Project: Rebeveling a Moritaka 270 Gyuto

[miggus]

Soo... this is quite the project for me. I had wanted to do something like this for a while now, I almost tried it at a 210 Denka. But the knive's profile didn't suit me, so I sold it on instead. I have a Moritaka AS 180 Nakiri which I really like. It's a lot of fun, getting super sharp easily and I have come to prefer iron cladding, even though the KU finish is not durable.

So I stumbled upon this 270 for a good price and went for it. It's quite nice and balanced and doesn't feel as large as one would have thought, even though at 263g, it's relatively heavy. But how Moritaka are selling so many of those with THAT geometry is a riddle to me. As long as I cut loose or soft things, it effortlessly rips through everything. But it's very low shoulders make dense ingredients a chore.

That, the decent price and the iron cladding make it a pretty perfect object for an extensive thinning.

Kudos to @ModRQC for doing and extensively documenting a very similar endeavor:
https://www.kitchenknifeforums.com/threads/moritaka-journey-through-hell.47874/https://www.kitchenknifeforums.com/threads/moritaka-pt-2-devils-in-the-stones.49292/
This is what they have changed the knife into: a much more performance-oriented, convex grind (not a zero bevel, right?) + a mirror polish.

I'm going for a different geometry and approach though. I have a Togashi 240 K-Tip Gyuto that is of excellent fit and finish with a high-powered geometry in very tall iron-clad shoulders. This knife is the blueprint for where I want to take the Moritaka:

This is the Moritaka's choil now:

I also won't even try doing all this by hand, I don't have the nerve for grinding hours on end, and am worried it will be inconsistent. I don't want to use a belt grinder either, since I'm inexperienced and think I would ruin the tempering, if not the geometry as well.
Instead I looked around and decided to get a horizontal wheel grinder, namely a Shinko TS-180. This grinder comes with a 1000 grit wheel for 150€, the 180 grit wheel cost another 70€. This doesn't turn so fast and should give me more time to evaluate what I'm doing. But since I can hold the knife steadily and won't tire as quickly, I hope it will aid in achieving an even result.

My plan is to take the re-working in several steps, raising the shoulders a few mm on the machine and then going back to a well-flattened stone. This should allow me to see if I am achieving an even result without grinding too deeply in one area.

Any comments / tips are appreciated. The machine will arrive at some point in January, I'll keep you posted

 

[ch_br]

following, should be cool.

 

[ModRQC]

Soo... this is quite the project for me. I had wanted to do something like this for a while now, I almost tried it at a 210 Denka. But the knive's profile didn't suit me, so I sold it on instead. I have a Moritaka AS 180 Nakiri which I really like. It's a lot of fun, getting super sharp easily and I have come to prefer iron cladding, even though the KU finish is not durable.



View attachment 213254

So I stumbled upon this 270 for a good price and went for it. It's quite nice and balanced and doesn't feel as large as one would have thought, even though at 263g, it's relatively heavy. But how Moritaka are selling so many of those with THAT geometry is a riddle to me. As long as I cut loose or soft things, it effortlessly rips through everything. But it's very low shoulders make dense ingredients a chore.

That, the decent price and the iron cladding make it a pretty perfect object for an extensive thinning.

Kudos to @ModRQC for doing and extensively documenting a very similar endeavor:
https://www.kitchenknifeforums.com/threads/moritaka-journey-through-hell.47874/https://www.kitchenknifeforums.com/threads/moritaka-pt-2-devils-in-the-stones.49292/
This is what they have changed the knife into: a much more performance-oriented, convex grind (not a zero bevel, right?) + a mirror polish.

I'm going for a different geometry and approach though. I have a Togashi 240 K-Tip Gyuto that is of excellent fit and finish with a high-powered geometry in very tall iron-clad shoulders. This knife is the blueprint for where I want to take the Moritaka:

View attachment 213255

View attachment 213256

This is the Moritaka's choil now:

View attachment 213257

I also won't even try doing all this by hand, I don't have the nerve for grinding hours on end, and am worried it will be inconsistent. I don't want to use a belt grinder either, since I'm inexperienced and think I would ruin the tempering, if not the geometry as well.
Instead I looked around and decided to get a horizontal wheel grinder, namely a Shinko TS-180. This grinder comes with a 1000 grit wheel for 150€, the 180 grit wheel cost another 70€. This doesn't turn so fast and should give me more time to evaluate what I'm doing. But since I can hold the knife steadily and won't tire as quickly, I hope it will aid in achieving an even result.

