Monday, November 16, 2015

Tooth angle on a Japanese crosscut saw


My sincerest apologies to my friends who have been wondering where I've been for the last 2 months. Popular speculation had me suffering an unlikely and grisly demise, fallen to my death in some hidden lava tube, but no....





Our house on the mainland Oregon coast sold, and there were a few projects that still needed to be finished up before handing off the keys to the new owner. It's an ironic cliche that the carpenter's house is never finished and this is no different. The cobbler's children that suffer from lack of shoes, that sort of thing. You probably know how it is. Anyways, 3 weeks of intensive house type woodworking, flat winter's lighting and rain. Lots of rain. That's at least one thing that Hawaii and the Oregon coast share.



Having been in Hawaii now for just over one year, visiting the mainland again reminded me of numerous things that I seem to have already forgotten, but one of the most notable for me was the light. Daylight that is. There's not much of it, and what there is comes at such a low angle, it seemed as though everything looked just the slightest bit "off" to me. Shadows were long and the colors didn't look as vibrant. My iPad evidently forgot about the relatively northern light too. The pictures that I took are, well, not my best. Yeah, blame the camera, haha.



The stairway to the attic bedroom needed a door and handrail.



I had to get a bit creative, trying to squeeze a manufactured door and jamb into such a narrow opening, but I got lucky. Down the road from our old house is "R. Gray's bargain yard", a wonderful resource for scroungeing unusual building materials. The owner, Bill, came to my rescue yet again and found me an off-size, special order return that fit the opening, needing only a bit more massaging than your typical install.



It was fun to do some plain old carpentry again, so different from the stick and log work that I've been doing in Hawaii. After packing off all my tools to bring home to the Big Island, it felt funny to be packing them back to Oregon again, but at least I got to plane some wood. Electricity came in handy. I still miss my old tablesaw at times.



Ahhhhh, my old workbench......didn't ever get that project completed either, but at least the new owner is an eager woodworker. She'll finish it up nicely. She was psyched to keep my old saw and I'm glad that it found a good new owner.



I brought along a minimal assortment of tools, nothing fancy.


The TSA always gets a treat, looking through my baggage. They generally do a better job packing my bags than I do, and never skimp on the tape that holds the lids on he boxes, haha. A tough and thankless job, to be sure.



I was so happy to be planing wood again, I maybe went a little above and beyond on some of the tasks that needed completion. The attic railing (Port Orford cedar....such a great wood!) posts and balusters received a winding chamferred edge and a simple bridle joint attachment, draw-bored and pegged using bamboo skewers.





And finally, capped with some nice ribbon figured African mahogany that I was saving for a special place. The light was so bad, I couldn't get a picture. It definitely made the colors in the attic look off. Ewww, yuck!



If I ever figure out how to plane that curly, interlocked crap with a kanna and NOT get any tear-out, I'll share the knowledge. It's good to have goals, right? The 47 degree kanna that Dave gifted me would've been just the thing, had it been here – sigh.



So where was I?


Before I left, I had started on this post, some thoughts regarding an optimized tooth pattern for a Japanese saw I've been using for working green wood, but maybe this should be a WIP thing instead. Get this thing going before I forget what I've already done. An aspect of blogging that I love......I can show my mistakes. Maybe we both learn that way, hmmmmm?


So, spoiler alert. I'm not satisfied with this saw, so you might not want to jump right in and copy what I'm doing here. Not quite ready for prime time...... yet.



I need a general purpose saw that works well on green, sticky wood.



I've had this old bugger kicking around for a while, but haven't really felt the need to use it very often.....'till now. This was 1/3rd of a lot that I bought for $15 on eBay nearly four years ago and I guess it's time I put this thing into circulation. They sell even cheaper on Yahoo Japan, so have Murakami get you a bunch.






Felling trees, even the relatively small ones, using a pruning saw (much less using a trusted ryoba) is good meditative work, but when a tree is in danger of dropping onto my head, I want to get done with the task as quickly as possible, you know?

It's time to pull out the big(ger) guns.






