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Quantifying Sharp

Definitions of Sharp and Keen

Sharp and Keen part 2

A Comparison of Several Manufactured Blades

The Bevel Set

The Honing Progression

The Diamond Plate Progression

It’s too big of a jump!

SWARF!

Abrasion rate vs “Grit”

Grit, Scratches and Sub-Surface Damage – Part 1

What is a Burr? – part 1

What is a Burr? – part 2

Burr Removal – part 1

What Does Stropping Do?

What Does Steeling Do? (part 1)

What Does Steeling Do? (part 2): The Card Scraper

Abrasive Particles Under the SEM

Optical vs Electron Microscopy

Diamond Plate break-in – part 1

Diamond Plate break-in – part 2

The Pasted Strop – part 1

The Pasted Strop – part 2

The Pasted Strop – part 3

The Pasted Strop – part 4

Simple Straight Razor Honing

Dulling on Glass

Does Jnat Slurry Break Down?

Jnat Slurry – part 2

Carbides in Maxamet

The Barber Hone

Sharpening on the King 1k/6k combination stone

Ceramic Blades

  150 comments for “Home

  1. Ben
    January 26, 2020 at 4:06 pm

    Hey Todd, I’m a 17 year old knife sharpener in high school, and I’m taking a class called AP Research. I hope to focus my project on the influence of sharpening on fine edge holding with high carbide steels. I want to reach out to the colleges near by in hopes they might let me take a couple S.E.M. images with their microscope.

    It’s quite safe to say that this aspiration to include actual S.E.M. images in my high school research project is lead purely on blind curiosity and interest in my topic, and not any sort of idea towards what might go into this process. I feel very unprepared, and I think it might be helpful if I knew exactly what to ask for before I asked. I also think letting colleges know that I already discussed the procedure with someone experienced would help my chances of getting a yes. I wanted to see if you had any helpful tips or if you could allude towards what the process might actually look like before I reach out. If you could email me back, that would be extremely helpful.

    Thank you Todd,
    I really appreciate it.
    Ben

    Like

    • January 27, 2020 at 5:10 pm

      HI Ben

      Awesome interest. You will be able to come up with some great images of your own just using a regular microscope with a digital camera insert and taking screen shots. Playing with the focus, depth of field, lighting angles and so on to get good detail in your images will also be something worthwhile. You will also be able to control variables and examine a specific thing or two with microscopic knowledge and images of your own.

      Todd’s SEM images are something special as they are professionally controlled and processed.

      All the best with your investigations.

      Cheers David

      Like

      • Ben
        January 29, 2020 at 12:28 pm

        Thanks a lot David,

        I have a microscope that I’m using, and it’s pretty high magnification (4x-1000x which is plenty) the trouble I am having is getting the image to be clear. It’s not a digical microscope, this microscope has a light on the bottom for viewing cells in glass blanks. I need to hold the knife at the right angle, and setup the flashlight to get light on top of the edge, and then focus with the knobs to get an image. It’s a work in process but already it’s proving extremely helpful. Sometimes the image looks unclear, even when in focus (I think) because of the lighting. I will see if I can get a book light or something. Regardless, thank you so much for your reply. If I have any more questions I will leave them here.

        Liked by 1 person

    • February 3, 2020 at 3:40 pm

      Sounds like a fun project. I don’t mean to discourage you, but imaging blades successfully with SEM is quite difficult. One of the biggest challenges is that they have to be extremely clean, otherwise you will only image oil on the surface. Also, most microscopes aren’t large enough to accommodate a knife. I normally use pieces of blades, or just the blades from small folding knives. Instead, you may have better success borrowing some time on a research-quality optical microscope (with a camera).

      Liked by 1 person

      • Ben
        February 6, 2020 at 12:56 pm

        Hey Todd,

        A professor of microscopy at a nearby college has agreed to let me use their SEM microscope for my project. If you could email me @ benspaloss@gmail.com within the next two weeks it would make a serious difference in making this opportunity come to fruition.

