# Article on gyuto design (for knifemakers)



## Matus (Feb 15, 2018)

It would appear that I tend compensate the lack of time for actual knifemaking with writing lengthy blog articles :dontknow:

Anyhow - I have written a *really long article *on how I proceed when designing a guto inlcuding different grinds and their properties. The article is built around trying to understand the design and properties of Japanese guyto knives. The main target group are young knifemakers who do not have experinece with high end kitchen knives (and may tend to full flat grinds with 'some' kind of profile).

I would very much appreciate any kind feedback should you find the time to check out some parts of it (the whole thing is really long, sorry)

Thanks


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## bkultra (Feb 15, 2018)

"Make yourself a nice tea and find a quiet place, this is a 6.500 word article "

You lost me at tea... 

Very fun read, even if it was with a coffee


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## LifeByA1000Cuts (Feb 15, 2018)

Just as interesting to knife fans and sharpeners.

Some naive questions from a non-knifemaker:

About your statements on grinds: So you consider an (accidental or intentional) hollow grind on a blade road to never have any functional merit, even if it gives thinness, guiding and/or food release advantages (at the cost of overall cutting ease and ruggedness of course)?

About your flat spot/curvature statements: Why is which is always good for usuba and menkiri users (truly flat profile) always bad for gyuto users - while there is the problem of board sticking, truly flat sounds advantageous when you are chopping tough ingredients (think chile pepper skins) that will accordeon if you leave them even a fraction of a mm...?

About blade height, precision: There is an observation I always make when using a chinese cleaver (as a rare user of these things): They actually take much above average force and concentration if you have to correct any steering (from the food not the grind itself) - probably due to the leverage working against your pinch... At the same time, holding them too tight gives you accordeons ... Probably natural to whoever uses them on a daily basis. Very narrow blades, opposite: No big lever against your pinch, but neither do you have a big lever against the edge.


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## milkbaby (Feb 15, 2018)

That's long but full of a lot of information... nice job Matus.

A lot of American knifemakers like a simple full flat grind for their chef's knives though.


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## Kippington (Feb 15, 2018)

Cool write-up Matus. Thanks for posting.

I find the part about the angle between the handle and the 'flat spot' to be particularly interesting. For sure, the two are not parallel. However I've noticed that there are very popular profile shapes out there that people love (used by many makers), where the angle is so close to parallel that I'm not sure people would care or notice if it actually _was_ parallel.







Having used this shape and finding it comfortable, I have to admit that maybe this handle angle is less important than I had previously thought.



LifeByA1000Cuts said:


> About your flat spot/curvature statements: Why is which is always good for usuba and menkiri users (truly flat profile) always bad for gyuto users - while there is the problem of board sticking, truly flat sounds advantageous when you are chopping tough ingredients (think chile pepper skins) that will accordeon if you leave them even a fraction of a mm...?



That slight curve along the flat spot is super important for three reasons. Lets say you have a pepper skin laid out flat on the cutting board surface. If you had a true dead flat spot on your knife, the pressure you exert down onto the pepper would be spread out over a long area, making it less effective and more likely to crush the food. A curved surface doesn't have this issue. It concentrates the pressure on one small location, also delivering that force in a more efficient direction. This is the same reason they don't put a flat cutting surface on an axe head.






Secondly, let's say you're using a chopping motion - straight up and down. If you use a true flat spot, you'd need to hit the flat cutting board surface with a high level of accuracy - dead on - each time. A slight off angle would give you a clunking feeling each time you make a cut, as one end of the flat would connect with the board shortly after the other - essentially a two-point contact. Using a slight curve turns it into a single-point contact. Holding the knife with a relaxed wrist, you can auto-correct the angle of attack each time it hits the board without a clunky feeling. With such a wide radius on the curve, you can cover a lot of contact surface area in just a few short degrees of wrist movement. This also negates the need for a dead-flat cutting board surface.

Finally, a dead flat spot is super difficult to maintain on the stones. Grind a little more (or a little less) in one area over another and you have yourself an over-grind/recurve.


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## gic (Feb 15, 2018)

Thanks, very useful!


