Ichimatsu Chisel

[Stanley Covington]

I would like to show you a rarely seen specialized paring chisel called the Ichimatsu Nomi (Nomi means chisel in Japanese). I hope you find it interesting.

This tool is used almost exclusively by joiners (tategushi 建具師) to precisely pare the many angled joints necessary to create smooth transitions between chamfers and other edge profiles at intersecting wooden members, such as rails and stiles, when making wooden doors, screens, dividers, windows, frame and panel interior woodwork, and coffered ceilings.

The most common cut is paring the 45 degree angle mitre where the chamfer or edge profile of a rail meets a stile. The chisel rides on a 45 degree wooden jig to pare the mitre very precisely.

To have a gap or mismatched angle at this sort of mitre is considered very embarrassing in Japan, and must be avoided. An open or poorly fitting mitre is said to be “ laughing,” in derision of the craftsman that made the joint, and is said to mock its maker for as long as it exists.

The chisel in the attached photos is mine. I had it custom made over 25 years ago in imitation of my Master’s by a renowned Tokyo blacksmith named Mr. Kosaburo Shimamura (島村幸三郎). During his lifetime, Mr. Shimamura was praised by metallurgists as the very best chisel blacksmith in Japan.

I have used this chisel a lot, so the blade is probably 2cm shorter than when it was new, and the ura, while still useful, have become considerably shallower.

While it is obviously a paring chisel, it has some unusual design features. Specifications are as follows.

Overall Length: 310mm
Blade width: 24mm
Blade Cross section: Rectangular kakuuchi style.
Ura: 3 - hollow grinds (Mitsuura)
Neck: Flat “Hiramachi” style
Steel: Hitachi Yasuki White Label No. 1 (plain high-carbon steel (1.4~1.2% carbon)
Forging: Hand forged
Finish: Scraper and file
Handle: Japanese Red Oak ( closed grain)

The kakuuchi style is old-fashioned and heavier than the more common mentori ( beveled) style. In this case, it is used for extra rigidity, and to provide a wide, flat top surface for the user to press down on as the blade rides the jig. This chisel is not typically used in tight locations, so beveled sides are not necessary.

Instead of the more common and graceful round neck, it has a flat “Hiramachi” style neck in the same plane as the blade to help it better ride angled jigs without the neck getting in the way or limiting travel.

I am not a fan of multiple ura, and find the detail silly, like putting skinny whitewall pimpmobile tires on a work truck. However, in the case of this chisel, the 3-grind mitsuura is a critical detail.

This chisel is used by holding the handle in the right hand which pushes it into the cut, while the fingers of the left hand press it tight against the jig’s face and guide the blade. If the blade had only a single ura, the pressure acting on the small bearing surface area would quickly wear out the jig.

The increased number of lands makes it possible to work the blade at an angle to, or even partially off, the jig’s face.

I hope you find unusual tools like this one interesting.

I am currently working with my blacksmith to have a reproduction made for a customer.

Stan
Ichimatsu Top.jpgIchimatsu Side.jpgIchimatsu Top Vert.jpgIchimatsu Blade Side.jpgIchimatsu Ura Long.jpgIchimatsu Ura.jpgKamachi2.jpgIchimatsu Tsuku Side.JPG

[Frederick Skelly]

Thanks Stan! I enjoyed reading this!
Fred

[Stanley Covington]

Thanks Stan! I enjoyed reading this!
Fred

You are always welcome, Fred.

[Rowan Page]

Interesting, thanks for sharing Stan.

[Stanley Covington]

Interesting, thanks for sharing Stan.

Thanks, Rowan.

[ernest dubois]

Very beautiful symmetry and lines in photo #3. Are we to understand there is no grinding involved in making the chisel?

[Stanley Covington]

Very beautiful symmetry and lines in photo #3. Are we to understand there is no grinding involved in making the chisel?

Thanks. Glad you like it.

I am sure Shimamura san used a grinder to shape it after forging, although I was not there to watch.

It's nearly impossible to obtain beautiful curves, symmetrical lines, and smooth transitions in chisels without using scrapers and files. He was very skilled at this handwork, and had a great eye. And of course, his forging and heat treating skills are unsurpassed. His blades cut and hold an edge better than any I have experienced.

A lot of his tool designs were informed by those of Chiyozuru Korehide.

Plane blades get all the attention, and are relatively costly, but chisels are much more difficult to make, and are subject to more difficult conditions.

[Brian Holcombe]

Thanks for sharing Stan! This is one beautiful chisel

[Stanley Covington]

Thanks for sharing Stan! This is one beautiful chisel

A man with an discerning eye!

It is an unusual shape to be sure, but it definitely has the simplified "less is more" vibe humming. It is a pleasure to use. I just hope my blacksmith can do a decent reproduction for my customer.

[ernest dubois]

but it definitely has the simplified "less is more" vibe humming.

Yes, its the attraction for sure.

[ken hatch]

Stan,

I'll join the others in thanking you for the post. Japanese chisels are such a beautiful and usable art form and one that unlike most art is accessible to most folks. It is a shame I'm so close to retirement I can't really let my inter tool freak flag fly.

ken

[Jim Koepke]

Thanks Stan,

A little eduction with my morning coffee is always enjoyed.

jtk

[Stanley Covington]

Stan,
I can't really let my inter tool freak flag fly.

ken

Sounds kinky!

[Pat Barry]

Thanks. Glad you like it.

I am sure Shimamura san used a grinder to shape it after forging, although I was not there to watch.

It's nearly impossible to obtain beautiful curves, symmetrical lines, and smooth transitions in chisels without using scrapers and files. He was very skilled at this handwork, and had a great eye. And of course, his forging and heat treating skills are unsurpassed. His blades cut and hold an edge better than any I have experienced.

A lot of his tool designs were informed by those of Chiyozuru Korehide.

Plane blades get all the attention, and are relatively costly, but chisels are much more difficult to make, and are subject to more difficult conditions.

Question: why isn't the chisel blade finished to a higher degree / polish? Why the black finish? The tool is obviously hand made given the nonuniformity of the three grooves. Given the apparent fascination with perfection of miters, I'm surprised that same expectation isn't applied to the finish and grooving. I do like the overall proportions though, particularly the sizing/ shaping of the handle. Why wouldn't the steel be polished?

[Stanley Covington]

Question: why isn't the chisel blade finished to a higher degree / polish? Why the black finish? The tool is obviously hand made given the nonuniformity of the three grooves. Given the apparent fascination with perfection of miters, I'm surprised that same expectation isn't applied to the finish and grooving. I do like the overall proportions though, particularly the sizing/ shaping of the handle. Why wouldn't the steel be polished?

Pat

I understand the apparent contradiction.

There have been a few blacksmiths I am aware of that polished some of their blades. Chiyozuru Korehide was one. Such tools were intended to be literal works of art, not working blades. Of course, this requires considerable extra work to do right.

The black finish is the oxidized "skin" created during heat treating. It is somewhat rust resistant, certainly much more than a white finish. The appearance of this skin tells you something about the completeness and quality of the heat treatment, so in a working blade, it is seen as a sign of quality. All such traces are lost when polishing, and so the quality of white working blades are seen as suspect. Such is the nature of hand-forged blades.

In Japan there is a traditional appreciation for factors called "wabi™ and "sabi." This is best seen in the design and construction of teahouses, if you want to check it out.

Of course, the men and tools used to make such structures have been influenced. There is more beauty in the eyes of many in the black oxide skin than a polished steel blade.

Stan