Thursday, January 1 2015

Tsune-gumi on the Bakadai

Baka no Takadai, version 6

15 inches high, 26 inches wide, 16 inches deep. These are terrible dimensions for a Takadai, but they work pretty well for an idiot’s makeshift version: the Bakadai. The braid is coming out nicely, at least; it’s 25-strand Tsune-gumi (3/3 twill), done with a single strand of cheap medium-weight acrylic yarn per bobbin, in a simple zig-zag pattern.

Tsune-gumi on the Bakadai

I’ve had to rebuild it several times already, as I discovered where the stresses were (version 2 included a 4-kilo kettlebell for stability…). The latest version added sandpaper on the takeup bar, to keep it from unwinding the finished braid every time I pull the shed open to pass a bobbin/shuttle through; a real takadai uses a ratcheting mechanism, but I didn’t have one laying around the house, and the only tool I’ve used so far is the saw blade on my Leatherman, to cut the dowel to size.

The key components are the 8 sliding koma and their frames, which are constructed out of two sets of the Martha Stewart Knit and Weave Loom Kit, which I found on sale on Amazon for $20. Side note: I couldn’t get it to work well for weaving or single knitting, but I did make a decent double-knit scarf before I tore it apart to use for takadai parts. It’s a decent kit, but much better at $20 than the current $33 or the retail $45.

The other parts are a cheap lap scroll holder from a craft shop, a three-tier sword stand that I don’t need while my swords are off being polished, two short lengths of dowel, a bungee cord, a “bone” folding tool, a chopstick, three little strips of sandpaper, some gaffer tape, and some rubber bands and string. And a bunch of weighted bobbins, which I already had from my Marudai.

Bakadai v6 close-up

(note that the uneven thread spacing and the camera angle make it look like I’ve only got 2 threads under the chopstick at one point; there are actually 3 there)

Technical limitations:

  • held together with string and rubber bands, so not the most robust thing in the world.
  • hard to set up at a comfortable height; currently it works best standing.
  • the front bar of the scroll holder is always in the way.
  • each koma only has 5 pegs, so I’m limited to a maximum of 15 strands per side.
  • the angle from front to back is way too steep (about 20°).
  • it’s too small to use my hand to create the shed, so I’m using a chopstick.
  • the scroll frame isn’t deep enough; another 6 inches or so, and I could use the biggest parts from the Martha Stewart loom to create a much longer frame for the koma to slide in, and use longer pieces for the koma, allowing me to increase the number of strands and even out the spacing between them.
  • the sword stand is too close to the scroll holder. On the plus side, it’s close enough that I can use the takeup bar to hold the chopstick in place while I pass bobbins through, which makes it feel more like using the real thing.
  • only one set of koma on each side, so it’s limited to single-layer braids. Not that I’ll be ready to try double-layer braids any time soon…

If version 6 holds up well, I won’t make any significant changes to it [okay, there will be at least one more version; the sandpaper isn’t quite enough to keep the weight of 25 bobbins from gradually unwinding the takeup bar]. Instead, I’ll focus my efforts on designing parts with OpenSCAD to be milled on a Shapeoko 3 in the Spring. I have two sets of plans, from Rodrick Owen (with errata) and Carol Franklin, and my experience with the Bakadai has already given me a few ideas that will simplify the milling.

The first thing I build will be a better-proportioned Chibi-Takadai and a set of smaller bobbins, with only the top sides milled to keep it simple. The bobbins will have to be done in two parts and glued together (with washers for weighting), and the koma will have to sit at an angle rather than running in a track; that works well on the Bakadai, and will be even better with purpose-built parts.

[Update: for version 7 I replaced the takeup bar with a 1-inch dowel, the largest size that just fit inside the rubber hooks of the bungee cord. The tension is perfect, and it didn’t unwind at all when I made another Tsunegumi braid. The only remaining modification I need to do is put longer leaders on my bobbins.]