The toothed length of this crosscut saw is a respectable 20" (about 510 mm) and the handle is nice and fat, perfect for two handed sawing. There are a few slight bumps to the blade that I still need to remove, as you can see from the slightly brighter spots on the body where it has been rubbing in the cut. Contact with the walls of the cut = friction, so hammering out the dents is a short list priority. You can also see a couple of lines of fairly severe corrosion that run diagonally across the blade. Bummer, but not the end of the world.


The farthest end of the saw where the teeth are largest has a vertical tooth angle. 0* rake angle.



90* and pointy, these teeth are similar to a rip tooth, but still have a front, back, and top bevel/facet.



I'm holding the file to show the approximate angle of the cutting face, around 75* or so. That would be 15* away from being a purely perpendicular rip tooth.


Not being the purely perpendicular face that you would see with a proper rip tooth, it's more of a hybrid, but this is a general purpose saw, I suppose. You might notice that I've already jointed the saw, the tops of the teeth are showing little flat surfaces.





As we approach the handle end of the saw, the teeth gradually assume a more relaxed slope.



These teeth are the familiar shape that you see on any crosscut blade, although the rake angle is more shallow than you'd see on a ryoba for instance, about a -10* rake angle. These teeth at the heel of the saw are probably shaped differently to make it easier to start the cut. The relaxed tooth angle gives a nicer shearing action.



The tooth pattern must have originally looked more like this example from a pruning saw manufacturer.



My saw is similar, but the saw in the photo above has both leading and trailing edges at much shallower angles, closer to 45* from the looks of it.



When I check my saw, the file shows a cutting angle of nearly 60*, so a 30* angle to the leading edge.



It's pretty much a standard crosscut tooth shape, although I'm going to try reducing the height of the teeth a bit, in orders to lend extra durability for cutting these dense Hawaiian hardwoods.




Rust is bad! Here is a closeup of the rusted area.



The tooth in the center has been polished using a hard novaculite oilstone and is tilted towards the viewer. Skip a tooth either direction and the two teeth at the edges of the photo are the rusty ones. The pitted rust on these teeth will prevent them from ever being truly sharp. Worse, the little pits will tend to hold onto little threads of wood fiber, increasing drag and tending to pull the cut to one side. Unfortunate.





So, this is all fine and dandy, but so far I am really just copying the tooth pattern as it is. The interesting points are that this saw has both a progressive tooth size AND shape. And of course, it has a hand forge-welded tang, the saw blade tapered in both length and height....all that good Japanese craftsman stuff.

What am I doing differently, you ask?


Every 5th tooth I mark with a pen, prior to filing the top facet of the teeth. The fifth tooth I will turn into a raker, to better clear away the wood waste.





I use the 5th tooth raker through most of the length, but leave the teeth closest to the handle alone.






In the interest of experimenting with saw tooth shape, I'm going to alter the shape of the teeth in stages, beginning with the rakers. The upper slope I'm going to start with is.....oh, maybe 12*, probably too shallow, although it's similar to the clearance angle you want for a plane blade.



Other than filing the raker tooth to a flat/chisel tooth, I leave the forward and trailing edges alone. It will be an admittedly crappy rip tooth shape, but I'm experimenting here, OK?


I give ALL the teeth a top slope of about 12*, but otherwise the other teeth are just copied as they were. Looking at the photos, I see that I need to work more on keeping my angles even from one side to the other. Everyone has a "strong" side, so it's just one more thing to give some thought to.




How did it work?


It cut. This is 8" of hard Ohia. felt crappy, haha. Both slow AND grabby, the worst of both worlds! The saw was dull and slow before, but sharp(ish) and slow?!



How about something softer? A low quality fir 4x.



Awful. Those big ol' teeth grabbed those growth rings and tried to rip that stick out of my hands on nearly every stroke. The cut surface quality is terrible as well (at least for a Japanese saw). And slow. Or perhaps my standards are just too high. Nawww. It sucked.



So there ya go. Universal Japanese saw v2.0......epic fail. There are some obvious things that can be improved, tip slope angle being the principle suspect, but we'll have to see. It's rare that sharpening a tool will lead to a decrease in performance and this was pretty lousy, so something interesting must be going on. It sure gets me thinking.



