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Step 5: Thin the Edge

Picture of Thin the Edge
Rub the knife on the coarse side of the stone at a 5 degree angle as shown. It doesn't matter what stroke you use or what direction.
You're just thinning the area around the edge a bit to save you some labor later on.
In each of the following sharpening steps, you'll raise the angle just a bit.
That way you're always shaving the stone with fresh metal.

Commentators to this howto are rightly pointing out the merits of a 20 degree knife edge, (knife held at a 10 degree angle to the sharpening stone) or a 17.5 degree wedge. I think my homemade plane blade sharpening fixture is set at 27.5 or something nerdy like that.
Use your own numbers, not mine, and by all means get carried away with your own refinements.
The numbers I picked aren't too important, just that you raise them with each step.
 
hedonistic6 months ago

Another consideration when selecting the edge geometry is the hardness of the steel. In traditional european kitchen cutlery is softer about 56hrc than japanese at 61hrc and some sashimi knives in steels like ZDP-189 are around 67hrc. Most european cutlery is sharpened to an angle around 20-22.5 for an included angle of 40-45 degrees. Japanese knives around 17 degrees per side is common as are chisel and asymmetrical grinds some sashimi knives may be chisel ground (one side only) to 9 degrees. Softer steels ground too thin will roll an edge on a hard vegetable. Thinning a knife as hard as some of the specialty steels on a stone like the one used by the author is not going to work, specialty or diamond stones would be all but required. Not mentioned is that a thinner edge at a higher angle may usually be restored to sharpness by using a more obtuse angle. Search micro bevel if you are curious.

jrsh927 years ago
I use a pretty average angle for my Opinel no. 8 knife, somewhere a touch over 17 degrees. I've seen a few people with these knives using a far shallower angle, using the entire bevel of the blade to come to an edge, the only angle coming from the thickness of the blade-- about 5 degrees! With the kind of work we do with them, these knives need resharpening very regularly no matter what angle is used, as we do things like scale fish, which destroys the edge no matter what angle it's at. Having an edge that would normally only last 2 or 3 days is irrelevant if you're just going to do something like that and resharpen after a day at maximum. Certainly I like a 20 degree angle because it's a good compromise, but people should consider that if you're going to be sharpening it pretty often as part of your routine, using a shallower angle will allow a sharper edge quicker when sharpening, and in that case you can live with the fact that it doesn't last as long as a steeper angle. Overall I'd suggest that people experiment, especially if you have an inexpensive knife like an Opinel, to find what works for them doing what they do with the knife.
AustralLord7 years ago
ya, my hunting knife is around 25-30 degrees and I hadn't had to sharpen it in a long time.
spectre659 years ago
A good thing to remember is that a "thinner" knife edge won't last as long. It will be sharper, but the knife on't hold the edge long, especially for a general use knife. For a genereal use knife, around 30 degrees is the about the best angle for a knife edge. And you're right...flattening the stone is a good practice also. It's hard to hold a steady angle on the knife when the stone dips.