Yanagiba out of the box with concave blade road

[Vitamin_Ke]

I decided to sharpen a new Shigeki Tanaka Ginsan Yanagiba for the first time today since getting it, and I can't help but notice that the blade road (kiriba) is concave. I tried performing Hamaguri sharpening, and it very clearly left a section in the middle un-touched.... After 1 hr and 10 mins on a Shapton kuromaku 1500, the scratches finally reached throughout the entire kiriba.
Is this normal? to have a Yanagiba shipped with a concave blade road that would need correcting out of the box?

 

[refcast]

Common, yes. Best practice of a maker, no. I've gotten a liittle better at determining it through pictures, though.

 

[nutmeg]

Yes, knives are almost always finished with machines. The grind can‘t be as ready-for-stones as one would expect.

 

[j22582536]

Yeah that's normal, most blades are grinded on machines so there're always some low spots.

 

[Vitamin_Ke]

Thank you all for the assurances.
I was hesitant about first-sharpening a knife with a rough stone but next time if it's warranted I will do just that.
Thanks KKF

 

[Checkpure]

I've been working out spots like that on my Yanagiba for a while. Almost all nearly gone but it has taken quite a bite of work on a course stone.

 

[big_adventure]

Just to go along with it, yes, this seems to be quite normal. Mine was forged by Shiraki Hamano and sharpened by Kasahara (so, extremely reputable people), and the blade road from shinogi to edge is slightly concave nearly the entire way. It's not identifiable as such by fingers or to the eye, but when you sharpen, it's clear as day. It will probably completely flatten in a few more sharpenings.

 

[Taz575]

Very common on many knives. I see this a lot in cheap tosa style knives, mid priced knives and even Konosuke Fujiyama Blue #2's I saw several years ago had this. Japanese makers often use the big wheels to grind their blades, which will leave a slight concave blade road. It also leads to over and under grinds. The videos I saw have the people attach the knife to a wooden handle, like this one:

 

[Checkpure]

Very common on many knives. I see this a lot in cheap tosa style knives, mid priced knives and even Konosuke Fujiyama Blue #2's I saw several years ago had this. Japanese makers often use the big wheels to grind their blades, which will leave a slight concave blade road. It also leads to over and under grinds. The videos I saw have the people attach the knife to a wooden handle, like this one:

This is exactly what I figured was causing it. The circular nature of the wheel is going to be concave between the highest and lowest points of contact. This is why I imagine knives done mostly or finished on stones by hand are much more coveted and generally more expensive.

 

[Taz575]

Correct. Also explains the bead blasted "kasumi" finish many knives have. They want the stone polished look (contrast) without the time/expense of doing it that way. If I get one with the bead blast, I notice a ton of extra drag in the cut. I use some non woven abrasive pads on it and it really helps a lot without losing the look of the contrast.

 

[Checkpure]

Correct. Also explains the bead blasted "kasumi" finish many knives have. They want the stone polished look (contrast) without the time/expense of doing it that way. If I get one with the bead blast, I notice a ton of extra drag in the cut. I use some non woven abrasive pads on it and it really helps a lot without losing the look of the contrast.

Dude same experience! I work out the bead blast and low spots because I'm a little OCD about that stuff, I just do it on stones. Do we have a list of makers who don't use these wheels or use them for minimal material movement and then finish on stones? Knives that come with true bevels and kasumi finishes other than Kaiju's?

 

[Vitamin_Ke]

To your point, there is a way of smoothing out the concavity on a wheel by running it in the direction of the spinning wheel after initially grinding the blade road horizontal to the turning wheel. I've seen the Yoshihiro sharpeners do this on youtube before then finishing on a stone.
But of course, more steps, more cost I guess...

 

[Vitamin_Ke]

Dude same experience! I work out the bead blast and low spots because I'm a little OCD about that stuff, I just do it on stones. Do we have a list of makers who don't use these wheels or use them for minimal material movement and then finish on stones? Knives that come with true bevels and kasumi finishes other than Kaiju's?

Same for me too! The bead blasted looks nice initially but creates noticible drag. I think this is why some knives are labeled and sold as "hon-gasumi" to differentiate that it was finished on a stone? Unless I'm reading that term wrong.

 

[Taz575]

Yeah, I think many grind parallel to the wheel or at a slight angle, but don't always go down to a true flat bevel. Time, skill and expense are the limiting factors I think like you said.

The super fine non woven abrasives work well to remove patina and reset a factory satin finish. I think I have the red and green, which are somewhat coarse, grey which is very fine and white is super fine. I went up from red, grey and white before I acid etched my Tanaka Sekiso to get a nice clean finish and remove the patina that had formed.

 

[adam92]

That's very common, almost all of the new knife have to even out the blade road... Even the Honyaki yanagiba from ikeda, took me a while to even the blade. But suggest to do this on rough stone. Otherwise waste your time & stone.

 

[Vitamin_Ke]

After this time, I will go coarse stone first for sure....

 

[VICTOR J CREAZZI]

What if you thought of the concave blade road like a hollow back chisel or the ura of your yanagiba, where the hollow is actually a sharpening aid. Aesthetically it may not be desirable, but I think it would be functionally superior.

 

[Vitamin_Ke]

What if you thought of the concave blade road like a hollow back chisel or the ura of your yanagiba, where the hollow is actually a sharpening aid. Aesthetically it may not be desirable, but I think it would be functionally superior.

Hmmm, that's an interesting take. The preference is to get it slightly covex on the blade road so the ingredients release better, I guess a concave road face could serve a similar purpose. And using sandpaper instead of stones to remove the sandblasted finish could preserve a clean look and reduce dragging.

 

[DavidPF]

What if you thought of the concave blade road like a hollow back chisel or the ura of your yanagiba, where the hollow is actually a sharpening aid. Aesthetically it may not be desirable, but I think it would be functionally superior.

Wouldn't the upper edge of the concave area need to be highly consistent, for this to work? (i.e. wouldn't every little overgrind up here affect the edge too?)

I'm asking because I don't know, not trying to find faults in what you're saying.

 

[VICTOR J CREAZZI]

Wouldn't the upper edge of the concave area need to be highly consistent, for this to work? (i.e. wouldn't every little overgrind up here affect the edge too?)

I'm asking because I don't know, not trying to find faults in what you're saying.

I don't see it causing problems at the edge as the stone can't drop into the low spots. It would result in a wavy shinogi, but that would be the same issue if you were flattening it. You would be slowly flattening the blade road over time, meanwhile the bevel sharpening would require far less steel removal at each sharpening session.

 

[DavidPF]

If that's the case - and I don't see why it wouldn't be - then it makes sense to me to avoid wasting metal and avoid wasting time. And potentially get a better edge too.