  1. Just a thought but I'm pretty sure that's a rip and not a crosscut saw.

    1. Hi Bill!

      The saw is more properly known as a temagori nokogiri. Crosscut or rip, it does it all (but maybe not perfectly?). There are hundreds of them that sell on yahoo Japan, so every carpenter must've had one. I assume that pro Japanese gardeners used them as well, but that's just a guess. The tiny uppermost facet on the tooth is what allows it to work in a crosscut capacity.

      Thanks for commenting! You are tough, reading through to the end of yet another of my too long posts, haha.

  2. Good to see a new post!

    Holidays are definitely lowering the amount of posts by everyone but Gabe, it seems. That dude's a friggin workhorse, how much caffeine does he ingest?

    Come to think about it, you are all making me ashamed of my own work output!

    Oh, to have sweet sweet light and woods...

    1. When you get off the plane in Kona (the typically sunny and warm side of the big island), there is not even a proper terminal, just a series of small buildings and lots of covered space. The air was warm, though it was overcast, and the smell of the air was a gently perfumed pleasure. The coffee is good here too. There are usually guys selling it from the backs of their pickups, by the side of the road.

      I've been getting lots of napping accomplished. Does that count? Cat petting? Trashy sci-fi and fantasy reading?

      I'm a slacker, it's true, haha.

    2. Oh, forgot one more thing- the warmth.

      We finally got Winter in Rochester, and I'm having to adjust to trying to work without being able to feel my fingers or my tools. Pretty hard to adjust a plane by touch at the moment, and touch is my best sense!

      I found warming up my saws in front of the heater helps prevent shattering. I almost broke my resaw saw when the vise got loose and the log I was sawing fell over, but the only bent is the one that was there originally-I think.

      To add to my frustrations, the hide glue on my kantele failed and the whole thing fell apart! And my kanna blade needs about two hours of grinding on an oilstone to get rid of a chip!

      I'm seriously thinking of making a new workbench and replacing my plywood bench, which is maybe a year old. Having a proper European vise would make life so much easier.

  3. The hand plane finish is so underrated for interior woodwork in a home, its great that you took the time to finish plane. We can't all be equipped with a super surfacer so any carpenter that knows how to use a hand plane these days, well, next level shit you know?
    I've missed these posts of yours on metate, you're always lighting the fire of discovery. There's so many woodworking blogs out there, podcasts, vbloggers. Some of the ones that draw a lot of traffic...what the? Boring pabulum for woodworkers soothed by industry trend making.

    I'm glad to hear you weren't trampled by feral pigs or crushed by a falling tree, haha. Now if we could just send some good healing vibes south to Sebastian.

    1. The pigs haven't gotten me yet....but my daughter is making them nervous. I've been working on some bow staves, using the guava that abounds here. She's getting awfully excited. Mmmmmmm......bacon!

      I check out other blogs, but for the most part, they bore the piss out of me, haha. Most people say that about my stuff too, so I feel entitled to say that. Passions are individual, and though I enjoy working wood, I lost the passion for furniture long ago. What I DO love is creation. The act of *making* something is pretty remarkable, and I think that is a large part of its draw for many. Working with wood as a media is very accessible, but it's the enthusiastic novices that do most of the consuming, therefore we have 50 blogs that appeal to the base. I'd rather read and write about the other end of things, but those guys are busy *doing*, and the really sophisticated stuff is so much of an experiential gestalt, it's hard to write about it. We got that with our joinery practice (not that it was particularly advanced, but...). It amounts to....."Draw the line, then cut".

      I've got, I think, 3 open ended series of posts on working the saws, and I miss working on them! I want to just drill down and learn some of this stuff, but I've got too much on my plate right now and it's frustrating, because I REALLY want to be banging on the metal bits! My perfect day right now would be to tap on a saw or two for a few hours, sharpen a saw, smooth a pile of wood using a couple of kanna, then sharpen the blades. Finally, fire up the forge for a little bit of hot work.

      At least right now I get to USE the saws, more than ever before. That's a necessary part of the greater understanding, so it's time well spent. Unfortunately, the work that I'm doing now is rough, the wood is green as can be, and not very subtle. The old 300mm ryoba that Sebastian gifted me is my everyday saw right now. It's big and gutsy, but not a very sophisticated instrument. It suits the work though. I've got a pile of nicer saws that I'm meditating on but that's an art that's slow to understand. I hope to learn something that's worth passing on, but it feels like it requires slow experimentation and there are few that are leading the way. Re-discovering the wheel is slow, haha!

