Do Androids Dream of Electric Sheep?

Is there a future in woodworking? Just thought I’d ask, seems like too many visions of the future paint a world where technology predominates as visceral and omnipresent, a world of flashing lights and gleaming switches. Where in that space is the wooden object?

I want to present a different prognostication. I’m thinking recently of the Philip K Dick novel in the title for this post, and a podcast I listened to on the future of automation, as well as reading H.G. Well’s “The Shape of Things to Come“.

Well, how should I put this. Is your cell phone getting bigger or smaller? Just how cheaply can you buy an Arduino these days? In the Japanese tradition for wooden joinery it is very often pointed out how the joinery is hidden. That’s a bit simplistic, maybe its better to narrow down that kind of refinement to sashimono woodworking specifically, though there is are still clear exceptions and important context in terms of how the furniture is used. But my point is that the process of technical refinement often makes things look simple that are quite complex in construction.

Technology will do the same things, the homes of the prosperous technological elite of the future will aspire to the aesthetic of sukiya, the rustic tea house. As Moore’s law pushes onward and functions stack into ever smaller packages technology becomes more seamless and integrated into our built environments. It struck me after reading Ty & Kiyoko Heineken’s “Tansu” how a fellow like me could find himself studying a dainty and refined sho-dana in the MET based on free standing shelves produces centuries earlier housed in the Shoso-in that originally were used to house perishables in the imperial kitchen.

Trend making is more diverse and confusing these days with the internet, but suffice it to say, people will continue to adopt the fashion of the class structure they aspire to. I can imagine homes of the future where every attempt is made to conceal and integrate technology, where the wealthier you are the less machines and technology can be apprehended. In that search for the look of simplicity natural materials will become prized above the manufactured. That’s good for the woodworker, no?

In the present age of resource abundance and availability you wind up with crazy shit like mansion sized sprawling and architectural log homes, quite ostentatious, but the pattern language still fits. Perhaps the best extant example is Larry Ellison’s (Google billionaire) home in Woodside, CA, which is modeled after a 16th century Japanese emperors palace.  The underclass imitates the upper crust, and that aristocracy aspires to the simplicity and ruggedness, not of the poor, but of a romanticized vision of a bygone past.


The wheel of the dharma continues to turn, and quality woodcraft will continue to have a future, perhaps quite a bit more so than the present. That said, looking into the future, perhaps its also a good idea to learn how to grow some of your own food, haha.


Rediscovering Lost and Forgotten Knowledge


Do you expect a challenge to lay down before you? No, it never happens that way. More often than not progress in this arena is made by repeated failure of one sort or another, and then the decision to keep on trying. On more than one occasion a problem that seemed almost intractable was overcome, not by some careful deliberative process, but a flash of insight after much frustration. Case in point, the above file, where I thought I was making good progress in my technique, but actually totally missed some crucial points of knowledge.

This type of work holding seems to be great for the larger files, but is really tricky with yasuri.


A lot of the challenge thus far has been how to start with a rough forging and end up with a really nice flat face for the teeth to be cut upon.


Reading an old book on machining from 1890 I came across an improvised surface grinder of sorts, and figured it could hold the key to the accuracy I wanted. This actually works pretty well considering that my grinder isn’t fixed to the table.

It also works nicely as a file launcher, same mode of action that a tennis ball launcher uses, haha. And I caught my index finger under the wheel, which I don’t recommend.

But it misses the point! Sure, I can rather tediously produce a good finish and flat parallel surfaces, but this doesn’t translate to yasuri.


I wasted a bunch of time, trying to save time, making various jigs for grinding the face angles when the hand tools actually turned out to be faster and more accurate. You see, I’m not trying to make files of all exactly the same dimensions. I care about proportion, not dimension.

For example, given a rough forging I start by profiling the thin edges parallel to each other, and then make the length of the file surface five times the width. I don’t care if its a 72 mm file and not a 75mm file. If I am going to make yasuri by hand I think its fitting that every one is slightly unique.


After abandoning the grinding method for finishing the faces I came to the realization that I should be keeping things a simple as possible. Give me all the equipment I want, sure, I could make some decent files. But this is not about re-creating a viable business or modern production process, its seeing what can be done with simple tools, hand work, and skill born of knowledge.

My sen-dai for yasuri is a most elegant example. Its a piece of scrap kumiko with the correct ‘v’ profile planed in, with a small nail at the front that acts as a stop, and some masking tape wrapped around the back that raises the tang a bit so that the clamp can hold the whole length of the yasuri flat on the wood.


As hard as I tried will a flat mill file to draw file the faces of the yasuri flat I couldn’t get there. It would seem as well that the thinner the face width, the harder it is to produce a flat surface.

The problem being the solution, the file must be curved. A curved file can yield a flat surface with the slight innacuracies of working by hand, nothing new to the world, just new to me. Thinking back upon the Nicholson company treatise on files and rasps its clear that there used to exist file holders that would flex a file, as well as curved files, and of course, tapered files, by which they mean a curved taper.

