Computer-Controlled Machining

This week's project went through several phases of development. At first, I want to fab a rocking chair, but that became too complicated very fast. Plus I was a little behind in the course. I made a .dae file in blender that turned out to be a massive headache to physical create. The original file was just one wavy strip of wood cut many times after which I would bind them all together to create a chair.. That didn't work at all. I would have needed 20+ sheets of lumber and that was out of the question.

So I approached the project from a different angle altogether. I asked the question: "can the chair be made with just One sheet of lumber?". Turns out it could be. I installed Qcad (a free and simple CAD program) and made a nice shape that was pleasing to the eye, then started adding slats for the seat. After I had the shapes and dimensions I desired, I moved them around on a 4'x8' rectangle (representing the sheet lumber) until all the pieces fit.

I used very cheap OSB board from Home Depot. The finished file only took 15 minutes to cut out on the Shopbot. I used a 1/2" end mill bit to cut with. I had to add fillets to all the corners where the slats were to slide into place. This was so the tool could cut the right size. This had no affect on the end product.

The chair assembled very easily and it held together nicely. There is a little wobbling in the chair but that's to be expected with a first try with no adhesives or nails/screws. The chair actually held my weight, although it did verbally complain a little. I don't think I'll be using it as a lawn chair any time soon. I also made it entirely to long. If the seat area were completely assembled, my legs would be stretched out straight in front of me. The back board is too short and narrow, therefore only fitting into one side of the chair or the other. I overlooked to width of this part. I am still proud of the chair and plan to fab a better one later.


The chair in dxf.


The chair design in Qcad.


I had to make the chair in installments because it took a little over 15 minutes for each side of the chair.


All the slats are not in place. I experimented with different plank placement. The best placement is in the previous image of the half built chair.