Futae Kaku-Tsunagi Pattern

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Finally I have a chance to put the new hikouki kanna I made to work with a little kumiko pattern exercise from Desmond King’s first book “Shoji and Kumiko Design”.  Futae Kaku-Tsunagi roughly translates to double right angle connection and is a great trial of accurate kumiko lap cut joinery, as well as careful fitting of mitered corners.

I cut a slew of 1/4″ thick kumiko from redwood, which takes a beautiful polish from the kanna. Any pattern starts with a plan, and for this one it can be layed out on a single story stick. As complicated as this pattern looks, it involves only two separate groups of kumiko.

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My workspace. The concrete gets pretty hard to sit on by the end of the day, but its worth it to not have my back feel like hell from spending so much time hunched over a bench.

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The POV for one of the fundamental tategu sawing positions, kneeling in front of low saw-horses. If your dozuki technique is not good you’ll bind in the cut and have a hard time holding the kumiko steady on the horses.

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Transferring marks from the story stick to each group of kumiko to be cut. The pencil line tells me which side of the line to cut on and mark for the other side of the lap cut that allows these pieces to fit together.

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Nakaya Eaks 210mm kumiko saw really leaves an amazingly thin kerf. I’ve cut kumiko joinery with a larger dozuki saw, but the Nakaya really has me spoiled. The problem is that the slightest slipup tends to kink the blade, and they have to be ordered from Japan. Time to stock up!

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With both groups of kumiko cut the assembly fun can begin!

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The jigumi gets glued together, hopefully with the right kumiko in the right place, with its proper up/down or left/right orientation. Somehow I always manage to turn one around and am left hoping that my layout was stellar enough that everything is perfectly symmetrical. In traditional shoji screens the kumiko are often sort of woven together, its not a true weave, but the notches tend to alternate top to bottom. With a jigumi like this where notches are all on one side of a given piece of kumiko you end up with a warped screen if your lap cut notches are too tight.

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All of the mitered end pieces are cut from the same stock of kumiko made previously, just with certain sections cut away. It wastes some lumber, but saves a tremendous amount of time from allowing you to cut the lap cuts as a group.  Pretty cool, it took me a long time of staring at this pattern to see that the whole thing is based on only two groups of kumiko.

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In order for the mitered corners come together tightly every piece is individually marked and trimmed so that it is slightly proud of its theoretical proper length.

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The horizontal pieces were cut for the top half first, and then verticals added. Because I was only installing a small piece from each kumiko at a time I had to keep things organized, and numbered each left to right.

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Finally you can see where this pattern thing is going, double right angle connection. It never ceases to amaze me how awesome some carefully cut bits of wood can look.

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Fitting kumiko is quite time consuming, and I stopped at the end of the day to go look at some logs of my neighbor. Its difficult to get an idea of scale, but the large ones in the group are just over 16″ diameter, pretty good size. But really long dead, super dry, and checked all to hell. As it turns out there’s quite a range in log quality when it comes to beetle kill lumber. I was recently trying to work out the value of a given log. I ran across a sawmill website:

http://www.sunrisesawmill.com/Log-Prices

Bascially, price payed by a saw mill is given per thousand board feet, determined by the cosmetic grading of the log and a calculation of volume using the diameter at the small end of the log and the Doyle scale.  The best I can tell a reasonable price per board foot would be something like $0.10. So a two foot diameter beetle kill log eight foot long, containing 200 BF of usable lumber by the Doyle scale is worth about $20 USD, haha. Try that with Black Walnut and the numbers come out much, much different. Of course, if you buy a peeled log from a sawmill of that diameter it will probably cost upwards of $15 dollars a linear foot! As it turns out, the price for blue stain pine at my local lumber dealer, at $2.82 per BF for flat sawn 4/4 is quite high, $1.50-1.75 is much more average across Colorado from what I can find online.

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I continued on the pattern work the next day, today, but got an email from another neighbor about the trees I had previously marked, and a chance to get them in my truck!

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I think I marked three trees, this is just one of them, the bottom half actually, cut into three 8′ sections. Finally, a big log at 16″! How do I call this big? Yes, there’s bigger out there, but just try to move this sucker! It was a real struggle just to get it in the truck, and the bar on my chainsaw wasn’t long enough to buck straight across.

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Standing dead, so still a bit of checking, but really beautiful by beetle kill standards. Only 1/8 twist in this tree compared to the 1/4 twist of the last one, with also very little taper. So much lumber! Cut with a hand-saw! Ok, I’ll save my excitement for tomorrow when I have to actually saw them. But you can tell, yes, I’m going to make some beautiful slabs and quarter saw. I sealed the end grain cuts with some wood glue thinned down by half with water, trying to head off additional checking.

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And came back inside to finish up the kumiko pattern. I hope you’ve enjoyed the juxtaposition of my day between large/heavy and small/refined, I do seem to get around. Lets just hope I can do at least one of these things well!

5 thoughts on “Futae Kaku-Tsunagi Pattern”

    1. Thanks! You know, I was actually thinking of Nakashima. Its fascinating that he was actually the one to decide how much of that lumber you speak of was cut. For some reason sawyers are often not exactly fine craftsmen. What practicing kobiki about isn’t so much the mechanism of the saw as how to best cut the boards from the tree, something we can all learn from.

  1. We really need to do something about that mortice chisel. When you come here to teach I give you one of mines.

    And don’t be too modest, you are doing both great. Each one impressive in its own way.

  2. You need a Wood Floor Gabe! Trust Me! Oh, please, please, please, you deserve a wood floor!

    You wouldn’t make love to your lover on a concrete floor.

    Maybe once. Quickly. But probably not twice.

    1. Haha! You are so very correct, I need a wood floor. If I can get enough lumber sawn I’ll lay a small square section of wood floor down, maybe 8’x’8, just enough space to get it on, haha.

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