Monday, June 29, 2009

First Light XI

The previous 10 parts of this series may be found archived to the right side of this page - those readers who are new to this blog may wish to back track in this thread a little before proceeding.

After completing work on the post cap, which also serves as a support for the upper tier of beams, I commenced the work on the dodai, or sill pieces for the lantern housing. These are to be partially housed in the upper tier of beams, which is a more stable and interlocked arrangement in general. The dodai themselves are joined with the same half-laps with mitered abutments I have been using elsewhere in this project. Here are the 4 sill pieces after most of the joinery cut out has been concluded:

You might note the presence of some little diagonal mortises in the piece on the left of the picture - these are involved with the lantern housing posts.

I checked the fit of the dodai pieces as I fittend them to one another:

Here's a close up of one of the corners of the sill:

Next it was time to begin fitting the sill to the support beams, which required they be fitted both one by one, and checked simultanueously for fit. I've pulled one piece out to fit:

Here I'm checking them simultaneously:

Also note in the above picture (and in some of the ones to follow) that the mortises for the lantern housing posts, which I elected to orient diagonally, have been processed at the dodai joint intersections.

After much fiddling, the first piece of sill was fitted. Here it is about 1/32" short of fully down in the housings:

Then two sill pieces were in place and it was time to lap the third piece, where it fits both on top of the first two and in among the supporting beams:

This shot gives a good view of the number of simultaneous engagements that the dodai must engage with, both with other sills and in the tier of support beams:

Finally it's down to the last piece of sill, here being slid down into position, then scribed to the housings, then removed, adjusted, and refit (and repeat as necessary!):

The dodai ring is now in place and ready for the next layer (well, almost!):

A view from the top:

And a close up of one of the intersections:

The nose atop of the diagonal support beam has been planed to a slope so as to shed and water that lands on it. Fitting the housing of the dodai to the sloped abutment takes a little extra time. The end grain of the sill pieces has yet to be finish planed.

The next installment in this thread will deal with the fitting of the lantern housing posts, which are splayed in two directions and thus involve the same sort of cross-section modification and compound geometry as we see in Japanese splayed sawhorses. See you next time at post 12.

1 comment:

  1. G'Day Chris,
    I am thoroughly enjoying this lamp build, probably the most of all your posts so far...

    I noted earlier your use of the half laps with mitred abutments and I had thought that they must be undesirable in one aspect in that they reduce the cross section of the joining members and therefore decrease overall strength. They look nice though and I was pondering the main reason for their use. Are they mainly used here so that finish planing will not create gaps in the joint like it would with normal half laps; is there some mechanical advantage such as resisting twisting in the plane of the joining pieces or is it largely aesthetic?


    Derek Cox


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