      It's worth doing, though.

      In my woodworking life, I've gone through a whole progression of furniture finishes, from brushed polyurethane to sprayed catalyzed epoxies. Stains and colorings have always played their part in that, too. Now I strive for a tolerable, tear-out free surface, right from the plane. I'm still having issues at times with tear-out, but some days it's like magic. It's faster, a tuned kanna makes cool sounds, and there's no dust. I like wax, and no stain, just the wood itself. Let it age, make its own color, true nature. I guess instead of progression, you might say it's a regression, haha. More fun though.

  4. Thanks for the update. I was getting a little worried! Yours is one of my favorite blogs...even if the topic is not of personal interest (it usually is). I simply enjoy following your pilgrimage.


    1. Hi Jeff!

      Though I wish for a more coherent organization to these posts, so much stuff is going on that bears little relation, one to the next. I end up jumping from one thing to another, but not much is being "completed". I feel bad for neglecting the saws, mostly. I wish that I could devote a solid month to immerse myself, but that needs to get set aside for the time being.

      I don't mean to sound as if I'm complaining. Life is wonderful! Thank you so much for your encouragement. I question my motivation at times, writing to no preconceived end, but without a doubt, the most valuable gain has been mine. Getting to know other people who I would otherwise never connect with is, hands down, a really incredible gift.

      Thank you!

  5. The inner facets look all ugly as hell. Too much variation from tooth to tooth. Look at photo 12, from one side mostly, the teeth facing up. I would also make a more negative rake to get chumasaru smoothness on the cut. And didn't get why the raker teeth have also a third face, as you say the angle is too low. I would keep just 2 facets for those. Sharp and slow could come from a larger distribution of angles, instead of all the teeth cutting the same place, some cut here and then others cout again in the same place but a bit off. I mean, a perfect saw slices fibers one after the other, and each tooth is working on the channel left by the previous one. On a lousy saw they all try to make all the work, thus slower. Just what it makes me think what you write/show.

    On the other hand, it's nice to see you back on line. I totally understand you about too much in your plate atm, mine is full with food for 3 people or so. I manage to plane a bit everyday, and sharpen once in a while to relieve the stress.

    There is a saw here that's very rough and fast, will send you pictures of the geometry. Almost like a pruning saw but an aggressive third facet, if i remember correctly.

    1. Sebastian! Shame on peeked, haha!

      The leading edge of the teeth DO change angle, and I've got my theory (but that discussion comes in part 2). The trailing edge does as well.

      The saw had no raker teeth originally, that's my input. On this first step, it might be better to not even call it a "raker" tooth. Perhaps a "proto-raker" would be better, as it surely isn't doing much raking yet, haha. To jump ahead some, I think that the "proto-raker" was causing the worst of the slow saw issues, scraping the kerf clean, then shoving it to the side....right in front of the next tooth. Interesting stuff to us saw nerds.

      It's good that you are well enough for meditation /sharpening. I'm looking forward to seeing those saw tooth geometries.

      My best to you and your family, and a belated "Merry Christmas" (and an early "Happy New Year").

  6. Sounds like the rakers are to low. BTW, I wasn't worried, I figured you were surfing, or swimming with dolphins, you know, like what I'd be doing if I lived there.

    Love your writing.

    1. Mark!

      It's island time setting in......insidious, and I never would've guessed at this before. The weather is TOO nice! When it rains, I think of all the stuff I should be doing, but then the sun comes out and all is immediately forgotten. I work for a few hours, then have to take a break so that I can better listen to the birds sing, haha. There's no fear of freezing/starving to provide motivation either. I worked slowly before, but this is something else.....who would'a thunk it?!

      I appreciate your suggestion, and I'm sure that you are correct. The rakers needed to be accurately lowered, and I also steepened the top facet to form a thinner edge profile, something to slice the wood more cleanly. My first round had the teeth too blunt I think.

      I need to finish the next installment here.... Island time is a bitch, haha!




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