Saturday, July 25, 2009

First Light XIX

Onward and upward with the lantern build-up, literally. New visitors and those returning after an extended period may wish to look at previous installments in this series - please take a look to the archives sidebar (scroll down to the right of this page), where you'll find them listed.

Today's post details work on the lower tier of roof boards. There are a pair of boards on each side of the gable; the lower of each pair of boards is set at a slacker pitch than the upper. This is in rough simulation of boards atop a temple roof, with the steeper inner roof to house a tall image of Buddha within the moya (the inner sanctum), and the slacker pitched lower roof enclosing a wrap around area for people to circulate, the hisashi. In the case of a temple, the fold in the roof formed by the intersection of the slack and steep pitches, when coated with clay, was faired out to produce the curvilinear profile many come to associate to Chinese/Japanese temple roofs. For more reading on the topic of roof development, I strongly suggest a look at Mary Parent's book The Roof in Japanese Buddhist Architecture (linked to in the Reading List sidebar at the right of this page).

Of course, in this lantern there will not be a bed of clay and ceramic tiling going on the roof. It's just a pair of boards each side with a pronounced fold - well, there are a few more bits to it than that, just wait and see. This lantern has, in short, a simplified roof. The next step in complexity would be to make the lantern roof using rafters and purlins, shingles, the double roof system, etc, as in a full size building roof. Like I said at the outset of this thread, the lantern I am building as a prototype is but of moderate complexity in the scale of these things, and simplifying the roof was one of the choices I made (even though the roof is my favorite aspect of Japanese architecture -go figure!).

The keta (the beams which lie atop the lantern housing posts) form the inner support for the lower roof boards, largely through the sloped rebate I processed on the long side pieces, and in tandem with the sloped projections of the short side keta pieces. When I initially cut the sloped noses on the short side keta, I did so roughly and left them with a surplus of material on top, as I had a plan for how I would go about cutting them more precisely. The reason for this precision will become apparent soon enough when you see what I do with them.

I disassembled the keta frame, and in doing so also removed the ceiling board, which as I mentioned in the previous installment was hanging up on of the keta lap joints. So, first order of business, before I forgot, was to adjust the board tongues a little bit, using a western metal-bodied shoulder plane:


Okay, now with the ceiling board re-fitted and all looking good, I could deal with the keta frame and prepare it to receive the lower roof boards. First I made up a cutting jig with some 0.5" MDF (Medium Density Fiberboard):


The above jig may look rudimentary, but it is made quite precisely and indexes to position on its supports- for a reason. This jig is designed for use with my router of course, and will produce repeatable and reliable results - the workmanship of certainty the David Pye talks about.

The first step was to chuck a straight bit into the collet, set it to depth, and then mill the top surfaces of the keta sloped noses to the same level all around:


The nose cuts I processed with the router slightly overlapped onto the long side sloped rebates, which gave me a gauging mark with which to address some final plane passes on the long side keta slopes to bring them down straight, flat, and in plane with the noses:


The result:


Then I needed to get the roofing boards in order. I was short one piece, so I needed to spend another $25 on a piece of Pattern Grade FSC Mahongany at the nearby hardwood supplier. I then ripped it to rough size with a handsaw. Next, as usual, it came time to get that piece cleaned up and flat. The rough-sawn side (from the original milling) was decidedly wavy, so I had a fair bit of planing to do to get the hollows out:


A while later:


While it is satisfying and enjoyable to be able to do these basic woodworking operations with a hand plane and saw, I really would prefer to have a nice 20" long bed jointer and power planer(!) Mmm, dreamy....

This rough dimensioning took a toll on my 70 mm plane, so it was of course time to resharpen:


Then a few more passes to get the board within one round of finish planing to completion:


Not the best picture - my camera is acting up with the focusing mode and I couldn't quite get the right flat angle view I wanted. I've had to toss out a bunch of pictures lately as a result of blurry images. Hopefully I'll be able to muddle along though the rest of this project on the photography side.

In the next step, I rough cut the slopes on the board's inner-side edges, so they will fit to their respective long-side keta rebates cleanly:


Then I clamped the two pieces together on top of my sawhorse and with a wider support thus created for the plane, refined the edge a bit with the 54mm:


Once the edges were cleaned up, I checked them against the long side rebates to which they fit, and made any necessary adjustments, usually to the rebate's vertical wall, to achieve an acceptable fit:


And here's the other side's fit of roof board to long side keta:


Obviously, the lower boards aren't going to stay put without some means of attachment to the frame structure (not to mention the upper roof boards), and I'll detail the first piece of that joinery equation in the next posting. All for now.

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