Mukomachi-Nomi Japanese Hand Made Mortise Chisel by Mitsuki - 3mm&5mm

Brand name: Mitsuki(光月)

Smith name: Yamazaki Nobutsugu(山崎信次)

Steel: White Steel 

Blade width: 3mm/5mm

Blade thickness: Blade Bottom(about 12.50/12.80mm)， The blade near the bevel（about 10.10/10.30mm）

Manufacture Era: Before 1980

Blade Angles: about 30°

Total length: 235mm/235mm

Neck length: 41mm/41mm

Blade length: 73mm/75mm

Types of wooden handles：Japanese Red oak (Akakashi)

Weight: 88g/106g

Accessories：—

Additional Information:  They are unused and in good condition, with minor rust on the edge that can be removed through sharpening. The overall craftsmanship is refined, with concave hollows worked along both flanks using a sen . However, as mukoumachi-nomi (mortise chisels), these two seemingly superior Tokyo chisels are actually less practical than the lesser-known ones currently listed on the site.

They have a fatal flaw, which is especially noticeable on the 3mm chisel. If you look closely at the third and fourth photos—setting aside the lamination lines on the bevel and viewing it strictly as a cross-section of the blade—you will notice that the cross-section is not a true rectangle. The line representing the ura slopes upward to the right. In other words, the reference registration plane of both chisels is tilted; if used to chop deep mortises, the resulting mortise will veer off at an angle.

The tilt on the 3mm chisel is too severe to correct through subsequent sharpening, meaning it is best repurposed for paring tasks, such as cutting grooves when making plane bodies (kanna-dai). The 5mm chisel, on the other hand, can still be trued up by re-flattening the ura.