Hatsu Sankaku Yari - professional development project

[islandblacksmith]

This project began as a personal challenge and an exploration of the beauty and symmetry that can be found in the sankaku style yari. The cross section of the blade is triangular in this style, the spine quite thick and strong, and the tip is centered on both axis. The basic form is fairly defined, but there are several historical variations on the lengths of the blade and tang as well as the style of sculpting the neck area.

"Appreciation for detail in everyday utilitarian objects is one of the elements that shows up in traditional Japanese craft. Historically, this was expressed by attention to the precise development of form, line, and detail, and is found even in components or areas that were hidden from view or secondary in importance."

Historically, this type of lance would have been mounted on a sturdy hardwood pole about two metres in length, though there were examples up to six metres for defense against cavalry. The top of the pole would have a lacquer finish, several iron bands, and a strip down each side, and like a tanto, the yari would have a copper habaki and a bamboo peg through the tang to hold it in place.

(click the centre photo to see the hada in more detail...)

Blade construction is muku with a sankaku profile and a raised/centered tip.
The blade is approximately 7.5″ long, the tang is 10.25″ long, and the overall length is about 17.75″.


Specifications

長さ/刃長 Nagasa: 6 sun 2 bu 7 rin (190mm)
元幅 Motohaba: 9 bu 3 rin (28mm)
重ね/元重 Motokasane: 2 bu 8 rin (8.5mm)
反り Sori: straight
中心/茎 Nakago: 8 sun 5 bu (258mm)

形 Katachi: sankaku
刃文 Hamon: suguha
帽子/鋩子 Boshi: ko-maru
中心/茎 Nakago: kaku, no mekugi-ana, signed midway
銘 Mei: hot stamped katabami-ken kamon


read more: islandblacksmith.ca/2015/07/hatsu-sankaku-yari/

 

[islandblacksmith]

This yari is made from reclaimed shear steel from a horse-drawn carriage axle. The axle has evidence of forge welds on it and may have been repaired by a blacksmith at some point using locally available materials. The blade was hand forged in a charcoal fire, shaped with files, differentially hardened using traditional water quench yaki-ire, and polished by hand with water stones to reveal a suguha hamon and a subtle hada.

On the left a horse-drawn carriage axle, in the foreground a forge weld where a last-century blacksmith joined the stock hubs to a length of available scrap to complete or repair the axle. While most stock axles in this era seem to be mild steel or wrought iron, a break test indicated the centre section to be in the neighbourhood of .5% carbon and possibly shear steel…about half (~4″ x ~1″ square) of the segment on the right was used for this project.

Top left the initial piece of axle, top right drawn out to about twice the length (a teko handle was attached during this stage). Bottom the sunobe begins to take shape, allotting material for the tang and the blade. A neck was forged and then cleaned up by hot filing at the vice with a rasp while at a red heat.

After the final rounds of forging. At this point it is about 18″ long, drawn out from the original 4″ bar. This type of yari has a sankaku (triangle) cross section so the back is flat and the spine is quite thick.

Top, the dried clay mask just before yaki-ire. The thicker clay slows the cooling while the thin charcoal-rich clay speeds the cooling causing a very hard edge to form while the body stays tough. Note that the centre spine is also exposed near the tip so that all three leading edges are hardened there for a distance. Bottom, showing the comparative size and shape of the same volume of steel at different stages from the original axle section at the top, pre-sunobe, and just after yaki-ire at the bottom.

Cutting dry with a very coarse diamond stone to true up the flats after yaki-ire and then down through the grits with water on the stones. At the coarse stages the blade moves perpendicular to the stones and for each new stone the scratch pattern angle moves closer to parallel (eg. 90 degrees, 45 degrees, 20 degrees) and then all the rest are at 0 degrees, along the blade.

Beautiful natural stones from Japan, I received them in fairly raw form and chiseled and chipped them into useable flat block shapes and saved the chips for making fingerstones. To make the hazuya and jizuya stones I flatten one side of the chip on a diamond plate and use natural urushi lacquer to paste on a piece of washi paper for strength, then when dry flatten the other side and cut to shape. The stone powder from flattening will go into the clay mixture for yaki-ire, "clay tempering" and into an uchiko ball for removing old blade oil.

The final stages take as long as all the previous stones together and involve working with a tiny piece of stone under the thumb to work over every few mm of the surface, removing the final scuffs and bringing up the texture and grain of the steel. Here the tojiru slurry forms an interesting wave pattern as the blade is polished with the narutakido jizuya fingerstones.


read more: islandblacksmith.ca/2015/07/hatsu-sankaku-yari/

thanks, yoroshiku!

 

[Steve Nuckels]

Always look forward to your threads, informative and very interesting with great photos!

Thanks for going to the effort!

If I had a fraction of your patience my work would improve greatly.

Steve
--------
Member, W.F. Moran Jr. Museum & Foundation
ABS AP

 

[P. McKinley]

I always look forward to your in-progress threads Dave. Informative, well documented, and a fascinating glimpse into the shop, and mind, of a maker fashioning true works of art. I eagerly await the further progression of this piece.

-Peter

 

[Mecha]

Really interesting and pretty work. The triangle-section yari blade is a fascinating design.

 

[Lycosa]

I better hang around.
Good crowd.

 

[Rick Marchand]

Oh boy... this one looks like fun. Subscribed.

 

[the possum]

A neck was forged and then cleaned up by hot filing at the vice with a rasp while at a red heat.

Interesting- I've never heard of rasping while red hot. Does this make it file much easier and faster than doing it cold? I'm surprised it doesn't ruin the temper of the teeth on the rasp; I'd think each tooth would heat up pretty quickly. Do you have to keep the file/rasp moving pretty quickly to prevent this?

 

[stezann]

It is a technique well known by blacksmiths, and very effective.
As you correctly pointed out you need a dedicated file/rasp for this very purpose, and maybe try to be quick (if you don't like roasted fingers).
A loss of hardness is not a concern since you always use the tool on red steel, and have other files for the cold workpieces.

 

[stezann]

Dave,
it is always a pleasure when you post the amazing pictures of your process, i spent hours at your website and i really admire your approach.
It is a way to tribute honor to....

 

[gga357]

This looks like a wonderful project.

 

[gregorio]

Looking forward to seeing more of this one. :thumbup: