The Varieties of Japanese Chisels Part 9 – The Uchimaru Nomi Gouge (内丸鑿)

“A good tool improves the way you work. A great tool improves the way you think.”

Jeff Duntemann

The name of the Uchimaru Nomi is composed of 3 Chinese characters (kanji): 内 pronounced “uchi “which means “ inside” or “interior,” 丸 pronounced “maru” which means “round,” and 鑿 “nomi” which means chisel.

This gouge has a blade very similar in cross section to its Western counterpart, but unlike Western gouges, it is made of laminated steel, has the combined tang and ferrule construction typical of Japanese chisels, and a crown to reinforce the handle and protect it from violent hammer blows. These are strong chisels used by carpenters to carve large-scale architectural components, and sculptors.

They come in different sizes and sweeps, although not as many as the Swiss make. Some are the size of typical oiirenomi bench chisels; others are the size of the larger heavy-duty atsunomi.

Carving an architectural detail for a temple.
Uchimaru gouges with various sweeps (radius). The shiny surfaces are hard steel, while the black surfaces are softer low-carbon steel.
Carving a tray out of Kiri wood, a lightweight, aromatic wood much loved in Japan. Being exceptionally soft, it requires extremely sharp tools to cut cleanly. Clearly, this craftsman knows his business. He is using a knee-clamp on a low workbench.

As you can see, these blades are are not hollow-ground.

The relatively hard layer of steel which forms the cutting edge is often subjected to more lateral forces when carving than their straight-bladed cousins, and are sometimes damaged as a result. Professional carvers will hold the thin cutting edge over a small candle flame to reduce the hardness over a small area to reduce this tendency. I’m not recommending this practice, just conveying information.

The technique used for sharpening Japanese gouges is identical to their Western counterparts. To sharpen the outside bevel, typically one will use dedicated sharpening stones with grooves worn into them that are slightly greater than or equal to the radius of the gouge. One removes the burr and polishes the inside curve by using a short stone with a radiused edge.

A piece of leather charged with polishing compound can be used to put a final polish to the bevel. One can also bend this piece of leather to polish the gouge’s inside surface. Easy peezy.

Standard sizes are 9mm, 12mm, 15mm, 18mm, 24mm, 30mm, 36mm, and 42mm.

There are also uchimaru gouges made as paring chisels, with longer blades and handles, slimmer necks, and without crowns.

If you need a gouge that that can hog a lot of wood, will take an exceptionally sharp edge and will maintain it a long time, then this is a tool you should consider.

In the next post, we will look at a different type of gouge, one you may not have seen before.

YMHOS

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