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