Tuesday, July 28, 2009

First Light XXI

In the previous post, I had detailed the fabrication of the dovetail sliding keys to help affix the lower ceiling boards to the wall plate, or keta, of the lantern housing. I try and restrain the number of pictures per post to a maximum of 15 or so, in the interest of keeping the download times for those with slower internet connections to a reasonable time frame. So last time I had to finish just short of showing the attachment of the lower roof boards to plate; therefore, without further ado, here's how that went:

The fit was quite snug, and I needed to use a mallet to help tap - not pound - each board into place:

They went in quite nicely I thought:

From underneath, here's a look at a keta nose-to-roof board intersection:

That should look a bit better when I get around to cleaning up the end grain cut of the nose, however I'm happy with it fit-wise.

And just to refresh the reader memory, and for those who just stumbled upon this page and are wondering what the heck I am making, here's a shot of the lantern housing with the pair of lower roof boards fitted up:

It's a pity I couldn't have come up with a mechanism of some sort to get the lower roof boards to flap like cuckoo wings, as the top of the lantern does look at this stage somewhat ready to fly off somewhere. Yes, I speak in jest.

I was surprised actually at how rigid the connection was between the plate and lower roof boards using just a pair of keys each side. It wasn't as if I could do chin-ups off the board edge or whallop it with a 2olb. sledgehammer, but it is quite a strong connection nonetheless and in concert with the other means I will employ to put the roof parts together should result in a solid construction. We'll see, I guess.

I could have moved on to a number of other tasks at that point, and I chose to proceed with working upon the gable end boards. In traditional Japanese construction, there is a fair amount of careful detailing an elaboration when it comes to finishing off the edge of a gable (or, kiru-zuma) roof. There is a barge board which forms a vertical fascia at the edge of the gable - called a hafū-ita (破風板). Then, along the top edge of the hafū-ita runs a horizontally-oriented cap board termed a nobori-yodo (登り淀). More elaborate roofs might have two or even three nobori-yodo, each offset from the one below. In this lantern housing I am employing a certain simplification and exaggeration of the respective roof components to achieve a traditional look. This is what the Japanese do as well, from what I have observed in studying these lanterns. The nobori-yodo in this lantern roof is relatively chunky compared to one in a full-size building, and thus suggests not just the board itself but the ridge of tiles that runs down the slope at the gable verge (or close to the verge, I should say, as the edge of the gable is also normally rolled over as well, a treatment called the minoko). I also have decided, for simplicity's sake, believe it or not, to make the nobori-yodo and hafū-ita out of one piece of wood instead of two. I make this decision partly out of practicality/efficiency, and partly as a result of my decision from the outset of this build to eschew the use of metal fasteners or glue, if at all possible, in the construction. Making the gable end boards one piece allow me to make a better connection that will prove stronger, or at least that is how I am planning it!

So, the first step in making the hafū, as I shall term this amalgamation of the two components into one, is to make a full size template. I will use this template not only to mark out the cut sections from board blanks, but to use as a guide for my router, with which I will do much of the curvilinear cut-out and shaping.

After the layout was done on a piece of 0.5" MDF, I used a jigsaw to cut the template to rough form:

Then I clamped the template to the sawhorse, my 'work bench', and used a spokeshave to shape the rough cut curves smoothly, fair and to the line:

Once I had the template cut to shape, I stuck another piece of MDF to it using double-sided carpet tape and used a bearing-guided pattern bit in my router table to create a duplicate directly:

After cut out, I transferred layout lines from the original template to its doppelganger.

Then I took the template sandwich and used it to mark out the finished shape on the four pieces of wood which would become the hafū. These pieces of course had already gone through the usual round of sawing, planing and jointing to get them to the dimension I wanted:

Most ideally I would have used wood that was both edge-grain on the face and curvilinear (from a curved tree) however that option was not readily available, as they say, so I had to 'settle' for rift grain pieces that have a slight amount of curve in their lines, hopefully not so much that the grain lines will 'fight' the line of the pieces, and certainly there will be no issue with short grain in this case at least.

Next I ran the pieces through my deluxe Italian Agazzani band saw - whoops! Wait a minute! I don't have a band saw, at least not on this end of the continent. Oh well. Out came the jigsaw again and I trimmed the boards to their layout, leaving the cuts about 2~3mm wide of the lines:

After rough cut-out the piece was starting to look like something, perhaps a blank for a field hockey stick:

And then there were four hafū, all ready for the chopping and hacking to come:

The next step was to use the double-sided carpet tape, a godsend for the woodworker if there ever was one, and attach each piece of hafū in turn to the template sandwich, which I then took to my router table and trimmed the boards to the template. For this I used a combination of three bits, a template bit with a 1/16" (0.0625") offset between bearing and cutter diameter, for the initial rough pass; then either a top-bearing mounted Whiteside bit, solid spiral carbide, or a bottom-bearing mounted flush cutting template bit. I had to alternate between cutters, sometimes cutting with the board on top, sometimes with the template on top, due to my desire to cut with the grain, not against it. The use of the additional offset bit as the initial step eased the work for the other two cutters which followed and meant that I was always using the router cutters as they should be: to trim, not to hog waste. Here's the piece after the trimming is complete, still stuck to the template sandwich:

A little while later, I had my stack of 4 boards all trimmed to shape:

The next stage (which I completed before I separated each board from the template) was to transfer layout lines from the template to each piece at their edges, and then connect the lines across the faces:

Next installment in this series (post 22) should see the hafū through to completion. I hope you'll enjoin with me then, enjoyin' the joining.

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