This past month I took apart some finely aged vinyl chairs to see how they were made and to soften my supper seating situation. The materials I found inside – wood, foam, cardboard, vinyl – were straightforward, yet revealed many clever design details that I want to share with you.
You can see that the seat of the chair is a flat plywood board with six holes. Extending from the tip of each leg is a dowel which pops into this hole and is expanded with a wedge, and then secured with screws. The seat back is held to the board in a similar manner. Stapled to it are two pieces of cardboard, onto which foam is spray mounted before the final fabric is stretched over the body. For ease of assembly the fabric of the seat top, welt cord, and boxing are actually the only pieces sewn together, everything else is pulled tight, stapled and hidden.
Intrigued by the shape of the legs, I created a digital model to determine how they could be machined from a square piece of wood. It appears that four legs together form a tapering cylinder, yet the top and bottom of each leg is cut in a way which angles it outward from the chair in two directions. Meanwhile the dowel maintains an angle perpendicular to the seat board. This keeps the seat board simple. The biggest mystery, which I have not solved, is that this dowel is not a separate piece, which means it is machined at the same time the legs are cut.
Below you can see some of the original cotton padding in the chair. I used a wedge to pull the back off and forced the legs out by hammering them through. This made sanding the dog teeth marks off easier! Matching buttons are made with a press and pulled tight through the cardboard.