# A Few Questions on Sharpening a Tanaka Blue #2 Gyuto.



## cazhpfan (Dec 19, 2013)

Hi All,

I followed the advice of the wonderful people on this forum and got a Tanaka 210mm blue #2 damascus gyuto.:doublethumbsup:

The knife is a fantastic cutter, and the F&F are more than adequate for the price.

While I have yet to sharpen it (the OOTB edge was really good), I can see myself putting the knife on the stones in the near future.

I have a few questions regarding thinning behind the edge:

The knife is nearly flat-ground on the right face and has a convex grind on the left face with a convex secondary bevel that tapers towards the edge.

Should I only thin the knife on the face that's more convex ground (the left)? Or should I thin equally on both sides (the right face has a barely perceptible secondary bevel)?

Will the knife's cutting performance decrease as the secondary bevel(s) become more flat ground from sharpening on the stones? Even though the Tanaka isn't very thin, it still cuts wonderfully, and I would love to keep it that way.

Once again, thank you very much to all the wonderful members of this forum. I really appreciate the knowledge that's passed around!


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## greasedbullet (Dec 19, 2013)

I would thin on both sides but try to maintain its original geometry if you like it. However I am afraid that you think thinning is something that needs to happen often, frequently, or soon. You will be able to go months and months (possibly years if you are a home cook and not a "pro") before you need to thin your knife. Some people here are a little too trigger happy on thinning their knives IMHO. But hey, do what you want. I am of the opinion that you should remove as little metal from your knives as possible so they will last and cut as originally intended longer. When you first pull your knife off the stones and you notice that it doesn't cut as well as it used to when you first got it then it is time to thin.


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## Benuser (Dec 19, 2013)

I would rather say thinning is a normal part of any sharpening. After all, you're not so much putting an edge on the end of a piece of steel, but restoring a former configuration that's moved towards the spine. But any operation below the angle of the very edge is a form of thinning. If you're happy with the existing configuration and start your sharpening a little above the bevel before going down to the edge, you will be fine, and won't indeed need a major thinning operation for quite a while.


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## Yamabushi (Dec 19, 2013)

Benuser said:


> I would rather say thinning is a normal part of any sharpening.


 lus1:
The proper way to maintain the geometry of your blade, IMHO.


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## cazhpfan (Dec 19, 2013)

I initially posed this question for two reasons:

1) I wanted to know how to thin the knife properly when the time comes.

2) Some folks (such as Murray Carter) recommend thinning the secondary bevel a little bit with each sharpening (thus avoiding the need to do a dedicated thinning session after several months of working on the primary edge only)

Should I take micrometer measurements of the edge to judge thickness as time progresses?

Also, how does one prevent thinning from scratching the blade? The thinning jobs done by Dave Martel, Jon Broida, Maxim, etc all look so clean.

Any tips from the pros? :thumbsup:


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## Mucho Bocho (Dec 19, 2013)

I've been sharpening knives for a few years now both with the EP and free hand on nice water stones and I have to say that thinning has to be one of the most misunderstood concept of sharpening.


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## cazhpfan (Dec 19, 2013)

Mucho Bocho said:


> I've been sharpening knives for a few years now both with the EP and free hand on nice water stones and I have to say that thinning has to be one of the most misunderstood concept of sharpening.



Would you mind explaining why that's so?


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## brainsausage (Dec 19, 2013)

^+1


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## Mucho Bocho (Dec 20, 2013)

Its just that there are so many types and styles of blade construction that say you should thin everything you sharpen is misleading. Guess it depends on how you define thinning.

Last night I touched up my month old AEBL ITK. I just gave it a few strokes on an 6-8K Takenono stone, stropped on it, then leathers diamond spray, then lghtly on leather. Didn't even bring up a burr. The edge is screaming and bitty again. 

Should I have removed more metal on the blade face? Why would i risk scratching up the finish on blade face on a knife without a clear shinogi. Why go through all stone progressions when all that was needed was a touch up.
 
Doesn't look like may others that have Mono-steel knives grind down the blade faces with low grit stones each time they sharpen? Japanese blades or wide bevel knives might require a different approach.