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## Matus (Feb 16, 2018)

LifeByA1000Cuts said:


> Just as interesting to knife fans and sharpeners.
> 
> Some naive questions from a non-knifemaker:
> 
> About your statements on grinds: So you consider an (accidental or intentional) hollow grind on a blade road to never have any functional merit, even if it gives thinness, guiding and/or food release advantages (at the cost of overall cutting ease and ruggedness of course)?



I discussed this part with Jon. I was wondering why some knvies have the wide bevel ground slightly hollow and his answer was, that that is more a result of the making process by given sharpener, rather than the 'final intended geometry' for the blade. After all - user can not maintain a concave grind anyhow.




> About your flat spot/curvature statements: Why is which is always good for usuba and menkiri users (truly flat profile) always bad for gyuto users - while there is the problem of board sticking, truly flat sounds advantageous when you are chopping tough ingredients (think chile pepper skins) that will accordeon if you leave them even a fraction of a mm...?



I think Kippington answered this really well. With regard to Usuba - I have never used one, but from the videos I have seen the cutting mothion is here slower, more precise - not a typical chopping style.



> About blade height, precision: There is an observation I always make when using a chinese cleaver (as a rare user of these things): They actually take much above average force and concentration if you have to correct any steering (from the food not the grind itself) - probably due to the leverage working against your pinch... At the same time, holding them too tight gives you accordeons ... Probably natural to whoever uses them on a daily basis. Very narrow blades, opposite: No big lever against your pinch, but neither do you have a big lever against the edge.


Interesting observation. I need to get my hands on a Chinese cleaver one day


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## LifeByA1000Cuts (Feb 16, 2018)

@Matus try cutting a thin slice off a carrot with a chinese cleaver ... that will inherently try to steer a bit (the slice gives way, the carrot won't). But you feel that bit more than with a normal chef knife in my experience.

The idea of the concave blade roads found in some very cheap knives is likely that you DON'T need to maintain it, since you can rasp away a lot of edge before there is much gain in thickness.


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## John N (Feb 16, 2018)

interesting write up, Thanks


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## milkbaby (Feb 17, 2018)

I finally read everything instead of merely scanning through. Ironically, the only major issue I have is the section about full flat grinds. The diagram is actually not representative because most of the makers who utilize a FFG for their kitchen knives are not grinding to zero edge but leaving maybe 0.005 to 0.010 inch thickness at the edge before sharpening. Most people probably do not maintain the geometry during thinning these knives, i.e. they don't thin the entire blade but instead wind up with a compound grid that ends up mimicking a short convex grind behind the edge.


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## Benuser (Feb 17, 2018)

Very interesting indeed. What made you choose for a symmetric grind as a starting point? They're rather the exception, both amongst Japanese and European blades.


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## Matus (Feb 17, 2018)

I really appreciate you guys taking the time to read the article and comment here.

milkbaby - you are right. I went unnecessarily off-focus with how I described the FFG. As you pointed out, nobody is probably really grinding their blades to zero edge thickness. I will rewrite that part.

Benuser - I went with a symmetric grind because I think before a maker will move to asymmetric grinds, he or she should first get a handle on symmetric grinds. Asymmetry is not easy to measure or quantify and thus possibly hard to control without a lot of experience.


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## LifeByA1000Cuts (Feb 18, 2018)

@Matus I thought asymmetric grinds emerged when knifemakers put much effort into grinding the right side ... but really had their nose stuffed of grinding afterwards


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## Benuser (Feb 18, 2018)

Just to explain why even French or German blades have at some degree asymmetric grinds.
http://www.kitchenknifeforums.com/showthread.php/33951-A-Basic-Explanation-of-Asymmetry


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## Matus (Feb 18, 2018)

@LifeByA1000Cuts [emoji28]

@Benuser - thanks! Than is a very well written article - I was not aware of it. My understanding on asymmetry of double bevel knives is the same, but the discussion on asymmetric sharpening is new to me. O will refer to that post on my blog, it is very well written.


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## LifeByA1000Cuts (Feb 18, 2018)

And I am still obsessively confused and confusingly obsessed about "grind right biased, sharpen right biased" vs "grind right biased, sharpen left biased". From experimentation, A seems best for already strongly asymmetric knives of which you expect asymmetric behaviour anyway, B for lasers and parers...


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