Measuring sharpening progress without the Loss of Arm Hair!
- This topic has 4 replies, 3 voices, and was last updated 04/20/2016 at 1:44 pm by
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Before we dive into this topic, I wanted to say this device is controversial and I am not sure why. This is the reason for the posted topic. I think this device has great value when comparing your edge progress while sharpening and believe for “newbies” using this can shorten the learning curve significantly and answer many elusive questions through their journey. It might even save some arm hair.
Clay posted a example of a custom made tool like this in my post Ever wanted to measure and view a Edge Profile? Check this out! The “BESS” device on the surface seems like it measures “sharpness” or better yet, “Keenness”, however, it is limited to testing only one small point on the blade and believe for accuracy, you would need to measure many points along the blade and then average them out.
Clay opened this door, so lets “hear” (Read) what you all think!
Note: I don’t fully subscribe to the idea that “sharp” should be determined by comparing the sharpness or keenness found on a factory manufactured razor blade to another blade. But I do like the idea of comparing the same blade to itself during the sharpening process to show improvement of keenness (Before and After). It’s my belief that “cutting” is a act of force and “sharpness” is a fact of (or result of) near perfect geometry. “Keenness” from new research on the topic is is what “Hair Whittling Sharp” is actually “measuring”. The video below does a great job at showing the fragility of a “Keen Edge” is still really “sharp”. Basically, I believe we obtain “Sharpness through Symmetry
-My motto”. Hopefully, I didn’t just throw a “hand grenade” in the room. Lets discuss this…. Wait for it……….I envision making a larger and longer stand and measuring the keenness of the edge while the knife is still in the Wickededge vise (See minute marker 02:39 in the first video and combine it with what you see in minute marker 04:17) Do you see the magic?.
Eddie Kinlen
M1rror Edge Sharpening Service, LLC
+1(682)777-16221 user thanked author for this post.
I think “keenness” is probably best defined as narrowness of the edge. From Merriam-Webster: “having an edge thin enough to cut or pierce something”
I’ve read varying numbers regarding the minimum theoretical thickness of a steel knife edge with somewhere between 0.03µ – 0.4µ. Even at the highest value, that’s a very small edge. It’s probably worth checking with Todd at scienceofsharp to see what he says. Here’s an interesting page on the subject: http://www.tameshigiri.ca/2014/01/07/razor-edged-how-sharp-is-sharp/. My understanding of what limits “keenness” is the grain size of the steel, the edge geometry and the finish. Theoretically, if you could polish an edge to a level that is finer than the grain size of the steel and you could form the edge at the lowest angle the steel can support, you’d be left with an edge that has the width of the grain size. The Bess and the homegrown version of a sharpness testing machine do measure keenness because they measure the amount of force required for the blade to rupture the material and the smaller the surface area being pushed against the material, the greater the concentration of local force, meaning that less overall force is required.
-Clay
3 users thanked author for this post.
Great article Clay!
Eddie Kinlen
M1rror Edge Sharpening Service, LLC
+1(682)777-16221 user thanked author for this post.
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