Monday, June 20, 2016

you do not know what sharp is

I've been watching "how to sharpen your knife videos" and there is a lot in common.

  • choose an angle
  • stroke until there is a burr along the entire edge
  • if you cannot get the burr then switch sides
  • when you finally get the burr start counting, alternating and reducing the strokes
  • start with coarse only if the edge is damaged
  • use a ceramic rod between grit and strop
places where they differ
  • sharp when you can cut paper
  • sharp when you can shave your arm hair
  • how many strops strokes
  • how fast to strop
  • how much pressure against the stone
  • care for the stone
  • water, bio-oil, honing oil or none at all
One thing all these videos have is that they cut paper. Usually an 8.5" x 11" is torn to shreds like an Errol Flynn movie. One fellow even cut a paper towel. What's next a tissue?

Let's look at the following pictures. These images are taken from my test paper with 4 different knives. Mora Companion, Schrade42D, Mora Black, Ganzo 738. Two of these knives have never been used and two I sharpened using everything I know and own. (DC4, Nagura, WorkSmart 4-1). Each of these cuts is thinner than the thickness of a dime. And some feathers have been thinner than a human hair (not pictured)

I don't know if my sharpness tests are a true test but I know for certain that it took a while to get these right and yet I've come to the conclusion that sharpness is only part of the equation. There are two attack angles for the blade to the paper. There is the pressure into the paper and the speed of the stroke. While I was tinkering with my Schrade bowie knife I was able to create a few of these paper feathers but VERY inconsistently.

Only one presenter said, of sharpening his ax with a Lansky puck stone, it just needs an edge that it can hold. Since he did not paper test the ax I assume he meant that the paper test was superfluous.

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