        Todd, I care about research in knife sharpening more than I care about anything else. It is my dream to have a site like this. It is my dream to do work like you do. I know you probably don’t have your contact info public for a reason, but sincerely it would mean the world if you could offer some guidance.

        Regardless,

        Thank you for the work you have done,

        Ben

        Liked by 1 person

  2. Gibbs
    February 17, 2020 at 8:58 am

    Dear scienceofsharp.

    U r the grand master of sharpening.
    I appreciate for ur study and letting me know the study.
    This is exactly what tortured me for several years.
    The approach is so nice. S.E.M. I have never ever dream of SEM.

    I’m reading the articles over and over again.
    But I have some difficulties to understand it.

    I don’t know what the term “micro-chipping’ means.
    Would u correct my misunderstanding?
    1. grain from stone when abrasion / will make some debris from the blade. is the debris micro-chipping?
    2. is the debris(from 1) which break the blade edge / micro-chipping?
    3. is the grain from water stone which break the blade edge / micro-chipping? (grit + steel = swarf)
    4. is the steel debris from blade edge by abrasion / micro-chipping?

    Like

  3. Corey W Radtke
    April 10, 2020 at 11:51 am

    Hi Todd I’ve been working for 2 years on making sharp knife edges on various steels, would you be interested in doing some purpose-driven microscopy? Happy to have a call. Sorry if this note is in the wrong venue…

    Like

  4. awestib
    July 25, 2020 at 4:50 pm

    What would you think is the next best material if I don’t have denim for the hanging strop with metal polish? This is for knife sharpening! Thanks!

    Like

    • July 26, 2020 at 12:01 pm

      Any heavy woven fabric should work, maybe canvas from a drop cloth. A couple of sheets of printer paper on a hard surface is nearly as efficient if you can find a suitable fabric.

      Like

      • Tony Langrish
        September 25, 2020 at 11:16 am

        Hi todd. I just was wondering after all this information if you could help me out if you have time please. Sharpening knives what would you use to sharpen them. What stones? And what stropping means (leather, wood, fabric etc) and in what order? And the amount of strokes on the strop and what type of compound. I have been using a king combination stone 1000/6000 but I have noticed that veritas stropping compound dulls the polish on the edge after the 6000 grit stone but the blade is then sharper. Does that mean that the stropping compound is not as fine as the stone? I’ve heard its not that great?

        Thank you mate you’re doing an amazing job

        Like

        • October 19, 2020 at 12:19 pm

          Forget you ever heard about “grit” and “polish” and just find/choose a way to determine when you knives are sharp enough. I like to to feel the edge with my thumb, but test cutting paper works too.

          Virtually any stone can get you 98% of the way, certainly the King 1k/6k can. The Veritas compound is as good as any, I’d just put it on a piece of denim. I do 30 laps as a habit, but not much happens after the first 3.

          Like

  5. Tim C
    July 30, 2020 at 11:41 pm

    Todd – I’ve seen you recommend a few times on different forums to strop with .25/.5 micron diamonds on leather, without regard to prior steps. But your Simple Straight Razor Honing technique suggests that doing so before microconvexing the edge will leave behind a foil edge.

    If my sharpening process uses a jig and doesn’t include the microconvexing step on pasted denim, it supposedly leaves behind a triangular edge. Is it the right move for me to strop on plain leather instead of pasted leather?

    Like

    • August 3, 2020 at 1:08 pm

      It’s really only an issue for straight razors, first because the angle is so low that the burr doesn’t get bent that far and survives longer, and second the spine ensures you are stropping at the same angle as you were on the stone.

      Like

      • Tim C
        August 4, 2020 at 12:43 pm

        Understood. This seems to suggest that the metal polish on denim step is unnecessary for knives. Is that correct?

        Like

        • August 4, 2020 at 1:07 pm

          I try to avoid making generalizations, but I would be more likely to use the denim/polish for a knife that has been sharpened at lower angles and coarser abrasives to remove the damaged metal from the apex region.

          Like

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