The sumitsubo, literally ink-pot, is a traditional Japanese layout tool. It works much like a standard chalk line except that it uses ink in place of the chalk and the line is made of silk. You can see several examples here. The video below is a demonstration the sumitsubo in use.
My interest in the sumitsubo lies not with snapping long thin lines, but as an ink reservoir for the another traditional Japanese layout tool, the sumisashi. This is an ink pen made from bamboo. One end is shaped for drawing long, thin lines along a straightedge and the other is shaped for writing. I have wanted to try this method of layout ever since first reading about it in Toshio Odate’s book, “Japanese Woodworking Tools: Their Tradition, Spirit and Use“.
The main reason I haven’t tried it yet is cost. A sumitsubo will set you back about $100. That’s a bit much for me to spend just to experiment. The ink and sumisashi are pretty inexpensive though. As I was researching the internet and reading articles about the sumitsubo, I discovered that it was traditionally made by the craftsman using it. Hey, I’m a woodworker. I should be able to make this thing. This first one will strictly be an ink reservoir. So no snap line or winding wheel. Maybe in the future I’ll tackle that setup. I can order the ink, silk wadding and sumisashi from Hida Tool.
I started with a well-seasoned block of maple that has been in my shop for a few years and sketched out the general idea of what I want it to look like. I based the design on my logo, a stylized koi fish. The overall shaping will be done with whatever gets the job done. Coping saw, bow saw, chisels, knife, rasp, files and sandpaper.
I used a brace and bit to remove the bulk of the waste for the “pot”. Followed that with a router plane until I had a depth that I was happy with. I then used a gouge to undercut the walls of the pot so that it will better hold the silk wadding.
I wanted a stand to rest the sumisashi on while not in use. I’ve seen several videos where the sumisashi is stored in a traditional sumitsubo by resting it in the groove of the winding wheel. Since I’m not going to have a wheel, I needed to add some sort of rest for the sumisashi. My idea is to have the koi swimming around a twig. The twig will be the rest and is made from a piece of dry limb.
I’ve not ordered my supplies yet but this piece of scrap plywood should give you the idea of what I’m going for.
There is still quite a bit of shaping and detail work to do. But not a bad start.