The latter is actually what I want the most, a three or four sided file with heavy curved taper, but what I have on hand is a small mill file that’s case hardening leaves is quite flexible and easy to bend into the curve I need. Once again I kept it as simple as possible.


Reminds me of a double masted sail boat for some reason, haha.


Get that damn high spot down son! I use Dykem layout fluid to show where I’m filing, but a felt tipped marker works just as well.


Its got to be a quality, if I may describe it so dry and technically, known as pretty damn flat. I use my chisel as straight edge with a light behind it to help sight the high spots.

The curved file was a break though of sorts, and with care can get things pretty damn flat, but I need it better.


The curved tip of a jewelers scraper/burnisher finishes things off.


Practice with the file teeth comes slowly when you have to forge and grind the practice material, but I’m making progress.


How about the odd man out? At 50mm its the smallest yasuri I’ve tried to make, tiny little thing!

I cut the right most one yesterday and actually almost did an acceptable job. The thin edge of the yasuri cross section presents an added challenge compared to cutting a flat file. If I was to simply strike the chisel squarely upon the face the tooth would cut cleanly towards the middle and fade at the edge, where the metal wants to yield. So the chisel has to be struck harder on one side than the other. In addition the edge must be quite perfectly supported by the lead underneath or no amount of hijinks with how the chisel is struck will cut an even tooth. If you’ve watched the video from yesterday I’m cutting on a tiny jewelers anvil, which is hardly ideal in terms of hammer response, but allows for a firm clamping situation which is more important.

In addition I could go on and on at length about how the chisel needs to be sharpened in such a particular way. When I started I left a knife edge on the chisel, but that edge is very weak and fails quickly. Besides, a file tooth cut with a knife edge will have an acute corner at the bottom of the tooth gullet that is almost guaranteed to pin and lodge material. The solution as I have mentioned is slightly dulling the edge, but as I’ve found out its not enough to simply round the edge. What I’m using now is a 20 degree back bevel, 25 degree front bevel, and  85 degree micro bevel on the front, maybe three or four strokes across a 1000 grit stone. By blunting the tip straight across you create a strong edge that still allows the ridge of the previously cut tooth to be felt, and the chisel slips less in use.

Up next is yaki-ire, the hardening.

Video of the File Making Process

I’ve been busy churning out files mass production style.

Haha, just joking. This is hand work, and every yasuri I produce I learn something. Sorry my hands are so bandaged and dirty…this switch to metal work has me finding new and creative ways to abuse my finger tips, but the work must go on!

Believe you me, I’d love to have an annealing kiln, power hammer, rolling mill, known steel, and a molten salt bath for hardening. But as I see it half of the point of this endeavor is using very simple tools. Enjoy!

Heard of Auriou rasps? Still stitched by hand. This video shows a lot of important parts of the production process.  I’ve made a couple of rasp punches, its really straight forward, but the guys in this video are very practiced hands.




My First Hardened Files

It is a strange thing to re-create skills and knowledge in the age of the internet. There is at once too much information and then not enough that is applicable. And then there is the annoyance of blogging about something apparently so obscure that your search queries return your own content.

If you want to make a file and have the limitation of a simple forge for heat treating, prepare for a challenge. But what a great challenge for learning this stuff, let me explain. You’ll need to forge your own file cutting chisels, they’re pretty much the unicorn of metal working chisels at this point. So you get the experience of heat treating an edge, and then testing that edge by repeatedly hammering it into a bit of steel. Right away you know if your work is not good enough, the edge tells you if the grain of the steel or temper is bad from how it chips or folds or tears.










I’ve been testing my chisels on a bit of mild 1/4″ bar stock, which is buttery soft compared to the tool steel I’ve been working on, for a number of interesting reasons. Jason dropped a comment in my last post that was manna from heaven, annealing tool steel is not as straight forward as ninety percent of the information out there might lead one to believe. Having previously tested all of my chisels, seeing how many inches of teeth they could cleanly cut with a given bevel angle, I re-tempered.

Normalize, normalize, normalize. That is what I was missing with my heat treatment for these chisels. It was obvious that even though I was hitting the right temps to harden, the grain growth was really bad, leading to an edge that would blow out large pieces. Moving the chisel through several rounds of normalizing (above non magnetic, and then a bit of soak, and then air cool to no longer glowing) made a tremendous difference in edge holding. I probably also did a better job of quenching at not too high of a temperature. What can I say, you’re kind of fucked trying to judge metal temps even in the shade during daylight.

I’ve been drawing the temper to a basic straw color after hardening, seems to be the right range for engraving tools, which I consider these file cutting chisels.


