The challenges of making a file by hand


My setup is extremely minimal.

I’ve gotten quite tired of digging back through the comments for previous posts trying to find various links:

The link from Sebastian regarding ale grounds and salt to protect the cut file from oxidation during hardening.

The link from Jason showing modern yasuri manufacture by Wataoka, lots of good pictures showing computer controlled kiln annealing, dressing at sen-dai with file, heating in lead bath for hardening.

I’ve watched this video so many times. The actual cutting of the file teeth is fairly easy and straight forward, though this fellow makes it look too easy. The greatest challenge of making a good file centers around proper heat treating.


Rough forging the shape close to the finished form is proving difficult. Its a small thin piece of metal that looses heat very quickly, especially as one tries to taper down the edges.


So in essence I have these ugly annealed forgings that require quite a bit of straightening, grinding, and shaping.


This is the smallest yasuri I forged, really tiny at 50mm, one sided. I established a flat back face, filed the width parallel with the help of a dial caliper, and then shaped the top bevels to an equal state by eye. There’s always the tendency to rock the file, you can see on the right side where I’m taking the middle of the face down by draw-filing. Before cutting the teeth I’ll further flatten on my coarse diamond plate to remove any twist in the faces, and check for consistency of the angle of the top faces relative to the flat back. I’m actually not too concerned about the angle here, it just has to be consistent along its length.


I had tried all of my chisels out on a piece of CR mild steel bar, the edges held up quite well and I was cutting teeth consistently. The file was another matter however. Any small defect in the chisel edge shows up in the teeth of the file, just as a small chip on a kanna blade will show up in the finished surface of the wood. So basically my annealing of the file blank is not good enough, the chisel is getting fubar, large chips that lead me to believe it has poor grain structure and needs a bit of tempering. These are really interesting challenges, but its daunting when you have so many at once, where to start figuring it all out?

I’ll start by sharpening the chisel again, testing it on some known pieces of mild steel. If the edge holding is acceptable I know that my annealing process is at fault. I’m going to batch anneal after shaping the next files (and grinding off the shitty teeth I cut on the tiny yasuri above), meaning wire all of the shaped files together, heat in the forge together with a large chunk of steel for thermal mass, and then place in the ash bucket, try to slow the cooling down as much as possible.

I feel like back when cutting my first dovetails, lots of coarse ignorant work slowly refining through experience and the process of discovery.

6 thoughts on “The challenges of making a file by hand”

  1. BanZai!! — I never heard anyone say that, just read it in manga — but I’ll say it BaannZaii !!


    Tsubo, as in Tsuboman, the name of the file company, means “pot” ,
    like a hibachi, which I allways wondered if – or how – that fit in. Might be good way to anneal. But look real close at the tang and un cut or back of a yasuri – odd texture.

  2. So the way I’m seeing the Japanese-Inspired American craft movement so far-

    Gabe Dwiggins: File, Saw Maker, Cabinetry artisan, a strong advocate for perfection and finding fulfillment in investing time and energy into the smallest parts of the whole;

    Mark Grables: Blacksmith, Teacher, Poet-Philospher, Timber framer- definitely known as a founder. Possibly known as the inventor for the home file-maker?

    Jason Thomas: Chisel, Knife, Plane maker, innovator of the 21st Hawaiian Style building style, which puts a heavy emphasis on found, natural and recycled building material;

    Who else will be on the list? I have to go back to homework now. Figured out my research question, but have some lab reports to type up along with a couple packets of plain ol’ busy work.

    1. On another break from homework…

      Perhaps, due to the influence of the internet, this fledgling movement will not be known as confined to a singular country, but rather to an international community.

      Afterall, it’s a bit silly to alienate Sebastian and the Shingle Maker as the headmasters of their own separate movements, when they have collaborated so much with each other and with us all; I refine the original name to an International movement; regardless of country, we’re all focusing on using hand methods to bring into the world new works to represent the humanity of craftsmanship.

Leave a Reply

Your email address will not be published. Required fields are marked *