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## MowgFace (Dec 20, 2013)

Mucho Bocho said:


> Its just that there are so many types and styles of blade construction that say you should thin everything you sharpen is misleading. Guess it depends on how you define thinning.
> 
> Last night I touched up my month old AEBL ITK. I just gave it a few strokes on an 6-8K Takenono stone, stropped on it, then leathers diamond spray, then lghtly on leather. Didn't even bring up a burr. The edge is screaming and bitty again.
> 
> ...



W


Sent from my iPhone using Tapatalk


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## The Edge (Dec 21, 2013)

In a perfect world, you would thin every time you sharpened your knife. Realistically, this doesn't happen. Most of the knives we deal with here are so thin behind the edge, that the time to do so, (leaving the knife face in the condition we got it) would outweigh any of the benefit you got from doing it. The ITK is a perfect example of this. And for a reference, here's a shot of the choil:

View attachment 21083


In all reality, you can go quite a while before you would notice any performance degradation without thinning the knife. Just because it is so frickin' thin behind the edge. It's actually more efficient to just wait for a while before attempting to thin the knife with the amount of time you would spend on the stones to get the finish back to where it was. It does become somewhat of a guessing game once you wait that long, to thin it to the right angle. But I'll try to draw something up tomorrow to better illustrate that point. For now, I would suggest just touching up the edge when you need to, as this will help you get a feel for keeping a consistent angle. Once you start to thin, the feedback is a bit harder to gauge.

The reason you don't see any scratches on the knives any of the pro's sharpen, is that they work through a full progression of stones, essentially re-polishing the knife as they've taken metal away at lower grits.


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## toddnmd (Dec 21, 2013)

I'd guess that the pros are more highly proficient at holding a consistent, low angle. It only takes a momentary lack of attention to go too low on the angle and scratch up the face a bit.


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## NO ChoP! (Dec 21, 2013)

The point of thinning with each sharpening is so you don't have to scratch way up the blade face.

If you sharpen at fifteen degrees; doing an initial bevel at ten, would be considered thinning. Blending the two together would leave you with a crisp, shiny new bevel, barely bigger than if you did 15 degrees exclusively.

I think of it as knocking the shoulders off...essentially keeping the transition from blade face to bevel from looking like an ax.


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## Yamabushi (Dec 21, 2013)

:goodpost:&#12288;Exactly!


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## cazhpfan (Dec 21, 2013)

Hi All,

Thank you very much for the great advice. It's been rely helpful! Here are pics of the blade. Do these images lend any additional info on the thinning, and sharpening, strategy for this knife?


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## icanhaschzbrgr (Dec 21, 2013)

You should use some sandpaper and round choil and spine of your knife, that would make pinch grip much more comfortable :knife:


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## The Edge (Dec 21, 2013)

I apologize for the crappy pic, but it should help me explain my thoughts. 





Let's say you sharpen the knife at the angle between AD and AE. As you remove more and more steel from each sharpening session, D and E keep getting further and further apart. Taking off the shoulders at D and E is thinning, and will help alleviate this problem in the short run. However, at some point you will need to remove metal between DB and EC to keep the knife performing at its best. The hard part is that these bevels are not often as straight forward as you would think. Sometimes you run into 3 or 4 blended bevels that aren't as obvious to the eye as in the picture. 

If you're new to sharpening, just touch up the edge. If you find it easy to do that, then feel free to knock off the shoulders at a lower angle, but don't feel you have to make huge leaps and bounds to keep the performance going strong. What's important is to feel somewhat comfortable when you put the knife to the stones, and to have an idea of what you are trying to achieve. Hope this helps.


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## cazhpfan (Dec 21, 2013)

I'll do that next time I sharpen it. 



icanhaschzbrgr said:


> You should use some sandpaper and round choil and spine of your knife, that would make pinch grip much more comfortable :knife:


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## cazhpfan (Dec 21, 2013)

Great stuff! Thank you for the drawing and the explanation. 

I feel comfortable sharpening the primary bevel and knocking down the shoulder. I have spent a month practicing on beater German knives... 

What I can't figure is where to thin between DB and EC (when the time to do so comes).

The secondary bevel on this knife is, just like you said, a blending of multiple bevels . I will grab a better picture under natural light later on today.

Do we just select an arbitrary angle and transform the convex secondary into a flat-ground secondary when "serious" thinning is necessary?



