In that case the hair's segments will slide over the edge. Cutting hanging hair, monofilament, dental floss ..... there is a vid wih Mastro Livi cutting up a feather ..... is all well and good but in the final analysis the question is always "how does it shave."
    I agree the HHT is easier with the root outboard... Ironically on the shave test the cut is reversed Just an observation.
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  6. #16
    Senior Member blabbermouth JimmyHAD's Avatar
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    Quote Originally Posted by onimaru55 View Post
    I agree the HHT is easier with the root outboard... Ironically on the shave test the cut is reversed Just an observation.
    I hadn't thought of that before you mentioned it but it is very true. Maybe that accounts for our ongoing struggle with comfortably removing those pesky whiskers that just keep coming back.
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  7. #17
    Senior Member deighaingeal's Avatar
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    Mono filament is extruded. It is generally extruded vertically starting as a liquid and hardening as it is exposed to the environmental change after the die. It is unfortunately not a very accurate process, if I remember correctly they utilize gravity to force the extrusion process. This causes the mono to form in a smooth slightly undulating pattern. The measurement listed for diameter isn't even the size of the die, but the experimental average from that size die.
    When I mention inconsistencies there will be inconsistencies within the spool.
    It has been some time since I've researched this so it may have changed and I may have remembered slightly different, but this should give you an idea.

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