CNC joinery and plywood combined
As CNC routers have found their way into small shops across the country, makers have been exploring how best to use their strengths to create beautiful and useful objects. While these machines can easily be used to cut solid wood parts to incorporate into traditional designs, they have also spawned a unique way of making entire pieces of furniture using plywood and slotted joinery. For this inaugural Digital Woodworking department offering, I designed a trio of three occasional tables that make use of this CNC-centric way of working. The three table heights work well beside a wide variety of chairs and sofas, and can also serve nicely as plant stands.
Make the parts from Baltic birch plywood, using 1" (25mm) for the legs and 1/2" (12mm) for the tops. One of the advantages of using this material is that you can simply rout and sand the edges to finish them rather than applying edgebanding. The uniform, void-free core looks good and finishes well. I added plastic laminate to the tops of my tables for carefree use, but you could just as easily finish the plywood to match the legs.
Order of work:
- Cut blanks
- Download CNC files
- Cut out parts
- Laminate tops
- Shape edges
- Sand, assemble, and finish
Construction notes
Download the CNC Cutting files to your computer and use them to generate tool paths for your router. As drawn, they use a 3/8" straight bit to make the cuts. Zero the bit in the center of the blanks, and cut the legs and then the top for the table(s) you want. There are two main things to be aware of: First, check the thickness of your material. These files worked well with the 1" sheet I purchased, which measured between .995 and 1.024" thick when I checked it. If necessary, you can tweak the horizontal scale of the file to change the width of the notches. Secondly, take note of the little overcuts at the corners of the notches. These “T-bone fillets” are a hallmark of CNC joinery. They allow the notches to nest together without your having to chisel the corners square. Once the legs are cut, bandsaw them free of the waste before shaping the edges with a 1/4" roundover bit in your router table. Avoid rounding the tops of the legs and the insides of the notches. Laminate the top as described below before rounding its edges. Then sand and finish all the wood surfaces, avoiding the notch faces. I stained the bases of the tall and short tables with General Finishes Mocha and Slate oil stains, respectively, then applied polyurethane to all three tables. To assemble, slide the pieces together with glue in between, then attach them to the underside of the top with four Figure 8 fasteners.
Laminate the top
For each table top, you’ll need two pieces of plastic laminate approximately 16" square. (Laminating both sides of the top prevents it from warping.) You may be able to buy cheap offcuts from a local cabinet shop. Bandsaw the pieces into circles about 1/2" larger than the tops. Spread a thin coat of contact cement on the underside of one of the laminate pieces and one side of the table top. Allow the cement to dry before bonding the pieces together. Before laminating the second side, round over the first side on your router table. Sand the edges to prepare for finishing.