My plan is to take the re-working in several steps, raising the shoulders a few mm on the machine and then going back to a well-flattened stone. This should allow me to see if I am achieving an even result without grinding too deeply in one area.

Any comments / tips are appreciated. The machine will arrive at some point in January, I'll keep you posted

Maaan you're really picking this up where I (poorly) left it eons ago.


This stage something that might speak to you more - coming from me at least - is the much more recent work on a similarly ground Kaji-Bei...

https://www.kitchenknifeforums.com/threads/comparative-review-three-small-sanjos.58714/post-898556
See part after the first three pics. You're getting there alright and of your own means and understanding which will yield at times much better results to where you stand before thinning anything. So glad you posted such work and mentionned me.

Edit and further hint: further flatten the non cutting side where you're at now if you still don't "feel it" quite right. Do leave the cutting side just about where you got it in the meanwhile. I promise about 200% performance should you make your mind right about it all.

 

[miggus]

Thanks @ModRQC for the hint. If I see it right, you basically turned the wide bevel into a convex side. I was thinking about how to go about this and will try a few different configurations. I'm ambidextrous, if I'm in a rush I use the left hand, if not, the right hand to harvest the full potential of most j-knives.

But no, I'm not trying to change the knife into a leftie, but keep the original bias. I think nothing else would work well since the cladding is of different thickness anyhow.

further flatten the non cutting side where you're at now if you still don't "feel it" quite right. Do leave the cutting side just about where you got it in the meanwhile. I promise about 200% performance should you make your mind right about it all.

Not sure I get exactly what you mean. But I'll report back once I have the first grinding sessions and will certainly appreciate your opinion. The plan is to first raise the shinogi line on both sides about 4-5mm and do some more thinning at the tip.

I hope I won't loose to much height. I saw that this was the case with your Moritaka, even though I don't exactly understand why this happens when one just wants to raise the shoulders.

 

[ModRQC]

Thanks @ModRQC for the hint. If I see it right, you basically turned the wide bevel into a convex side. I was thinking about how to go about this and will try a few different configurations. I'm ambidextrous, if I'm in a rush I use the left hand, if not, the right hand to harvest the full potential of most j-knives.

But no, I'm not trying to change the knife into a leftie, but keep the original bias. I think nothing else would work well since the cladding is of different thickness anyhow.


Not sure I get exactly what you mean. But I'll report back once I have the first grinding sessions and will certainly appreciate your opinion. The plan is to first raise the shinogi line on both sides about 4-5mm and do some more thinning at the tip.

I hope I won't loose to much height. I saw that this was the case with your Moritaka, even though I don't exactly understand why this happens when one just wants to raise the shoulders.

It happened because it was the very first knife I had sharpen so much during the whole progress and I had created in my noob efforts a hollow at the heel so I proceeded to grind the extra steel at the very heel down. Height was pretty much all lost there. There were a few stages of work to this knife they’ve all been published here you’d get around to that bad part explained somewhere along…

What I meant is that I like what you did with the Moritaka and one way to have it perform even better without losing nice food separation is to kill the non cutting side shoulder entirely.

However in your case - using the left hand naturally - it would be a bad idea. just keep at what you’ve been doing it’s all fine and nice work done.

 

[miggus]

Small first update. I got the sharpener and forgot that it comes as a 100V appliance. I also had some trouble using it efficiently, since the stones are very very soft. I think they are from King.

It turned out I don't have the patience to preserve the KU after all. I stripped it and did some preliminary easing of the bevel. It's more difficult with the grinder than I thought due to the length of the knife. The first half is ok, but then you start to touch the opposite end of the wheel. And putting it in another spot than 3 or 9 o'clock leads to wobbeling since the disc moves in an awkward angle. What makes it worse is that the stone dishes so quickly. I had to remove deep scratches because the inner rim stood taller than the middle of the stone and very quickly created unfortunate grooves. I'd love to get a hard s&g disc for this.

I might have to do this by hand after all. I ordered an SG 120 and 220, because I'm so fed up with my pink brick needing to get water ever 5 seconds. Don't have the nerve to involve a belt grinder... I got quite fond of this knife and don't want to ruin it. I'm afraid such a strong power tool in my inexperienced hands would either overheat the edge or get a unrepairable overgrind. So manual it is.

Anyways, knife looks quite rough at the moment, but I got nice first experiences. It had a ton of drag after thinning, so I smoothed the bevel with a progression from SG 500 up to SG 4000 and a BBW. Looks evil, because the bevel isn't totally flat, but cutting performance is good again.

