Ask TTAK: “Proper” Japanese Edges?

I recently received a question from a reader who wishes to remain anonymous. We’ve been kicking around the idea of launching an Ask the Experts type of column here at The Truth About Knives, and his question was the perfect catalyst to help us kick things off. So here we go!

Hi David,

I was hoping you could help me with a sharpening question. I recently received a nice set of Japanese kitchen knives with damascus blades and a double bevel secondary edge. Until I am able to master a whetstone, I am looking at the EdgePro Apex vs the Work Sharp Ken Onion w/attachment that I know you are familiar with.

Given the style of the knives would you have a recommendation between the two? I’ve read that the Ken Onion may not produce a flat/V-grind and have some convexing of the bevel.

Is this a concern? Would this be traditionally/typically not recommended for Japanese knives, or would it even make any considerable/noticeable difference.Thank you very much in advance for your time, expertise and advice.


Good morning sir!

First off, congratulations on the nice set of knives. Those sound beautiful!

Now regarding the Work Sharp units, they will indeed put a convexed edge on the knife. This happens as the belt wraps around the edge, whereas the stones of the EdgePro will keep a flat bevel.

Either type of edge will work in the kitchen just fine. In use, unless you are highly attuned, the differences between a convex or flat edge are purely academic. I have knives with both types of edges in my kitchen and I have never noticed a difference.

In the end, I would say it comes down to how precise you want your edge angle to be, and only you can answer that question.

If you want to keep the edge angle as close to original as possible, the EdgePro or similar would be your best bet. The Ken Onion Work Sharp is fantastic, but as I stated in my review of that unit, I consider the angle guides on it to be pretty worthless, so you are relying on your handhold to keep things consistent. You could have the steadiest hands in the world, but they can’t compete with the jig for accuracy.

That said, my personal preference would be the Ken Onion Work Sharp with the Blade Grinding Attachment, which is what you were asking about. It works better on longer blades like your kitchen knives, and you can at least set an angle on that unit, whereas on the base device I only freehand without the angle guides.

The reason I prefer the convexed edges provided by the Work Sharp is they tend to respond to stropping a little better than a flat edge. This is how I like to maintain the edges on my higher end kitchen knives rather than using a chef’s honing steel. If you do use a steel, either type of edge will be fine, but it is just something to keep in mind.

So, hopefully I’ve given you enough insight that you’ll be able to decide what works best for your needs. Just remember, if you do get the Work Sharp, make sure to practice on cheaper blades before taking them to those stunners of yours. There is definitely a learning curve to getting the best results with that machine and you wouldn’t want to ruin the tips of your new kitchen Cadillacs, (Or would they be Lexuses?) before getting the hang of it.

Now before I go, a little side note regarding whether a convex edge would be “traditional” or not. On modern, high end Japanese kitchen knives, a precise, 15-degree flat bevel is typical. Notice I say “typical,” rather than “traditional.”

An actual “traditional” knife would have been sharpened by hand on flat stones with no jigs. By the very nature of this hand sharpening, all edges eventually become convexed. Just look at any old, well used slipjoint pocketknife and you will see exactly what I mean.

So I say, don’t worry which type of edge should be “proper” in this case, and just use the tool that will fit your needs best.

So ends the first “Ask TTAK” segment. I hope this can be a recurring feature, but in order for that to happen we need your help. Between me, Clay, Todd Hunt, and Will Woods we have a big knowledge base at our disposal but we need you to supply the questions. Send your queries to and we may feature your question in a future installment of “Ask TTAK!”

This is also our opportunity to throw the question to you all! We would love it if you weigh in on the subject with your own suggestions in our comments section below.

Until next time!

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Ask TTAK: “Proper” Japanese Edges?

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