How to deal with an overgrind on the edge

This Tanaka Blue#2 gyuto is a really great knife, it cuts very well and I am very impressed by its edge retention.

However, it arrived with a low spot/overgrind on and around the edge on the left-hand side of the blade (you can see it at the bottom left corner of the youtube play button).

Below is a short video to show the low spot and it effect it has on the cutting edge. The low spot is around a third of the way from the heel to the tip and can be seen by the differential scratch pattern. It is particularly clear between 27 and 34 seconds.

[video=youtube;fRJbiAoDc5s]https://www.youtube.com/watch?v=fRJbiAoDc5s[/video]

In order to get the edge into a straight line, I'm thinking that I should remove some height while keeping as much of the knife edge as possible on the stone - as per the photo below (I know I have the unaffected side of the knife on the stone, I wanted to hold the camera in my right hand).



And then to continue, in future, to sharpen the knife using an angle like this to try to avoid wearing the edge at the low spot faster than the surrounding areas (which I think is why I have ended up with the un-flat edge section).

Any thoughts or advice?

check the edge, see if it is straight. It could be the knife is slightly bent rather than an overgrind (based on my dealings with Tanaka knives). Good luck.

pkjames said:

check the edge, see if it is straight. It could be the knife is slightly bent rather than an overgrind (based on my dealings with Tanaka knives). Good luck.

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Thanks for the reply.

The knife did arrive with a slight bend, which I fixed at the time. Looking again today, it could be that a slight bend has returned during a year of use. But I don't think that this is a factor as: (i) the bend was in the opposite direction from that which would cause the low spot to be worn on that side of the knife; and (ii) the low spot is quite clear to see if you sight down the knife from heel to tip (clear to see, but very hard to picture or film!).

I've had a couple knives with low spots: one from a famous custom maker here on the forum, one a 1930's hyper-thin Henckels Grand Prix. In both cases, I (a) straightened the edge on a file, then (b) sharpened on a worn high-grit belt. Hole reappeared. I repeated (a) and (b), hole reappeared. Did it again, hole reappeared. I ended up giving the knives away. If your hole is less than a mm or two, you might be able to sharpen it out. Otherwise, toast.

Is it straight on the spine and edge and do they both line up?

rick_english said:

If your hole is less than a mm or two, you might be able to sharpen it out.

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This low spot is only a fraction of a mm. A very small fraction at that.

cheflivengood said:

Is it straight on the spine and edge and do they both line up?

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There's no issue with the spine/edge alignment.

Devon_Steven said:

This low spot is only a fraction of a mm. A very small fraction at that.

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Well, if that's the case then I think you've already answered your own question. Sharpen as evenly as you can from heel to tip to keep the present profile intact.

labor of love said:

Well, if that's the case then I think you've already answered your own question.

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It seems that I have... but it's never a bad idea to canvas opinion from the depths of experience within KKF :biggrin:

The way to get a bend permanently out is to overbend a couple degrees then bend back to straight.