Wednesday, April 29, 2015

Convex saws

I was cutting a dovetail the other day. No pictures of that because I was in a hurry and the day was nice and I was outside in the street doing some street carpentry and busy answering the questions of sexy chicks. Well, just one stopped to ask but several peopled looked perplexed at my japanese tools and the fact that someone was actually “making” something there in the street. Not selling, not asking, just making.


My favourite saw — that is in due of a proper sharpening and some teeth setting after the last sanding — is slightly concave. Just to set the reference frame, when you put the edge on a flat surface, there is a gap in the middle of the saw where you can barely can put a piece of paper. This made a bit difficult cutting the female part of the dovetail without marking the edge of the piece. It was a cross cut dovetail, and the vertical piece is on top of that so you anyway don’t see it but it got me thinking.

Jason once commented that some japaguys un-set one side of the saw slightly so it undercuts the joint. I didn’t understand what he meant back then but now I think I’m starting to see it.

Let’s start with a straight saw, as they come from factory and let’s try to cut a dado in a piece. It should look something like this:

You try to reach the horizontal dashed line with your saw and not to pass your marked line on the side of the piece, so the saw is always at an angle. (In mathematical terms one would say that having the saw at the perfect horizontal position has measure nil, that is you never nail it: computational error will fuck up your cut.) In this way, the resulting cut instead of being horizontal is bowed and higher in the middle of the piece.

Now, if instead of a straight saw you would have a gentle curve on the edge, you would have the following situation (the curve is exaggerated for the sake of illustration, as Presidente Correa likes to say):

Note that I show just one position for the saw: horizontal, and not two angled ones as before. This is because you can check at the same time if you are not under your deep mark. The resulting cut will be hollow in the middle. This is perfect to have beautiful sides and be sure you are right on the money in the middle. Which in turn implies that you can chisel the waste away faster, ie, this is better. Furthermore, you have a finite interval of angles around the horizontal that will give you a good result, so it also easier to saw with a convex saw.

That’s it for today.

Soon in the store we will have Convex Chumaruri Saws. That is, chumasaru pattern saws made in Maruri, the street where I was born and where my mom’s house is.

One last thing:

I’m leaving Graz this friday. Besides some planes, chisels, a bike and 50kilos of books (that will go to a friend’s in Leipzig) waiting for me in Germany, those are all the material possessions that I have accumulated this 6 years in Europe. In chile I have another bike, a small japanese lathe, more books and perhaps some clothes. I usually go in summer so I’m most of the time wearing just a sari. Hopefully I will manage to inherit some of the furniture of my mother. It would be nice to have a couch again. Last time I had one was in 2012, I think.

The bags are mostly tools. The small one it’s only tools whereas the others have a few clothes, a comforter and shoes inside too. My diploma. A few cups and tea caddies (I like tea and tea caddies, metal ones).

All in all, I think I spent around 2 or 3k usd in tools during this last year. If somebody steals my bags and I had to start again collecting tools I think I would go to Japan and buy from fleamarkets and buyee auctions, these ones that sell a complete carpenter set for 20k yen, around 200usd. You can flight easily 50kilos of tools with you in the plane, that should be enough to get you started anywhere in the world. And I guess it would be slightly cheaper than buying the tools one by one. Plus the sushi and gardens.

If everything goes well tomorrow with the taxes and the bank, I will be finally done with all the paperwork, moving, packing, shipping, fixing, burning and arranging shit that has been these last two (or three? or ten?) weeks. We have a small todo list for the week in Germany (move bike, ship books, visit Julia’s father and use the lathe for making dolls for the game...) but I should be able to manage at least 3 or 4 full workshop days and nights. My new naniwa 12000 will be waiting there and a Tamahagane plane from Junji. Also the anvil, so I will definitely try to straighten some metal. Perhaps even a saw. I want to file into a more convex shape my favourite saw, select the mortice chisels I take to Chile, sleep... plenty of stuff to do.

When we left Europe 2 years ago we didn’t have any idea of what the future was going to look like. I didn’t have any idea of what I was going to do next. I still don’t have an “idea” of what to do. But I know I can make.

In spanish, there is only one verb for doing and making, “hacer”. So when you are bored you say you don’t have anything to do, nada que hacer. But also means that there is nothing you can make. I realised about this when living at my brother’s house in Chile a few years back when I was finishing my PhD thesis and needed a quiet place to write. There was nothing to do there, since there was nothing that needed to be made. Even the food was made by the “nana” and packed in plastic boxes. Dreadful.

Now I go, with no contract, no definitive plan, no idea of what will happen, but knowing that whatever it is, it will have solid wood, will be hand made, have nice joinery and will use tools made by other humans like me. And that’s perfect. I don’t need to know in advance what I will do if I know the way I want to make it.

The tools in those bags are not only sharp steel pieces with wooden handles, they are a metaphor for something deeper, for something very human, and it gives me the confidence that it lays in me the power to shape my world, the world, even if it’s in the small little scale of a few tables — but a few tables make a cafe, and cafes are good ground for breeding revolutions. And this confidence doesn’t come from my degree in physics, or my bank account or my time in Celle with Opa and his eleven generations of violin makers. It is born solely from the close contact with the material world and the opportunity to talk about it with other people who are also close to it. And like that, talking about a world that is the same here in Graz, in Japan or Hawaii, we can educate ourselves and each other. And that’s all there is to it.


  1. Ah my friend, I was just thinking of you and wondering at how excited you must be. Change is in the air! My admiration for you continues to grow, due to both the beauty of your prose and the restraint that you are showing through your commitment to the bare essentials.

    I have been doing more sawing (by hand) in the last few weeks than I have done in my whole life prior, and these lessons that you are reinforcing are truly showing their value. When my cut begins to drift, I think "Posture and technique, then sharpening", but that is only because I've already got a sharp saw.....thanks to your encouragement, sharp comes first. Now I can truly see how bad my form is, haha.

    Part of gaining proficiency is knowing where and when the user of a crutch is justified. To my mind, the use of saw that is oh-so-slightly bowed ("breasted", in western saw terms) would only amount to a fraction of a millimeter of undercut given the length of the typical tenon, but would help assure me of achieving a good fit, without resorting to multiple trial fittings. Cheating? Perhaps, but it sounds reasonable to me.

    Thanks for your good work,


    1. Thanks for your words my friend... but I don't know how much Julia would agree with your statement about the bare essentials. I think I got far too many kanna and saws. But each one is different and essential in its own way...

      I'm glad to hear you've been sawing and these rambles have been of some use :)