So now I have a few chisels that I feel have basically decent edge holding, how about my problems cutting the file blanks? I knew that my simple annealing process using wood ash as an insulator wouldn’t be the same as a full kiln annealing, but its so often spoken of as adequate I didn’t consider that there was more going on in the structure of the steel. Certainly heating my file steel up to non-magnetic and allowing to cool in an insulated medium softened the steel, that was clear from how easily it bent. The unintended consequence, best explained by Kevin Cashen here:

“….,the ideas of overnight cooling all work fine with 1084, 1080 and other steels with less carbon, but will give you no end of troubles with a hypereutectoid steel like 1095, and is exactly why you found it less than pleasant trying to drill your holes. Heating to above critical (or even non-magnetic) and allowing the steel to slow cool is called a lamellar anneal and it forms coarse pearlite within the metal. This state is made up of extremely hard carbide segregated out into sheets between areas of soft iron, so such a blade will bend and seem soft but will rip drill bits up! No amount of reheating (tempering type) short of a full normalization will have any effect on these sheets. But of even more concern is that leaving hypereutectoid steel that is in solution to slow cool will allow all the carbon in excess of .8% to fill the grain boundaries and cause a very weak an brittle condition that would be rather bad for a knife.

Hypereutectoid steels, and forgive me for not explaining the term which simply means steel that has more carbon than the eutectoid or .8%, really should be spheroidized if you are going to be doing any machining with them. It is best done with well controlled heat treating equipment but it can be approximated in a simpler shop as well. To accomplish this with just a forge you should heat the steel up and normalize it well to homogenize things and get any carbide our of the grain boundaries that may be there. Next reheat it a couple of times at lower temperatures to refine the grain and on the last cycle heat it to just above non-magnet and then quench it in any oil you may have.

Now for the anneal- reheat the hardened blade to red but never allowing it to lose magnetism, do this several times and it will ball all that extra carbon that you trapped in the quench up into little spheres suspended in a soft iron matrix. The steel will be soft and bendable and when a drill or mill hits those little spheres they will just move out of the way and allow you to keep cutting .

This jives with how the chisel felt cutting the file blank previously, little hard spots that wreak havoc on the chisel edge.


So after grinding and hand shaping a couple of files I went through the above normalization and spheroidization. I didn’t wind up with the buttery consistency of my mild steel test piece, but it was an improvement.


My work holding is way off from historical president, same with anvil shape, but you use what you have and make it work. If I can actually get a file to harden properly I’ll have to think about refinement here.

Only last night did I read back through a book written by the early Nicholson File Co, “A Treatise on Files and Rasps Descriptive and Illustrated“, which of course speaks only favorably about their new at the time “increment” cut file that reproduces some of the valuable irregularity in hand cut files. It does however mention one important detail about sharpening the chisel for hand cutting, that of rounding off the newly honed edge by dragging a few strokes of the stone across the edge, much as one might sharpen a plane blade for working abrasive material like bamboo that might otherwise lead to chipping.

Another small detail, but important not only to edge retention, but gullet formation for the file tooth. In some sense then the sharp edge of a file tooth is formed by upsetting the steel, not merely cutting into the file blank.

It took a hell of a lot of sharpening to cut these three files. I then mixed up a thin paste of flour and water, coating the file and wiping off the excess with a swipe of my fingers. In a mortar and pestle I ground some table salt to a powder, which was then used to liberally coat the sticky files, as much as I could get on there. After drying they kind of looked like incense sticks, I figured a heavy coating of salt was better than too little. I didn’t include any pictures of this yet because I need to work with the technique more. Supposedly I should be able to see the salt subliming as it reaches non-magnetic temps.

In practice I ran into a simple problem. If I’m moving the file around in the fire to check its heat, try to heat it evenly, the salt coating gets worn off. I resorted to laying the prepared file on the coal bed, covering it over, and trusting in a bit of intuition to remove it a the right moment for quenching.


Such is the way of things that my first file warped quite noticeably in the water quench. I’ve read that if they’re pulled out at just the right moment with enough residual heat its possible to straighten. Of course, a tiny file like this cools very, very rapidly, so I pulled it out an promptly snapped it in half trying to straighten. At least I know my hardening was good!

And it gives the chance to look at the grain structure, which doesn’t look too terrible thanks to the normalization.


The above photo shows a couple of interesting things. The salt coating protected the top half of the file quite nicely, but fell off too soon on the bottom and scale developed. Testing for this file proved immediately destructive of the thin edges. Perhaps I should try an oil quench for a forging so thin and delicate of proportion?


This file (with 135 deg. face angles for sharpening chone-gake on maebiki-oga) seemed to have the best annealed state as you can see by how cleanly the teeth were cut, and didn’t warp during quenching. Both of which I’m attributing to the more even cross-section. I still need to clean it up with an acid wash followed by a neutralizing alkali wash.

Finally, finally I get to the point of my first hardened files! I’ve learned more about blacksmithing and heat treating tool steel in the past week than in the previous seven years, seriously.

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.