Also, I like the look without the KU, but i'm a bit scared of hyper reactive iron It has already started rusting lol. We'll see. I will continue with this once i have more time.

The structure is nice though, looks good! I stripped the Nakiri, too while I was at it.

 

[miggus]

Very quick addendum to this update. I've cooked 6 dishes for 6 people in the last two days, and put the Moritaka through it's paces. It doesn't look much now, but is already strongly improved. I have gotten lazy on my ambidextrous cutting project and returned to lefty cutting mostly. Lifting the shinogi on the right side (that is not intended to face food, but does in my situation) has improved the cutting feel and ability significantly. Onion performance went from bearable to quite decent, and it can now do thin julienne with fresh carrots much more adeptly. I'm especially happy that no steering has been introduced.

To be clear: The goal is to make the grind more performance-oriented, not to convert the knife to a lefty. That wouldn't be a good idea for several reasons, mainly because the cladding is much thicker on the right side, the knife is inherently asymmetric. I can cut with both hands and am not pursuing lefty knifes at the moment. But making it more lefty-friendly is a beneficial side-effect in raising the shinogi lines, since more of the knife is very thin and asymmetry is generally reduced somewhat.

I like this design, it makes it easy to raise both shinogis without having to worry about the knife becoming perfectly symmetrical, which I hear isn't good for cutting performance.

Food release is still very decent, which actually I expected to suffer more. Maybe also a side effect of the somewhat uneven blade road? Anyhow, the gyuto cuts very well at the moment. So I'm happy: performance-wise this has been a significant improvement, as amateurish the aesthetics may be at the moment.

 

[ModRQC]

Food release will remain decent as long as you don't flatten out the primary too much with raising the shinogi line. Accordingly food separation should remain way better with raised/rounded shinogi line instead of lower/crisper line.

From what I saw with your pictures you're quite on the right track about it so no worries.

Your pictures reminded me of something: at some point of getting the Kurouchi off with mine, there was a residue much like what I see in your pics. I'm curious to know if you've found like me that the faces tend to patina weirdly and very uglily? Had to polish mine quite a way up from there for a more regular patina to be acquired. YMMV but I'm curious.

 

[miggus]

Thanks for the encouragement I was a bit worried i might mess it up, so it's good to see that I'm moving in the right direction.
About your question: I'm not sure what you mean by residue. There is some spots that are deeper than the rest that the abrasive paper hasn't touched as much, as well as some "rice grain pitting" that still has the KU. I tried to preserve the surface structure and wasn't overly concerned with getting every last bit off.
About the patina: That should be interesting. As much as I love ironclad, I usually am not a huge fan of patinaing the knives through and through. Most times, I'll remove it with baking powder after using the knife. So I wonder how the newly exposed iron cladding here will do.
Since there wasn't much time for anything the last 2 days, I haven't removed anything yet. Patina so far seems nice to me, some even dark greying without fancy colors. I have used a pretty strong oil on it yesterday to stop the rust from progressing (Livos Ardvos). This might have inhibited patina formation so far.

I'll not remove the patina from this knife for now and see where it goes

Here are some pics. Not so great since it's artificial light. I'll post some more after a while in better lighting

 

[ModRQC]

Thanks for the encouragement I was a bit worried i might mess it up, so it's good to see that I'm moving in the right direction.
About your question: I'm not sure what you mean by residue. There is some spots that are deeper than the rest that the abrasive paper hasn't touched as much, as well as some "rice grain pitting" that still has the KU. I tried to preserve the surface structure and wasn't overly concerned with getting every last bit off.
About the patina: That should be interesting. As much as I love ironclad, I usually am not a huge fan of patinaing the knives through and through. Most times, I'll remove it with baking powder after using the knife. So I wonder how the newly exposed iron cladding here will do.
Since there wasn't much time for anything the last 2 days, I haven't removed anything yet. Patina so far seems nice to me, some even dark greying without fancy colors. I have used a pretty strong oil on it yesterday to stop the rust from progressing (Livos Ardvos). This might have inhibited patina formation so far.

I'll not remove the patina from this knife for now and see where it goes

Here are some pics. Not so great since it's artificial light. I'll post some more after a while in better lighting
View attachment 215980


View attachment 215981

I think you have too much of the original grain and darker shade left for the residue or effect I’m talking about to show. And by too much I mean it’s perfect that way. Looks kickass and seems to patina normally.

I’d aim to preserve just that from here onwards.

 

[miggus]

I take it that this is what you mean:

From your thread

Let's see how things develop from here

 

[ModRQC]

Totally!