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    This is TMAP — fabrication

    A hori hori prototype

    About a year ago I discovered the magic of a tool called the hori hori. In Japanese it means "dig dig". By now you should be able to infer that it is an Ancient Canadian papyrus calligraphy tool.

    But it can also be used for gardening. It can tear up soil, slice through roots, and the concave side is great for scooping, like a spade. It's extremely versatile and remarkably simple.

    Soon after I discovered its existence, my friend Aaron told me how he had fallen in love with his, and we talked about it for a while. Because the design is so simple, I said I'd make one for him. I've seen several in stores, usually selling for around $35. Most appear to be pressed steel with a crude edge ground into them and a plain wooden handle. You really don't need much to make a good hori hori. But I want to make the perfect one.

    The one in the pictures, doing its job, is the prototype, and the hands belong to Aaron. The tool is made out of 1/8" stainless steel. I spent a while grinding out the backside and grinding down the blade edges. I was surprised to find that the heat generated by grinding was enough to dramatically warp the steel. I put it in the forge and knocked it flat, then let it air cool, believing that the stainless steel would remain hard through this process.

    I was wrong. In fact, this blade is now very soft. The handle is on it, and it's kind of too late to quench harden it. The tool is far from perfect here, but it's good enough to use. This is a huge success because I learned a lot of lessons. For my next attempt, I will:

    • Consider using a high carbon steel.
    • Deliberately harden and temper it according to the type of steel I use.
    • Use slightly deeper scallops.
    • Add 1" to the handle and remove the bumps on the end.
    • Subtract 1/2" from the blade, because an additional inch on this tool would be too much!
    • Use a thicker material for the handle.
    • Add a large lanyard/wall hanging hole.

    Prototyping is an invaluable process. So many things come up when you attempt to finalize a design. No amount of design speculation can make up for testing a finished prototype.

    And yes, once I perfect a hori hori, I will be selling it through TMAP. Let me know if you're interested, and I'll push it down the pipeline a little faster. Expect a price point in the $60 - $100 range, depending on the features I include, and how many steps I can streamline or remove from fabrication.


    How Bicycles Are Made

    More from the excellent internet series called There Is No Such Thing As Magic, this short film covers the manufacture of an English bicycle as done a few decades ago. Some of the technology is outdated - for example, no one uses cotter pin cranks anymore, except for cursing at, and very few wheels are made of steel anymore.



    TMAP classes in Seattle

    Lately I've been teaching a lot of classes around town. At the Seattle Public Libraries I've been teaching folks how to maintain their bicycles. Mostly this is a matter of breaking the fear barrier. I've found that the number one obstacle to bicycle maintenance is not lack of knowledge, but the belief that that knowledge is forbidden.

    Also, at Makerhaus I've begun teaching an intro to metalworking class.

    I designed a wall sconce for the students to copy if they wanted to, but in the first class I told them: This class is about prototyping. I encourage you to modify this design heavily. There's a lot of flexibility built in to it, and beyond that, you don't even have to make a wall sconce if you don't want to.

    One student is making a mug out of sheet metal with a certain well-known number milled into the outer surface.


    Then another one is cutting the classic section of a bottle opener into a piece of aluminum round bar.


    I'm impressed by their fearlessness. These tools are completely new to them, and they want to dive into unknown projects.

    I'll post updates on their progress over the remaining two classes.