Cross Tenon Coat Rack

This project explores the possibilities presented by 3d printing to advance traditional joinery techniques beyond what is possible to do in wood alone.

Step 1: Design

Like other 3d-printed/mixed media projects I've done before, the design builds all the complexity into the 3d-printed pieces and lets the wood be as simple as possible. The challenge for this project was to get a tight fit at the joint while using only wood and the 3d-printed connector - no glues or fasteners of any kind. Consequently, the system had to be able to accommodate variations in the wood while also maintaining the predetermined geometry of the 3d print. Ultimately, I landed on the cross tenon shape as an evolution of the traditional wedged tenon joint. The cross tenon joint allowed for a customizable fit for each joint that turned out to be very sturdy, as it can expand in four directions rather than just two.

Step 2: Proof of Concept

I did a quick mock-up of the joint with a scrap of wood and 2 3d-printed pieces that fit perfectly inside each other.

Step 3: Making the Joints

To make the joints, I used two different colors of 3d-printed resin so that the geometry of the joint would stand out. My first attempt was a very minimal design, and turned out to be too wobbly when assembled with the wood. The second time around I doubled up on each joint and added cross members to stabilize the wood pieces.

Step 4: Making the Wood

I made the 3 wood pieces out of a single plan of white oak. The process was very straight forward as the final design for the wood was so simple. I planed and jointed the plank, ran it through the table saw to get the proper dimensions, and marked and drilled the holes for the 3d-printed joints. I set up a guide on the drill press to ensure that the holes were always centered on the wood.

Step 5: Assembly

My first assembly attempt was with the original, slim joints and the whole thing proved to be too wobbly for comfort. Once I re-printed the sturdier joints and drilled an additional set of holes in the wood, the whole thing came together like butter. Once the white joints were in the wood I hammered the clear crosses into the joints until they wouldn't go any further in and then sliced off whatever was remaining. I finished it all with a clear coat of poly.

Step 6: Piling It On

The coat rack turned out to be steady and sturdy enough to hold all sorts of things, not just coats! Sunglasses, bags, hats, and yoga mats!