Sharpening wide bevel knives

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brianh

brianh

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So, Dave has my Kochi carbon 240mm kurouchi gyuto (http://www.japaneseknifeimports.com/kitchen-knives/kochi/kochi-240mm-kurouchi-wa-gyuto.html) for sharpening and I don't want to keep bugging him for learnin' me on wide bevel knives. He's going to do the full treatment on it and fully sharpen from the kurouchi down. I'm new to wide bevels and am not sure I completely understand what it takes to maintain the edge. I have Dave's basic 500-1200-5k stone setup and some strops. When the edge needs a touch-up sharpen, can just the edge be sharpened on this setup as non-wide-bevel knives, or is a WHOLE bevel sharpening required each time from the kurouchi down?

And that being said, what additional stones do you guys recommend as a bare minimum for sharpening the whole bevel? I've been reading and watching stuff on Youtube, even saw one guy do this on marble and sandpaper.

thanks
 
I have never owned a wide bevel gyuto and am actually looking at buying one right now. I would assume that you don't want to just sharpen the edge. With any knife if you just sharpen the edge the angle will get very obtuse over time.
 
That's what I was thinking, and Dave confirmed the same. I just wish I could find more videos and such on sharpening one of these and if there is a stone setup that works for most, especially with a kurouchi finish, if that even makes much difference.
 
brianh said:
That's what I was thinking, and Dave confirmed the same. I just wish I could find more videos and such on sharpening one of these and if there is a stone setup that works for most, especially with a kurouchi finish, if that even makes much difference.
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Whether the knife has a kurouchi finish or not matters not at all, as you aren't going to be touching the side of the blade.

What might make a difference is if the blade is san mai construction and you want to preserve/recreate the kasumi finish of the blade road. Most synthetic stones will not create a contrast between the hagane (core) and jigane (cladding). Usually you need a natural stone to do this. (Dave maintains that the King 800 is one of the few synthetic stones that will produce the contrast.) You don't need the contrast to have a well-performing knife, it just looks nice.

Regardless of the type of stone, the technique is the same: put the blade road flat on the stone and grind away, putting pressure on the blade midway between the edge and the shinogi line. Grind until you are almost hitting the edge, working both sides alternately. You've now thinned the blade. Take the blade road to whatever grit finish you want. (A natural stone will be around a 6000-10000 grit polish.) The first time you do this you may not get a completely flat blade road, but over time you will get there. Of course, you can work until it is flat, but you are going to lose a not insignificant amount of steel (and life) from your knife.

Finish at the usual fifteen degrees. The edge bevel is probably going to be very narrow, which is normal.

Hope this helped.

Rick
 
brianh said:
Yes, it did, Rick! Thank you. Shouldn't the blade road be slightly convex?
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On single-bevel knives like debas and yanagibas, yes. On a double-bevel knife, not so much, and actually the blade roads OOTB are slightly concave, rather than convex, because they are ground on wheels.
 
Really helpful, thank you. I need to learn more about which stones will generally help preserve the kasumi finish. Dave did mention he'd likely use the King 800 on my Kochi and might have some stone suggestions after sharpening. I also have a Takeda nakiri which I believe will need the entire blade road flattened when sharpening?
 
Rick is a wealth of knowledge.
 
brianh said:
Really helpful, thank you. I need to learn more about which stones will generally help preserve the kasumi finish. Dave did mention he'd likely use the King 800 on my Kochi and might have some stone suggestions after sharpening. I also have a Takeda nakiri which I believe will need the entire blade road flattened when sharpening?
Click to expand...

My experience with Takedas is limited, but they are thin knives that don't have a distinct blade road. I believe that they are best maintained by thinning when needed and then blending the thinned area so it is convex. One of the neatest tools to use is Takeda's hand-held whetstone. http://www.chuboknives.com/products/takeda-two-sided-hand-held-sharpening-stone#.UqKGXJFMjLQ

Takeda_sharpening_stone_large.jpg
 
I have a Heiji gyuto and petty coming in a few months so this topic is particularly interesting to me. Here is a thread that is specific to sharpening wide beveled Heiji's, but the advice should be helpful and apply to wide beveled knives in general.
 
I never sharpening my wide bevele knives on cutting edge only! it will cause the edge thick up quickly..... there are two ways to sharpening wide beveled knives: V shape edge & hamaguri edge. personally, I prefer hamaguri edge much more!

V shape edge(easy way) - you thinning/sharpening entire wide bevel under shinogi line, then you put a primary bevel on at whichever angle you prefer(higher angle for tough edge, lower angle for thinner edge)

hamaguri edge(harder way) - same way you sharpening a single bevel knives.....only doing on both sides! Jon's video will demonstrate how to sharpen a single bevel knives better than my crappy English!
[video=youtube;gvDjASvVHek]https://www.youtube.com/watch?v=gvDjASvVHek[/video]
 
Pensacola Tiger said:
On single-bevel knives like debas and yanagibas, yes. On a double-bevel knife, not so much, and actually the blade roads OOTB are slightly concave, rather than convex, because they are ground on wheels.
Click to expand...

How do the makers manage to send them out with a kasumi finish without flattening the bevels?
 
JBroida said:
magic ;)
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So, I shouldn't be surprised if I start polishing a bevel and notice my stone is hitting the top and bottom of the bevel (leaving out the edge as expected), but not the middle, even though the knife had a kasumi polish OOTB? I noticed that with a Konosuke Fujiyama.

To be clear, what I observed was:
- grind marks (top of bevel)
- no grind marks (middle)
- grind marks (bottom of bevel)
- no grind marks (last few mm down to edge)

I got the knife second hand with a sandpaper finish, but from what I see online Konosuke Fujiyamas do come with a kasumi finish.
 
yeah... it will come out over time... you can use finger stones or sandpaper to make it look nice in the meantime if you want
 
How exactly do you go about using finger stones?

Ps, cclin I would have no idea English isn't your first language.
 
Thanks, that's reassuring, I thought I was doing something wrong.

So you're not planning on sharing anything about the magic part? :)
 
the easiest way to replicate the look at home is with finger stones or a really soft/muddy stone (i mean REALLY soft and muddy)
 
My extremely uneducated guess would be something like sandblasting. I have seen that effect done with a small sandblaster on metal... not knives, mind you.
 
on some knives that is the case, but in the case of many of the knives you will see (specifically hand made ones) from japan, that is usually not the case
 
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