# Hiromoto revisited - new geometry



## Benuser (Sep 4, 2013)

Handled a brand new Hiromoto AS
190 Santoku today, and wondered
about the geometry that has
changed compared to what I was
familiar with. It obviously got a spa treatment. The good old Hiromotos weren't so much thick behind the edge, but the thickening was quite abrupt. Now I found the left face slightly convexed instead of deadly
flat, and a much larger part of the
clad ground away. So, thinning the back face, which was the first thing to do, is done already.
Did any others notice the same?


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## Benuser (Sep 4, 2013)

http://postimg.org/image/vj48jppr3/


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## Benuser (Sep 4, 2013)

http://postimg.org/image/b0dxse17j/


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## Benuser (Oct 19, 2013)

Here the left face of a new 270 gyuto after one day of use. The clad starts much higher than with older batches.


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## chinacats (Oct 19, 2013)

Liked the santoku so much you bought a gyuto?


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## Benuser (Oct 19, 2013)

The new geometry was decisive. Had sharpened a few older gyutos and didn't want to start with a heavy thinning operation. Don't care much about thinning in general, but haven't too much fun in removing all that soft stainless clad which is remarkably abrasion resistant.


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## Mr.Wizard (Jan 2, 2015)

What is the advantage of convexing the back (left) side of the knife over simply grinding it thinner but flat, or thinning on the front (right) side?

After reading http://www.kitchenknifeforums.com/showthread.php/4684-Mighty-Knives-and-Wedging/ I guess you would not advocate convexing the left side but given your comments there don't you see the observation of "the left face slightly convexed" as a negative thing?


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## Benuser (Jan 2, 2015)

I haven't been very precise. I should have said the left side comes thinned behind the edge, which makes the grind slightly convexed, while the left bevel remains straight. Once you have friction balanced on both sides to eliminate steering, thinning should be performed equally on both sides or you will disturb the said balance.


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## Mr.Wizard (Jan 2, 2015)

Thank you.


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## mark76 (Jan 2, 2015)

I got a Hiromoto about half a year ago. I don't know whether it's got the new geometry, since I don't know what the old one is. However, I read that the old one was pretty thick behind the edge (or abruptly changing, as you write Ben). This one is definitely not. It also seems pretty symmetrical, the left site doesn't seem any different from the right site. It's definitely my favourite large gyuto.


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## riba (Jan 2, 2015)

Looking good! 



mark76 said:


> I got a Hiromoto about half a year ago. I don't know whether it's got the new geometry, since I don't know what the old one is. However, I read that the old one was pretty thick behind the edge (or abruptly changing, as you write Ben). This one is definitely not. It also seems pretty symmetrical, the left site doesn't seem any different from the right site. It's definitely my favourite large gyuto.


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## Benuser (Jan 2, 2015)

I'm quite sure the edge is still a bit off-centered to the left, so it's asymmetric, even when it's less obvious than with previous batches.


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## mark76 (Jan 2, 2015)

I'll see if I can get a better look of it and make a choil shot. (That said, if my photo camera is better than my eyes, the differences must be pretty minor.) When and where did you buy this Hiromoto? Apparently there have been some changes recently.


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## CoqaVin (Jan 2, 2015)

hey ben, since you are a Hiromoto promoter, it looks as if it has a nice amount of belly, and that is the only thing I am worried about


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## Benuser (Jan 2, 2015)

Lot of belly? Always hard to find out from a photo. Only a perpendicular position of the lens may give an idea. Here, a 250mm modern Thiers-Issard, a 240mm worn Misono, and a 270mm Hiromoto.


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## Benuser (Jan 2, 2015)

This one is slightly better.


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## CoqaVin (Jan 2, 2015)

well not an extraordinary amount of belly, but some...


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## Keith Sinclair (Jan 2, 2015)

Nice looking Hiro Mark.


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## mark76 (Jan 24, 2015)

Here's a choil shot of my Hiromoto.





Indeed great geometry. And it looks pretty symmetrical to me.


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## Benuser (Jan 24, 2015)

Nothing symmetric about it. The left face is flat, except for a slight convexing near the edge; the entire right face is convexed; above all, the edge is strongly off-centered to the left. Treat it as a symmetric one and enjoy its wedging and steering after only a few sharpenings.


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## mark76 (Jan 24, 2015)

You're right it's centered to the left a bit. 

What's most important: thin behind the edge and cuts like a dream.


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## Mangelwurzel (Jan 24, 2015)

Benuser said:


> Nothing symmetric about it. The left face is flat, except for a slight convexing near the edge; the entire right face is convexed; above all, the edge is strongly off-centered to the left. Treat it as a symmetric one and enjoy its wedging and steering after only a few sharpenings.



Also, don't think it's particularly thin behind the edge relatively speaking...


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