Monday, August 10, 2009

First Light XXX

Well, I am kind of dreading what might happen now that the milestone of 30 posts in this particular thread has been reached. Not so much for the number of posts, but rather because 30 is 'XXX' in the Roman numbering system I started out with. Does this mean that my page will be deluged from visitors searching out, um, a different kind of 'XXX'?

That other kind of 'XXX' does account for more than half of all internet traffic, if I remember the statistic correctly. Well see what happens. for those that come looking for the other kind of 'XXX', please be advised that you'll find lots of wood, but might not have much luck getting a woody :^)

Last time I had completed more of the work on the gegyo - the hanging pendants which serve to protect the exposed end grain of the sub ridgepole on this lantern. These I attached to the ridgepole using a spandrel. The spandrel attached to the underside of the ridgepole with a sliding dovetail, and to the gegyo with a pair of sliding half-dovetails. Here's a look at the connection:


At this point, the spandrel was the same thickness as the sub-ridgepole, however I later used a plane to shave their sides down a bit more, about 0.035" (a bit more than 1/32") each side to give a bit of a reveal. I generally strive, at least in timber frame work, to avoid connecting pieces such that their surfaces are flush to one another, as differences in grain pattern between the pieces will express themselves with a size mismatch (one piece's surface will stand proud from the other) at certain times of the year.

Here's a view from the front:


At this stage, the gegyo is still sticking forward of its final position by 0.25", and needs to be fitted to the lower protrusion of the ridge. This had been carved to accept the hafū however the gegyo were a later design addition so I had to modify the lower end of the ridge some more. The upper edges of the hafū end up taking the place of the former protrusion when all is said and done.

Back to the custom MDF super-deluxo gegyo holder, where I chopped out a couple of small trapezoidal mortises:


You can see in the above picture that I have also transferred lines to the surfaces of the gegyo, lines which define the lower edge of the hafū - these in turn came directly from the original MDF template I made for patterns on the hafū in the first place. Not shown here is the work to reshape the projection on the ends of the sub-ridge into two small trapezoidal tenons.

The lines now marked, I cut the gegyo to rough length:


Considering the assembly as a whole, the gegyo attaches to the spandrel by sliding upward, then the spandrel/gegyo assembly slides inward along the end of the ridge. To prevent the assembly from simply being pulled back out again, the hafū will now slide on top and trap the gegyo in place using a rebate. I scribed out and started cutting the rebate on the gegyo with a chisel:


Somewhat later the piece was a bit closer to where it needed to be:


It was then a process of fitting up, scribing, and trimming to the line (and repeat if necessary):


Next step was to give a treatment to the lower outside edge of the hafū - this profile is designed primarily to decrease the apparent visual mass of the piece and, it must be said, to provide another point of decorative interest. For this project, a simple in-cut profile would suffice - for large temples and similar structures with enormous barge boards, the profile can however have a quite involved multi-tier appearance and require much detailed carving.

The Japanese refer to these hafū edge profiles as mayu '眉'. The kanji stems from a pictograph of an eye, '目', turned on its side and with a curvy eyebrow on top:


A curved eyebrow shading an eye is the literal idea expressed then, which gives rise to a modern meaning of eyebrow-shaped object.

I toyed with the idea of making a pair of special planes for doing the mayu, but later decided I could do it with a jig in my router table and some careful workmanship of uncertainty (meaning I had to use my hands to carefully control the piece, and couldn't rely upon the jig). I couldn't control the piece in the cut completely with a jig because it does not have a simple curve - rather a continuously-changing curve - and I don't have provision for mounting the router horizontally, which would have allowed for a template guide to be used.

This cut process was a bit nerve-wracking, as a moment of inattention could have resulted in a ruined piece, however all pieces came out well:


The mayu is not typically run all the way along the board to the end, as it would be visible at the end and would look a bit, uh, clumsy; normally it is terminated with a curved-stop. I worked this with a bit of chisel and gouge action:



The result:


Now with the gegyo mounted and the newly-profiled hafū reinstalled, things were looking a lot better at the end of the ridge, IMO:


More to come - next on the slate are the dovetail locking pins to fix the lower ends of the hafū to the roof boards. I hope you'll visit again. --> Go to post 31

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