Thursday, February 4, 2010

A Shoji Inspired Screen -- Out From Underfoot

It would seem like one quick hop from designing and cutting the kumiko (lattice) to final completion.  But as this is an insulated Shoji screen, there are a few more challenges which require some chess-like strategy.

In a traditional screen there would be a single lattice covered with rice paper attached by means of rice glue (or wallpaper paste or double sided tape.)  My project is sort of a sandwich -- two kumiko lattices surrounding a 1/2" piece of rigid insulation that is covered in rice paper.  I start by using my story stick to transfer the half-lap marks to the rails and stiles.  This ensures that the kumiko will run in straight lines.  I considered marking right from the assembled lattice work itself, but it is cumbersome and way too flexible to give a true reference.

After marking, I ganged the rails and stiles together and drew out the mortices.  They are 1/4" by 1/2" and sit 1/4" from the outside of the frame.  This leaves a 1/2" space for a groove that will hold the insulation.  For whatever reason it seemed easier to drill the mortices, then cut the groove, and finally chisel the mortices to final dimension.  Cutting the groove was a machine job (as I don't have the right plane) and it was just a case of running it over the dado blade in the tablesaw, both ways, to ensure that it was centered.  After that, the handwork was a piece of cake.

The trickiest bit was trimming the tenons to proper dimension.  On paper I have left 1/2" on each end to be tenoned into the frame.  I've learned (through bitter experience) that as a project gets bigger, the chance for measuring error increases.  So to give myself the greatest chance at success I developed a system.

1.  Leave some excess on one end when cutting the kumiko piece to length.  Mark the end with the correct dimension with the 1/2" tenon.  Trim accordingly and fit into place.

2.  Mark the actual intersection with the frame on the long end of the kumiko and dimension the tenon.  Insert in place -- it should be a custom fit.

3.  If you are confident about the squareness of the frame, complete the rest of those in that direction using this piece as a story stick.  If not, repeat for all those on that row using the same process.

4.  Now set these in place and (because this is a half weave) thread the first perpendicular piece in place.   Give it a wiggle and make sure it is square.  Now mark both ends where it intersects with the frame and dimension.  Again, you can use this as a story stick for the rest, or do each one individually.

If you remember, I did one set of kumiko in an alternate stick weave and one in a flat weave.  The former is stronger, but more complicated, and is best installed before you glue up the frame.  It is, shall we say, the bottom slice of bread in the sandwich.  For ease of installation I opened the frame by about 1", placed the alternate weave kumiko nearly in place, and drank a cup of coffee.

The next step is to glue up the frame and capture this first alternate weave kumiko in place.  As you can see, the glue only reaches the first 1" or so of the tenon.  This is fine (and I think, better) because we will be wedging the end of this big through tenon.  Once glued, I created this awkward little rig to hold it in place.

In the final post of this project,  I'll outline the process of affixing the rice paper to the kumiko, wetting it to (hopefully) tighten it on the frame, and the installation of the door on its tracks.  While I wait for the proper hardware to arrive,  I'll take a look at the progress of the Telecaster and maybe even make a tool or two.

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