Monday, March 10, 2014

Kiridashi E/R- An old Japanese craft knife gets a face lift

I need to remember to take better photos. Sorry for the lack of "before" shots.....

Close to the center of the photo is a wooden handle, single edge knife, a kiridashi.

Probably nothing too special, just a good knife. My friend Junji has been looking for a decent knife for me, and knowing my tastes in tools, he found me a good, old one.

The mei (name) is a bit stylized and hard to read (not that I can read kanji, but I am starting to recognize a few symbols).

A screw acts as a retainer, holding the blade in place. A bit of  #0000 steel wool cleaned the grime off of the handle, then I rub in a bit of BLO ( boiled linseed oil).

There was no finish to speak of, so I give it a quick soak in some vinegar. 30 minutes was all it took to remove the bit of rust and leave the metal clean and lightly etched.

I gave the blade a blackened finish. I like the look, but it also helps me with the initial sharpening by acting as a reference mask, like machinist's dye.

The blade has a wicked hook to the steel side. The two layers of metal, steel and iron, contract at different rates when quenched by the blacksmith. This causes the blade to warp towards the harder steel side. I want to make the blade's back flat, right at the cutting edge (the uppermost edge in the photo above). A lot of the blades that I see have been done poorly. It's not difficult, but does require a bit of thought and intent.

Grinding down the edge left the steel a bit thin at the very tip of the blade, which could lead to poor edge retention. 

I grind a new contour to the back, turning a flat line into a gentle curve. You can see that the right side of the blade is no longer straight. The camera angle makes the curve look rather abrupt. 

After the rough grinding with a fine India stone, I finish sharpening the blade using native Oregon coast waterstones. 

But first.....

What's in the box?


My family know how to make me smile.

But whatever in the world will I do with a rock?

Yeah, I know.....

This stone looks identical to another chuck of sandstone from the front yard, but actually finishes slightly finer. This one will go up to around #8000 grit, if you work on the drying slurry bed.

I am really liking these stones, but I am running out of space. I need to build a stone storage rack or something....

Just for fun, I finish polishing the edge using the Nakayama asagi mystery whatever-it-is "Asagi of indeterminate origin" stone.

Sooooo nice. This stone is FAR above my pay grade. I am getting spoiled....

My first project is a foam quadrupedal octopus.

Actually it is a quick and dirty, duct tape sheath. This blade actually scared me, it takes such a fine edge. I was afraid the I might bump into it, requiring a quick trip to the hospital.

The bevel angle is about 27 degrees, pretty fine, and I will be curious to see how well the edge retains its sharpness. This is easily the sharpest tool that I have ever used. In any task of a reductive nature, much of the difficulty lies in directing the tool, I making it do what you want it to do. Cut here, not here, that sort of thing. REALLY sharp tools just cut, right where you want them to. Please let me never suffer dull tools, ever again.

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Like all of us, I am figuring this out as I go, so when you see something that is incorrect or flat out wrong (and you will!), let me know. This is a learning process. Real people and names, please. Constructive comments and questions are very welcome, but hate speak/politics are not! Life (get one!) is too short.

Thanks, Jason