Monday, January 18, 2010

A Shoji Inspired Screen -- A Hybrid Approach

I have a little ritual that I go through with my local librarian.  When I bring a book to the desk, she looks down at the title, (Pigeons!, Lord Krishna's The Art of Indian Vegetarian Cooking, The Compleat Squash: A Passionate Growers Guide) and like Jeeves inspecting a particularly colorful pair of spats that Bertie Wooster has picked up at the Burlington Arcade, her lip quivers, her expression remains unchanged, and she slides it back at me.

"Three weeks."

Her reaction was the same to Shoji:  How to Design and Install Japanese Screens.  And while this book lands somewhere between being the definitive guide and being not too useful, it was what was available through my library system.  I suspect that it would be a good complement to books available by Toshio Odate.  Nonetheless, it was enough to get me started on the sliding, insulated door that I had in mind for my next project.  Unlike traditional shoji screens this door would not be translucent.  It is designed as a door to divide spaces in a basement -- isolating heated space from unheated space.  In the place of rice paper will be (rice paper covered?) 1/2" rigid insulation.  Also, I plan to suspend it on housed roller hardware, similar to a barn door.  The material is white oak, the method will be a hybrid of hand tool and machine techniques.

One of the main challenges, right out of the gate, is the sheer size of the components.  The rails and stiles are roughly 5'6" by 6'6" and I'm looking for the stock to finish around 6/4".  Using only machines to cut the mortices and tenons would present a challenge, and I realized that in some cases I don't quite have hand tools that are robust enough to tackle these big joints.  So I will improvise.

I started with rough 8/4" stock and employed a hybrid approach to the dimensioning.  A quick going-over with a #5 1/2 plane on the high ends of the faces of the stock, followed by several passes across the jointer prepared each piece for the thickness planer.  I brought the components to within 1/8" on one day, and three days later, after things had settled down, passed both sides through the planer to 6/4"  Because of the weight of each piece, it was important to support the stock on both ends as it entered and exited either machine.  The edges of the stock were planed by hand, then cut to width (rails: 3 7/8", stiles: 3 1/2") on the table saw and the rough edges planed again.  The sight and smell of a sharp card scraper on the faces of the white oak, to acheive the final finish, was a welcome respite to the noise of the machines.

For aesthetic reasons, and because I can get away with it in oak, I decided to make the mortices about 3/4" wide.  While slightly non-traditional, I have a system for cutting mortices that gives me good results on oversized work (since I do not have a 3/4" mortice chisel.)  Feel free to discard this if it doesn't work for you.

1.  Determine the length and center line for all mortices and mark them (go pretty deep with your marking knife on the outside dimensions to save yourself some anguish later.)

2.  Take the stile to the drill press and place a support level with the table.  As you see here, I use a two foot level to ensure that any hole will be straight.

3.  Using a 3/4" forstner bit, align the piece so that the tip of the bit enters the center line of the mortice.  The edge of the bit should just touch the outside dimension of the mortice.  On a slow speed begin drilling.  A forstner bit only works when it can expel chips effectively.  Once clogged it becomes just a spinning, overheated cudgel -- so on the first full holes withdraw the bit and clean it often.  Once you have drilled through halfway, slide the piece down to the other end of the mortice and repeat.  Now go back and drill out the middle bits.  As these holes will adjoin other holes, the chips will exit more easily and things will go faster.  Flip the piece and repeat, breaking through the mortice in the middle.  When you are done, it will look like this:

4.  Now take your gauge and check how far from the faces your hole begins on each side.  In a perfect world a 3/4" hole in 6/4" stock will leave you 3/8" on each side. So set your gauge to 3/8" and see if you can scribe a line along the edge of each set of holes -- chances are you will need to reduce this width a hair so that you can scribe a solid line on each side.  For the sake of consistency I like to check all mortices, find the setting that will work for all, and scribe this line on every mortice.  You now have a consistent size for every joint.

5.  By any means at your disposal, chisel out the mortice.  White oak is tough, but sometimes stringy.  Deep lines, scribed and followed by a chisel can stave off disaster.  As I true the walls I like to think that I'm biasing them a bit to the inside (undercutting) when I do that they come out close to square.  For the final cuts I like to angle the chisel to take a shear cut along the edge.  A good skew chisel would be great, if I had one.

Shoji making is an art with hundreds of years of tradition.  I hope that this approach is not being disrespectful to the craftsman who do it properly, but I'm pleased with results so far.  I will be doing some things to this joint to raise it above a simple M&T, but for now, this will be good and I will proceed to cutting the tenons.


  1. Looks good Chris,
    I too have always loved the look of Shoji and it's something I've been interested in doing. I'm interested to see how this unfolds for you!

  2. thanks for your sharing , I like your article