My Aritsugu came with a much more slender blade and a 12 degree inclusive final edge bevel. I haven’t sharpened it yet, but I have sharpened my sister’s twin to it. With my Low Angle Adapter and extra-long 12″ rods, I was able to get down to 16 degrees inclusive (8 dps) on my Gen 3 Pro (2017). The masters at the Aritsugu shop in Kyoto sharpen in two stages – first on a rotary drum abrasive,with the blade held at the top and parallel to the drum’s rotational tangent, then with a more typical sharpening on waterstones, but with a very low angle. You can see them work in one of several Youtube videos. I’ve been starting with 800 grit diamond stones, then progressing to 1500 grit. I then continue with 6, 3, 1.5 and 1.0 micron diamond films on brass platens (aluminum or glass will do as well), using 50 to 100 strokes per grit. At the finish, I have an edge refined well beyond that supplied by the Japanese masters. I don’t think there is any value in trying to replicate a variable bevel angle, as I cannot imagine why one would attempt to create one deliberately. Judging from your photos, I think you can calculate the factory angle with a little trig by measuring the width of the bevels and the thickness at the bevel shoulders. You’ll want to use an angle somewhat more acute, as trying to replicate the factory bevel angle would require a very extensive stoning process.
Dragging up this old thread as I am the proud new owner of a single bevel usuba knife. I am getting confident sharpening my kitchen and butcher knives, but completely unsure about Japanese knives after searching this forum. Could you kindly elaborate on the above TCMeyer? At one time I did calculus, so guessing I can figure out the angle? All I know for sure is all 3 angles must equal 180….
Angle 1= 90 degrees
Angle 2= degree at bevel
Angle 3= ????
side a (thickness at the shoulders)
side b (bottom width of knife)
side c (top width of knife)
What am I missing here…..
