from what I understand the sharpening angle only affects the immediate area behind the apexhow does the sharpening angle affect the apex?
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Heres a pic of thin secondary bevel (left) and thick secondary bevel (right). The primary bevel is like 3 degrees. The angle of the secondary bevel doesn’t matter much if its thin. The angle matters a lot if its thick. Its best to start with a thin knive and good steel. The one on the right is an old wusthoff and its too soft to take a thin acute edge.
Here is a link to another thread that discusses zero grinds, microbevels, and edge durability:
Durability testing Watanabe Pro Gyuto
Durability testing Watanabe Pro Gyuto
what i dont understand is how does a micro bevel strengthen the apex
M1k3
Senior Member
It increases the width directly behind the edge. Giving more support for the edge. Good for when the edge is to thin, are abusive or the steel is softer. But a lower angle increases edge retention, as long as the steel can handle it.
Follow the red line below the apex and you can see it is wider/thicker on the left than the right. This makes it less prone to damage as @M1k3 stated. As long as two blades are sharpened in the same manner and same grit, it does not matter the difference of one having a large angle and the other a small angle. They are equally sharp, at least theory according to science of sharp. In terms of cutting feeling, a smaller angle will feel sharper but will be damaged easier.
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interesting i read this arcticle "You can see that the initial cut length with a smaller angle is considerably higher and that the difference holds basically to the end of the test. This finding is significant because some have speculated that lower angle edges start out sharper but a more obtuse edge lasts longer [2]. And with the high wear that occurs in the CATRA test it isn’t likely that the situation would reverse with even further cutting. The initial blunting rate is relatively rapid regardless of angle and it then begins to level out. The highest TCC measured was over 1000 mm with an angle of 20°, and this decreased all the way to under 100 mm with 56°. In a CATRA study by Bohler-Uddeholm [3] with a range of steels, but unspecified edge geometry or sharpening, 154CM was measured at 547 mm, and M390 was measured at 959 mm. The 547 mm value would be with an edge angle around 30° in this study if other parameters are similar. So if the edge angle of a 154CM knife is reduced from 30° to 20° then it can match or exceed a steel with 75% greater wear resistance."
You can see that the initial cut length with a smaller angle is considerably higher and that the difference holds basically to the end of the test.
https://knifesteelnerds.com/2018/06/18/maximizing-edge-retention/
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This is true if the steel can handle it and not break or deform. Lower angle is better as long as it doesn't get damaged. Microbevel increases the angle, thus providing more material behind the apex. It technically decreases theoretical performance if you dealt with a material that doesn't chip or deform and only gets blunted by wear. Steel is not such a material, so sometimes microbevel helps to increase real world performance even though it decreases theoretical performance. This is due to blunting of a knife edge being a complex phenomena which occurs in multiple ways.
I drew a thing. Hope this helps. This is how I understand Science Of Sharp's definitions of sharp and keen. And some of the other terms that tend to go around.
Upon board contact, a zero edge (while sharp by definition) tends to lose keenness – roll-overs, micro-chips, flat spots (“mushrooming”).
The micro-bevel represents an attempt to preserve keenness at the expense of sharpness at the apex.
Upon board contact, a zero edge (while sharp by definition) tends to lose keenness – roll-overs, micro-chips, flat spots (“mushrooming”).
The micro-bevel represents an attempt to preserve keenness at the expense of sharpness at the apex.
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