The Edge said:


> I apologize for the crappy pic, but it should help me explain my thoughts.
> 
> View attachment 21093
> 
> ...


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## The Edge (Dec 22, 2013)

Since you have your German knives to practice on, I would suggest when you want to start practice thinning at that level to give it a go on them. The steel will remove slower than at the edge since there is more surface area to grind. This will mean it will take longer to do, and you'll need to be patient. Let's pretend you're going to thin the Tanaka, so you set it on the stones at BD and CE as such:




Once you make a few passes, you'll want to lift up the knife and check to see where the scratch pattern is actually forming. It will be easier at this point to see if you're hitting any high spots, or if you're flush with the bevel. Try to keep it flush, but you'll also want to eventually remove steel at B and C as well to knock off some of that shoulder. To remove the scratch pattern, you'll have to work your way up slowly to higher and higher grits to polish them out. The only time I tend to go through this process is when the knife really starts to wedge in potatoes. It becomes a slow process, and you'll be tempted to push the side of the knife into the stone as hard as you can and grind away for 5-10 minutes, but don't. Work it a little, wipe it off, slice something to see how it is progressing, and then go back to thinning. The more comfortable you get at thinning, and eventually you'll be able to grind away. Sharpening is an intimate thing, and it will bring you closer to your knife than you knew possible. It will also give you more respect for what these knife makers do. 

This is how I learned to do it, and I'm still learning something every time I put the knife to the stones. If anyone else has a different thought, please feel free to chime in...


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## cazhpfan (Dec 23, 2013)

Hi Taylor, 

I apologize for the late reply. Thank you very much for the time you spent to explain thinning!. Everything makes perfect sense. :doublethumbsup:



The Edge said:


> Since you have your German knives to practice on, I would suggest when you want to start practice thinning at that level to give it a go on them. The steel will remove slower than at the edge since there is more surface area to grind. This will mean it will take longer to do, and you'll need to be patient. Let's pretend you're going to thin the Tanaka, so you set it on the stones at BD and CE as such:
> 
> View attachment 21102
> 
> ...


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## adicrst (May 5, 2014)

Good info in this thread.
However, I think that in a normal home use it can take years to need a thinning, am I right ?


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## icanhaschzbrgr (May 5, 2014)

adicrst said:


> Good info in this thread.
> However, I think that in a normal home use it can take years to need a thinning, am I right ?



If the knife was already thin behind the edge then you could go away without thinning for a few sharpening sessions. Tanaka knives aren't the thinnest out there, but still pretty thin behind the edge. Let's imagine you'd sharpen your knives once in 2-3 months. That would means you'd do 4-6 sharpening sessions a year. So you could get away without thinning for a year or two. Or three. But each next sharpening session would make knife a little bit thicker behind the edge, which means with each session performance would deviate from optimal more and more. 

There was a good suggestion in this thread: thin a knife a little bit with every sharpening session. It doesn't take long a allows preserving optimal performance.


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## cazhpfan (May 5, 2014)

Hi Adicrst,

Having sharpened my Tanaka a few times, here are my thoughts:

1) The knife I have isn't particularly thin behind the edge and the cladding is quite thick starting at the middle of the blade and going towards the spine.

2) While there's pronounced convexity to the left face of the blade, the right face is almost flat ground. Because I'm right-handed, this means that food-release is quite poor.

3) The lack a 'true' secondary bevel (i.e. a shinogi+lamination line) makes thinning more difficult--not in the sense of execution but in the notion of esthetics. Thinning the blade inevitably scratches the damascus. This is a shame as Shigeki makes beautiful knives.

4) Besides sanding down the both blade faces w/600 grit wet/dry sandpaper, etching in FeCl3, and then buffing with micromesh pads, I'm not sure of any other way to make the damascus cladding look good after thinning.

5) Thinning with each sharpening session is really the way to go if you wish to the maintain the blade's geometry.

I hope a more experienced member can comment on how to thin convex blades w/o secondary bevels while still maintaining the finish.

I sometimes wonder how folks like Dave Martell and John Broida do it...
Maybe one of them can share their approach. :knife:

Hope some of this helps...



adicrst said:


> Good info in this thread.
> However, I think that in a normal home use it can take years to need a thinning, am I right ?


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