Monday, December 1, 2014

ChoMasaru a la Sebastian.......


I am an edge tool kind of person. My passions are sharp and polished to a beautiful haze and cleave wood as though it were an illusion. I love planes and chisels, axes, adze and knife. 

First, though, comes the saw. The saw is the primary tool, all others being secondary. I mean, think about it.... All of those other tools are only used to make up for the sawyers deficiency. We use the plane to remove the saw marks, and the chisels to pare to the line. In my deepest (darkest?) fantasies, I can wield the saw so skillfully, that no further work would be required. 

I used to detest sawing, seeing it as a necessary evil that should be completed as quickly as possible. Possibly that feeling originates with using dull tools? Japanese saws present me with a unique conundrum. When new, they are a pleasure to use but, as they get dull, they become progressively more difficult to use, wandering further from the line and grabbing, bending, then buckling. And breaking... Don't forget breaking. Japanese saws can break, oh yes.

The frustrations of a dull saw are common and universal, so much so that the saw market has shifted almost entirely to a disposable blade philosophy. When the blade gets dull, throw it away and pop in a new blade. Therein lies the conundrum...... I'm not a throw away kind of person.

The new blade is so nice, but each time that I use it, it gives me a little bit of sadness. I am thinking that  the blade will never be as sharp, the cut will never be as clean, the act will never be as much fun as it is right now. It's all downhill from here.

The disposable blades are impulse hardened, which is great, meaning that they are super hard, and stay usable for a longer period of time, but it also means that they are difficult to re-sharpen. You need a diamond grit yasuri file for that. Not to mention that I've been putting off saw sharpening for far too long and have very little experience, much less skill. 

Being who I am, need to be honest with myself. I need to use traditional (not impulse hardened) Japanese saws, and I need to learn to sharpen and maintain them. For me, this begins with research.

My Chilean friend Sebastian has been immersing himself in the Dao of the Japanese saw, and has sent me some of his early experiments in shaping a particular saw tooth design. 

There is a Japanese saw sharpener (a "metate", and actually soooo much more than just a sharpener) by the name of Nagakatsu/ChoMasaru that has been promoting a different style of saw tooth design. The ChoMasaru design supposedly cuts more smoothly, and requires less effort than more traditional tooth designs, but his work is seldom seen on this side of the world. 

Sebastian has been working on replicating this ChoMasaru design, in his ongoing effort to save every old, rusty and neglected Japanese saw that he can find. Obviously we are cast from the same mold, haha! You can read more at:

The two saws that he sent me exhibit two different style of tooth design, but both share a common philosophy. They are intended for different uses, but work in a similar fashion. Cousins, perhaps?

The big 320mm ryoba (on top) has a standard ChoMasaru tooth, and is for cutting big stuff, rougher work on thicker stock. The smaller 245mm ryoba (bottom) is a "window" style (madronoko, I believe) that is designed to cut efficiently on a bias. It is intended for finer, more detailed work.

The big 320mm is bigger than anything I've got, so for comparison I need to use a smaller 275mm ryoba. That is one big ryoba!

The cut quality (in Port Orford cedar) between the two is very similar, despite the 320mm being a much larger saw. The size of the saw generally determines the size of the saw tooth, with a smaller saw usually showing smaller and more numerous teeth. Many little teeth result in a finer cut, but that's not the case with this saw. 

Although I was surprised by the quality of the cut, what really impressed me was the ease of use. This is a big saw, with good sized teeth, but it showed no tendency to grab or skip out of the kerf. It is nearly effortless to use, you just move the handle back and forth, and guide it the direction you want to go.

It's fast, too. I need to make a handle, pronto!

I tried the saw out on some Beech and Meranti, too. The Beech is hard, while the Maranti is soft.

Both cut beautifully, particularly for a saw this big. Notice the nearly complete lack of tear-out. That's surprising.

The madronoko saw is a more typical 245mm size, perfect for most of the work that I do. The window style has large gullets to get the sawdust out of the way of the cutting teeth. In the west we associate this style of saw with very coarse, timbering saws like lumberjacks used. 

I have another 245mm ryoba, to compare it to, that is my current baby. It's a nice saw and I am liking it a lot. 

Oh my.

Very easy action, and faster than my saw.

The cut surface looks planed, it's so smooth. Really amazing for a saw of this size, and with teeth that are relatively large, too.

The only reason that the cut is less than perfect is that this old saw has a couple of good kinks in the blade, making for some slow going at times.

And more than a few dents.

Each of the shiny spots is a dent that causes the blade to drag and slow down. The spots are shiny because they are rubbing against the sides of the cut, polishing themselves smooth. This blade has seen some battles.

The cut quality is every bit as good on the beech and maranti. Again, there is very little tear-out. If not for the drag imposed by the bent blade, this saw would be extremely fast. As it is...merely very fast. I give it a 4/5, haha!

As for fineness of cut, I can only compare it to my Nakaya D-210C joinery saw, commonly used for cutting kumiko for shoji screens, and one of the thinnest blades available (0.3mm thick!). This saw its fast AND fine (and a REALLY nice saw BTW).

Look at how tiny the teeth on the Nakaya are (32 dpi, I believe), compared to the ChoMasaru diagonal cut pattern that Sebastian made.

Close! Sooooo close! If not for the bent blade and a few errant teeth, these would be a match. The ChoMasaru might even be a touch better. As it is, the ChoMasaru shows better clarity and color in this Oregon walnut. That Nakaya is a surprisingly fast saw, but the ChoMasaru is faster.

And the scary thing about all this? These are some of Sebastian's earliest versions. He's gotten better. It kinda makes you wonder.

It sure works great for trimming doors. The handle is growing on me, too. 


  1. You know what's the best of it? That in contrary to disposable blades, you know that your saw will be better after each time you sharpen it, because you get better at it.

    If you manage to straighten it, once it's dull I'll sharpen it again. The rip teeth could use some more jointing but I feel wasteful filling steel on a perfectly functional saw.

    I bet the big ryoba will be useful with those monster trees of Hawaii.

    I'm very tempted of sending you my dosuki. That girl is leaving an almost mirror finish now.

    Have fun!

    1. Exactly!!

      Perfectly put, my friend.

      In a very important way, these saws are the opposite of the disposable mentality, and just get better and better.

  2. Jason,

    appreciate the review. Sebastian has been posting in detail about his saw sharpening methods on the Craftsmanship in Wood forum and mentioned he had sent you a saw or two for a look-see. I like Seb's point about each saw sharpening being better than the last. I have a few of my own that could be sacrificed for practice...

    1. Now, if only my skills matched the saws......

      The next step (for me) will be straightening, then probably work on tensioning the plate, after I muck it up, haha. It's too good to leave as-is.

      This design has great potential, and is very interesting.

      Thanks for your comment, Chris!

    2. Jason,

      I don't know about you, but it's the tensioning aspect where I would feel the most clued-out. That seem to be where the art of the saw sharpener comes through loud and clear.


    3. +1 on that.

      Tensioning is something I cannot even think of yet. I guess I really need a first hand lecture on that. I am especially intrigued by the little triangular marks I found in some saws, big triangular dents whose orientation depends on which side of the blade they are.

      Thankfully, most of my saws are already tensioned, and they are a pleasure to use. The large one Jason has was a particularly solid one, I think in part due to a good tensioning. You can see some marks (lines) on the second picture.


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