Tang gap

https://www.google.ca/search?q=honyaki&tbm=isch&ei=x3EKV5jCKKiljgSW_IXIDA&start=40&sa=N#mhpiv=13

Every once in a while i come across an image where the shoulder on a hidden tang blade isnt resting against the furrel. It always looks like incomplete handle installation. i prefer a tang without a shoulder for several reasons. I can see a tight fitting shoulder being a place for grime and food waste to collect if not kept clean. So, allowing a gap may help this.

Thoughts?

It's called a machi or machi gap. It's there to allow for room if or when you need to remove the handle and put it back on. There's a whole thread about this somewhere. I'm on mobile so I can't find it.

It a matter of personal tastes... Some like a machi gap and some don't.

http://www.kitchenknifeforums.com/showthread.php/12520-Adjusting-machi-gaps

Quotes from Jon in the above link:

"there is a purpose... its about finger spacing and handle installation"

"sometimes handles are removed and replaced (the same handle), and the extra space is very helpful."

Second what others have said.

Here is also a post on JKI blog talking about the machi gaps and some other stuff.

Now that I know what it's called I can read more. In reading through those threads there still doesn't appear to be a clear answer. Be it for handle removal or finger spacing, cutting the shoulder then becomes my point of focus. Why cut a shoulder if you don't intend on closing the machi gap.

I just read probably the most convincing explanation. It's an affectation of sword making where the gap was infilled by the tsuba and seppa. This explains why the shoulder is cut on a sword and perhaps why it carried over into knife making. I also suspect it is the way it is because it's always been that way. People have rationalized it into existence.

jessf said:

I just read probably the most convincing explanation. It's an affectation of sword making where the gap was infilled by the tsuba and seppa. This explains why the shoulder is cut on a sword and perhaps why it carried over into knife making. I also suspect it is the way it is because it's always been that way. People have rationalized it into existence.

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sadly, that is just not at all true.

jessf said:

In reading through those threads there still doesn't appear to be a clear answer.

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What? Several clear answers were given in the linked thread and in the jki blog post. Go back. Read it again.

i thought it would be interesting to ask Shinichi Watanabe because he is always helpful with his explanations. Rather than paraphrasing, I'll quote his response below:


"The gap is for the future. Wood is natural material. After using long time, it is possible to loose the blade. Then you can insert more. So we assemble new knives having the gap. Some people take out the handle for perfect re-sharpening. Then the blade becomes loose.

Yanagi, Usuba, Takohiki, Mioroshi etc come with machi, but Deba, Gyuto, Nakiri don't. Machi knives seem for precise works. On the other hand, Without Machi knives are strong works or all purpose.

We have more than 500 kinds of Japanese knives. I can not explain their mechanism of all knives and the reason. But I think Machi knives are for precise cutting blades like Yanagi, Usuba, Mukimono. On the other hand, strong or utility blades like Deba, Gyuto don't have machi.

There are various opinions.

Machi knives have wider necks. The wider neck is easier to control the blade precisely. But we need to make too wide a handle for the wider neck. It is unbalanced. So we made Machi, I think. Machi is for the whole balance."

I did. Explanations are there, but they still don't make sense of the shoulder. Even if it's for future use there's no reason to cut a shoulder. Just blend it into the choil.

Does the machi gap pre-date 1945?

The only reason I can think of relates to the usuba and seppa thing. Imagine you're a swordsmith after 1945 and sword making is banned. Now you need to make use of your forge and skills as well as your fabrication methods until such day that the ban is lifted. Cutting a shoulder and exposing the machi may have served to subvert the ban on sword making while at the same time kept the technique and skill alive to pass on to your apprentice.

If the machi gap pre-dates 1945 and beyond then perhaps it dates back to the abolition of the samurai at a time when Japan adopted a more western style military. The face of sword making changed. Perhaps the machi appeared as both a literal and figurative expression of a people who have cast off their traditional "guard". Maybe it's a protest of sorts and the gap a place holder should the guard ever return.

ThEoRy said:

What? Several clear answers were given in the linked thread and in the jki blog post. Go back. Read it again.

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yes... the machi gap predates 1945 by a decent bit... without the shoulder, the wider tang wouldnt fit in the handles that make sense size-wise... they also dont allow the spine to be as flush with the top of the handle

Yeah I understand why someone would cut a shoulder to allow the spine to be flush with the top of the handle and to allow a wider appearing blade. But to cut a shoulder then leave a gap vexes me. If it pre-dates 1945 then what about the 19th century idea?

JBroida said:

yes... the machi gap predates 1945 by a decent bit... without the shoulder, the wider tang wouldnt fit in the handles that make sense size-wise... they also dont allow the spine to be as flush with the top of the handle

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i've seen images of knives with these features dating back at least that far (when i was in college, i ended up writing a lot about various aspects of japanese food as part of my thesis)... the gap allows for finger spacing to be adjusted on a case by case situation, and leaves room for the handle to be taken off and reinstalled for sharpening and maintenance (as it gets looser each time and will need to be more deeply installed each time).

wouldn't finger spacing be explained by the length of the tang? And as it is taken off and reinstalled and pushed in closer to the shoulder the finger spacing would become less and less. Would finger spacing change with time as well?

JBroida said:

i've seen images of knives with these features dating back at least that far (when i was in college, i ended up writing a lot about various aspects of japanese food as part of my thesis)... the gap allows for finger spacing to be adjusted on a case by case situation, and leaves room for the handle to be taken off and reinstalled for sharpening and maintenance (as it gets looser each time and will need to be more deeply installed each time).

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not necessairly... there is a lot of room for play irrespective of tang length. Moreover, repeated removal and installation does not have to change the spacing so significantly, but yes it does change a bit. Lastly, if you installed flush up and the wood changed shape over time (which wood does), there would be no room for adjustment to keep a tight fit.

Jon's got this, but I'll pitch in.

Most of the "it's from swordmaking" explanations are flawed or outright false.

If handles were permanently fixed or mounted like sword handles, there would be no gap. Such handle construction and mounting was (and generally still is) impractical for kitchen knives.

The amount of wood change would be minimal and likely on the shrinkage side. It might swell with moisture but it's also oiled to help prevent this and the swelling would be significant perpendicular to grain direction and less parallel to it.

JBroida said:

not necessairly... there is a lot of room for play irrespective of tang length. Moreover, repeated removal and installation does not have to change the spacing so significantly, but yes it does change a bit. Lastly, if you installed flush up and the wood changed shape over time (which wood does), there would be no room for adjustment to keep a tight fit.

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i think you'd be surprised to find that shrinkage is actually just as much of a problem as swelling

A traditional Japanese knife with machi is first and foremost a tool for a Japanese chef. The blade will last many years through heavy use. A handle, usually made of Ho wood, may wear down over that same time and use. These blades with machi tend to be thicker and single bevel to achieve a certain edge. The tang and insert design meets specific purposes.

If you wanted a particular knife made with a different design, could you find a traditional smith who would make it?

Yes I am well aware of how wood changes with time. It also changes more across the grain than it does with the grain. So the gap being there to provide room for dimension changes seems less likely as they change end to end may only amount to a 1mm or a few mm at best. Additionally, if handles were swelling or shrinking as much as you're suggesting we'd see more furrels cracking or separating as the two materials interact and change shape differently. A blade without a shoulder has as much or more adjustable qualities in terms of blade insertion.

I'm going to keep searching.

JBroida said:

i think you'd be surprised to find that shrinkage is actually just as much of a problem as swelling

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