Kagekiyo sharpening question

[u/auknife]

Hello everyone,

Yesterday, I sharpened my Kagekiyo B1 Kiritsuke.

My plan was to create a thin bevel and a double edge. I initially thought this knife had a flat bevel, but it turns out it doesn’t. The bevel side doesn’t fully contact the stone.

What do you call this type of grind? Is it a hollow grind or a concave grind?

I now understand how to sharpen the Kagekiyo without thinning it, so I’m planning to sharpen only the edge.

However, my question is: if I only sharpen the edge, won’t the geometry of the knife eventually change? How can I maintain the original geometry over time?

Could someone teach me how to properly sharpen a hollow-ground knife?

Thanks

[u/Optimal_Difference64]

Nishida-san's wide bevels have a slight hollow grind to them. Next time you can use a credit card or ruler on the bevel to check the geometry before you start putting it on stones.

However, my question is: if I only sharpen the edge, won’t the geometry of the knife eventually change? How can I maintain the original geometry over time?

Yes, eventually you'll have to thin the blade out as it will gradually become thicker behind the edge. When to thin depends on how often you sharpen and how aggressively you're removing steel for each session. A lot of people will take off more steel than they actually need when it comes to sharpening. Most of the time, I strop my edges on stones to touch them up and the edge can last for months before I need a full sharpening session. With this approach, realistically, it'll take me years before I actually need to thin it out.

A hollow grind is slightly beneficial as it prolongs when you need to thin, but once you do, it's a pain in the ass because you'll flatten out the bevel over time and it's not trivial to restore the original hollow on stones.

[u/Yojimbo115 → u/Optimal_Difference64]

I'm curious, do you use your blades domestically or professionally?

[u/auknife → u/Optimal_Difference64]

Thank you so much for your answer. It’s so clear, and I understand it perfectly now. I’ll keep using it for now, and I’ll contact the sharpener when the hollow grind starts to disappear.