Sharpness test
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I’ve got one of those smaller phone books; maybe 5 X 9. I’ll slice thru a page very slowly. This shows any dull sections or nicks in the edge. Funny thing about this paper… I can’t slice into the paper on the short edges. Even a scalpel can’t start a slice without tearing it. On the long edges, no problemo.
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Funny thing about this paper… I can’t slice into the paper on the short edges. Even a scalpel can’t start a slice without tearing it. On the long edges, no problemo.
It is because particles in paper are oriented. For example if you cut firewood, you can split it along fibers in one hit. But it much harder to chop it across fibers.
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Yup. In paper making, as in carpet making, the lay of the fibers creates a “nap” where the fibers orient themselves in the machine direction. Entanglement between fibers give the paper its strength. Less entanglement in the cross-machine direction, so less strength. What I found interesting is that I couldn’t start a cut on the short sides, no matter how sharp the knifes was.
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Funny thing about this paper… I can’t slice into the paper on the short edges. Even a scalpel can’t start a slice without tearing it. On the long edges, no problemo.
Scalpels are not that sharp. Knives sharpened on WE can be much sharper. Scalpels are sharpened in one pass under high pressure coolant. Grit is pretty low.
Scalpels are not that sharp. Knives sharpened on WE can be much sharper. Scalpels are sharpened in one pass under high pressure coolant. Grit is pretty low.
That’s correct. I recall that they are sharpened at 600 grit or so. What makes them sharp are their thin blades and acute angles. And they are used only once.
Molecule Polishing: my blog about sharpening with the Wicked Edge
All true. I once did a little studying of scalpels in my curiosity as to what causes a blade to be truly sharp. I found that of the blades I studied, the inclusive angle at the edge was 30 degrees. They appear to be ground at about 600 grit, but only one side is polished. See the photos below. Pls forgive the poor resolution for the cross section, as it was overly compressed. Being polished only on one side would seem to preserve the tooth which would be needed to “bite” into soft, living tissue.
https://tcmeyer.smugmug.com/Knife-Stuff/i-hzVVmnN
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The M1rrorEdge Sharpening routine and testing:
Test 1- During sharpening and after edge setting, I run my Sharpie Marker end cap across the the edge of the blade (lightly) feeling for snags in the blade (Basically, rough points). I have seen others use this tool which does the same thing: https://www.razoredgesystems.com/products/testers/product/9-edge-tester (See Attachment for more detail) If I feel multiple points, I may mark the blade with the marker so I can focus attention at these points later.
Test 2-I then observe the edge under a loupe or USB Digital microscope focusing on the points of snag. I keep sharpening until I no longer see or feel any damage at these points of interest on the edge.
Test 3- Once the edge passes test one and two (Basically, the edge is now Smooth as butter and I see no reflected light coming off the edge), I will then “push cut and pull cut” cigarette rolling paper. It’s cheep and effective at showing the “keeness” of the edge of the edge.
Test 4- If the results are not good with the cigarette rolling paper, I will push cut and pull cut copy paper. This test just helps me gauge how close I am and isn’t really needed and is rarely used. I will continue stropping until it does cut rolling paper.
After the rolling paper push cuts with ease, the blade is “Scary Sharp” and off to the customer. No arm hair lost….
Eddie Kinlen
M1rror Edge Sharpening Service, LLC
+1(682)777-1622Test 1- During sharpening and after edge setting, I run my Sharpie Marker end cap across the the edge of the blade (lightly) feeling for snags in the blade (Basically, rough points). I have seen others use this tool which does the same thing: https://www.razoredgesystems.com/products/testers/product/9-edge-tester (See Attachment for more detail) If I feel multiple points, I may mark the blade with the marker so I can focus attention at these points later.
Awesome! Very interesting method. Thank you! With Sharpie Marker I definitely can feel imperfections that are not visible to naked eye. I immediately found a few dents on a knife that I thought was sharp enough.
All of your tests are very useful.
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