Sunday, June 14, 2009

First Light

I've long wanted to make a wooden lantern - I'm not talking about andon, the small paper-screened portable lamps that might be placed on the floor of a room, but the type that stand as high as a person and are part of the built environment. The type of lantern I refer to is often seen in the vicinity of a Shintō Shrine, and stands atop a post. Here's what I mean:

The above two are relatively simple ones, and I personally don't care much for the pattern of the kumiko. I've now looked at more than 80 examples of this type of lantern, and they range from fairly simple, crude even, to highly elaborate and refined. Though strictly speaking not a single post type, here's an 'over the top' example just to illustrate what I mean:

After looking at some many examples, and doing some research, I learned that these type of single-post mounted lanterns, though common at shrines, are not strictly speaking a piece of religious paraphernalia. In the Edo period, these lanterns also associated to the red light districts, and today they can also be seen in parks and even in front of restaurants. Thus, I don't feel that it is inappropriate to 'borrow' the form and make a lantern for a different context. I think these lanterns look awesome and would grace many different settings.

There's a Japanese proverb, chōja no mandō, hinja no ittō - 'Better one lantern from a poor man than 10,000 lanterns from a wealthy man'. Lanterns are often made as votive offerings at shrines, whether of bronze, stone, or wood. The meaning of this proverb is that the poor man's offering is appreciated more because of the donor's sincerity and sacrifice. In my case, in this economy, I'm a pretty poor man right now myself, so I hope my offering in showing the making of a lantern will be found worthwhile by the reader.

These lanterns can get quite complicated. I've undertaken a design which I feel would be best classified as moderately complex. The roof, for instance, will not have individual rafters, or two-tier rafters, but will use a pair of offset planks on each side. It will be a gable roof, not a hipped gable. While I would like to do a copper-shingled roof, that will wait until the next lantern (I plan to make more of them, each one different). To support the lamp housing atop the post, there are numerous possible ways of doing it, and after some thought I am intending to use a single layer of pillow blocks. I am still finalizing designs in that area, so that might change slightly.

The drawing work has taken a fair number of hours, and here is what I have so far:

Of course, to get the entire lantern into the field of view, I had to move the 'camera' far away, so the details aren't terribly clear at this point in terms of what you can see. A little mystery is good, I suppose, so I can bring out the various finer points of the construction as I proceed with this thread. At this stage, the shōji panels are omitted from the drawing, though I have completed their design on my MacDraft software.

The first issue that immediately came to mind concerns the post. Now, it's 'just' a post fer gawd's sake, how complicated does that need to be? Well, it would be a simple matter if there were no electrical wiring involved - but I plan to use wiring, and thus the predicament soon becomes apparent: there's no good way to drill a small (0.5" or less) wiring chase through a 4'~5' long post and have confidence that the hole will go through straight or meet in the middle. Additionally, I will be scribing the post to a rock and bolting the post through the rock to a concrete foundation, so I need to be able to give space for both the wire and the threaded rod at the base of the post and in the area of the post where they both run. Additionally, the wire should ideally emerge though the top of the post in a centered position due to the various support arms that converge at the top of the post.

What do the Japanese do to handle this situation? Well, from what I have seen, they either run the wire, in bx cable housing, up the outside of the post (ugly!) or they make the post out of concrete, so that casting a hole within the post is a fairly simple matter -- 'no thanks' to that option. There's my break with 'tradition' right there.

Of course, I considered the possibility of slotting a groove in the post, putting the wire in, and then gluing a strip on to cover it. There are two problems with this approach, in my view:

1) It depends upon glue, and for an outside structure, I don't find glue to be reliable, not over the long term
2) the groove must be very deep to get the wire centered, thus weakening the post

I could also cut the post in half, machine a groove up the middle, and then glue the pieces back together. Again, two problems:

1) it depends on glue, and for a key structural part
2) the centered wire gets in the way of the threaded rod

I decided pretty much at the get-go, actually, that I wouldn't be using any glue on this project, if I could help it, and that my use of metal fasteners would be ideally confined to just the connection between post, stone and foundation. That's the bar I've set for myself, and designing an all-joined solution has proven challenging, but not insolvable.

Another problem relating to the post, given that I wanted a section size of 4.5"~5", was the availability of such material on the East Coast. Back when I was living on Vancouver Island on the West Coast, obtaining a FOHC (Free of Heart Center) piece of Fir or Yellow Cedar in that size would have been simple enough, and I could also obtain the Fir radio-frequency dried, or the Yellow Cedar from standing dead trees, so the material wouldn't have been much of a problem to source. Most times, given the choice, I would make the entire lantern out of Yellow Cedar.

