Kumiko Simplified

Add geometric grace to your projects using basic jigs and almost no glue.

Learn more about Japanese handsaws. woodmagazine.com/ helpfulhandsaws

Even a tiny difference from the 3⁄8" spacing between the pin and kerf adds up as you build the panel. Making the panel first lets you build the box to fit it.

The art of kumiko, practiced in Japan for 1,400 years, decorates shoji screens and transom windows with its geometric grace, beauty, and quiet elegance. The seemingly delicate frames and intricate patterns appear difficult and fussy to make, but the techniques shown here make the process less challenging, ensuring success.

We’ll make a small cross-lap panel with the asa-no-ha (hemp leaf) pattern [Drawing 1], probably the most widely used in kumiko. This panel adorns the lid of the tea box shown on page 58.

What you’ll need

I used basswood for this panel, but eastern white pine or any other fairly soft, closegrain, light-colored wood works well. Avoid wood with coarse grain or bold patterns as this disrupts kumiko’s linear beauty. Cut one 3⁄8×5×6" blank for the short frame members, and two 3⁄8×5×15" blanks for the long frame members and the infill patterns.

Outfit your tablesaw with a thin-kerf, 40-tooth combination blade, a crosscut sled, and a pair of shop-made cross-lap joint jigs. You’ll also need a pair of shop-made guide blocks, a wide chisel, and a dozuki saw. Let’s start by making the cross-lap jigs.

Jigs mean consistent spacing

For the cross-lap jigs [Drawing 2], cut two 1⁄2×3" pieces of MDF as long as the width of your crosscut sled. Cut a 3⁄16"-deep saw kerf at the center of each piece. For Jig 1, which controls the spacing of the frame’s border members, simply glue the registration pin into the kerf. Screw the jig to your crosscutsled fence, positioning the pin 3⁄8" to the left of the blade.

Use the same blade for cutting the dadoes that you used to cut the kerfs in the jigs.

For Jig 2, retrieve the second piece of MDF and fit its kerf over the registration pin of Jig 1. Cut a second notch, place this notch on the pin, and repeat until you have three notches. Glue a registration pin into the first kerf you cut. This jig locates the interior square frames holding the asa-no-ha pattern.

A frame of interlocked dadoes

Using Jig 1, cut the first dado in one of the 15"-long blanks [Photo A] and in the 6"-long blank. Then, cut a second dado in each blank [Photo B]. Register Jig 2 on the registration pin of Jig 1 [Photo C] and cut the dadoes for the interior squares. Remove Jig 2 and use Jig 1 to cut the last dado across each blank.

After cutting all the dadoes, raise the blade, place the last-cut dado on the jig’s pin and trim each blank to length.

Next, rip the blanks into strips the same width as the dadoes. First, rip two strips from one of the dadoed boards and press a joint together. You should be able to do this with just finger pressure. Take the joint apart. Look at the strips to see if there is any compression at the joint. A small amount (barely visible to the eye) is acceptable, but a too-tight fit causes the frame to curl up as the notches spread open to accommodate the extra thickness of the mating part. Once you have the thickness dialed in, rip the blanks to create the notched strips for the frame [Photo D] and the unnotched strips for the asa-no-ha patterns. Then, assemble the frame, using glue only in the joints around the perimeter of the frame [Photo E].

Having two blocks with 671⁄2° bevels allows for two setups later when cutting different-width bevels.

Guide blocks for exact angles

A pair of guide blocks guides a chisel as you bevel the ends of the pattern pieces. One block has 45° and 671⁄2° guide surfaces, while the other one has 221⁄2° and 671⁄2° guide surfaces [Drawing 3]. Make these angles dead-on.

For each block, make a slotted stopblock that fits in its groove [Drawing 3]. You’ll secure each stopblock with a washer and roundhead screw so you can trim parts to identical length. The slot allows for making small adjustments as you do this.

Now, the pattern pieces

Each asa-no-ha consists of four squares in the frame [Drawing 4]. Each square contains one diagonal piece, four hinge pieces, and two locking pieces. Mark the length of each piece directly from the frame, and cut the pieces 1⁄8" longer to allow for beveling the ends.

Cut 45° bevels on one end of all the diagonal pieces [Photo F]. Adjust the block forward

slightly and bevel the opposite end of one diagonal. This test piece fits when it slides snugly into the frame without pushing it out of square [Photo G]. Once the test piece fits, bevel the remaining diagonals. The four diagonals for a single asa-no-ha form an X in the frame [Drawing 4].

The hinge pieces prove trickiest to make because at the end where the pieces meet, the bevels are not centered on the piece’s thickness [Drawing 5]. Using both 671⁄2° guide surfaces, set a stop on one to bevel across the piece’s full thickness, and the second to make a bevel that’s one-third the part’s thickness [Photo H].

Trim these pieces with the 221⁄2° guide, sneaking up on the final length until they fit into the frame without gaps [Photo I]. Note that the one-third bevels touch in the center, and the two-thirds bevels create a 90° birdsmouth opening into which one end of the locking piece fits. The locking piece is just a shorter version of the diagonal. Its fit is critical because it holds the entire pattern together [Photo J].

With the frame fully assembled, place it on your saw table and press all the pattern pieces down. Turn the panel over and sand it with a half sheet of 320-grit paper glued to a piece of plywood, moving the sandpaper in a circular motion.

Clamp the frame in your bench vise, and carefully saw and pare the ends of the frame pieces flush with the faces of the frame [Drawing 1]. Fit the panel into the lid of the tea box, use it on another project, or simply display it on its own.

15"-long frame blank Jig 1 Registration pin A Set the blade to cut slightly over halfway through the blank's thickness. Butt the end against the registration pin, and cut the first dado. Press firmly on the blank to ensure a uniform depth across the width. B Fit the dado on the pin, hold the board tight against the sled’s fence, and cut the second dado. Jig 2 Place this notch on the Jig 1 registration pin. C Secure Jig 2 to Jig 1, seating the indicated kerf on the registration pin. Seat the last-cut kerf in a blank on the Jig 2 pin, make a cut, and repeat, cutting six dadoes across the 15" blank, and two across the 6" blank.

Pushblock Frame strips D Rip the strips to match the dado width. Use a pushblock to hold the blank down and guide it through the blade. Glue only the outermost joints. No glue on inside joints E Glue the four outer strips together, then glue in the three remaining long strips. Finally, add the inner short strips. Always apply pressure directly over the joint and work back and forth across the panel until all of the joints seat fully.

45˚ bevel F Set the guide’s stopblock so that the end of the diagonal piece aligns with the end of the groove. Pare one side, flip the piece over and pare the second side. G Test the fit. Pressing the diagonal piece into the frame should require a bit of pressure but not a struggle. If needed, adjust the guide’s stop and recut one end of the diagonal. Check the fit and continue to adjust the stop until the piece slides into the frame without deforming it.

67½˚ bevel H Cut a bevel across the hinge piece’s thickness, using one 671⁄2º guide. Set your second 671⁄2º guide block to cut the second bevel. Two-thirds bevels One-third bevels Diagonal I The two hinge pieces fit correctly when they touch in the middle without gaps at the corners. Remedy a gap between them and the diagonal by shortening the hinge pieces. Locking piece J The locking piece should slide in without damaging any other parts, but be snug enough so that the pattern becomes stable and a unified whole.