Wednesday, September 17, 2014

Rip pattern — close up

By popular demand, a follow up on the rip pattern I'm using on my Ryoba. (Actually, on my large Ryoba, I have a small one and a medium one that now is being welded by a friend of mine – more on that later.)

This is how the Azibeki looks under light:

Again, focus on the light spots on top of the teeth. This is a diagram I made of how a tooth looks from the side.

This "third face" is something I haven't seen on any of my other Ryobas, it's also really small. However, Paul Sellers has something similar (but comparatively larger):

I put the hammer marks to indicate the direction in which the tooth is set, in this case going inside the screen. If the set is towards the other direction, the "third face" is on the other side.

The rationale for this, I guess, is to make it easier to start the cut. Since the area of contact is smaller, the pressure on the wood is higher, ie, there is more shear on the wood. This makes sense to me since the Azikibi is a saw to make cuts on the middle of a board and not on the edge, so at the start you need to slice the fibers of the wood. 

Finally, the teeth are filed without fleam so the inside of the teeth reflect light in the same direction, independent of the set:

Hope this clarifies the rip pattern I talked on the last post. If not, just ask and I try again. 

(On the back of the last picture you can see the files I use, and some of the sharpening stones I have, soon a post on them.)

NB: The saw I have I bought from dictum but there is a cheaper version (and signed, mine is not) on ebay


  1. Thank you for the clarification Sebastien. I was unsure as to whether the third facet was cut on the inner side/outer side, so this helps me. I am a little mystified as to *how* this helps..... It would seem to offer increased clearance for the cutting edge perhaps? Instead of forming a small chisel shape, the profile would be more akin to a slicing/knife blade.

    I was expecting something like this example, which seems similar, if I am understanding you.

    Your blog has pushed me over the edge, into Japanese saws (something that I've been trying to delay, haha!). I have many questions, but am finding very few answers.

    Thanks for writing about this,


  2. Interesting... that looks like a "back bevel" on the tooth. But it kinda gets overly complicated, like that you need to file 4 sides in each tooth, 3 is already lots of work :P

    Btw, If I understood the ChoMasaru geometry, isn't it like a western filling? Save for the "top Eye" that is. Which made me think of this, I don't know if you have seen it:

    and you are more than welcome, writing also pushes me to work more constantly and try new things.

  3. That ChoMasaru gets around! Once I began looking for Japanese saw tooth patterns, I was seeing his work everywhere. The Douglas Brooks link has a perfect picture of what he (Nagatsu-san/ChoMasaru) considers a rip tooth shape, at least assuming that he didn't modify the shape to facilitate using the saw with a "push" action. At least I "think" that it would be a rip tooth, as his crosscut pattern is slightly different.

    The Paul Sellers "micro-bevel-progressive-rip" pattern just cuts a small facet, perpendicular to the primary axis of the saw and with no fleam, effectively steepening the cutting angle and reducing the clearance angle of the cutting edge. This makes for a "tougher" tooth that last longer between sharpening sessions, but may leave a slightly more ragged finish. Is this basically the tooth style that you are using, the one found on your azebiki-noko?

    I must apologize for all of this persistent questioning, but much of this has been stewing in my mind for quite a while now. No one seems to be writing about this. I need to just get on with it, start cutting my own teeth (in more ways than one! ).

    Thanks again,


  4. don't apologize, it's real fun for me.

    I "kind of" finished filing the new angle. Kind of because I file one side, I try to cut. I file the other side, I try to cut. I file the other facet, Cut again. When it cuts, I stop and see the results. (I like to work to the least workable level of sharpness to know how much work I need to put to achieve a given precision... one of my manias)

    In boxwood the saw this morning was cutting better than with the older angle, but got stuck more. Maybe it was the set...

    I tried some soft-wood, I think it's spruce from the construction market, and despite not seeing a difference with the universal kataba I have in terms of speed, the finish is different.

    With the Chomansu (hope you don't mind my changing of names but I'm a bit dyslexic) the soft part of the wood does not tear apart so much. In some places it looks like "planed", as the blog in japanese says. You certainly can "feel" the difference if you pass your finger over it.

    I think it has to do with the angle of attack. A la low angle block plane I would say.

    I will try to post photos when Julia arrives, she has the camera. It is not such a big difference, but then again, the sharpening could be much more finished. I am just lightly tired, not used to file so much in one day. I may even invest some time on making a saw vise. It's getting really interesting this thing.

    Anyway, for a cheap and old saw, it cuts better than a 6 month old disposable blade, so I'm really happy with the results. Thanks a lot for the info.

    and to answer your question, no, it's not the same as Paul Seller's, in my azibeki the facet is at an angle (say 45 degrees) from the saw plane. I tried
    to show that on the diagram.


  5. and btw, do you have a good source of files? At the moment I just have found fine-tools and a guy in the states who has NOS file, but with the american shipping prices they become quite expensive on this side of the pond...

    1. This talk of Japanese saw files is funny for me. I had a dream a few weeks ago about Japanese saw files, before we had started this conversation about saws...... Seriously! I dream of tools! What a sad little life I lead, haha! Anyway, a few days after my dream, I ordered a NOS Ryoba and a 75mm aburame-yasuri feather file (and a #400/#1000 diamond stone, like you have). I bought them from eBay seller: Sakura-pink

      The files are $12,

      He's a great guy. In my searches for more saw related info, I've seen ! LOTS ! of boxes of saw files, but from wholesale sites that aren't exactly aimed at the american consumer market. Prices are about $10USD for a box of 24 files...... Really cheap! Old files seem to be very common still, but will be more rare in the future. Also, I don't know which brands are good, and which are s**t.

      I want to try the diamond files that Tsuboman (the guys who make the good Atoma diamond stones) makes.

      Hida tools in the USA sells them for about $38 USD. They also sell the traditional saw files, too. Prices are $12-$14, which seems to be a fair price (but still expensive!).

      As you may have guessed, I am hoping to figure out a way to make a diamond saw file, using some cheap China diamond files. My fingers are crossed!


  6. I still don't dream of sharpening tools :( I think I'm doing something wrong.

    I actually thought you were going to forge files, and I was thinking of ordering a few... you know this?

    my goldsmith friend pointed to something I haven't realised about the diamond files, and is that they cut slow. I totally got his point. And also, you don't have a nice scratch pattern with diamond files. I've really started to think on how to make my owns.

    Furthermore, I've been reading about impulse hardening, and it's really only the surface that becomes hard... so, or I need to harden and temper (and then relieve the stress – I'm REALLY bad at hammering saws, the saws where I've tried look like they were on a fight with the hammer, more on that later) or you make a surface hardening machine. I guess the latter cannot be THAT difficult. It's like a welding machine (in my mind at least). I will ask a friend of mine who's doing his phd on electric things what he things about it.

    now that I think of it, if the core of the impulse hardened teeth is soft, you can anneal them and then file them with a normal file. Anyway, once you filed the surface with your diamond file all the hardness went to the trash... don't know, hard decisions.

    Anyway, what I've been really considering, is going to Japan for a short visit next year, try to lear first hand. Tanaka sends his saws to the same metata we've been talking about, so it seems he's the guy to visit. And Kioto, well, nice added value for a trip