Here on the East Coast, things are different, as trees are smaller and obtaining FOHC pieces not so easy. and then there is the problem with getting dried wood in those sizes. Typically, what I might be able to find would be a boxed heart timber that was green - and if it was of Atlantic or Northern White Cedar, I could expect a knot or three as well. I also considered Black Locust, which was ideal in some respects, but not in others.

The post was looking like a most difficult proposition. My budget for materials was also limited and I preferred to obtain material from a local supplier if possible. Squeezing all those problems into my mind for a few days, and out of the oven, so to speak, popped an idea a few days later: I would make the post out of 4 interlocked sections of 12/4 material. The 12/4 size can be obtained dry, and in a number of different species, and I realized that by making the post in 4 sections, I could:

a) join the sections together using hiki dokko (floating double dovetail keys)
b) make space in the middle of the 4 sections for the electrical, and,
c) switch from a central threaded rod hold-down to a pair of diagonally-opposed hold downs in a smaller size of rod.
d) get a stable post from the union of 4 rift sawn pieces
e) get good grain match among the pieces

I realized that one issue might be that the join between the sections of the post could wick rain water inside. I solved that by adding a tongue and groove joint to each connection. Any water that wicked in would swell the tongue and seal it tight.

Next came the hunt for wood. I considered lots of possibilities, and in the end, after some 3 weeks of looking, obtained some Honduran Mahogany from the door and window woodshop (it's too small to call a factory) just down the road. This is a place that specializes in Mahogany doors and windows, primarily for the restoration market, and they've been very helpful to me on a number of occasions. They sold me the pattern grade 12/4 at $10.67/board foot, which was reasonable I thought. All their material is FSC certified. Honduran Mahogany is both extremely stable and extremely rot resistant, two qualities which were top of the list from a design perspective.

Are Japanese lanterns made from Honduran Mahogany? No. Am I in Japan with access to choice materials (and budget!) from which to make the lantern? No. Is the Mahogany a logical choice from a performance and durability standpoint? Yes. Is it a wise use of the material? I certainly think so! I'm making this lantern to last, and will take no short cuts in its construction.

The Mahogany will weather to a dark brown, and I have in fact come across lanterns which are painted dark brown, so I really have no 'authenticity' qualms here folks. I'm drawing design inspiration for many examples, and adapting as best I can to local realities and adding my own ideas and problem-solving approach as to how to make something like this as best I can. There are no measured plans to follow, or 'thou shalt nots' to observe. It's a prototype, lantern numbah 1.

After I plonked down my money, the 12/4 cant was ripped to size, then the pieces jointed and planed. I was left with a 3' slab, 10" wide from which I thought I could get most of the rest of the lantern parts. Also, the window and door people down the road also let me pick through their scrap pile and I hope to obtain any other materials I might need from that source - save for the glass and electrical parts of course.

Here's a picture of the four pieces and some preliminary scribbles:

I spent a while flipping the pieces around to get the best combination of grain direction and visual harmony I could. Generally each face is showing edge grain, as each piece is sawn on the rift, and that makes for good match-ups.

Some work with my router to process the t&g, then a bit of hacking and wrangling later with my corner-cutting plane,

...and I had the post sections together like old friends:

You can see in this photo how completely interchangeable the pieces are - If I'm not paying attention, I can easily have a couple of them switched I did this a few times before my brain, er, started working (and I mean that in the loosest possible terms).The matchmarks are important.

Just to get a visual, I popped the post onto a candidate stone (I had also spent more than a few hours scrounging local riverbeds for the right sort of pedestal stone):

I decided against the stone you can see in this picture, judging it to be a little too small, and have since located one about 50% wider.

Once the overall configuration was looking okay, I set about cutting out the parts of the the hiki dokko joint. in total there are 12 floating dovetail keys, in a staggered arrangement inside the post.

Next, I reassembled, trimmed the end clean and square, and then I chamfered the top of the post with my handy-dandy 45˚ chamfer plane:

As a security against any potential for the post sections to shear in relation to one another due to side loading (ie., wind, someone bumping into the lantern), I mortised crosswise in both directions at a certain place on the post to accommodate some diagonally opposed locking wedges I plan to fit later:

The wedge mortises are 0.5" x 0.625", so I was able to use my portable hollow chisel mortiser to get most of it done. The rest is chisel work.

Well, that's a good portion of the work completed now on the post. In the next installment I'll start in on the support arms for the top, where the joinery starts getting funky.

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